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UZ INTERN

Materialul prezentat n continuare reprezint traducerea capitolului XI intitulat

SWITCHES AND CROSSINGS(= aparate de cale) din lucrarea: MODERN RAILWAY TRACK (= Calea ferat modern)

- ediia 2-a 2001 - scris de Coenraad ESVELD

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Din partea traductorului:

1. Traducerea capitolului XI intitulat SWITCHES AND CROSSINGS(= aparate de cale) din lucrarea: MODERN RAILWAY TRACK (= Calea ferat modern)

- ediia 2-a 2001 - scris de Coenraad ESVELD, a fost efectuat de subsemnatul. 2. Originalul capitolului menionat mai sus este dat n anexa I. 3. La parcurgerea textului urmeaz a fi avute n vedere urmtoarele:

a. Prin culoarea maro i font redus(10 pt)- n paranteze - sunt trecute n limba englez cuvintele (sau grupurile de cuvinte) subliniate; de asemenea, n acelai fel sunt date semnificaiile diverselor abrevieri ntlnite n cuprinsul capitolului.

b) Prin culoarea maro i font normal (12 pt) sunt evideniate cuvintele sau grupurile de cuvinte adugate de subsemnatul la textul original pentru:

- a uura parcurgerea textului tradus, - pentru a scoate n eviden modificrile de text fa de

original. c) Prin font mai mare(14 pt) n albastru sunt scoase n eviden cuvintele sau afirmaiile deosebit de importante privind domeniul aparatelor de cale.

Prof. univ.dr. ing. C-tin RADU

iulie, 2014

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11 APARATE DE CALE 11.1 Schimbtorul simplu standardizat (=the standard turnout) Schimbtoarele simple(= turnouts) sunt utilizate spre a se realiza desprinderea

dintr-o linie dat a unei alte linii; uneori, din linia dat se desprind alte dou linii. Scopul traversrilor(=crossings) este de a permite intersectarea a dou linii la acelai nivel. n lipsa plcilor turnante (turntables) sau n lipsa transbordoarelor (traversers), schimbtoarele simple(=turnouts) sunt eseniale. dac un tren complet n timpul deplasrii i fr a fi descompus trebue s treac de pe o linie pe o alt linie.

Pe aparatele de cale (=switches and crossings) se poate circula n ambele sensuri. Dup cum se arat n figura 11.1, un schimbtor simplu (=single turnout) sau un schimbtor normal (normal single turnout) (normal turnout schimbtorul simplu avnd linia direct situat n aliniament) permite micarea n ambele sensuri

- pe linia situat n aliniament - numit linie direct (through track) - sau - pe linia care se desprinde - numit linie n abatere (divergent direction)

Sfritul schimbtorului simplu(=rear of turnout) ina coad situat pe direct(= through rail) Arip(= wing rail) Inim simpl(=crossing) Contrain(=check rail) in de legtur(=closure rail) Partea curb a inelor de legtur(=curved part of closure rail) Punct de intersecie(=punct geometric = intersection point) nceputul schimbtorului simplu( = front of turnout) Contraac( = stock rail) Ac( = switch blade) Vrful acului(=switch point) Semimacaz (= subansamblu ac-contraac = half set of switches)

Figure 11.1: Schimbtor simplu (= turnout) standardizat cu abatere la dreapta (= right-hand)

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Schimbtorul simplu ( = turnout) este alctuit din trei pri majore: - macaz (dou semimacaze = dou subansamble ac-contraac (=set of switches)); - inim de ncruciare obinuit(= common crossing); - ine de legtur(= closure rail).

Aceste pri vor fi discutate separat n continuare.

Figura 11.2: Imaginea schimbtorului simplu (=turnout)

cu abatere la dreapta (= right-hand) 11.1.1 Macazul(= set of switches)

(dou semimacaze = dou subansamble ac-contraac (=set of switches)) Macazele (switches) sunt alctuite din

- dou ace (=switch blades) i - dou contraace(=stock rails).

Acele(=switch blades) pot fi deplasate(=acionate) i astfel se impune pe care dintre liniile menionate anterior ( linia direct sau linia n abatere) s se poat efectua deplasarea materialului rulant. n figura 11.1, deplasarea materialului rulant este pe linia direct (=through rail).

Figura 11.3: Desenul cuprinznd seciuni transversale pentru ac(=switch blade) i pentru contraac(=stock rail)

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Figura 11.4: Ac (=switch blade) i contraac (=contraac)

n proiectele moderne, seaciunea transversal a acului(= switch blade) este o seciune asimetric care are nlimea mai mic dect nlimea profilului standard de in (=standard rail profile). Aceast seciune a acului are avantajul c este necesar o prelucrare foarte redus a tlpii acului(=base of the switch).

Ca urmare a tlpii asimetrice (=asymmetric base), momentul de inerie al acestui tip de ac(=switch blade) este mai mare dect momentul de inerie al acului (=switch blade) fabricat din in standardi-zat (=standard rail). nlimea mai mic a acului (=switch blade) permite s fie folosit sistemul elastic de prindere (=elastic fastening system) pe ambele pri ale contraacului (=stock rail); sistemul elastic de prindere (=elastic fastening system) pe ambele pri ale contraacului (=stock rail) este o necesitate n cazul schimbtoarelor simple moderne (=in modern turnouts). Figura 11.3 i figura 11.4 arat un exemplu.

Figure 11.5: Seciune transversal n cazul inei ac -T (switch blade = in ac)

Anumite ci ferate utilizeaz nc ace (=switch blades) fabricate din ine standardizate. Figura11.5 arat o seciune transversal printr-un astfel de schimbtor simplu (=turnout).

Schimbtorul simplu (=turnout) poate fi acionat cu diferite tipuri de dispozitive de acionare (point machines = dispozitive de acionare), de exemplu, electrice, hidraulice sau pneumatice. Sistemul de nzvorre (=locking system) poate fi

- fie n interiorul dispozitivului de acionare(=in the switch machine) (nzvorre interioar(=internal locking))

- fie n cale(=in the track) (nzvorre exterioar(=external locking)). La macazele (=in switches) pentru vitez medie (=medium speed) i , n special, la macazele(=in switches) pentru vitez ridicat (=high speed) sunt necesare mai multe locaii pentru nzvorre (=locking locations).

Cu ct unghiul schimbtorului simplu (=the angle of the switch) este mai redus, cu att acul (=switch blade) este mai lung. Acul (=blade) poate intra n contact cu roata

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la trecerea roii prin jghiabul dintre contraac (=stock rail) i ac (=blade). La un ac lung (=long blade), pentru a preveni deplasarea prea mare a acului la vrful lui, se aplic nzvorrea suplimentar (=extra locking).

Aceste nzvorri (=lockings) pot fie s fie acionate prin intermediul unor dispozitive de

acionare unice (=single point machines) amplasate la fiecare poziie de nzvorre (=locking location)

fie prin - intermediul unui dispozitiv de acionare (point machine) amplasat la vrful macazului (=toe-end of the switch) i

- a barelor de conexiune (= connecting rods) care conduc la alte poziii de nzvorre (= locking stations). Noile dezvoltri privitoare

la liniile de cale ferat de vitez ridicat sau la liniile de cale ferat de mare capacitate

ncorporreaz(integreaz) la un loc sistemele de nzvorre (= locking system), de acionare(=switching system), i de detectare(=detection system).

Figura 11.6 arat un nou sistem integrat de manevrare hidraulic i de nzvorre (= integrated hydraulic setting and locking system). Aici, sistemul de nzvorre (= Iocking system) este ncorporat n cilindrul hidraulic de acionare (=hydraulic setting cylinder); nu este necesar ungere (=lubrication) sau ntreinere (=maintenance). Un dispozitiv integrat de acionare i nzvorre (=integrated locking and switching machine) permite acelor (=blades) s se deplaseze succesiv; astfel, n acelai moment de timp, este necesar o putere mai mic (=less power). Acele(= blades) i contraacul(=stock rail) sunt nclzite cu ajutorul sistemelor

- cu gaz sau - electrice,

pentru protecie n cazul ngheului (=frost), zpezii (= snow) sau al apei de ploaie care se transform n ghia n contact cu pmntul(= freezing rain).

Figura 11.6: Macaz(=switch) cu sistem integrat de manevrare hidraulic i de nzvorre (= integrated hydraulic setting and

locking system)

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Figura 11.7 arat un dipozitiv electric de acionare a macazului (=electrical point machine) care necesit ntreinere redus (=low maintenance). ntreinerea preventiv (=preventive maintenance) este cerut numai odat la cinci ani. Fora de tragere (=tractive force) poate fi reglat ntre 2 i 10 kN. Unitatea de nzvorre (=locking unit) lucreaz ca un arc(= spring function), care, n poziie de nzvorre, provoac acului (= blade) o for de contact (=contact force) de 2,5 kN. Sensorii(=sensors) arat(=detecteaz) poziiile ocupate de ace ( = detect whether the blades are open or closed).

n cadrul sistemelor moderne de cale ferat (=modern railway systems), instalaiile sunt acionate de la un post de comand central(=central operating post).

