5211 5215.output

* GB785618 (A)

Description: GB785618 (A) ? 1957-10-30

Improvements in or relating to thermostatic devices

Description of GB785618 (A)

COMPLETE SPECIFICATION. Improvements in or relating to Thermostatic Devices. We, THE BRITISH THERMOSTAT COMPANY LIMITED, a British Company, of Teddington Works, Windmill Road, Sunbury-on-Thames, Middlesex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to thermostatic devices in which the movements of the operated member, which may be a valve, switch or the like, are effected by the thermal expansion of liquid in a charged system consisting of a flexible capsule of either the bellows or diaphragm type arranged to act on the operated member and communicating through a capillary tube with a phial or bulb which is subjected to the temperature to be controlled. In thermally sensitive systems of this kind it is essential to provide some means for counteracting the effects of the head temperature, i.e. the temperature of any heat acting on the liquid that is contained within the capillary tube and the capsule, in order that the operated member shall respond accurately to variations in the temperature at the phial and thereby maintain accurate control of this temperature. One known method of counteracting the effects of the head temperature is to transmit the movements of the capsule to the operated member through the intermediary of a hi-metallic element responsive to the head temperature. Such an arrangement is not entirely satisfactory, however, because of the inability of the bi-metallic element to develop high torque values for small temperature variations. For example, a bimetal that is selected to give a relatively large deflection has to be made from relatively thin material because of the

limited space available inside thermostatic devices, with the result that the element is not rigid enough to cope with variations in the load, due to friction and the like, from the operated member. The object of the present invention is to provide improved means for compensating for the effects of head temperature in a thermally sensitive system of the kind referred to. According to the invention, in a thermostatic device having a thermally sensitive system of the kind referred to, the expanding movements of the capsule are transmitted to the operated member through the intermediary of a spring of sufficient stiffness to overcome any load from the operated member, and an additional capsule charged with liquid and subjected to the head temperature is arranged to act on the operated member independently of the main capsule and against the opposition of said spring, said additional capsule being movable with the main capsule but expansible relatively thereto in response to an increase in the head temperature so as to adjust the operated member, against the resistance of said spring, relatively to the main capsule and in the reverse direction to that of the movement of the operated member by the expansion of the main capsule. According to a further feature of the invention the spring acts as an overload device to protect the system against damage if the liquid therein continues to expand, due to temperature conditions at the phial, when the movement of the operated member is arrested, for example by the valve seat if the operated member is a valve, The compensating capsule is preferably of the bellows type and is so designed that its movement/temperature characteristics are directly proportional to its length but independent of its diameter. This is achieved by providing the capsule with flat, rigid end-plates so that the contained volume is dependent only on the form and dimensions of the bellows of the capsule. The extension of the capsule is then derived from the sum : - expanded volume transverse area i.e. expanded length X transverse area transverse area and the transverse area therefore has no influence on the capsule's movement/temperature characteristics. Thus, the diameter af the bellows does not have to be determined within fine limits such as are compulsory in liquidexpansion systems that have additional sensitive capacity in the form of a phial or a length of tubing for compensating for the effects of head temperature. The spring which opposes the expansion of the compensating capsule and through which the expanding movements of the main capsule are transmitted to the operated member (which spring will be hereinafter referred to as "the intermediate spring") is arranged to maintain the liquid in the compensating capsule under a pressure substantially the

same as that obtaining in the main capsule. A variation in the degree of compensation can be achieved by charging the compensating capsule to a different initiaI length aril/or selecting a liquid with a different coefficient of expansion. An embodiment of the invention will now be described with reference to the accompanying drawings of which the single figure shows a sectional elevation of a combind gas cock and valve assembly incorporating the compensating means according to the invention. Referring to the drawing, a gas supply cock I of the rotary plug type is mounted in a casing 2 having an inlet passage 3 adapted to be connected to a main gas apply and an outlet passage 4 adapted to be connected to the gas burners in an oven. Communication between the said inlet and outlet passages is controlled by the plug cock 1 and by a valve member 5 movable towards and away from a normally fixed but adjustable seating 6 by the operation of a flexible metallic bellows device 7 connected in known manner by a capillary tube 8 to a thermally sensitive phial 9 disposed adjacent the burners. The bellows, tube and phial form a closed system charged with a liquid whose expansion under heat causes the bellows 7 to expand and move the valve member 5 towards its seating 6. Adjustment in the position of this seating varies the temperature range of the apparatus, that is to say, it will raise or lower the temperature at which the gas supply to the burners will be reduced or cut off. The mechanism provided by the present invention for adjusting the position of the valve seating 6 will now be described. The adjustable seating 6 is formed at the lower end of a cylindrical element 10 slidably mounted in a vertical cylindrical passage 11 forming a communication between the inlet and outlet passages in the casing, a by-pass passage 12 being provided between the cylindrical passage 11 and the outlet passage 4 to prevent the burner flames being extinguished when the valve member 5 is seated. The cylindrical element 10 is connected to the lower end of a trimming rod 13 extending vertically in a position offset from the axis of the plug cock 1. The upper end 14 of the trimming rod is bent at right angles and passes through slots in a main range screw 15 which immediately surrounds the rod and in a sleeve 16 disposed rotatably around a cylindrical casing extension 17 through which the trimming rod 13 passes axially and in which the main range screw 15 has screw-threaded en=,age- ment. The exterior of the rotatable sleeve 16 carries an operating knob (not shown). Rotation of this knob is communicated through the upper bent end 14 of the trimming rod 13 to the range screw 15 which is also turned carrying the rod and adjusting the valve seating 6 to vary the closing position of the thermostatically controlled valve 5 In the embodiment

shown, the upper end of the cylindrical element 10 is separate from the lower end of the trimming rod 13 and is urged to follow its movement by a spring 18 acting on the seating 6. The bellows 19 acts as a sealing member between the fixed and moving parts. In order to compensate for errors in position of the valve head 5 caused by varying temperatures at the lower end of the device use is made of the compensating arrangement now to be described. The main capsule in the form of bellows 7 is provided at its movable or free end with a flanged cup 20 in which the intermediate spring 21 is disposed. The spring extends beyond the flanged rim of the cup 20, which rim is fixed to The end of the bellows wall of the main capsule, to engage the base of a U-shaped member 22 within which the compensating capsule 23 is located. Fixed across the open top of the U-shaped mem 22 ?g? is a bridge piece 25 to which the operated member, i.e. valve element 5, is connected. The compensating capsule, which is also of the bellows type but is self-contained, is arranged coaxially of the main capsule, and at its end remote therefrom is anchored to the centre of a yoke member 24 which passes freely through the Ushaped member 22 substantially at rightangles thereto. The yoke member 24 is formed with flanged ends that are held in contact with the flanged rirn of the cup 20 on the main capsule by the latter's return spring, i.e. the spring 18 which acts through a sliding guide member 26 and is provided to oppose the expanding movements of the main capsule, so that the compensating capsule 23 moves bodily with the free end of the main capsule in both directions. The free end of the compensating capsule 23 bears on the base of the U-shaped member 22 against the opposition of the intermediate spring 21, and the arrangement is such that the liquid in the (closed) capsule 23 is maintained by the spring at the same pressure as that obtaining in the main capsule. In operation, the movement of the free end of the main capsule 7 due to a rise in temperature at the~ phial 9 is transmitted through the intermediate spring 21 to the U-shaped member 22 and thus to the valve element 5, the spring being of sufficient stiffness to overcome any load that may reasonably be expected from the valve element, such as the load caused by frictional resistance to movement thereof. The movement of the main capsule is also transmitted through the yoke member 24 to the compensating capsule 23 and there is thus no charge in the relative positions of the various parts of the compensating assembly. If the head temperature now increases, the main capsule will be extended further by a ccrresponding amount. The compensating capsule will be simultaneously extended by the same amount in the opposite direction, however, and thereby act on the U-shaped member 22

