US2246923A - Brake for hoists - Google Patents

Description

June 24, 1941. L. F. MEUNIER l BRAKE FOR HoIsTs Filed July 26, 1958 3 Sheets-Sheet 1 ATTORNEY June 24, 194. 1 F. MEUNIERA BRAKE FOR HOISTS Filed July 26, 1938 3 Sheets-Sheet 2 BY WTRNEY June 24, 1941. L. F. MEUNIER BRAKE FOR HoIsTs `3 Sheets-Sheet 5 Filed July `26, 1938 amie/Ng* ma E n., T E WM WE N 0 E ATTORNEY Patented June 24, 1941 BRAKE FOR 'HOISTS Leon F. Meunier, Cleveland, Ohio, assignor to Chicago Pneumatic Tool Company, NewYork, N. Y., a corporation of New Jersey Application July 26, 1938, Serial No. 221,324

7 Claims.

This invention relates to controlling mechanlsm for power operated hoists and more particularly to a braking device for retarding rotation of the cable drum while the load is being lowered. The invention is especially suited for hoists operated by a fluid pressure rotary vane typeof motor.

In the case of conventional hoists operated by a reciprocating air motor, the motor itself may act as a braking device while lowering the load slowly, due to the vacuum pull on the pistons and compression of the exhaust, as when the control valve is partly open. When a motor of the rotary vane type is employed, however, the braking action of the motor is not effective at slow speeds-V due to leakage between the vanes and the cylinder of the motor.

Mechanical brakes of the Weston type are generally used on electric cranes and hoists, but this type of brake would not function properly with a rotary vane motor because o f the friction factor in the brake. In such device the air pressure in the motor cylinder would rise gradually to overcome the friction of the brake and after the friction has been broken, the motor, due to the increased pressure, would drop the load for a short distance until the pressure was reduced to permit the brake to stop rotation of the drum. The use of an electric motor in association with a. Weston brake however is not attended by such acceleration of the motor. In other words, an electric motor will maintain a substantially constant speed after overcoming the friction, and a rotary vane motor will accelerate.

An object of the present invention is to permit lowering of the load at any selected speed fromzero to maximum feet per minute with smooth precision control, such as required for foundry use, and without vibrating the load. p

In the present invention, a hydraulic gear pump is adapted to be connected to and driven by the cable drum and is arranged' to impose a variable torque resistance on the drum. A feature ofthe invention is an adjustable control valve in the hydraulic system which controls the resistance to the iiow of oil and, therefore, to the rotation of the pump and cable drum.

Another object is to render the. gear pump inoperative during the time that the drum is lifting the load.

A further object is to maintain the hydraulic gear brake in fully primed condition, whereby upon lowering the load the hydraulic brake cony will appear more clearly from thefollowing de- 1 being shown in the neutral or closed position, the

`section being indicated by the arrows l. in Fig. 1; Fig. 3 is a cross section similar to Fig. 2, but taken through the inlet end of the rotary vane motor, as indicated by the arrows 3 in Fig. 1; Fig. 4 is a fragmentary cross section through Athe throttle valve as indicated by the arrows 4 in Fig. 1 showing the ports controlling the flow of compressed air to and from the mechanical brake;

Fig. 5 is a sectional view as indicated by the broken line 5-5 in Fig. 1 showing the mechanical load brake which locks the cable drum when the throttle valve is adjusted to neutral position;

Fig. 6 is an elevational view,.looking in the direction of the arrows 6 in Fig. 1, of the operating lever and associated return spring;

Fig. 7 is a view of the operating lever and associated linkage, taken generally as indicated by the irregular line 1--1 in Fig. 1,4 the lowering position of the levers being shown in full `lines and the neutral position in broken lines;

Fig. 8 is 'a cross section through the gear pump and associated control valve, as indicated by the arrows 8 in Fig. 1, the position of the parts corresponding to that shown in full lines in Fig. 7;

Fig. 9 is a view similar to Fig. 7, the full lines indicating the position of the parts when adjusted for 4lifting the load and the broken lines the neutral position;

Fig. l0 isla cross section similar to Fig. 8 showing the position occupied by the control valve ,when the operating lever is adjusted to lift the v load;

Fig. 1l is a cross section of the roller clutch showing the roller ratchet body rotating counterclockwise and driving the gear pump sleeve quill through the medium of the clutch rollers; and

Fig. 12 is a sectional view similar to Fig. 11 but showing the roller ratchet body rotating clockwise and the gear pump sleeve quill stationary as when lifting the load.