Figura 11.7: Dipozitiv electric modern de acionare a macazului (= modern electrical point machine)

11.1.2 Inima simpl obinuit (common crossing = inim simpl obinuit); n funcie de ncrcarea datorat circulaiei(=traffic load), sunt folosite diferite

tipuri inimi de inimi simple( = crossings). Pentru - sarcini medii pe osie ( = medium axle loads) i - viteze pn la 200 km/h,

sunt folosite inimii simple rigide ( = rigid crossing). Pentru sarcini mai mari pe osie (= higher axle loads) i viteze mai mari (= higher speeds), trebuie s fie utilizate inimile simple cu pri mobile (=crossings with movable parts).

Inima simpl obinuit (= common crossing) i aripile(= wing rails) sunt astfel construite din punct de vedere geometric nct

- roata care trece peste inima simpl rmne susinut n permanen (=remains supported) i

- este garantat jghiabul pentru trecerea buzei bandajului (=wheel flange clearance).

n cazul inimii simple obinuite (= common crossing), firele de in care se intersecteaz formeaz un unghi ascuit(= acute angle).

n cazul inimii simple obisnuite (= common crossing), poriunea fr ghidare (= unguided part) conduce la o comportare agitat (=unquiet behaviour) a boghiului pe schimbtorul simplu(=switch) i provoac o ncrcare dinamic suplimentar (=extra dynamic load) asupra

- inimii simple obinuite (common crossing) i - asupra contrainei(=check rail).

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Pentru a se evita poriunile fr ghidare (=unguided parts) din cazul inimii simple obisnuite (=common crossing), trebuie s fie folosite vrfurile mobile (= movable points).

Exist mai multe tipuri constructive de inimi simple rigide (=rigid crossings): - O alctuire familiar (= familiar construction) este reprezentat de inima

simpl asamblat (= built-up common crossing) cu vrful inimii simple format din dou cupoane de in. Dac se utilizeaz oelul de calitate standard (=standard steel quality), inimile simple obinuite (= common crossings) sunt clite prin tratament termic (= heat treatment) pentru a rezista la fore de ciocnire ridicate(=high impact loads). De asemenea, se utilizeaz

- ine cu ciuperc clit (= head-hardened rails) sau - ine fabricate din oel austenitic manganos (=austenitic manganese steel).

Inima simpl asamblat(=built-up common crossing) se utilizeaz n cazul ncrcrilor de mivel sczut (=low end applications).

- n cazul sarcinilor mai mari (= higher loads), sunt utilizate inimile simple (=crossings) care

au vrful inimii (=crossing nose) fabricat ca un bloc din oel tratat termic (=heat treated steel) i care

sunt prinse cu buloane (=bolted) de aripi (=wing rails).

- O alternativ la aceast inim simpl asamblat (= built-up crossing) este o inima simpl (= crossing) cu

vrf al inimii simple (=crossing nose) fabricat din oel austenitic manganos turnat (Cast Austenitic Manganese Steel-AMS) i

aripi (=wing rails) prinse cu buloane (=bolted). O dezvoltare austriac(=Austrian development) permite sudura ntre

oelul austenitic manganos (AMS) i oelul inei (= rail steel) prin folosirea unui piese intermediare din oel special. Aceast folosire a peselor intermediare din oel special (=this welding technique) elimin conectrile din trecut cu buloane i cu folosirea ecliselor (=bolted and fish-plated).

- Dac ncrcarea din circulaie este mare(=traffic load is heavy), se acord prioritate inimii simple monobloc din oel austenitic manganos ( = monobloc AMS crossing) cu 4 cupoane de ine sudate (= with welded on legs on all four ends). Aceast inim simpl( = crossing)

este foarte rezistent la uzur(=wear) i poate fi ncorporat n calea fr joante (=in CWR track)

prin executarea de suduri. nainte de montare (= installation), aceste inimi simple(= crossings) pot fi

tratate folosind ecruisarea prin explozie (=prehardened by explosive hardening) care micoreaz

uzura iniial (=initial wear) i,de asemenea, n mod considerabil, nevoia (=need) de ntreinere

(=maintenance).

Figura11.8 arat inima simpl monobloc din oel austenitic manganos (= cast monobloc AMS crossing) cu ine cozi sudate (=with welded on legs)

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Figura 11.8: Inima simpl obinuit turnat din oel manganos (= cast manganese frog)

Pentru sarcini pe osie mai mari (= higher axle loads) i pentru viteze mai mari de 200 km/h sunt folosite inimile simple cu pri mobile (= crossings with movable parts). La aceste inimi simple (= crossings),

dispare golul (= gap) dintre arip (= wing rail) i vrful inimii simple (= point) i

fora de ciocnire (= impact load) este micorat. Exist trei tipuri principale de inimi simple cu pri mobile (= crossings with

movable parts):

- vrf articulat al inimii simple (= Swing Nose Crossing = SNC). Vrfull inimii simple(= nose crossing) se poate roti n plan(=swing); acest vrf al inimii simple(=nose) este realizat dintr-un bloc prelucrat i tratat termic (= machined and heat treated block). Inimile simple (crossings) mai mici de acest tip au - la clciul lor- o joant de dilataie (=expansion joint) pentru a compensa diferena de lungime de la trecerea vrfului inimii simple(=nose) de la o poziie la alta.

- Inima simpl cu vrf mobil (= Movable Point Frog = MPF) cu vrf (= nose) realizat din ine, cu un vrf principal mai lung (= main point) i un vrf mai scurt (=counter point) (=with a nose made out of rails as main and counter point). Compensarea de lungime se realizeaz ntre cele dou vrfuri(= between the two points); nu este necesar o joant de dilatare (=expansion joint). Figura 11.9 arat o inima simpl (= crossing) 1:38, montat pe linia de mare vitez FS (FS = Ferrovie dello Stato = Italian railway).

- Inim simpl cu aripi mobile (= crossing with movable wing rails). Acest tip de inim simpl este folosit pentru

schimbtoare simple mici (= small turnouts) i lungimea schimbtorului simplu (= turnout) este restricionat.

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Figura 11.9: Inima simpl cu vrf mobil (Movable Point Frog = MPF)

1:38, FS (FS= Ferrovie dello Stato = Italian railway)

Contrainele (= check rails) mpiedic buza bandajului roii s ptrund, pe poriunea fr ghidare (=unguided part) din

alctuirea inimii simple(=crossing), n jghiabul greit (=wrong groove) sau

s loveasc vrful inimii simple (=crossing).

Concepia modern privind schimbtoarele simple (= turnout) folosete profilul UIC 33 pentru contraine ( = check rails). Aceste contraine sunt fixate pe plci suport speciale, nefiind legate cu ajutorul buloanelor (= are not bolted) de inele de rulare (= running rail); aceast reolvare( fr utilizarea buloanelor) permite o reglare uoar a poziiei contrainei n cazul n care aceast contrain se uzeaz.

11.1.3 in de legtur(=closure rail) inele de legtur(closure rail = in de legtur) leag acele (=set of switches) de

inima simpl obinuit (=common crossing). 11.1.4 ine i traverse n cuprinsul schimbtoarelor simple (= turnouts) Schimbtoarele simple (= turnouts) sunt, n principiu, fabricate din ine cu profil

normal (= normal rails). Pentru ace (= switch blades) i pentru contraine(=check rails) sunt folosite profile speciale. n mod uzual, calitatea oelului inelor (=steel grade of the rails) este aceiai ca a inelor folosite pe liniile din afara aparatelor de cale (=on plain track). Nuanele speciale de oel (=special grades) de felul inelor cu ciuperc clit (=Head Special Hardened (=HSH) rails) mbuntete rezistena la uzur a schimbtorului simplu (=wear characteristic of the turnout).

Toate joantele din cuprinsul schimbtorului simplu(= turnout)

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sunt suduri(welded joints) sau, dac este necesar, sunt joante izolante lipite (glued insulated

joints). n proiectarea modern nu trebue s fie folosite mbinrile cu buloane i cu eclise (= bolted and fish-plated joints).

n mod normal, pentru schimbtorul simplu sunt folosite traversele speciale (= long switch sleepers), realizate din lemn tare (=hardwood) i cunoscute de asemenea sub denumirea de supori(= bearers). ns, utilizarea traverselor din beton (=concrete sleepers) este n cretere. n mod special,

pe linii principale (in main line) i la calea pentru vitez de mare

are loc folosirea pe scar larg - a traverselor monobloc din beton(= monobloc concrete sleepers) sau - a cii pe dale (=slab track).