independently of the main capsule, and against the opposition of the intermediate spring, to maintain the position of the valve element 5 constant in relation to its seating 6. To permit this relative extension sf the two capsules, the yoke member to which the compensating capsule is anchored, and which moves with the free end of the main capsule, is free to move axially in the U-shaped member. If, as a result of temperature conditions at the phial 9, the main capsule continues to expand when the valve element is fully closed and is thus, together with the Ushaped member 22, Drevented from further movement, the intermediate spring 21 a'osorbs flits continued expansion and the yoke member 24 moves the compensating capsule away from the base of the U-shaped member. There is thus no danger of any damage being inflicted on the system by such over-expansion. In order that the operation of the return spring 18 shall not be affected in any way by the intermediate spring 21, even when the latter is under increased compression due to the expansion of the compensating capsule, the return spring is made with a load value in excess of that of the intermediate spring. The actual load value of the spring is determined from the ratio of the transverse area of the main capsule to that of the compensating capsule, multiplied by the load of the intermediate spring. As this ratio can be approximately 5 to 1, there is thus no danger of the intermediate spring interfering with the operation of the return spring. What we claim is : - 1. A thermostatic device having a thermally sensitive system of the kind referred to, in which the expanding movements of the main capsule are transmitted to the operated member through the intermediary of a spring of sufficient stiffness to overcome any load from the operated member, and in which an additional self-contained capsule charged with liquid and subjected to the head temperature is arranged to act on the operated member independently of the main capsule and against the opposition of said spring, said additional capsule being movable with the main capsule but expansible oppositely thereto in response to an increase in the head temperature so as to adjust the operated member, against the resistance of said spring, relatively to the main capsule and in the reverse direction to that of the movement of the operated member by the expansion of the main capsule. 2. A thermostatic device as claimed in Claim 1, in which the spring acts as an overload device to protect the system against damage if the liquid therein continues to expand, due to temperature conditions at the phial, when the movement of the operated member is arrested, for example by the valve seat if the operated member is a valve. 3. A thermostatic device provided with temperature compensating means

substantially as described with reference to the accompanying drawing.

* GB785619 (A)

Description: GB785619 (A) ? 1957-10-30

An improved electrical relay device


PATENT SPECIFICATION Inventors: SAMUEL NEVILLE SHAW MEB and EDWARD HARRY ATTENBURROW 785619 Date of filing Complete Specification: Feb 8, 1956. Application Date: Feb 24, 1955. No 5565/55. Complete Specification Published: Oct 30, 1957. Index at acceptance:-Class 40 ( 4), F 9 (C: J). International Classification:-HOE 3 f COMPLETE SPECIFICATION An improved Electrical Relay Device We, PA Rm Em O LIMITED, a British Company, of Parmeko Works, Percy Road, Aylestone Park, Leicester, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention appertains to electrical noncontact making changeover relay devices, and glas reference particularly to such devices of the class having two interconnected circuits each incorporating a signal receiving element and in which the acceptance of a signal by one element causes one of the two circuits to be operative and the other inoperative, whereas upon reversal of the polarity of sudh signal at the start of the said eleinent or the transference of the same signal to the other element the operative circuit becomes inoperative and the previously inoperative circuit is rendered operative. In using a relay of the class referred to, transference of signals to and fro between the accepting elements can be effected either at will, or automatically, e g in response to any appropriate external conditions, and the output from each of the two interconnected circuits in the operative condition can be used to operate a warning or signalling device, such as a lamp, or can be amplified for

actuating solenoids, electromechanical devices, and so on, according to requirements. The objeczt of the present invention is to provide an improved relay device olf the class referred to, as will be hereinafter described. The relay device according to this invention includes two auto-excited transductors, each having two A C output windings, two rectifier elements for effecting the auto excitation, a single cut-off winding and a single control winding, the said control windings being so arranged that a signal from a D C source can be fed into either of them, the transductors being generally so interconnected that a proportion of the output power of one is fed into the lPrice 3 s 6 d l cut-off winding of the other, depending onil which control winding accepts a signal, and the arrangement being such that the acceptance of a signal by either transductor causes the output of this same transductor to, be at a minimum and the output of the other transductor to be at a maximum, and that the output of the last mentioned transductor can be caused to be at a minimum whilst the output of the first mentioned transductor is at a maximum, either by transferring the said signal from the control winding of the first mentioned transductor to the other control winding or by reversing the polarity of the signal at the start of the control winding of said first mentioned transductor, and vice versa. The electrical connections of a relay device incorporating this invention are shown in the accompanying drawing, in which the two transductors are denoted A and B In this drawing the A C output windings of transductor A have been designated 1 and 2, its auto-exlcited rectifier elements 3 and 4, its single cut-off winding 5, and its single D C. control winding 6 In the case of transductor B there are A C output windings 7 and 8, auto-excited rectifier elements 9 and 10, a single cut-off winding 11 and a single D C. control winding 12. Eadh of the D C output windings of one trans'ductor (e g winding 1) is connected at one end to the associated rectifier element (e.g 3) and at the other to one end of the single cut-off winding (e g 11) of the other transductor Centre tappings 13 and 14 are taken off the windings 5 and 11 respectively and these tappings are connected in parallel to one pole of an A C supply, the other pole of which is branched to the loads (e g lamps) and 16 associated respectively with transductors 1 and 2 As will be observed, the output connections from rectifier elements 3 and 4 are connected in parallel to the line incorporating load 15, and similarly with the rectifier elements 9 and 10 and load 16. SO The operation of the device is, therefore, such that when the