The terms clockwise and counter-clockwise," wherever used in this specification, refer to the direction of rotation as it appears when v looking toward the left in Fig. 1.

The illustrative embodiment of the invention comprises a cable drum, a reversible rotary vane motor and reduction gearing for driving the drum, an operating lever and throttle valve for controlling rotation of the motor, a mechanical brake for locking the drum when the throttle valve is adjusted to neutral position, a hydraulic gear pump adapted to be driven by the motor, and a roller or free wheel clutch for disconnecting the hydraulic pump from the motor and drum excepting when the latter are rotating in a direction to lower the load.

As shown in'Fig. 1, the hoist comprises a reduction gear housing I4, a drum housing I5,.a pump housing, I6, and amotor housing I1, all of which are bolted or otherwise secured together to form a rigid frame structure. A bracket I8, secured to the drum housing I5, cooperates with a suspension hook I9 to provide a swivel support for the hoist. The location of the hook and the distribution of the weight of the parts of the hoist are such that the axis of the cable drum tends to assume a horizontal position.

Drum 20 is grooved on its periphery in the usual manner to accommodate a supporting cable 2|. The drum is keyed to a shaft 22 supported in bearings 23 and 24 formed in the end Walls 25 and 26 respectively of the drum housing. Bearings 23 and 24 also restrain the drum against axial movement. The drum shaft 22 is hollow and surrounds a motor shaft extension 21. The latter is supported, near its front end, by a roller bearing 28 mounted in a wall 29 of the gear housing I4. The rear portion of the motor shaft extension is supported by a ratched body 3I' with which the shaft has splined interengagement. Ratchet body 3 I, hereinafter more fully described, also has a splined connection with motor shaft 32 whereby the motor shaft, ratchet body and shaft extension 21 rotate in unison. The motor shaft extension 21 is connected to the drum shaft 22 by means of reduction gearing 34 which is of a type well known in the art and requiring no detailed description.

The motor 35, which drives the shaft 32, is of the conventional fluid pressure operated rotary vane type. It comprises a cylinder 36 and end plates 31 secured within a cylinder bore 38 in the motor housing I1. A rotor 39 is eccentrically mounted in the cylinder and is integrally connected to motor shaft 32 (hereinbefore mentioned) and shaft 40. Shaft 32 is supported within a roller bearing carried by the associated end plate 31, while shaft 49 is supported in a roller bearing 4I carried by a housing 42 secured to the rear end of motor housing I1.

As shown in Figs. 2 and 3, the rotor 39 is provided With vanes or blades 44 mounted for radial movement in slots in the rotor. The motor housing I1 has a pair of recesses 45a and 45b, situated on opposite sides of the cylinder 36. A plurality of narrow segmental slots 46 in the cylinder 36 establish communication between the adjacent portion of the interior of the cylinderA The supply of pressure uid to recess 45a or 45h and the venting thereof, are controlled by a throttle valve 46 mounted for limited turning movement in a valve case 49 which is secured to the motor housing I1. Referring to Figs. 1 and 3, the valve case has a port 59 communicating with an inlet 5I in the motor housing I1, which inlet may be connected to an air hose 52 for supplying the compressed air or other pressure fluid that operates the motor. Near the admission port 50,` the valve case has a pair of ports 53a and 53h communicating, either directly or according to any other well-known type of construction, with respective recesses 45a and 45b.

Throttle valve 48 has an opening 54 adapted to connect the admission port either to port 53a or to port 53h for supplying live pressure fluid 'to recess 45a or 45h.

Referring particularly to Fig. 2, th'e throttle valve 48l has an exhaust port 55 registering selectively with either of two ports 56a and 56h in the valve case 49 which communicate with the segmental recesses a and 45b respectively. The

motor has an exhaust outlet 51 leading to atmosphere or to any suitable chamber (not shown) of relatively low pressure." A port 58a in the valve is arranged to complete the passageway between the recess 45a and the exhaust outlet 51 whenever .the port 55 registers with port 56a. A similar port 58h is associated with port 56h and recess 45h.