11.2 Geometria schimbtorului simplu(= turnout) nceputul schimbtorului(= front of turnout): nceputul schimbtorului se

situeaz la mijlocul joantei extreme (=rail ioint) situat de partea schimbtorului simplu pe care se afl o singur linie (=on the side of the non-divided track);

Sfritul schimbtorului(= rear of turnout); Sfritul schimbtorului se situeaz n dreptul joantelor corespondente extreme ale schimbtorului simplu dinspre linia care se ramific (= corresponding joints on the side of the divided track);

Punctul geometric(intersection point = mathematical point): punctul geometric este definit ca fiind punctul de intersecie dintre

axa liniei directe (=centre line of the straight track) i dreapta care este tangent (=tangent) la axa liniei

deviate n punctul de la sfritul schimbtorului (=centre line at the rear of the diverging track).

Unghiul inimii simple(=crossing angle) pentru schimbtorul simplu (=turnout): axa liniei directe(=centre line of the straight track) i dreapta care este tangent (=tangent) la axa liniei deviate n punctul de la sfritul schimbtorului (=centre line at the rear of the diverging track) formeaz unghiul inimii simple(=crossing angle) pentru schimbtorul simplu(turnout). Acelai unghi poate fi observat, de asemenea, la inima simpl (=common crossing). Cnd unghiul inimii simple(= crossing angle) este prezentat sub forma 1:n, pentru n se aleg numere intregi, Valorile obinuite pentru 1:n sunt 1:7, 1:9, 1:12, 1:14 , 1:15 , i 1:20 .

Schema geometric a schimbtorului simplu(=layout geometry of the turnout): Schema geometric a schimbtorului simplu(=layout geometry of the turnout) definete

viteza care este posibil pe linia abtut (=diverging route) a schimbtorului simplu (=turnout) i

forele care se nasc ntre roat i in.

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O proiectare modern utilizeaz o curb a schimbtorului simplu care, la nceputul ei, este tangent la axa liniei directe (= tangential beginning of the turnout curve). Astzi, se utilizeaz mai ales

arcele de cerc (=constant radius curyes), clotoidele, i o combinaie a acestor tipuri de curbe.

Cu programe de simulare speciale, se poate optimiza schema geometric (= layout geometry) pentru obinerea de fore minime (=minimum forces) i a confortului maxim (=maximum comfort) (a se vedea paragraful Schimbtoare simple pentru viteze mari (=High Speed Turnout)).

Geometria de tranziie la macaz(= in the switch): n Germania, a fost dezvoltat o geometrie special de tranziie de la contraac (= stock rail) la ac (=switch point). Aceast geometrie - denumit FAKOP sau KGO - ajut

osiile montate s se nscrie(=to steer) pe linia n abatere (= diverging route) i

reduce forele care se nasc ntre roi i ine. Aceast geometrie sporete grosimea acului (=switch blade) i, prin urmare, crete durata de exploatare (= useful life). (a se vedea paragraful Schimbtoare simple pentru viteze mari (= High Speed Turnout)) nclinarea inei (= rail inclination in turnouts): inele din cuprinsul schimbtorului

simplu (=turnout) pot fi introduse astfel nct - axa lor de simetrie s fie vertical(ine n poziie

vertical) sau - axa lor de simetrie s fie nclinat. n vederea realizrii unei mai bune comportri privitoare la

nscrierea n curb (= better curving behaviour), o mai mare conicitate este preferabil, i, prin urmare, sunt recomandate inele montate cu nclinare,

Trecerea de la zona schimbtorului simplu cu inele n poziie vertical la inele montate cu nclinare normal (= normal rail inclination) are loc n afara schimbtorului simplu (= turnout) prin rsucirea uoar a inelor (=slightly twisting the rails).

11.3 Schimbtoare simple pentru viteze mari. 11.3.1 Elemente generale Circulaia cu viteze ridicate(=high-speed traffic) reprezint o nou provocare

- att pentru operatorii feroviari(=railway operators) - ct i pentru industra feroviar (=railway industry).

Factorii de timp i de calitate devin treptat elemente decisive n acceptarea i folosirea sistemelor de transport. n consideraiile legate de vitez i de confort se afl potenialul aferent succesului din viitor al liniilor de cale ferat.

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Componentele i materialele asemenea

- inimilor simple cu vrf articulat (= swing nose crossings), - macaze nesimetrice( = asymmetrical switch points), - sisteme elatice de prindere a contraacelor n partea lor dinspre ace

(= elastic inner fastening systems of stock rail), - ine cu ciuperca clit (=head special hardened rails), - oel manganos cu rezisten ridicat la uzur(=high wear-resistant

manganese steel), - plci de prindere amortizoare de vibraii(= vibration dimpened fastening

plates) i traverse de beton(= concrete sleepers), - sisteme integrate de exploatare (= integrated operating systems), - ungerea i ntreinerea componentelor libere(= free components)

trebue s fac parte, astzi, din alctuirea oricrui schimbtor simplu modern pentru viteze ridicate (= modern high-speed turnout).

11.3.2 Metoda tradiional de proiectare a schimbtorului simplu

Metoda tradiional de proiectare a schimbtorului simplu (=turnout) presupune c rspunsul vehiculului (=vehicle response) este determinat mai degrab de cinematic dect de dinamic. [123], [184]. Pentru un vehicul dat i presupunnd vehiculul ca fiind un punct material (= point mass), poate fi calculat acceleraia lateral necompensat prin schimbtorul simplu. Schimbtoarele simple (=turnouts) sau diagonalele(=crossovers) - mai ales n cazul aplicaiilor de vitez ridicat(=high-speed applications) - sunt, n general, proiectate pe baza a trei parametrii legai de acceleraia cinematic(=kinematic acceleration).

Aceti parametrii sunt: - acceleraia lateral maxim(= maximum lateral acceleration) care nu este

compensat(= maximum lateral acceleration) (m/s2); - viteza maxim de modificare a acceleraiei (maximum rate of acceleration change) (m/s3);

- Modificarea maxim n timp a acceleraiei laterale la intrarea n curb(= maximum entry jerk) i modificarea maxim n timp a acceleraiei laterale la sfritul curbei (=exit jerk) (m/s3).

11.4 Despre rspunsul vehiculului (Vehicle dynamic)

Neajunsul metodei tradiionale de proiectare este reprezentat de faptul c rspunsul vehiculului (=vehicle response) este n mod clar un rspuns dinamic. Dup cum arat figura 11.10, consideraiile cinematice simple vor subestima rspunsul real al vehiculului. Msurtorile din teren, efectuate n cazul schimbtoarelor simple, confirm faptul c acceleraiile laterale din vagonul de cltori(= passenger compartment lateral accelerations) se pot ridica la dublul valorilor cinematice [291].

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Figura 11.10: Rspunsul cinematic fa de rspunsul dinamic

Recunoscnd neajunsurile proiectrii existente (= existing design approach), acum, sunt utilizate noi metode pentru proiectarea i evaluarea geometriei schimbtoarelor simple (=turnout geometry). Proiectarea schimbtorului simplu(turnout) trebue luat n considerare ca fiind o problem de interaciune dintre vehicul i cale (= as a vehicle/track interaction problem). Metoda const n a utiliza simularea dinamic vehiculului pentru a prezice forele i acceleraiile pe ntreg cuprinsul schimbtorului simplu( = turnout). n mod uzual, geometria optim (=optimum geometry) este reprezentat de clotoida dubl(= double clothoid or vertex clothoid).

O metod de a reduce suplimentar forele care se nasc atunci cnd vehiculul intr n curb iar roata face trecerea de la contraac (= stock rail) la ac (= switch blade) este denumit Optimizarea lrgimii cii cinematice(=Kinematic Gauge Optimization = KGO"). KGO face o mai bun utilizare a diferenei dintre razele de rulare ale celor dou roi aparinnd osiei montate(=axle) atunci cnd osia montat (=axle) intr pe schimbtorul simplu, prin ncovoierea contraacului spre exteriorul cii. ncovoierea contraacului spre exteriorul cii mrete diferena dintre razele de rulare ale celor dou roi aparinnd osiei montate (= rolling radius difference) i face ca osia montat(axle) s se orienteze (=steer in) n sensul dorit (=desired direction). Rezultatele calculate au prezis un avantaj n comparaie cu proiectarea convenional a schimbtorului simplu (=conventional turnout design) .

Consideraiile menionate mai nainte i metodele ar trebui s constituie premise atunci cnd are loc crearea geometriilor noi i avansate pentru schimbtoarele simple de mare vitez (=high-speed turnouts). Numai atunci putem elabora schimbtoare simple (=turnouts) care ndeplinesc cerinele pentru cea mai mare siguran (highest safety), pentru cea mai bun eficien (=best efficiency), i, n acelai timp, pentru un excelent confort (= excellent riding comfort).