positive of a D C signal is applied to the start S of the control winding of either transductor and the signal is accepted by that winding the output of the same transductor will be reduced to a minimum as a consequence of which the proportion of this reduced output which is fed into the cut-off winding of the other transductor will be commensurately reduced to a minimum Now since it is a characteristic of each of the transductors incorporated in the improved relay device that the output thereof is at a maximum when no signal is applied at its control winding, or the negative of a signal is applied to the start S of said winding, and no current is accordingly being fed into the cut-off winding of the same transductor, it follows that the output of the other transductor will rise to its permitted maximum Thus, referring to the drawing, when the positive of a D C signal is applied to the start S of the control winding 6 of transductor A and the signal is accepted by the said winding the output of A will be automatically reduced to a minimum, whilst the output of transductor B is simultaneously caused to rise to a maximum Conversely, if and when the same D C. signal is removed from the terminals of the control winding 6 and is transferred to the terminals of the control winding 12 of the transductor B, with the positive of the signal applied to the start S cif the winding 12, then the output of B will be reduced to a minimum and the output of A will rise to a maximum. Instead of transferring the signal from the control winding 6 to the control winding 12 in the manner just described, precisely the same result can be achieved by reversing the polarity of the signal applied to the winding 6, that is to say by applying the positive of the signal to the finish F instead of the start S of the winding 6. Similarly, when the positive of a D C signal is applied to the start S of the control winding 12 of transductor B and the signal is accepted by the said winding the output of B will be automatically reduced to a minimum whilst the output of the transductor A is simultaneously caused to rise to a maximum If and when the same D C signal is removed from the terminals of the control winding 12 and is transferred to the terminals of the control winding 6 of the transductor A, with the positive of the signal applied to the start S of the winding 6, then the output of A will be reduced to a minimum and the output of B will rise to a maximum Here again, instead of transferring the signal from the control winding 12 to the control winding 6, the same result could be achieved by applying the positive of the signal to the finish F instead of the start S of the winding 12. As will be aunreciated, with the improved relay in operation neither of its two interconnected magnetic circuits are at any time actually broken; but when the output of either transductor is reduced to a

minimum the output circuit of this transductor can for all practical intents and purposes be regarded as being inoperative Thus, for instance, if the outputs from the transductors are used to light lamps, then the lamp which is connected at any given time to the transductor whose output at that time is reduced to alninimum as aforesaid will not emit any light, albeit that A.C current is still flowing through the filament of the lamp-the reason being that the value of this current is too small even to cause the filament to glow It is only when the A C output of the same transductor is caused to rise to its maximum that the lamp will light up. Moreover, when once the output circuit of, for example, the transductor A is at a maxi 85 mum and that of the companion transductor B is at a minimum the continuing presence of A.C current in the interconnected magnetic circuits will maintain these conditions even if the D C signal which initiated them is 90 removed from the control winding 6 of the transductor B And these conditions can then only be reversed, to render the output circuit of the transductor B a maximum and that of the transductor A a minimum, either by apply 95 ing a D C signal to the control winding 6 or by reversing the polarity of the signal applied to the control winding 12. Any appropriate method of feeding a proportion of the output power of either trans 100 ductor into the cut-off winding of the other as aforesaid may be adopted In performing this in the preferred embodiment of the invention illustrated, the connections of the cut-off windings are such that the D C currents flowing 105 in the A C windings of either transductor act as control currents in the other transductor. This represents an important and advantageous feature in that it reduces the components incorporated in the improved relay to 110 a minimum. A D C signal applied to the control winding of a transductor may be in the form either of a single pulse of short duration or of a train of pulses The D C input may be de 115 rivedfrom a battery, from the anode circuit of a thermionic valve or from the output of a suitable rectifier supplied with A C The electrical non-contact making changeover relay of this invention will function on very 120 low input wattages-in the order of llt W. On the other hand the outputs of the two transductors may be fed into the control winding of a magnetic amplifier designed to supply higher powers to any appropriate apparatus 125 The windings of each transductor may advantageously be toroidally wound on a spiral core. The improved relay may, if desired, be permanently embodied in a suitably moulded one 130 785,619 785,619 piece casing, for example one made of a polyester resin In any event, the size of the magnetic relay

of this invention will generally be about the same as, and need not be larger than, the equivalent electromechanical relay. The particular non-contact making changeover relay herein described would be eminently suitable for the control and operation of, say, green and red indicating lamps in any circumstances wherein the green lamp is normally alight to indicate that a process, machine, apparatus or the like is functioning properly and wherein it is desired that the green lamp shall be extinguished and the red lamp lit up, in the event of abnormal functioning or failure of the said process, machine or apparatus In such a case the development of the abnormality or failure would effect, or at least initiate, a transference of the D C signal from one control winding to the other. For convenience, the D C input lines to the two control windings may be three in number, viz a common centre line and two outer lines Thus, the centre line and one of the two outer lines provides one pair of lines to receive D C signals for acceptance by the appropriate one of the control windings, whilst the said centre line and the other outer line provides what is, in effect, another pair of lines to receive signals for acceptanice by the companion control winding.

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* GB785620 (A)

Description: GB785620 (A) ? 1957-10-30

Improvements relating to fluid pressure braking systems for road vehicles


PATENT SPECIFICATION Date of filing Complete Specification: March 8, 1956. Application Date: March 8, 1955 No 6743155.

Complete Specification Published: Oct 30, 1957. Index at Acceptance:-Class 103 ( 1), E 2 G 1, F 1 Bi. International Classification:-B 61 h B 62 d. COMPLETE SPECIFICATION. Improvements relating to Fluid Pressure Braldng Systems for Road Vehicles. We, WESTINGHOUSE BR Ax E & SI Ga TAI COMPANY LIMITED, a Company incorporated under the laws of Great Britain, and ARTHUR W A Mrira SM Mo Ns, a Subject of the Queen of Great Britain, both of 82, York Way, King's Cross, London, N 1, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to fluid pressure braking systems for road vehicles of the kind in which brakes are operated by compressed air or vacuum under the control of a pedal operated control valve which, to release the brakes, places the brake cylinders in communication with a passage, herein referred to as an exhaust passage, through which air passes to or from the brake cylinders in order to release the brakes Such brakes are herein termed air brakes and it is to be understood that this term includes both those controlled by compressed air and those controlled by vacuum. It is sometimes desirable that vehicles, especially heavy vehicles, equipped with air brakes controlled in normal manner by means of a foot pedal and with mechanically operated hand brakes, should be provided with means for increasing the power of the hand brakes when, for example, starting from rest on a steep hill when both feet of the driver are engaged with the operation of the accelerator and clutch pedals and the vehicle has accordingly been prevented from moving back by the hand brake. In an attempt to solve this problem, it has previously been proposed to utilise the air supply and the cylinders of the air brake, and to provide a separate control valve, operated by the hand brake lever, with a lPrice 3 s 6 d l double cheek valve to connect it to the normal power system. It has also been proposed to provide the 45 hand brake with an isolating valve in the pipe line from the normal control valve to the brake cylinders, together with a by-pass cheek valve in parallel with the isolating valve 50 Both of these arrangements are expensive and need connections to the air brake system and the addition of piping and valves provides additional points of possible leakage and further pieces of apparatus which may fail 55 According to the invention an additional valve is provided interposed in the exhaust passage of the pedal operated valve and controlling communication between this

