04 Sistem Puli Dan Tali

8/17/2019 04 Sistem Puli Dan Tali

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MS 416 Pesawat angkat

,

Tito Shantika, Meng

Mechanical Engineering Department


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Komponen pesawat angkat pada

umumnya:

Perlengkapan Pengangkat Fleksible (misal Tali kawat

baja) Puli, Sistem puli, sproket dan Drum

Alat Penghenti (Rem)

Motor Pen erak

Sistem Transmisi (poros, bantalan, kopling dansebagainya)

e an a au ro a penggera Struktur atau rangka pesawat angkat


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Sistem uli


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Sistem Pull –Drums

W → berat beban & berat lower

block,

P → gaya pada winding drum

μ → loss coefficient.

Pada saat turun


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Part line


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Ro e forceIf n is taken as the number of parts of line supporting the load and m is the number of

180° turns taken by the rope between the upper block and the drum (turning angles

for each of the sheaves are added to find the number of 180° multiples), then

raising the load:

lowering the load:

s mp e


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Friction coefficient

4½% of rope load for a sheave mounted onbronze bushings to a low of as little as 0.9% for a

sheave on precision ball or roller bearings.

An arbitrary value of 2% is a reasonableapproximation for sheaves on common ball or roller

bearings when the rope makes a turn of 180°.


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exam le


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exam le


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exam le


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DRUMS AND SHEAVES


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Drums


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Fleet an le

When using a pivoted block, one must be sure that it is set close enough to

the drum to provide at least 1 ⁄ 2° of fleet angle in the maximum layover

pos t on. oo sma a eet ang e w cause t e wraps to p e up at t e ange

(particularly at low loading levels), whereas an adequate angle will guide

the rope away from the flange.


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Drum ca acit

-L→ is drum capacity [feet ]

- ,

-the spooling factor (s) → is taken from Table 1.1 or

calculated

- d → as the actual rope diameter.-Table 1.1 assumes new rope and includes a rope

diameter oversize factor of 5%.


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S oolin factor


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maximum uantit of ro eThe first case involves the maximum quantity of rope

a can e s ore on a rum w en e o s s no n

operation. Dimension C is taken as zero (Maxcapascity

The second case is used to determine the

maximum uantit of ro e that can be s ooled

onto the drum of an operating winch. C is taken

as ½ in (12.7 mm) or preferably as one rope

diameter, and

The third case is used to estimate the quantity

of rope found on a drum.


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Line PullHoist drums are rated b line ull the tension the drum is ca able of a l in to a

rope leading onto it) and by line speed.

T→ rated torque

r→ ne pu on e rs ayer,

D→ Dia. Drum

d → rope diameter.

for a system with nominal rope diameter d and with consistent dimensional units. The

usable line pull Pu

at any other drum layer is found from


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drum s eedω

& line s eed V

t e rum spee ω in revo utions per minute is given y

ω → drum speed [rpm]

Vr → rated first-layer line speed [feet per minute]

D → drum dimensions [inches]

d → rope diameter [inches]

The line speed V u at any other rope layer


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Sheaves Sheaves are used to chan e the direction of travel of wire

ropes. Assembled in multiples, in the form of blocks, they are

able to provide almost any required mechanical advantage.

Sheaves rotate about their mounting sha ts on bushings or

bearings. A reasonable value for friction loss at bushings can

be taken as 41 ⁄ 2%, while bearings produce losses of 1% to2%, depending upon their quality and the conditions of

service. These losses are rough average figures for ropes

°

for smaller turning angles. Actual friction losses are a function

of the style of rope, the ratio of sheave to rope diameter, and

t e earing type.


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Service life

curve


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The ratio of the relative ro e lives Lr

where r1 and r2 are the D/d ratios being compared and Lr is the ratio

of the relative rope lives.


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Blocks


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TERIMAKASIH

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04 Sistem Puli Dan Tali