A mechanical braking device, which is operative while the throttle valve 48 is in neutral position, is housed within a flange 58 integral with the end wall 29 of the gear housing I4. A plate 59 forms a cover for the housing. As shown in Figs. 1 and 5, the brake comprises a pair of suitably lined shoes 60 adapted for frictional engagement with the opposite sides of a brake drum 6I affixed to the end of the motor shaft extension 21. The shoes are pivoted to a pair of approximately parallel bars 62. The lower ends of the bars are pivoted to a link 63 which is supported' for pivotal movement at its center by a pin 64.mounted in the wall 29. A tension spring 65 is connected to the upper ends of the bars 62 and tends to hold the shoes 60 in tight frictional engagement with the brake drum 6I to lock the motor shaft extension 21 and consequently the cable drum 20 against rotation. For the purpose of releasing the brake, a piston 66 is connected to the upper ends of the bars 62 by a pair of jointed toggle levers 61. The piston reciprocates in a cylinder 68 formed at the upper end of the flange 58. A plate 69 closes the upper end of the cylinder excepting for communication through a pipe 1I).

Referring particularly to Fig. 4, the front end of pipe 10 leads to a port 1I in the throttle valve case 49. Throttle valve 48 has a port 12 registering with port 1I when the former is adjusted to neutral position to vent the pipe 10 through ports 1I, 12, 58a, 58h and 51 to atmosphere. When the throttle valve is turned either tothe right or to the left to raise or lower the load, port 1-2 is closed and port 1I is brought into registry with one of a pair of grooves 13 leading to port 54 by means of which the live air is supplied to pipe 10. From the above description, it will be apparent that the mechanical brake 60, 6I, etc., is effective to lock the motor 35 and cable drum 20 when the throttle valve 48 is in neutral A position and is released by air pressure when the throttle valve is adjusted for either lifting or lowering the load.

Throttle valve 48 is manipulated by an operatthe chamber.

ing lever 14 supported for turning movement in a bearing provided on housing 42 and having a polygonal socket receiving a correspondingly shaped extensionv 15 on the throttle valve. The operating vlever is normally retained in a horizontal or neutral'position by the usual return spring 16. Cooperating pins 11 and 18 are carried by the lever and stationary housing 42. re-

spectively, and are engaged by the free ends ol tween the link and the bell crank arrangement when the operating lever is moved from the neutral to the -lifting position, or vice versa. When theoperating lever is moved to the lowering position,- however, the link 98 rocks the bell crank lever 94, 488 against the tension of spring 93 to\rotate the gear pump control valve '9i through an arc corresponding to the movement of the operating lever.

The following is a brief resume of the operation o! the illustrative embodiment of the invention. Normally the operating lever 14 is held in the neutral or horizontal posltion'by lthe return` spring 18. The position of the motor throttle valve 48 at this time is such that the pipe 18 leading from the air brake cylinder 88 is vented through ports 12, 58a, 58h and 51 to atmosphere,

able liquid, such as oil, to ilow into and out of Gear 88 is rotatable on a shaft 83 supported by lwall 28 and plate 82. Gear 8l is keyed to a sleeve quill 84 rotatably mounted within wall 26 and plate 82. An oil seal 85 surrounds motor shaft extension 2l and is interposed between the sleeve quill and the drum shaft 22.

The gear pump sleeve quill 88 is arranged to drive the gears 88 and 8l only during the time that the motor 35 and cable drum 28 are rotating counter-clockwise, or in a direction to lower the load. For this purpose, a plurality of spring pressed rollers 86 are mounted in complementary recesses 81 in the roller ratchet body 3l, as shown in Figs. 11 and 12. The rollers cooperate with the sleeve quill to form a free wheel clutch between the motor shaft 32 and the gear pump. When the load ls being lowered, the gear 8l is driven counter-clockwise and gear 88clockwise, whereby the gears pump the oil. from the pump inlet 88 along the paths designated by the arrows in Fig. 8, through the pump outlet 89 and port 98 in control valve 9i, from whence the oil is conveyed through any suitable conduit (not shown) back to the pump inlet 88. Valve 9| may be adjustedas shown in Fig. 8 or as in Fig. 9, or in any selected intermediate position. The amount of resistance oiered to the liow of oil, and therefore to the rotation of the gears 88 and 8l, depends on the position of the valve port 98 in relation to the pump outlet port 89.