passage and the external atmosphere, this additional 60 valve being normally open and arranged to be operated to its closed position by the driver of the vehicle so as to close the exhaust passage and thus prevent the release of the air brakes. Preferably the closure of the additional valve is arranged to be effected by the operation of the hand brake lever so that the valve remains closed for all braking positions of this lever 70 Alternatively the additional valve may take the form of a simple cock operated from the vehicle dashboard or other suitable point. It will be seen that by this arrangement 75 there is no modification made to the normal air brake system, and therefore no additional risk of leakage Furthermore, failure of the additional valve cannot prevent the satisfactory application of the normal air brake 80 The method of operation is simple The vehicle can be stopped on a hill by means of the air brake, in the usual manner by operating the pedal operated control valve. 785,620 The hand brake may then be applied and the driver is then able to release his foot brake pedal without releasing the air brakes and has both feet free for the operation of the clutch and accelerator for starting, the air brake being graduated off at will by means of the hand brake lever. The accompanying drawing is a view in longitudinal section illustrating a preferred construction of the additional valve of the invention. Referring now to the drawing, it wil I be seen that the valve comprises a casing or body 1 in which is slidably mounted an operating rod 2 the end of which projecting beyond the casing 1 is screw-threaded and carries a cross-head 4. Adjacent to the opposite end of the casing an exhaust chamber 5 is provided communicating with the external atmosphere through a port or passage 6 An internal partition 7 separates the chamber 5 from a chamber 8 in open communication with the exhaust of the pedal control valve of the braking system through a port or passage 9. A valve seat member 10 having a seat rib 11 is mounted in the partition 7 and the reduced end 12 of the rod 2 passes through the interior of the seat member 10 as shown. A valve member 13 is located in an extension of the chamber S and is provided with an annular leather or rubber packing 14 and a controlling spring 15. The cross-head 4 is mechanically coupled in any suitable manner to the hand brake lever so that when the latter is in its release position the parts of the valve occupy the position shown, the valve member 13 being held off the valve seat rib 11 against the opposing action of the spring 15 by the rod 2 the end 12 of which engages with the head

16 of a short bolt holding the packing 14 in position in the valve member 13 The position of the operating rod 2 can be adjusted by rotating the cross-head 4 and securing the latter by a locking nut 17. It will be evident that under these conditions the exhaust port or passage 9 is in free communication with the atmosphere through the port or passage 8 and the air brakes can thus be released in the normal manner. When, however, the hand brake lever is moved to a braking position the rod 2 is moved by the cross-head 4 to withdraw the reduced end 12 of rod 2 from engagement with the bolt head 16 of the valve member 13 and the latter is -then free to move into engagement with the valve seat member 10, the packing 14 seating on the rib 11 thus cutting off communication between the chambers 5 and S so as to shut off the exhaust port 9 from the atmosphere. The pedal of the air brake control valve can thus be released by the driver without causing release of the air brake which will remain applied until the additional valve is reopened by releasing the hand brake lever. This release of the air brake can evidently be graduated if necessary by intermittently operating the hand brake lever to its release position. In an alternative arrangement the additional valve may be constituted by a simple hand operated valve or cock having the means to operate it by hand mounted on the dashboard or other position convenient to the driver. It will be seen from the foregoing that the invention provides a simple and inexpensive means for controlling the release of the brakes of a compressed air or vacuum braking system by hand without impairing the efficiency of the system and without increasing the risk of leakage in the system. so


* GB785621 (A)

Description: GB785621 (A) ? 1957-10-30

Improvements to filtering network


PATENT SPECIFICATION 7859621 tg illi A Date of Application and filing Complete Specification: March 15, 1955. No 7559/55. Application made in France on March 19, 1954. Complete Specification Published: Oct 30, 1957. Index at acceptance:-Classes 40 ( 5), L 26 H; and 40 ( 8), U( 2 A 2 A: 3 C: 4 C: 12 F). International Classification:-H 03 h H 04 c. COMPLETE SPECIFICATION Improvements to Filtering Network We, Socii TL NOUVELLE DE L'OUTILLAGE R.B V ET DE LA RADIO-INDUSTRIE, 43-45, Avenue Kldber, Paris 16 eme, France, a Body Corporate organised according to the laws of France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to the realisation of filtering networks of transfer characteristic of the type G((o) such that A sin a(Q-w 0) G(-) = a(a-EO ) where A and a are parameters independent of the frequency f O of the incoming signal lf O r = -l 27 r assuming that f O may take any value including zero The use of such filtering networks is very wide Indeed they can be used each time that it is necessary to develop a transfer characteristic of the type G(w) since they may operate in a very wide band of frequencies from video frequencies (f = 0) up to ultrahigh frequencies and hyper-frequencies as will appear later on This wave shaping may be required either at the transmitting end or at the receiving end of a transmission channel. Considering the use of such circuits at the receiving end, some results of the information theory should be recalled to point out the advantages which are provided by the use of circuits according to the invention in detecting incoming, pulses which are mixed up with noise signals Indeed, it is well known that the best conditions to detect such signals when the noise is supposed to show a random distribution in all the frequency spectrum, is to use a receiver the gain or transfer characteristic of which is conjugated with the information

through a Fourier transformation Function G(w) may be shown to be the Fourier transformation of a sinusoidal oscillation at frequency f, which is modulated by a rectangular pulse of duration 2 a Since this function is real, it is its own conjugate This shows that the filters according to the invention are the best circuits to detect recurrent pulses which are received together with a randomly distributed noise signal Such a problem has a very large technical application since it corresponds to the problem of reception in most of the pulse type telecommunications at fixed carrier frequency, and also to all the pulse detecting systems such as radar. The description which follows is mainly directed to the use and embodiment of the filter according to the invention when applied to the reception of pulses However, this choice of one particular type of utilisation of the filters according to the invention should not be considered as a limitation of its scope of application Indeed, the filter according to the invention is also very useful when used to operate on video signals, that is rectangular pulses which do not modulate any carrier wave. Such filters may be used indeed as aperture correcting means in pulse transmitters or receivers. It is therefore an object of the invention to provide a filtering network the transfer characteristic of which is of the type. A sin a (w-(,) G(-) = a It is another object of the invention to provide means whereby a filtering network of transfer characteristic A sin al(w-o)-) G(-) = a may be obtained by combination of lumped or distributed impedances. It is another object of the invention to pro2 785,621 vide means for the realisation of a circuit, the transfer function is of the type A sin a ( 4-wo) G(-) = comprising a limited number of circuit elements. It is another object of the invention to provide means of realisation of a filter of transfer characteristic A sin a (o,-coo) G(o) = a (w 0-o) in which f O =-may take any particular value 2 z T including zero. According to the present invention we provide a filtering network of transfer characteristic A sin a (w-tow,) G(a) = a (where A and a are parameters independent from the pulsation W and wo is a constant such K 2 nz that W where N is an integer and K a is an integer > O comprising elementary cells in series connection, each cell comprising at least a delay line, a direct connection in parallel with said delay line and an additive network for the direct and the delayed portions of the signal, the delays introduced by the different cells being chosen so as to constitute a geometric series of decrement -2, the largest delay introduced by any one of the cells being equal to parameter a.