11.4.1 Exemple de schimbtoare simple moderne pentru viteze mari(=modern high-speed turnouts)

n figura11.11 se prezint fotografia schimbtorului simplu F S ltalia pentru viteze mari (=F S ltalia high-speed turnout) avnd inima simpl cu vrf articulat(=swing nose crossing) pentru viteza de 160 km/h pe linia abtur(=diverging track),

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geometrie UlC60-7300/3000/15000-1:38 - clotoid dubl(=vertex clothoid),

geometre a schimbtorului simplu(turnout) care a fost proiectat i optimizat prin simularea dinamic a vehiculului (=vehicle dynamics simulation). Acest schimbtor simplu(=turnout) a fost montat la Gallese, ltaly pe Direttissima Rome/Firenze n 1999(=Diretisima Rome/Firenze = cea mai direct cale ferat Rome/Firenze).

n figura 11.12 se prezint fotografia schimbtorului simplu pentru viteze mari (=high-speed turnout) avnd inima simpl cu vrf articulat(=swing nose crossing) pentru viteza de 200 km/h pe linia abtut (=diverging track), folosit la DB(DB = Deutsche Bahn),

geometrie UlC60-16000/6100/infinit -1:48,

schimbtor simplu(=switch) care cuprinde concepia KGO (=including KGO design) care deja este un schimbtor simplu standardizat (= standard

turnout) la (DB = Deutsche Bahn). i care este montat la Bitterfeld, Germania, pe linia de mare

vitez(=high speed line) Berlin/Leipzig n 1998.

Figura 11.11: Schimbtor simplu FS (=turnout FS) avnd inim simpl cu vrf mobil(movable point crossing) pentru 160 km/h

(FS= Ferrovie dello Stato = Italian railway)

16

Figure 11.12: Schimbtor simplu DB(turnout DB) avnd

inim simpl cu vrf articulat (swing nose crossing) pentru 200 km/h (DB = Deutsche Bahn)

n cele din urm, figura 11.13 prezint o schem nou (= new track lay-out) a diagonalei pentru viteze mari (=High Speed crossovers), constnd din arce de cerc i curbe progresive (consisting of a circle combination of spiral segment- circle - spiral segment). (spiral segment = curb progresiv); Diagonala are forma literei S

Figura 11.13: Diagrama tipic pentru o diagonal S - 160 km/h (100 mph)

(= S - 160 km/h (100 mph) cross-over)

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11.5 Notaii folosite n cazul aparatelor de cale (=switches and crossings) Pe plane (=on drawings), schimbtoarele simple(= turnouts) i traversrile (=

crossings) sunt artate (marcate) n diverse feluri. Desenul conine toate detaliile necesare de proiectare i de fabricare. Desenul n care se reprezent firele de in este ilustrat n figura 11.1.

Exist schie n care se arat numai axele liniilor i tangentele.

Punctul geometric(=mathematical point) este indicat printr-un cercule(= small circle); de asemenea, pot fi inducate i cele mai importante detalii.

11.6 Tipuri de schimbtoare simple(turnouts) i traversri(crossings) Utiliznd figura 11.14, cele mai importante tipuri de schimbtoare simple (=

turnouts) i de traversri (= crossings) vor fi discutate n mod amnunit. n cazul schimbtoarelor simple standard (= standard turnouts) sau schimbtoarelor simple (= single turnouts), se face distincie ntre schimbtorul simplu cu abatere spre dreapta(right-hand turnout) i schimbtorul simplu cu abatere spre stnga(left-hand turnout),

n funcie de abaterea curbei liniei deviate n cazul observatorului aflat la vrful schimbtorului simplu i care privete spre sfritul lui. Schimbtorul simplu (= turnout) din figura 14.14a este schimbtorul simplu cu abatere spre dreapta(= right-hand turnout).

n cazul schimbtorului simplu (= turnout) cu linia direct situat n curb(= with the straight track lying in a curve)(caz nereprezentat n figura 11.14), linia abtut (= turnout track) se poate desprinde

- spre partea liniei directe (= through track) dinspre centrul curbei aparinnd liniei directe

sau - spre partea liniei directe(= through track) care este opus centrului

urbei aparinnd liniei directe. Un schimbtor simplu simetric (=symmetrical turnout) (figure11.14b) este un caz

special de schimbtor simplu (=turnout) cu dou linii abtute simetrice care se desprind din linia simpl situat n faa lui (= with two routes diverging symmetrically from the common route).

O traversare dubl jonciune (=diamond crossing with double slips) se formeaz atunci cnd dou linii care se intersecteaz sub un unghi ascuit (= two diagonally intersecting tracks) sunt conectate ntre ele prin intermediul a dou curbe (figure11.14c). nseamn c, la o traversare dubl jonciune (=diamond crossing with double slips) exist patru posibiliti de circulaie (four routing possibilities).

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Figura11.14: Tipuri de aparate de cale(= switches)

O traversare simpl jonciune (= diamond crossing with single slip) este o traversare (= crossing) care are conectarea numai pe o parte ntre cele dou linii care se intersecteaz(= intersecting routes) (figure11.14d) i, ca urmare, traversare simpl jonciune (=diamond crossing with single slip) are 3 posibiliti de circulaie (3 routing possibilities).

Se atrage atenia asupra diferenei de notare dintre traversrile fr jonciune i traversrile cu jonciune (=Reference is made to the difference in notation for diamond crossings with slips and crossings(figure 11.14e).

O traversare (= diamond crossing) este considerat normal dac

unghiul de intersecie (=angle of intersection) este egal cu cel al schimbtorului simplu(=single turnout),

i, de asemenea, liniile care se intersecteaz sunt situate n aliniament(are straight) (figure 11.15f).

O traversare (= crossing) are n alctuire dou inimi simple obinuite (= common crossings) (cu unghi de intersecie ascuit(= acute angle)) i dou inimi duble(= obtuse crossings) (cu unghi de intersecie obtuz(= obtuse angle)).

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Figure 11.15: Tipuri de traversri (=crossings)

O traversare curb (= curved diamond) apare la intersecia (= junction) dintre

o linie situat n aliniament (= straight track) i o linie situat n curb (= curved track) sau

dou linii situate n curb (= curved tracks) (figure11.15g). Unghiul traversrii (= crossing angle) este diferit la cele dou extremiti (=at both ends) ale traversrii.

Circulaia (=traffic running) pe traversrile n unghi drept (= right-angle crossings) (figura11.15h) produce fore de ciocnire substaniale(=hefty impacts) la joante(joints).

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n cazul unei traversri oblice (=oblique crossing) (figure 11.15i) fora de ciocnire

este mult mai mic. La traversrile (=crossings) cu un foarte mic unghi de intersecie (=very small angle of intersection) vor aprea poriuni mari care nu asigur ghidarea (= large unguided parts). Pentru valori mai mici dect 1:12,

inima dubl (= obtuse crossing) este prevzut cu vrfuri mobile (= moveable switch blades) i

inima simpl obinuit (=common crossing) este prevzut cu vrf articulat (= swing nose) aa cum se arat n figura11.15j.

11.7 Diagonale(cross-overs) O schi a legturii dintre dou linii paralele care este alctuit din dou

schimbtoare simple(= single turnouts), mpreun cu lungimea total necesar a acestei legturi, este dat n figura 11.16. Dimensiunile standard sunt folosite pentru distana w dintre axele liniilor.

Legturile (= connections) dintre mai mult de dou linii paralele se poate realiza prin cuplarea legturilor simple (= single conections) n concordan cu figura 11.17a, sau, prin folosirea traversrilor cu jonciune(= diamond crossings with slips), aa cum se arat n figura 11.17b. Sistemul (a) este folosit ct se poate mai mult pe liniile directe (= main lines).

Figura 11.16: Legturile (=connections) cu schimbtoare simple (=switch)

ntre dou linii paralele

Figure 11.17: Legturi (= connections) cu schimbtoare simple ( = switch)

ntre mai mult dect dou linii paralele

Diagonalele duble (= double cross-overs) permit circulaia (= traffic) n ambele

sensuri pe legturile prin intermediul crora se realizeaz parcursurile de trecere de la o linie la cealalt linie. Figura 11.18 arat dou astfel de soluii.

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Figure11.18: Diagonale duble (= double cross-overs)

Figure 11.19 ofer alte cteva exemple de diagonale duble(= crossover). Dac dou linii paralele sunt conectate folosind o traversare(= crossing) care se leag prin patru schimbtoare simple (= turnouts) la liniile directe (=main tracks), atunci, se realizeaz o bretea (= scissors crossover), dup cum se vede n figura 11.18 c i figura 11.18d.

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Figure 11.19: Diagonale(= crossovers)

Figura 11.20 arat un exemplu cu amplasamente ale aparatelor de cale (=switch and crossing) n Utrecht. Exemplul arat

- ct de complexe pot s fie aceste situaii n practic i - ce probleme imense de ntreinere pot s rezulte.