The adjustment of the control valve 9| for the gear pump is responsive to movement of the operating lever 14. When the operating lever is either in the neutral or in a lifting position, the control valve 9i occupies the closed position shown in Fig. l0, cutting off communication between the gear pump outlet 89 and inlet 88. The valve tends to remain closed under the influence of a tension spring 93 interposed between a pin ailxed to plate 82 and a lever 94 which fits a square extension. 95 on the control valve 9|. A lever 96 has a simile' connection with the control valve, and cooperates with the lever'94 to form a bell crank arrangement. The front end of the throttle valve 48 is supported in a bearing provided by plate 82 and, adjacent said bearing, the throttle valve has a square portion supporting a lever 91. The lever rotates in unison with the throttle valve 48 and operating lever 14. A link 98 'has a pivotal connection with lever 81 and a pin and slot connection with bell crank lever 96, the slot being so designed that there is lost motion bethe opposite side 45h to 4drive the motor.

yspeed of rotation depends ypartly on the load,

whereby the brake drum 6I, cable drumy 18 and motor are mechanically locked. To raise the load, the operator pullsthe operating lever 14 to the lifting position shown inFig. 9, thereby movingv the throttle valve 48 to a position wherevsainev time, the throttle valve admits live air to the inlet side a of the motor 35 and exhausts The and partly on the supply of live air which may be controlled by the operator by varying the ex- .tent of movement of the operating lever, whereby Ithe motor inlet ports 54 and 53a and exhaust ports 56h' and 55 may register completely or partially. The motor rotates clockwise during the lifting operation, carrying with it the motor shaft 32, ratchet body 3l and motor shaft extension 21, the latter driving the cable drum in the same direction but at a reduced speed, through the gearing 34. The hydraulic gear pump 88, 8l is inoperative at this time because the direction of rotation of the ratchet body 3l is such that it does not drive the quill sleeve 84, as will be apparent from an.inspection of Fig. 12.

To lower the load the operator, of course, first stops the motor by moving the operating lever 14 to the neutral position, whereupon the mechanical brake again functions. Upon movement ofthe operating lever to the lowering position, the mechanical brake is released and the motor 35 is conditioned for rotation in a counter-clockwise direction. The motor, while turning in this direction, drives the gear pump through the rollers shown in Fig. 11, causing the cil to surge through the pump, as shown in Fig, 8. The control valve 9| is rocked by the bell crank lever 94, 96 .to cause the valve lport 98 to register parigally or completely with the gear pump outlet The operator may control the speed at which the load descends by moving the operating lever 14 to any selected position intermediate those shown in full and broken lines in Fig. '7. Movement of the operating lever affects both the throttle valve 48 and gear pump control valve 9 I, whereby when the supply of air to the motor is either increased or reduced, the resistance to the flow of oil in the gear pump is concurrently lowered or increased. Thus, the invention provides a smooth, sensitive control for varying the speed of the cable drum 28 within wide limits.

What is claimed is:

1. A holst comprising a rotatable cable drum, a iluid pressure operated rotary motor for driving said drum, a hydraulic system comprising a -chamber through which a working liquid may -be circulated, a gear pump disposed in said chamber for effecting the ,irculationA of liquid in said system, means including a free wheel clutch for establishing a driving connection .between the drum and pump only when the drum is rotating in a direction to lower the load, a throttle valve having an adjustable opening for controlling the supply of pressure fluid to the motor, and means controlled by said throttle valve for increasing and reducing the resistancev to the flow of liquid in said hydraulic system.

2. In a hoist, the combination of a reversible rotary motor, a cable drum adapted to be driven thereby, an operating lever for controlling the supply of power to said motor and having raising, neutral and lowering positions of adjustment, a hydraulic system comprising a chamber through which a working fluid may be circulated, a. rotary pump disposed in said chamber for effecting the circulation of fluid in said system,

means including a free wheel clutch for establishing a driving connection between the motor and pump when the operating .lever is adjusted to the lowering position, a control valve in said hydraulic system for imposing a variable resistance to the flow of fluid therethrough, linkage connecting the operating lever to the control valve, a spring tending to hold the control valve in closed position, said linkage comprising a lost motion connection so constructed and arranged that the control valve is moved from its closed position only when the operating lever is moved to the lowering position.