Preferably an amplifier stage is provided between successive cells. According to another embodiment of the invention, the coupling element between cells comprises an additive stage which provides the direct connection and which is connected in parallel with the delay line. In other embodiment of the invention, amplification may be provided at the output of each cell or of some of the cells or at the end of the filtering network. According to another feature of the invention, the band-pass filter associated to the cells may be constituted by several elementary bandpass filters connected separately to individual cells and showing different characteristics versus frequency It may also be included in the source of input signals when such a source comprises a pulse receiver the pass-band characteristic of which is of course limited. As is well known from the theory, the transfer characteristic of the filtering network is the product of the transfer characteristic of each of its constitutive cells Such a product is of the algebraic type and therefore, it is possible to change the order of succession of the different cells which constitute the filter from the normal sequential order of terms of the series of decrement -i- This is also the reason why it is possible to constitute the passband filter associated with the elementary cells as several elementary filters where such a possibility is preferred from the technical point of view. To fully understand the operation of the filter according to the invention, it is necessary to recall some well known mathematical results. Curves A and B of figure 1 of the accompanying drawings show respectively a rectangular impulse as a voltage amplitude versus time, and the Fourier transformation of such a signal as amplitude versus frequency f or pulsation W (with W= 2 Ar The mathematical expression of impulse A in terms of the time t may be written as: A = lU(t + a) U(t a) exp I outl =A(t) ( 2) where U(t) is Heaviside's impulse function, 2 a is the pulse duration and o) the pulsation of the carrier wave of frequency f E The Fourier transformation of function Aft) is given by G(w) with sin (s-to)) a G()) = K ( 0)-0)o) a ( 3) 80 Function G(w) may also be written as follows: G(O) = Y Kl lcos (t,) a/2 l lcos (t-o)a/4 l sin (w-w 0) a/2 " .lcos ( o),a/2 "l l (S-so) a/2 ( ( 4) When N becomes infinite the product of equation 4 is convergent and therefore, it is possible to write G(o)n-=K lco S a/2 ( lcos ( 5-)) a/4 l lcos a/16 l lcos (o-w) a/2 "l ne-oc ( 5) If identity 5 is limited to a finite number of terms, the 'limited product gn( 0)) is no longer identical to Goo) However, in a limited range of variations of the variable ( 0-o) around (o, gn( 0)) is all the more near to G(Lo) that the number of terms of the product of cosine is greater Accordingly, if N terms are considered n being

finite, and representing the number of cells which constitute the filter network, the limited product 78,5,621 785,621 g.(,) = D cos (o-w 0) a/2 cos (w-o) a/4 cos (-) a/2 ( 6) may be taken instead of G(H) in a frequency periodical function of w, the period being ( O band around f, = -. 27 r T= a This function is an even function K 2 n of (w-o) Curve C of figure 1 is representaThe right end part of equation 6 is a tive of function g,,(w) such as g,,(w) = 2 cos (w-co 0) a/2 cos (w-wo) a/4 cos (w-w) a/8. ( 7) Around w-oj, curve C is very near curve B. 8 The periodicity of curve C is F= and the a frequency interval between a maximum and 4 the adjacent minimum is df=-. a Figure 2 is a schematic diagram of an elementary cell constituting the filter according to the invention E shows the input of the cell. Lead 1 shows the direct coupling between input E and the additive circuit 3 which feeds output S 2 is the elementary delay line The filtering network is supposed to comprise n such elementary cells The delays introduced by successive elementary delay lines such as 2, constitute a geometrical decreasing series of decrement the longest delay being equal to a The output signal developed at terminal S feeds a band pass filter tuned at frequency f, or an harmonic of f L As will be understood, this filter may be connected to any other elementary cell of the type shown on Figure 2, the elementary delay line 2 of which introduces a a a delay where p-1 <n if is the shortest 2 P t 2 n delay of any cell of the network (p relating to the pth network, and being an integer whose value lies between 1 and n, according to the cell being considered). Figure 3 shows a filter incorporating three elementary cells The output band-pass filter is shown at 4. It is easy to show that the transfer characteristic of the circuit made of a set of elementary cells such as shown on Figure 2 is of the form g(w) which has been referred to above. Let A(t) be the input signal applied at E of the elementary cell of Figure 2 The output signal from delay line 2 may be written as A, = A(t) expj -a/21 ( 8) assuming that this cell is the (n-1)th. The output signal from the elementary cell is given by 51 =,A(t) ( 1 + expjwa/2 n-1) ( 9) = A(t) ( 1 + cos a/2 ' + j sin a/20-1) ( 10) The transfer characteristic of the elementary cell is thereby given by St gm-, ((') = A(t) gn-1 (-) = ( 2 cos t a/20) expjpv sin x a/2 n-1 tan o = =tan a) a/2 " 1 + cos (o a/2 n-1 ( 11) ( 12) ( 13) 55 The transfer characteristic of a set of three elementary stages such as shown on Figure 3 is given by: (na wa wa woa g,(-)=( 2 cos o a/2) ( 2 cos W a/4) l 2 cos-expj'(- -±)l 8 2 4 8 ( 14) since the successive delays introduced by the elementary

delay lines constitute a geometrical series of decrement - When the input signal A(t) is a rectangular pulse such as shown by curve A of figure 1 and if the carrier wave 2 'n K frequency f is such that f = where K is a an integer, the carrier wave amplitude of the output signal from each elementary cell will be in phase at the maximums and minimums of the representative curve as explained above (see curve B and C of Figure 1 in the vicinity of W = % or w=nwo,). K 2 n The condition f O = corresponds to a values of ao) such that the terms in cosine of the equation sin (w-woo) a G(-)=' for t=uto are simultaneously equal to + 1 or -1 Therefore, at frequency f of the carrier wave, each -one of the terms of the product must be either minimum or maximum This condition may be written by reference to equation ( 14): C 03 a W O a oa -=-+ 2 k-r =-2 k'sr 2 4 8 k a In other words, the carrier frequency should be a multiple of the reciprocal of the shortest delay (a/8) introduced by one of the elementary cells of the filter network Assuming that a is known it is easy to fulfill this condition, by heterodyning the input signal with a local oscillator of correct frequency When the filter is such as shown on Figure 3, that is when the filter comprises three elementary cells, the transfer characteristic of the circuit is equation ( 14) The filter is connected to a band pass filter 4 which transmits only the output signal frequencies which surround frequency f or another maximum or minimum of curve C of Figure 1 The dashed line on curve C shown by reference 4 corresponds to the band pass characteristic of output filter 4 of figure 3. It may be seen that each time another elementary cell is added to the filter, another cosine term is added to the transfer characteristic equation In other words, the frequency interval df between two successive maximums of the representative curve of the transfer function g(w) is multiplied by 2 This remark will help in designing filter 4 It is also easy to show that the output energy transmitted through pass-band filter 4 is increased approximately by the same factor 2 Therefore, it is possible to decide how many cells will 'be used to obtain a given energy at the output of the filter. Figures 4, 5 and 6 show detailed wiring diagrams of embodiments of the invention designed for reception of pulses, the duration of which ( 2 a) is equal to pus at a carrier frequency f of 16 Mcs These numerical values have been chosen because they correspond to actual realisations but do not constitute any limitation to the scope of application of the filters according to the invention Of course, owing to the fact that the total delay of the elementary cells is at most equal to the pulse duration, the input signal which may be applied to the circuits according to the invention should have a recurrent periodicity smaller