Figura 11.20: Amplasamentele aparatelor de cale (switch layout) n Utrecht

11.8 Calculul schimbtorului simplu(=switch calculation) 11.8.1 Relaia ntre raza arcului de cerc(=curve radius) i unghiul inimii simple(=crossing angle)

Aici, prin Calculul schimbtorului simplu(= switch calculation) se nelege determinarea celor mai importante dimensiuni (= most important geometric measures). Aceste dimensiuni sunt bazate pe acceleraia lateral admisibil (= admissible lateral acceleration) a = 0,8m /s2 care a fost menionat mai nainte. Legtura dintre acceleraie, vitez i raza arcului de cerc este:

2va=R

(11.1)

Prin urmare, viteza maxim poate fi calculat ca fiind:

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max 2,79V R (11.2)

cu V[km/h] i R[m]. n figura11.21 un schimbtor simplu cu abatere la dreapta avnd linia direct

situat n aliniament (= normal right-handed turnout; normal turnout schimbtorul simplu avnd linia direct situat n aliniament) are o inim simpl cu ambele fee active n aliniament (= straight crossing). Dac presupunem c arcul de cerc situat de partea axei liniei abtute care este opus centrului de curbur (=outer curve) este tangent la contraac (=stock rail) n punctul de contact(= point of contact), atunci, din figura 11.21 rezult c:

1 cosd R (11.3) n care: d = indic punctul de trecere de la linia situat n curb (= curve track) la linia

situat n aliniament (= straight track), care depinde de cerine constructive (=constructional requirements);

R = raza poriunii arc de cerc (= curve part closure rail); = unghiul inimii simple(= crossing angle).

Presupunnd c

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timp ce, n cazul inimii simple curbe(= curved crossing), valoarea lui d este de cel mult 1,70 m. Aceste valori sunt determinate de

- lrgimea cii(= track gauge) i - distana care este necesar pentru a monta creuzetul pentru sudura

aluminotermic (= crucible of a thermit weld) cu limea de 300 mm. Lund n considerare acest lucru, urmeaz: pentru inim simpl dreapt (=a straight crossing) (R rezult n [m]):

22,5R n (11.5) pentru inima simpl curb(= curved crossing) (R rezult n [m]):

23, 4R n (11.6) Pentru cele mai multe cazuri obinuite, se folosesc tabele cu dimensiunile

principale ale schimbtoarelor simple (=turnouts); dimensiunile trecute n aceste tabele au la baz formulele prezentate mai nainte. De asemenea, n aceste tabele este menionat valoarea corespunztoare pentru viteza maxim (=maximum speed) Vmax(11.2).

Aceste tabele arat c, chiar n cazul unghiurilor mici pentru inima simpl (= small crossing angles), viteza maxim (=maximum speed) este relativ sczut. O vitez de 120 km/h cere o raz a arcului de cerc (= curve radius) de circa 2000 m; aceast raz corespunde unui unghi de circa 1:25. Astfel de schimbtoare simple (= turnouts)

se fabric cu dificulti(= dificult to manufacture) i lungimea schimbtorului simplu (=turnout) va fi destul de mare.

Un schimbtor simetric (= a symmetrical turnout) este folosit n cazul n care liniile din cuprinsul schimbtorului sunt simetrice n raport ci axa liniei care duce spre vrful schimbtorului respectiv(in case of symmetrically diverging tracks). Folosirea schimbtorului simetric (= symmetrical turnout) n cazul legturilor (= switch connections) dintre linii paralele (= parallel tracks) este nefavorabil din cauza generrii situaiilor de curbe - S(=S-curve situations). Din figura11.22 se poate deduce cu uurin c unghiul dintre liniile din cuprinsul schimbtorului simetric(= symmetrical turnout) este dublul unghiului unghiului de abatere ce corespunde curbei arc de cerc din lungul fiecrei linii din cuprinsul schimbtorului n discuie (= is only half-effective with respect to the curve radius). Potrivit cu (11.6), pentru schimbtorul simetric (=symmetrical turnout), relaia ntre raz i unghi arat astfel:

26,8R n (11.7)

nseamn c, la unghiuri egale, raza arcului de cerc de la schimbtorul simplu simetric (=symmetrical turnout) este dublul razei arcului de cerc de la schimbtorul simplu normal (=normal turnout schimbtorul simplu avnd linia direct situat n aliniament). Bineneles, viteza maxim (= maximum speed) calculat cu (11.2) se aplic ambelor linii. Schimbtoarele simple simetrice (=symmetrical turnouts)1:15 i 1:20, cu razele 1200 m i 2000 m, se pot folosi la vitezele respective de 100 km/h i 125 km/h respectively.

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Figura 11.22: Relaia dintre unghiul schimbtorului simplu (= turnout) i raza curbei(schimbtor simplu simetric(= symmetric turnout))

11.8.2 Calculul dimensiunilor principale(=main dimensions) n figura 11.23 desenul n care apar toate firele de in din cuprinsul

schimbtorului simplu(=double line drawing) reprezint - linia direct(= straight track) i - linia abtut(= diverging track)

aparinnd schimbtorul simplu avnd linia direct situat n aliniament(= normal right-handed turnout; normal turnout schimbtorul simplu avnd linia direct situat n aliniament). Dup cum se poate vedea, acul(=switch blade) se afl la o deprtare CD fa de punctul teoretic de contact (=theoretical contact point) C. Mai mult, acul (=switch blade) nu este tangent la contraac (=stock rail) n punctul D, ns, face un unghi redus, deoarece, din punct de vedere constructiv, nu este posibil s fie fcut un ac (=switch blade) care s fie perfect tangemt la contraac(=stock rail).

Se utilizeaz - att ace drepte (= straight switch blades) - ct i ace curbe (= curved switch blades).

n cazul acelor curbe (= curved switch blade), poriunea t dintre D i clciul (=heel) E este curb. n poziia n care acul este deprtat de contraac(=open position), pentru a fi permis trecerea liber ( = free passage) a buzei bandajului (= wheel flange), trebuie s existe spaiu suficient pe ntreaga lungime a acului (=switch blade). Aceast cerin determin lungimea acului(=switch blade).

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Figura 11.23: Calculul razei arcului de cerc (= curve radius) i calculul lungimii schimbtorului simplu normal (=normal turnout;

normal turnout schimbtorul simplu avnd linia direct situat n aliniament)

Avantajul acului drept (= straight switch blade), n afara fabricrii lui simple, const n faptul c acelai desen este folosit

pentru schimbtoarele simple cu abatere la stnga (= left-handed turnouts)

i pentru schimbtoarele simple cu abatere la dreapta (=right-handed turnouts).

Un ac curb (= curved switch blade) necesit o lungime mai mic i permite raze mai mari ale arcului de cerc.

Curba complet se extinde ntre E i F i se termin la distana g dinaintea punctului teoreticG al inimii simple (= theoretical point G of the crossing).

Mrimile urmtoare, care depind de dimensiunile prilor de construcie existente ale schimbtorului simplu (= dimensions of existing constructional parts), se presupun a fi cunoscute:

= unghiul inimii simple(=crossing angle); = Unghiul fcut cu contraacul de dreapta tangent la clciul acului (=heel) (punctul E);

s = lrgimea cii(=track gauge); e = poziia clciul acului (=heel); g = Lungimea poriunii situate n aliniament (= straight part) dinaintea punctului

teoretic Gaparinnd inimii simple (= theoretical point G ); p = Distana de la nceputul schimbtorului simplu(= front turnout) la nceputul

acului(punctul D)(= beginning of switch blade(point D)); q = Distana de la nceputul inimii simple (= beginning of crossing) la sfritul

schimbtorului simplu (= rear of turnout); t = Lungimea acului(= switch blade) (proiecia pe contraac(= stock rail)).

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Din figura 11.23 rezult c:

cos cos sins e R g (11.8)

De unde, poate fi determinat raza arcului de cerc (= curve radius): sin

cos coss e gR

(11.9)

Lungimea complet a schimbtorului simplu (=turnout) poate fi calculat cu:

sin sin cosL p t R g q (11.10)

n cele din urm, rezult poziia punctului gemetric aparinnd schimbtorului simplu(= mathematical point):

1 1cotg2 2

MH s

(11.11)

Valorile mrimilor date n tabelele NS(NS = Cile Ferate Olandeze) rezult din relaiile:

B= MH+q (11.12)

A = L -B

Tabela 11.1 prezint principalele dimensiuni pentru unele tipuri de schimbtoare simple (=switch types) care se aplic n mod obinuit de ctre NS(NS = Cile Ferate Olandeze).