3. In a hoist, the combination of a fluid pressure operated motor, a brake for said' motor and normally effective to hold said motor against operation, fluid pressure means for disabling said brake, a. valve for controlling the ow of lpressure fluid to said motor and said brake disabling means, said valve lbeing so arranged that operation of the motor is accompanied by a simultaneous disabling of the brake, a hydraulic system including a gear pump positively connected to said motor, a valve for controlling the ow of fluid in said system whereby the a-ction of said gear -pump and thereby of said motor may .be retarded to any desired extent, and connecting means between the two said valves whereby both are moved simultaneously from and toward closed position.

4. In a hoist, the combination of a uid pressure operated motor, a control valve so constructed as to act when set in one position to admit pressure fluid in a direction to operate said motor in one direction` and to act when set -in another position to admit pressure fluid in a direction to operate said motor in the opposite direction, a hydraulic system including a gear pump for circulating fluid through the system, means including a free wheel clutch for establishing a driving connection between said motor and said pump during one directi-on of movement of said motor, a control valve for imposing a variable resistance to the flow of fluid through the hydraulic system, and means connecting the first and second mentioned control valves, said means including a lost motion connection so arranged that the setting of the first valve to a position causing movement of said motor in a direction to operate said gear pump is accompanied by a simultaneous movement of said second -valve from closed position and the setting of the rst valve to another position is accompanied without effect on said second valve.

5. In a hoist, the combination of a fluid pressure operated motor, a control valve so constructed as to act when set in one position to admit pressure fluid in a direction to operate said motor in one direction and to act when set in another position to admit Ipressure fluid in a direction to operate said motor in the opposite direction, a hydraulic system including a gear pump for circulating fluid through the system, means including a. free wheel clutch -for establishing a driving connection between said motor and said pump during one direction of movement of said motorya control valve for imposing a variable resistance to the flow of iluid through the hydraulic system, means connecting the first and second mentioned control valves, said means including a lost motion connection 'so arranged that the setting of the first valve to a position causing movement of said motor in a direction to operate said gear pump is accompanied -by a simultaneous movement of said second valve from closed position and the setting of the rst valve to another position is accomplished without effect on said second valve', and a resilient means for retainingsaid second valve in closed position.

6. In a hoist, the combination of a fluid pressure operated motor, a brake for said motor and normally effective to hold said motor against operation, iluid pressure means for disabling said brake, a valve for controlling the flow of pressure fluid to said motor and said -brake disabling means, said valve being s-o arranged that operation of the motor is accompanied by a. simultaneous disabling of the brake, a hydraulic system including a pump connected to said motor, and means movable under the control of said valve for restricting the flow of iluid in said hydraulic system.

7. In a hoist, the combination of a fluid pressure operated motor, a throttle valve so constructed as to act when set in one position to admit pressure fluid in a direction to operate said motor in one direction and to act when set in another position to 'admit pressure fluid in a direction to operate said motor in the opposite direction, a circulating fluid system, a ypump connected to said motor for circulating the fluid in said system, a control valve for imposing a varia-ble resistance to the iow of liuid through said system, means for holding said control valve yieldingly in a normal position, and means connecting said throttle valve and said control valve, said means including a lost motion connection so arranged that the setting of the throttle valve to 4a position causing operation of said motor in one direction is accompanied by a simultaneous movement of said control valve from normal position' and the setting of the throttle valve to another ,position is accomplished without effect on the control valve.

LEON F. LIEUNIER.

oERTImcATE QF comemos. patent No. '2,2LL6,925. Juneau, 19in.

LEON F. MEUNiER.

It is hereby certifiedythalt .error appears 1n the printed 'Specification ofthe above numbered patent requiring correction as fellows: Page 2, first tqimnn, line 21-,'gtrike out'the article '"the" before "weight";1ine 55, for

"matched" readnrtchetu; pg'e 5 first column, line 63,' fof "simil" fread 1|., y second-column, line 6, claimh, for "accompanied" read "accomplished-L;

and that the said Letters.' Patent should be read withthi s. cr-'rectitn therein that the same may conform to the record. ofthe case the Patent Offoe.

signed and' sealed this 29th diy of July, 'AQ D. A191m.

4Henry Vgn sdgle (Seal) f Acting comssonler of Patents.

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