than the pulse duration. The reference numbers on Figure 4 are the same as the one used on Figures 2 and 3 The delay line introduces a delay a= 0 5,us. In a particular embodiment of the invention the line is made of an artificial line comprising 60 identical cells made of a coil of inductance L = 4 9 j JH and a condenser of capacity C= 25 p F The mutual inductance between two adjacent turns of the coil is approximatively 0 09 p H The total inductance of the 65 line is 250 AH; the characteristic impedance is equal in value to the resistance of terminal resistors R that approximates 530 ohms The complete/elementary delay line of forty cells is placed on an insulating plate of 30 centi 70 meter length As shown, the delayed signal delivered by the line is applied to the control grid of valve V, The input signal is transmitted, through attenuator R 11 which provides the same attenuation as the delay line so that 75 the peak levels of both signals should be equal, to the control grid of a second valve V 2 Addition of these two signals is obtained by connecting the plates of valves V 1 and V 2 in parallel The output signal is applied by means 80 of coupling condenser C, of high capacity to the following stage of the filter shown at 12. This stage is designed in the same way as the stage which has just been described with the difference that the delay line comprises only 85 identical cells In the same way, stage 13 of the filter includes a delay line comprising 10 identical cells which introduce a delay equal to ps The output from stage 13 is fed to passband filter 4 The latter may be reduced to a 90 circuit tuned at frequency f, the transmission characteristic of which is as shown on curve C of Figure 1 at 4. In another embodiment of the invention, the output from attenuator Rll of each stage is 95 applied directly to the input of the delay line of the following stage which avoids having to pass the output through valve VI, the addition being provided directly by connecting in parallel the direct lead from the anode of valve 100 V, and the delay line terminal. Figure 5 shows another embodiment of the invention in which the input signal is applied to the control grid of a first amplifier stage V feeding a resistive load R The delay line, 105 shown as an artificial line of surge impedance R is connected in parallel with load resistor R. .The end of the-line is opened (that is the line is terminated on the condenser of the last cell) so that the signal will be reflected at the end 110 of the line Therefore, the delay introduced corresponds to the duration of the propagation of the signal in both directions along the line. This delay is equal to 0 5 us The line comprises for instance 20 cells

identical with the 115 one just described and therefore requires a volume half of -the volume occupied by the delay line -of the first stage of the embodiment shown of figure 4 The output signal from V 5 is applied to the control grid of amplifier V, 120 785 i 621 785,621 5 which feeds the second stage and so on. Coupling is performed by condenser 15 of high capacity with respect to the condensers of the artificial line It is easy to show that the input impedance of the delay line associated to stage Vs is given by j R Ze= tan wa/2 where R is the characteristic (or surge) impedance of the line The load impedance of valve V 5 comprises the parallel network made of a resistor R and the delay line It is easy to calculate the modulus of the load impedance Z and the exponent respectively Z R cos a/2 4 =) a/2 The embodiment shown on Figure 6 requires the use of a greater number of valves but allows amplification between two successive stages of the filter, together with automatic compensation of the losses in the delay lines. In this embodiment, coupling between stages is provided by means of cathode follower stages which provide a stable operation of the filter relatively to variations of the internal resistance of the coupling stages either due to ageing or to the valve manufacture Input signal is applied to the control grid of amplifier stage V,, the load impedance of which comprises resistor R connected in series with the delay line of characteristic resistance R closed on a matched resistor The delay introduced by the line is 0 5 sus The signal across load resistor R is applied to the control grid of a first cathode follower stage V 10 The output signal delayed by the line is applied to the control grid of a second cathode follower stage V 11. The output circuits of V,, and V 1, are connected in series by means of balancing resistors R 1 and R 2 A potentiometer P is used to pickup the correct fraction of the output signal which is the sum of output signals from V,0 and Vn 1 The use of two resistors R 1 and R 2 of different values and the control of the gain of stages V 10 and V,1 enables to compensate, in each stage, the losses occurring in the delay line The use of valves V 10 and V 11 provides a better adaptation of the delay line and prevents multiple reflections of the pulses at the end of the line. The embodiment shown on figure 5 provides an economy on the required number of valves and may be advantageously used when the delays a, a/2, etc, are sufficiently small so that the losses in the delay lines are negligible. The embodiment shown on Figure 6 is preferred when this condition is not fulfilled. The realisation of the delay line of the different stages depends on the frequency of operation At ultra high frequency these lines should

comprise either a certain length of transmission line or some kind of cavity; at microwave frequencies the delay is provided by a length of wave guide. When the incoming signal is constituted by video signals, that is rectangular pulses without carrier wave, the filter according to the invention may be used and will operate in the same way The delay line should be designed to operate at video frequencies and the passband filter 4 is replaced by a low pass output filter. As was said above, the use of the filter according to the invention is by no way limitated to pulse reception For instance, if very short pulses are sent in the filter according to the invention, the output signal from the first stage (see figure 2) will comprise two short pulses separated by a time interval equal to the delay a introduced by the first stage. This is true if a is very large with respect to a the pulse duration or more precisely if 2 n which is the shortest delay introduced by any of the stages constituting the filter, is very small with respect to the pulse duration of the input signal The output from the second stage will be a set of four short pulses occurring at a time intervals of and so on from stage to 2 stage After the nth cell, the output signal is a set of 2 " pulses which are regularly. occuring at time intervals and which 2 " occupied a time duration equal to 2 a ( 1-1). 2 " The envelop of this set of pulses is a pulse of the same duration This pulse is composed of a finite series of sinusoidal waves, the frequency of which are successive harmonics and which are set by the delay introduced by the successive stages of the filter The phasing of these sinusoidal waves only is determinated by the leading edge of the input signal.


* GB785622 (A)

Description: GB785622 (A) ? 1957-10-30

Improvements in or relating to horizontal boring, drilling and millingmachines and other machine tools


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PATENT SPECIFICATION 785,622 Date of Application and filing Complete Specification May 10, 1955. No 13483/55. Application made in United States of America on May 13, 1954. Complete Specification Published Oct 30, 1957. Index at Acceptance:-Classes 78 ( 3), H ( 2: 8); and 83 ( 3), D 4 A 3 ( 31: 32: J 5), D 4 A 4, D 4 B( 3: 5). International Classification: -B 23 h B 66 f O COMPLETE SPECIFICATIONT l Mprovements in or Crekatng to Horizontal Boring, Drilling and Mi Rling M, es and othher achine Toos We, GIDDINGS & L Ew Is MACHINE To OL COMPANY, a corporation organised under the laws of the State of Wisconsin, United States of America, of Fond du Lac, State of Wisconsin, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention pertains to improvements in horizontal boring, drilling and milling machines and other machine tools. The general aim of the invention is to make it possible for the operator of one of the huge horizontal boring, drilling and milling machines and other machine tools encountered in current practice, to