Tabela 11.1: Date privind unele schimbtoare simple obinuite(=survey of some common switches and crossings)

Unghiul de intersecie

(of Intersection)

schimbtorul simplu

(construction)

L [mm]

A [mm]

B [mm]

R [m]

V [km/h]

1:34,7 UlC54 cu vrf mobil al inimii simple (=movable crossing)

99332 36878 62454 2300 140

1: 15 UlC54 cu inim simpl curb(=curved crossing)

47277 21221 26056 725 80

1 : 15 UlC54 cu inim simpl dreapt(=straight crossing)

42706 1 6550 26056 600 70

1: 12 UlC54 cu inim simpl curb(=curved crossing)

38320 17420 20900 465 60

1: 9 UlC54 cu inim simpl curb(=curved crossing)

32185 14185 '18000 260 40

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11.8.3 Proiectarea aparatelor de cale (= design of switches) din punct de vedere geometric. Pentru ca o schem de aparate de cale (=switch and crossing layout) s poat fi

fabricat, asamblat i montat pe amplasament, fiecare parte a schemei trebuie s fie specificat precis din punct de vedere dimensional, n mod usual pe un desen. n acest scop se folosete scara de 1:100, iar scara 1:50 sau scrile chiar mai mari pot s fie folosite ocazional(=on occasions). Nu este de dorit ca, n vederea obinerii preciziei necesare spre a se realiza piese care s se potriveasc n mod corespunztor mpreun, s se ncerce reprezentarea la scar a celor mai mari dimensiuni. Prin urmare fiecare linie din desen trebuie s fie definit prin dimensiuni, iar aceste dimensiuni trebuie s fie confirmate prin calcul. Numai atunci putem fi siguri c fabricantul va realiza componentele care s corespund cu inteniile proiectantului. (lt is to this end that it is necessary to define all layouts in geometrical terms.)

Pn de curnd, acest lucru a trebuit s fie fcut prin calcul individual, i, ca urmare a fost dezvoltat un volul mare de formule de-a lungul anilor pentru a face sarcina mai uoar. O mare parte a acestei tehnici a devenit nvechit prin introducerea sistemului de proiectare automat(CAD = Computer Aided Design)

Un exemplu de astfel de program de calcul eate programul TURN care este folosit de ctre TU Delft n combinaie cu pachetul de programe FEM ALGOR.

11.9 Producia, transportul i montarea schimbtoarelor simple(=switches)

Schimbtoarele simple(=switches) sunt realizate de fabricantul de aparate de cale (=switch manufacturer). n figura 1.24 se arat produsul care reprezint partea central a unei diagonale (= crossover) pe traverse din beton.

Dup confecionare, schimbtoarele simple(= switches) vor fi transportate la destinaia final

fie cu maini, vase fie cu trenuri speciale pentru transportat schimbtoare simple

(= special switch transport trains).

Pe antier, schimbtoarele simple(= switches) sunt manipulate cu macarale feroviare speciale grele (=special heavy rail cranes) sau macarale rutiere (cranes from the road). O alternativ const n folosirea

- de macarale portal mobile (= mobile gantries) pe o cale de rulare provizorie (on temporary rails) - sau de macarale portal mobile cu roi de cale ferat retractabile (at

retractable rail wheels).

Dup ce schimbtorul simplu (= switch) este montat i diferitele pri sunt legate mpreun prin suduri, sunt folosite una sau mai multe maini speciale de burat (special tamping machines). Apoi, schimbtorul simplu (= switch) poate

s fie conectat la sistemele de semnalizare(= signalling), de nclzire (= heating) i de exploatare(= operation) i poate s fie testat pentru folosire.

Schimbtoare simple (= switches) pentru tramvaie i pentru metrou. Pentru metrou i pentru tramvaie, principiul schimbtorului simplu ( = switch)

este acelai ca la calea ferat. Totui, trebuie notate urmtoarele diferene (structural differences):

- Raza curbei(= curve) de la schimbtoarele simple (= switch) pentru tramvaie i de la schimbtoarele simple (= switch) pentru metrouri poate fi mult mai mic; urmare vitezei mai mici i ampatamentul mai

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mic al boghiurilor(= bogie distance), lungimea schimbtorului simplu este mai mic

- Schimbtorul simplu (= switch) poate fi ncorporat n mbrcmintea strzii (= pavement of the road)

- Tipul inei poate fi diferit pentru ncrcre i vitez mai reduse - Uneori, schimbtoarele simple (=switchs) pentru tramvaie nu au

dispozitive de acionare (power or have simple engines); acul (= blade) va fi acionat de ctre roile tramvaiului.

- Schimbtoarele simple (=switch) sunt acionate de conductorul vehiculului( = tram driver) prin signal, i nu prin centrul de exploatare (= operating centre)

- Pe liniile de tramvai exist mult mai multe traversri (crossings) la unghiuri mult diferite(at more different angles).

Figura 11.24: Asamblarea unei diagonale cu traverse de beton (crossover in

concrete) - // -

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Anexa I

11 SWITCHES AND CROSSINGS 11.1 The standard turnout Turnouts(=schimbtoarele simple) are used to divide a track into two, sometimes

three tracks.The purpose of crossings is to allow two tracks to intersect at the same level. lf a complete train is to pass from one track to another while moving and without being subdivided, tunouts are essential in the absence of turntables or traversers.

It must be possible to run through switches and crossings in both directions. A normal turnout or single turnout, as shown in figure 11.1, allows movement of traffic in a straight direction on the through track or in a divergent direction. A picture of the right-hand turnout is given in figure11.2.

Figure 11.1: Standard right-hand turnout

The turnout (=schimbtorul simplu) consists of three major parts: - Set of switches(switch blades); - Common crossing(inima de ncruciare obinuit); - Closure rail. These parts will be discussed separately below.

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Figure 11.2: Picture of right-hand turnout (schimbtorului simplu

cu abatere la dreapta)

11.1.1 Set of switches(macazul) Switches consist of two switch blades(=ace) and two stock rails(=contraace). The

switch blades (=acele) can be moved and determine which of the above-mentioned tracks will carry traffic. ln figure 11.1 this is the through track.

Figure 11.3: Cross-sectional drawing of switch blade(ac) and stock rail(contraac)

Figure 11.4: Switch blade(=ac) and stock rail(contraac)

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The cross-section of the switch blade (ac) in modern designs is an asymmetric

section that is lower than the standard rail profile. This has the advantage that there very little machining of the base of the switch(ac) is necessary.

Because of the asymmetric base, the moment of inertia is higher compared to a switch blade(=ac) made of standard rail. The lower height allows the use of an elastic fastening system for the stock rail(contraac) on both sides which is a must in modern turnouts. Figure 11.3 and figure 11.4 show an example.

Figure 11.5: Cross-sectional drawing of T-rail switch blade(in ac)

Some railways still use switch blades(=ace) made of standard rails. Figure 11.5 shows the cross-section for such a turnout(=schimbtor simplu).

The turnout(=schimbtor simplu) can be operated by different types of point machines, e.g. electrically, hydraulically or pneumatically. The locking system can be

- either in the switch machine (internal locking) - or in the track (external locking).

In switches for medium speed and especially for high speed several locking locations are necessary.

The smaller the angle of the switch the longer the switch blade(ac) is. The blade can get in contact with the wheel by passing a wheel through the gap between stock rail and blade. With a long blade extralocking is applied to prevent a switch blade(=ac) from moving too much.

These lockings can either be operated by single point machines at each locking location or by one point machine at the toe-end of the switch and connecting rods that connect to the other locking stations. New developments for high speed or high capacity railway lines are integrated locking, switching, and detection systems.

Figure 11.6 shows a new integrated hydraulic switching and locking system. Here the Iocking system is integrated in a hydraulic setting cylinder; no lubrication or maintenance is necessary. The principle of an integrated locking and switching machine enables the blades to move sequentially(=succesiv) so less power is needed at the same time. The blades(=acele) and stock rail(=contraacul) of the switch are heated by means of gas or electrical systems for protection in case of frost, snow or freezing rain.

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Figure 11.6: Switch with integrated hydraulic setting and

locking system Figure 11.7 shows a low maintenance electrcal point machine. Preventive

maintenance is only required once every five years. The tractive force can be adjusted between 2 and 10 kN. The locking unit is equipped with a spring function that gives the blade a contact force of 2,5 kN in the locked position. Sensors detect whether the blades are open or closed.

In modern railway systems the installations are operated from a central operating post.

Figure 11.7: Modern electrical point machine

11.1.2 Common crossing Depending on the traffic load, different types of crossings are used. For normal

to medium axle loads and speeds up to 200 km/h rigid crossings are used. For higher axle loads and higher speeds, crossings with movable parts have to be used.

The common crossing and the wing rails are built up geometrically in such a way that the passing wheel remains supported and wheel flange clearance is guaranteed. In a common crossing the intersecting rails form an acute angle.

ln the common crossing the unguided part leads to an unquiet behaviour (comportare agitate, comportare nelinitit) of the bogie in the switch and causes an extra dynamic load on

- the common crossing and - on the check rail.

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To avoid unguided parts in the common crossing movable points should be used.

Several construction types of rigid crossings exist:

- A familiar construction is the built-up common crossing formed from two machined rail elements. lf standard steel quality is used, the common crossings are hardened by heat treatment in order to resist the high impact loads. Use is also made of head-hardened rails or rails made of austenitic manganese steel.This crossing is used for low end applications.