be always in position for effective manipulation of the intricate controls he must deal with, to have a good view of the progress of the work, and yet not to be fatigued with constant climbing, twisting and turning in crawling over the machine On his quickness of perception and shrewdness of judgment depends not only the safety of the machine itself but also that of the elaborate work in which a large investment of time and money has often already been made. Additional objects and advantages of the invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings, in which:Figure 1 is a front elevation of part of an exemplary machine tool provided with a combination operator platform and elevator constructed in accordance with the features of the present invention; Fig 2 is a plan view corresponding to Fig 1; Fig 3 is a fragmentary side elevation of the machine headstock, the operator platform, and the elevating means for the latter; Fig 4 is a diagrammatic elevational view which is similar to Fig 3, showing the combined drive of the machine headstock and the operator platform; lPrice 3 s 6 d l Fig 5 is a fragmentary elevation showing details of the operator platform drive and limit components; Fig 6 is a horizontal section, taken generally along the line 6-6 in Fig 5 and showing details of the platform slide or trolley engaged with a vertical guide beam; Fig 7 is a detail view taken in horizontal section substantially along the line 7-7 in Fig 3; Fig 8 is a detail view taken in vertical section substantially along the line 8-8 in Fig 7; and Fig 9 is a schematic diagram of an electric control circuit for the elevator platform. The machine tool which has been selected to illustrate one application of the invention is a horizontal boring, drilling and milling machine (Figs 1 and 2) having a vertically movable element or headstock 11 which is translatable along vertical ways 12 carried by an upright column 14 The column 14 is movable along horizontal ways 15 formed on a base 16 from which a work bed 18 (partially shown) extends. Although the details of this particular machine tool are shown only by way of example and such details may vary in the practice of the present invention, the headstock 11 may be provided with main and auxiliary horizontal spindles 19 and 20, together with numerous control levers and switches 21 The headstock is raised and lowered by power means driving a vertical elevating screw 24 (Fig 4) which is journalled in the column 14 and engaged with a nut member on the headstock itself The headstock during such movement slides along the ways 12 between their upper and lower extremities. The machine tool 1-0 also is equipped with a tracer head 25 having a stylus 26 adapted to follow the contour of a master pattern (not shown) and through appropriate control circuits to cause relative

movement between a cutting tool on one of the spindles 19 or 20 and the workpiece (not shown) so that the latter is machined to the same shape as Lhie pattern the rollers and plugs should an undue amount The tracer head 25 is mounted on a slide of wear occur on them, or alternatively, the movable along the vertical ways 12 and rigidly take-up of such wear by the removal Of shims attached to the headstock by two tie-rods 28 originally located beneath the cap flanges 41. The tracer head 25 thus moves in unison with For cooperating with the elevating screw 35 the headstock 11 along the ways 12, although to move the platform 29 vertically and at the it is adjustable in a vertical direction relative same timeto support the ho-sing 36 wvinh pieper to the headstock by threads and cooperating spacing from the guide beam 31, a nut 44 nuts provided at the upper ends of the tie (Figs 7 and 8) is journaled in the lower end rods 28 of the housing 36 by suitable anti-friction bearIn accordance with the present invention, a ings 45 The nut 44 surrounds the screw 35 novel arrangement has been provided in the and is threadably engaged with the latter so illustrated machine for making it possible for that vertical movement of the platform 29 and an operator to be always in touch with the the attached housing 26 results from rotation controls 21 as the headstock 11 goes up and of either the screw 35 or nut 44 relative to the down the towering column and yet with full other. freedom to move swiftly to any other vertical In accomplishing the objects of the invenlocation on the machine where his presence is tion, provision is made for rotating the elevator required Pursuant to that purpose a platform screw 35 whenever the headstock screw 24 is 29 is guided for vertical movement along a driven And means are provided which are path adjacent the vertical path of the head selectively operable to lock the nut 44 against stock, and elevating means are provided for rotation relative to the housing 36 As shown raising or lowering the platform optionally in in Fig 4, the headstock elevating screw 24 is unison with the headstock or independently of adapted to be drivingly rotated by means of a the latter power shaft 48 suitably connected to a motor As shown in this instance, the machine tool (not shown) By selective operation of the is equipped with the combination operator controls 21 on the headstock face, the power support and elevator platform 29 having a shaft may be driven in either direction and at guard railing 30 The platform 29 is vertic variable speeds to raise or lower the headstock. ally slidable along a guide beam 31 extending The shaft 48 has a bevel gear 49 meshed with for support between the outer ends of a pair a mating gear 50 on the lower end of the screw of horizontal extension arms or brackets 32 24 The shaft 48 also includes an extension and 33 mounted respectively at the upper and 40 a which is journalled in and

projects through lower ends of the column 14 A vertical elevat the lower bracket 33 and which carries at its ing screw 35 for the platform 29 is journalled extreme end a second bevel gear 51 which is at its upper and lower ends in the extremities in driving engagement with a mating gear 52 of the brackets 32 and 33, such elevating screw fast on the lower end of the elevator screw 35. being disposed between the flanges and the The mechanical ratios for gears 49 and 50 and guide beam 31 which, in this instance, is for gears 51 and 52 are so chosen with regard formed in the configuration of an: beam to the pitches of the elevating screws 24 and As shown best in Fig 3, the platform 29 has 35 that the headstock 11 and platform 29 move attached at one edge a vertical hollow housing in unison whenever the power shaft 48 is 36 which surrounds the guide beam 31 and rotated For example, if the pitches of the the elevating screw 35 The housing 36 serves screws 24 and 35 are the same, then the both as a trolley carrier for slidably engaging mechanical ratios for the gears 49, 50 and 51, the guide beam 31 and as a casing which pro 52 would be identical. tects the operator's clothing and hands from As here illustrated, the means for selectively nbilrv hv rrnntacrtwifh-the 2 uide-hean 31 or 1 nckine the unit 44 awainst rotation-rlative to Ac 785,622 785,622 24 is driven, the platform 29 will move in I unison with the headstock under these conditions, a selected spacing or adjustment of the two being maintained. In order that the platform 29 may serve as an elevator when the headstock remains stationary, provision is made for moving the platform vertically and independently of the headstock To this end, the nut 44 is arranged to be driven by the electric motor 58 when the brake device 59 is released When the headstock 11 is stationary both the elevating screws 24 and 35 will also be stationary Under these conditions, with the brake 59 released and the motor 58 energized, the resultant rotation of the worm 54 and the nut 44 serves to raise or lower the platform 29 according to the direction in which the motor 58 is turned In order that the platform 29 may be both raised and lowered, therefore, the motor 58 is reversible and provided with suitable controls to be more fully described Briefly, it may be observed at this point that control push-buttons and 61 are located on the inner side of the housing 36 for convenient operation by an operator Actuation of the push-button switch releases the brake 59 and turns the motor 58 in a first direction to raise the platform 29, while actuation of the push-button 61 releases the brake and energizes the motor to turn in the opposite direction to lower the platform 29. In order to supply electric power to the motor 58 and the brake device 59 under the control of the push-buttons 60 and 61 and a control

circuit to be more fully described, stationary bus and sliding contact means are provided respectively on the guide beam 31 and the housing 36 As shown more particularly in Fig 6, a three-phase stationary vertical bus 65 is rigidly mounted within the flanges of the guide beam 31 and suitably surrounded by a protective casing 66 The bus 65 includes three contact strips 65 a suitably mounted in strips of insulating material and engaged by sliding contacts 68 which move with the housing 36 In the specific bus structure here illustrated, the sliding contacts 68 are mounted on a carrier 69 which is supported by a hollow S arm 70 rigidly fastened to and projecting inwardly from the housing 36 The necessary wiring (not shown) leading to the motor 58, brake 59, and other control components may be passed through the arm 70 The carrier 69 extends through a slot in the casing 66 and has rollers 69 a riding on opposite sides of the casing 66 to provide smooth sliding engagement. To prevent the housing 36 from striking the upper and lower brackets 32 and 33, through inadvertence of an operator, two limit switches T and 75 B are mounted on the upper end of the housing 36 and respectively adapted for cooperative engagement with actuating cam strips 76 T and 76 B welded or otherwise fastened to the web of the guide beam 31 (Fig. 3) The cam strips 76 T and 76 B are suitably located in a vertical direction such that the corresponding one of switches 75 T and 75 B are actuated whenever the top of the housing 36 70 approaches the upper bracket 32 or the lower end of the housing 36 approaches the lower bracket 33 These switches are arranged, in a manner to be more fully described, such that they deenergize the brake 59 and motor 58 75 Thus, whether the platform 29 is being raised or lowered in unison with the headstock 11 or independently of the headstock, actuation of the limit switches 75 T or 75 B releases the nut 44 for free rotation relative to the housing 80 36 and prevents further vertical movement of the platform 29. Refering next to Figure 9, a schematic diagram of an exemplary electric control circuit for the combination support and elevator plat 85 form is there shown The motor 58 is in this instance a three-phase induction motor connected for energization from a voltage source through either of two sets of relay contacts R,_ and R,-a respectively It will be apparent 90 that the motor 58 runs in one direction or the other, thereby raising or lowering the platform 29, depending upon which set of contacts is closed The contacts Ri-a and R,,a are contolled respectively by relay coils R,, and R, 95 the latter being connected in series respectively with the push-button switches 60 and 61 across a single phase circuit supplied through a transformer T Normally closed contacts R,-, and R,-b controlled by the respective

relay coils 100 R, and R,, are connected in series with the coils R and R, respectively, thereby assuring that both the contacts R,-a and R,-a cannot be simultaneously closed. A brake coil 59 a for the electromagnetic 105 brake 59 is supplied with direct current through a rectifier and normally closed contacts R,-a of a control relay The latter relay includes a coil R, which is connected in series with the parallel combination of contacts R,-, and R,,0 110 respectively controlled by the coils R 1 and Ra,. Normally, therefore, the coil R, is deenergized, and the brake coil 59 a energized to lock the nut 44 against rotation relative to the platform 29 and housing 36 Driving of the lead 115 screws 24 and 35 will thus cause the headstock 11 and platform 29 to be raised or lowered in unison However, when either of the switches 60 or 61 is closed, and thus either the coil R 1 or R, energized, the coil R, will 120 be energized and the contacts Ra, opened to release the brake 59 Thus, the motor 58, energized through either the contacts R,-, or R,-, may drive the nut 44 relative to the stationary screw 35 to raise or lower the plat 125 form 29 independently of and relative to the headstock 11. In the event that the platform 29 reaches either its top or bottom limit of travel, whether moving in unison with the headstock 11 or 130 relative to the latter under drive from the motor 58, the limit switches 75 A and B prevent it from moving farther and damaging the machine Each of the limit switches has one 7 normally closed and one normally open set of contacts The first limft sw 7 itch 75 T is actuated by the cam strip 76 T at the top of the guide beam 31 (Fig 3) and has its normally closed contacts 75 T,, (Fig 9) connected in series with the coil R, to thereupon effect deenergization of the motor even if the switch 60 is inadvertently held closed The second limit switch B is actuated by the second cam abutment 76 B at the midportion of the guide beam 31 (Fig 3) when the lower end of the housing 36 approaches the bracket 33 The normally closed contacts 75 BI of this latter switch are connected in series with the coil R to thereupon deenergize the latter coil and prevent the motor 58 from lowering the platform fu-ither. Additionally, the two limit switches 75 h ve their respective normally open contacts 75 T 2 and 75 BW connected in parallel with the contacts R,-, and R_,, that is, individually in series with the coil R, When either of the limit switches is actuated, the coil R is energized and the brake coil 59 a is deenergized to release the nut 44 for free rotation In the event that the platform 29 reaches one limit -; of its travel before the headstock 11 as the twro are being raised or lowered in unison, the nut 44 is released and simply turns freely with the screw 35 The platform 29 thus remains stationary at its limit position

while the headstock 11 may continue to move. By this arrangement complete safety is provided whether the platform is being moved by power from either the extension shaft 48 a (Mig. 4) or the motor 58 And the headstoch 11 is not halted in case the platform reaches its limit position first as the two are driven in unison from a common drive shaft. RESUMA OF OPERATION. While the operation of the novel combination support and elevator platform will be clear from the foregoing, a brief summary will be useful The operator, at the beginning of a day's work, may step on the lowered platform 29 and operate the push-button switch 60 so as to elevate thie platform to a convenient level adjacent the headstock 11 regardless of where the latter may be The vertical position of the platform 29 relative to the headstock may be adjusted to suit the preference of the individual operator The operation of the switch 60 energizes the motor 58 and releases the brake device 59 so that the nut 44 is rotated relative to the stationary elevating screw 35 in effecting this initial raising of the platform. If the headstock 11 is moved vertically during machining operations, as by caus Ing the power shaft 48 to be rotated, the platform 29 will automatically be moved a corresponding amount by virtue of the common drive connection of the lead screws 24 and 35 with the 65 power shaft 48 Thus, the previously adjust-I relationship of the platform 29 and headstoch 11 will be maintained W'hen the ocerator desires to descend to the shop floor, whil n O. wishing to disturb the position of the headstoc' 70 in an incomplete machining process, lhe e operates the push button 61 so as to release the brake 59 and energize the motor 58 in the opposite sense The nut 44 will thereby be driven in the opposite direction so as to lovwer 75 the platform 29 If at any time it is necessary to service the tracer head 25 the operator may raise and lower the platform independently of the headstock 11 simply by utilizing the pushbutton switches 60 and 61 80 While with the arrangement shown it is possible for an operator to have complete access to any part of the vertical column by riding ur and down on the elvator platform 29 a ladder has been illustrated connected with the 85 machinery in Fig 1 This ladder 80 is solely for emergency or occasional use as, for example, when all electric power has been shut onf from the machine 10 This ladder 80 may be integrally connected with the vertical column 90 14 as in prior conventional arrangements It will be evident, however, that the present invention eliminates virtually all necessity for climbing a ladder Accordingly, operator fatigue and the hazards of ladder climbing are 95 reduced to insignificance.


Law

5211 5215.output