- For higher loads, crossings are used which have a crossing nose machined out of a block of heat treated steel and bolted on wing rails.

- An alternative to this built-up crossing is a crossing with a crossing nose made of Cast Austenitic Manganese Steel(AMS) and bolted on wing rails. An Austrian

development allows the welding of AMS to rail steel by use of an intermediate piece of special steel.This welding technique e liminates the bolted and fish-plated connection of olden days.

- lf the traffic load is heavy, preference is given to the monobloc AMS crossing with welded on legs on all four ends. This crossing is very wear resistant and can be welded in CWR track. Before installation, these crossings can be prehardened by explosive hardening which reduces the initial wear and the need for maintenance considerably. Figure11.8 shows a cast monobloc AMS crossing with welded on legs.

Figure 11.8: Cast manganese frog For higher axle loads and speeds of more than 200 km/h, crossings with

movable parts are used. In these crossings, the gap between the wing rail and the point is closed and the impact load is reduced.

Three major types exist: - Swing Nose Crossing SNC with a nose made out of a machined and heat

treated block. Smaller crossings of this type have an expansion joint in the heel to compensate for the difference in length after switching from one position to the other.

- Movable Point Frog MPF with a nose made out of rails as main and counter

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point. Compensation for the length is achieved between the two points; no separate expansion joint is necessary. Figure 11.9 shows a crossing 1:38, installed on FS high-speed line.

- Crossing with movable wing rails. This type is used for small turnouts and when the length of the turnout is restricted.

Figure 11.9: Movable Point Frog 1:38, FS

Check rails prevent the wheel from running into the wrong groove in the unguided part of the common crossing or from striking the crossing. Modern turnout design uses the UIC 33 profile for check rails that are attached to special plates and are not bolted to the running rail. This allows easy adjustment when the check rails wear

11.1.3 Closure rail The closure rail lies between the set of switches and the common crossing. 11.1.4 Rails and sleepers in turnouts Turnouts are in principle constructed of normal rails. Special profiles are used

for the switch blades and check rails. The steel grade of the rails usually is the same as on plain track. Special grades like Head Special Hardened HSH rails improve the wear characteristic of the turnout.

All rail joints within the turnout are welded joints or, if necessary, glued insulated joints. No bolted and fish-plated joints should be used in a modern design.

Normally long switch sleepers made of hardwood, also known as bearers, are used, although use is increasingly being made of concrete sleepers. Especially in main line and high-speed track much use is made of monobloc concrete sleepers or slab track.

11.2 Geometry of the turnout

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Front of turnout: this lies in the centre of the rail ioint on the side of the non-divided track;

Rear of turnout; this lies at corresponding joints on the side of the divided track;

Intersection point (Mathematical point): this is defined as the point of intersection of the centre line of the straight track and the tangent to the centre line at the rear of the diverging track.

Crossing angle of the turnout: the above-mentioned centre line and tangent form an angle which is referred to as(=care este denumit ca) the crossing angle of the turnout. The same angle can also be seen in the common crossing. For the crossing angle 1:n, whole numbers are chosen. Common values are 1:7, 1:9, 1:12, 1:14 , 1:15 , and 1:20 .

Layout geometry of the turnout: The layout geometry of a turnout defines the speed that is possible by means of the diverging route of the turnout and the forces created between wheel and rail. A modern

design uses a tangential beginning of the turnout curve. Today, mainly constant radius curves, clothoids, and a combination of these types of curves are used. With special simulation software it is possible to optimise the layout geometry for minimum forces and maximum comfort. (See also paragraph

High Speed Turnout). Transition geometry in the switch: In Germany, a special transition

geometry from stock rail to switch point has been developed. This geometry called FAKOP or KGO helps the axles to steer into the diverging route and reduces the forces that are created between wheels and rails. lt also increases the thickness of the switch blade and, therefore, increases the useful life. (See also paragraph High Speed Turnout).

Rail inclination in turnouts: The rails in the turnout can be placed vertically or inclined. In order to achieve a better curving behaviour a higher conicity is preferable and, therefore, vertical rails are recommended.

The transition to the normal rail inclination takes place away from the turnout by slightly twisting the rails.

11.3 High-speed turnouts 11.3.1 General High-speed traffic is a new challenge

- both for the railway operators - and the railway industry.

Time and quality factors are steadily developining to the decisive elements in the acceptance and use of transport systems. The areas of social considerations, speed, and comfort are where the potential for the future success of the railwaysli es.

Components and materials like swing nose crossings, asymmetrical switch points, elastic inner fastening systems of stock rail, head special hardened rails, high wear-resistant manganese steel, vibration dimpened fastening plates and concrete sleepers, integrated operating systems, lubrication and maintenance free components should nowadays be part of any modern high-speed turnout.

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11.3.2 Traditional turnout design method Traditional turnout design methods assume that vehicle response is

determined by kinematics rather than dynamics [123], [184]. For a given vehicle speed and assuming the vehicle to be a point mass, the lateral cceleration which is not compensated through the turnout can be calculated. Turnouts or Crossovers particularly for high-speed applications - are generally designed based on three parameters derived from the kinematic acceleration.

These are: - Maximum lateral acceleration which is not compensate(m/s2); - Maximum rate of acceleration change(m/s3);

- Maximum entry jerk and exit jerk (m/s3). 11.4 Vehicle dynamic

A failing of the traditional design method is that(=neajunsul metodei tradiionale de proiectare este reprezentat de faptul c) vehicle response is clearly dynamic. As shown in figure 11.10, simple kinematic considerations will underestimate actual response. Field measurements confirm that passenger compartment lateral accelerations in turnouts can go up to twice the kinematic values[291].

Figure 11.10: Knematic versus dynamic response Recognising the shortcomings(=neajunsuri, deficiene) of the existing design

approach, new methods for the design and evaluation of turnout geometry are now being used.Turnout design has to be considered as a vehicle/track interaction problem. The method is to use a vehicle dynamics simulation to predict forces and accelerations throughout the turnout. The optimum geometry usually is a double clothoid or vertex clothoid geometry

One method to further reduce the forces that are created when a car enters a turnout and the wheel makes the transition from stock rail to switch blade is called Kinematic Gauge Optimization KGO". KGO makes better use of the rolling radius difference of the two wheels on an axle when it enters a turnout by bending the stock rail out.This increases the rolling radius difference and makes the axle steer in the desired direction. Calculated results have predicted an advantage compared to conventional turnout design.

Above-mentioned considerations and methods should form the p rerequisites when developing new, advanced geometry for high-speed turnouts. Only then can

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we develop turnouts that meet the requirements for highest safety, best efficiency, and excellent riding comfort at the same time.

11.4.1 Examples of modern high-speed turnouts Figure11.11 shows a photograph of the F S ltalia high-speed turnout with

swing nose crossing for 160 km/h on the diverging track, geometry UlC60-7300/3000/15000-1:38 - vertex clothoid,

turnout geometry designed and optimised by using vehicle dynamics simulation. lt was installed at Gallese, ltaly on the Direttissima Rome/Firenze in 1999.

Figure11.12 shows a photograph of a high-speed turnout with swing nose c rossing for 200 km/h on the diverging track used on DB,

geometry UlC60-16000/6100/infinit -1:48; switch including KGO design which is already a standard turnout at DB. Installed at Bitterfeld, Germany on the high speed line Berlin/Leipzig in 1998.

Figure 11.11: FS turnout with movable point crossing for 60 km/h

Figure 11.12: DB turnout with swing nose crossing for 200 km/h

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Finally, Figure 11.13 shows a new track lay-out for High Speed crossovers, consisting of a circle combination of

spiral segment- circle - spiral segment.

Figure 11.13: Typical diagram for a S - 160 km/h (100 mph) cross-over

11.5 Notations used for switches and crossings Turnouts and crossings are indicated in different ways on drawings. The

design drawing gives all the necessary details for the design and construction. The double line drawing with the two rails of a track drawn separately, an example of which is given in figure 11.1, illustrates this principle.

There are also sketches in which only centre lines and tangents are shown. The mathematical point is indicated by a small circle.The most important details of the turnout or crossing can also be indicated.

11.6 Types of turnouts and crossings Using Figure11.14 the most important types of turnouts and crossings will be

discussed in more detail. In standard or single turnouts, a distinction is made between

right-hand turnout and left-hand turnout,

depending on the direction the diverging track takes, seen against the direction of the switch point. The turnout shown in figure11.14a is a right-hand turnout.

ln a curve the turnout can diverge in or against the direction of the curve (not drawn) with the straight track lying in a curve and the turnout track curved opposite the through track or in the same direction.

A symmetrical turnout (figure11.14b) is a special case of a turnout with two routes diverging symmetrically from the common route.

A diamond crossing with double slips consists of two diagonally intersecting tracks which are connected by two curves (figure11.14c). This means there are (=acest lucru nseamn c exist) four routing possibilities.

A diamond crossing with a single slip is a crossing which only has one connection between intersecting routes (figure11.14d) and because of this has 3 routing possibilities.

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Reference is made to the difference in notation for diamond crossings with slips and crossings(figure 11.14e).

Figure11.14: Types of switches A diamond crossing is considered normal if

the angle of intersection is equal to that of a single turnout, and the intersecting tracks are straight as well (figure 11.15f).

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A crossing comprises two common crossings (acute angle of

intersection) and two obtuse crossings (obtuse angle of intersection). A curved diamond is a junction between

straight and curved track or between two curved tracks (figure11.15g).

The crossing angle is different at both ends. Traffic running over right-angle crossings(figure11.15h) produces

hefty impacts(hesty=substanial, greu) on the joints. In the case of an oblique crossing (figure 11.15i) this is much less the case. In

crossings with a very small angle of intersection large unguided parts will occur. For values less than 1:12, the obtuse crossing is provided with moveable switch blades and the common crossing with a swing nose as outlined in figure11.15j.

11 .7 Gross-overs A sketch of the connection between two parallel tracks consisting of two

single turnouts, together with the required total length, is given in figure 11.16. Standard dimensions are used for the distance w between rails.

Connections between more than two parallel tracks can be made by joining up single conections according to figure 11.17a, or by using diamond crossings with slips as shown in figure 11.17b. System(a) is used as much as possiblr on main lines.

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Figure 11.15: Types of crossings

Figure 11.16: Switch connection between two parallel tracks

Double cross-overs allow traffic from both directions to change from one route to the other. Figure 11.18 shows two solutions of this type.

Figure 11.17: Switch connection between more than two parallel tracks

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Figure11.18: Double cross-overs

Figure 11.18 gives a few more examples of crossovers. lf two parallel tracks are connected by means of a crossing which joins(=leag) four turnouts to the main tracks, this produces a scissors crossover as seen in figure 11.18c and figure 11.18d.

Figure 11.19: Crossovers

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Figure 11.19: Crossoyers Figure 11.20 shows an example of the switch and crossing layouts in Utrecht. This shows how complex these situations can be in practice and what immense problems of maintenance can result.

Figure 11.20: Switch layout in Utrecht

11.8 Switch calculation 11.8.1 Relation between curve radius and crossing angle Under switch calculation we understand here the determination of the most

important geometric measures.These are based on the admissible lateral acceleration a = 0,8m /s2 which was mentioned before. The connection between acceleration, speed, and curve radius is:

2va=R

(11.1)

Therefore the maximum speed can be calculated as:

max 2,79V R (11.2)

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with V[km/h] and R[m]. ln figure11.21 a normal right-handed turnout is drawn with a straight

crossing(=inim simpl cu ambele fee active n aliniament). lf we assume that the outer curve is tangent with the stock rail at the point of contact, which is approximately correct, it follows from figure11.21 that:

1 cosd R (11.3) in which: d = indicates transition point between curve track to straight track, depending

on constructional requirements; R = radius of curve part closure rail; = crossing angle.

Assuming

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for a straight crossing with R in [m]: 22,5R n (11.5)

for a curved crossing with R in [m]: 23, 4R n (11.6)

For the most common cases tables are used of the main dimensions of turnouts based on these calculations.The appropriate value of the maximum speed Vmax(11.2) is also mentioned.

These tables show that even with small crossing angles the maximum speed is relatively low. A speed of 120 km/h requires a curve radius of about 200 m which corresponds with an angle of ca. 1:25. Such turnouts are difficult to manufacture and the length of the turnout will be rather high.

A symmetrical turnout is used in case of symmetrically diverging tracks.The application in switch connections between parallel tracks is unfavourable because of the creation of S-curve situations. From figure11.22 it can be easily deduced that the angle between both tracks is only half-effective with respect to the curve radius. According to (11.6), the relation between radius and angle reads for a symmetrical turnout:

26,8R n (11.7)

This means that regarding equal angle the curve radius of a symmetrical turnout is twice that of a normal turnout. Of course, the maximum speed calculated in (11.2) applies to both tracks. The symmetrical turnouts 1:15 and 1:20, with radii 1200 m and 2000 m, can be utilised with speeds of 100 km/h and 125 km/h respectively.

Figure 11.22: Relation between turnout anqle and

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curve radius (symmetric turnout)

11.8.2 Calculation of main dimensions In figure 11.23 the double line drawing represents

- the straight track and - diverging track

of a normal right-handed turnout. As can be seen, the switch blade is retracted over a distance CD with respect to the theoretical contact point C. Moreover, the switch blade is not tangent with the stock rail at point D, but makes a small angle because it is not constructively possible to make a perfect tangent.

Figure 11.23: Calculation of curve radius and length of normal turnout Both straight and curved switch blades are used. In case of a curved switch

blade, the part a from D to the heel E is curved. In open position there should be enough space over the full length of the switch blade to allow a free passage of the wheel flange.This requirement determines the length of the switch blade.

The advantage of a straight switch blade, apart from (n afar de) its simple manufacture, is that the same design is used for left and right-handed turnouts. A curved switch blade requires less length and allows a larger curve radius. The full curve runs from E to F and ends at distance g before the theoretical point G of the crossing.

The following quantities depend on the dimensions of existing constructional parts and are supposed to be known:

= Crossing angle; = Angle of tangent line at the heel (point E);

s = Track gauge; e = Position of heel; g = Length of straight part before theoretical point G;

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p = Distance from front turnout to beginning of switch blade(point D); q = Disiance from beginning of crossing to rear of turnout; t = Length of switch blade (projection on stock rail). lt follows from figure 11.23 that:

cos cos sins e R g (11.8)

from which the curve radius can be determined: sin

cos coss e gR

(11.9)

The full length of the turnout can be calculated from:

sin sin cosL p t R g q (11.10)

Finally, the location of the mathematical point follows from: 1 1cotg2 2

MH s

(11.11)

The values of the quantities printed in the NS tables follow from the relations: B= MH+q

(11.12) A = L -B

Table 11.1 lists some switch types commonly applied by the NS with their main dimensions(NS = Cile Ferate Olandeze) .

Table 11.1: Survey of some common switches and crossings

Common turnouts

angle of intersection

construction

L [mm]

A [mm]

B [mm]

R [m]

V [km/h]

1:34,7 UlC54 with movable crossing 99332 36878 62454 2300 140 1: 15 UlC54 with curvedc rossing 47277 21221 26056 725 80

1 : 15 UlC54 with straight crossing 42706 1 6550 26056 600 70 1: 12 UlC54 with curved crossing 38320 17420 20900 465 60 1: 9 UlC54 with curved crossing 32185 14185 '18000 260 40

11.8.3 Geometrical design of switches and crossings In order that a switch and crossing layout can be manufactured, assembled,

and laid into a track, every part of it must be very accurately specified in dimensional terms, usually on a drawing. Scales of 1:100 are used for this purpose, and 1:50 or even larger scales may be used on occasions. lt is undesirable to attempt to scale off from even the largest scale drawing dimensions in order to achieve the necessary accuracy to obtain parts which properly fit together. Hence every line on the drawing must be defined by dimensions, and these must be confirmed by calculation. Only then can it be reasonably certain that the manufacturer will produce components

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which correspond with the engineers intentions. lt is to this end that it is necessary to define all layouts in geometrical terms.

Until recently, all this work had to be done by individual calculation, and, as a result, a substantial body of formulae has been developed over the years to make the task easier. Much of this technique has been made obsolete by ihe introduciion of Computer Aided Design CAD)

An example of such a program is TURN which is used by the TU Delft in combination with the FEM package ALGOR.

11.9 Production, transport and laying of switches Switches are prepared at the switch manufacturer. In figure 11.24 the

production of the middle of a crossover in concrete is shown. After preparation the switches will be transported to the definitive location

- either by car, ship - or by special switch transport trains.

At the building site the switches can be handled by special heavy rail cranes or cranes from the road. An alternatrve is the use of

- mobile gantries (= = macarale portal) on temporary rails - or mobile gantries(= = macarale portal) at retractable rail wheels. After the switch is installed and the several parts are welded together one or

more special tamping machines are used. The switch can now be connected to the signalling, heating and operation systems and tested for use.

Switches for trams and metros For metros and tramways the principle of a switch is the same as for railway

track. However, the following structural differences should be noted: - The curve in switches for trams and metros can be much lower by the lower speed and bogie distance, so the switch length is shorter - The switch can be integrated in the pavement of the road - The rail type can be different by the lower load and speed. - Sometime, switches for trams have no power or have simple engines; the blade will be moved by the tram wheels. - The switches are operated from the tram driver by signal, not from an operating centre - By tramways there are much more crossings at more different angles.

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Figure 11.24: Assembling of a crossover in concrete

- // -