US3601235A

US3601235A - Hydraulic elevator drive

Info

Publication number: US3601235A
Application number: US881516A
Authority: US
Inventors: Hans Hermann Huf
Original assignee: Aufzuege AG Schaffhausen
Current assignee: Aufzuege AG Schaffhausen
Priority date: 1968-12-04
Filing date: 1969-12-02
Publication date: 1971-08-24
Anticipated expiration: 1988-08-24
Also published as: CH502948A; AT296548B; DE1959025A1; FR2025192A1

Abstract

The hydraulic drive motor for the cable drum of an elevator is supplied with pressure fluid through a pressure control valve, a reversing valve, and a brake valve. The pressure control valve adjusts the liquid pressure in response to the torque transmitted between the motor and the cable drum, the reversing valve controls the direction of flow through the motor and also the flow rate, and the brake valve controls the return of liquid from the motor in response to the magnitude and the direction of the transmitted torque.

Description

United States Patent Hans Hermann Hut Schafihausen, Switzerland 881.5 16

Dec. 2, 1969 Aug. 24, 1971 Autzuge AG. Sehafthausen Scluifhousen, Switzerland Dec. 4, 1968 Switzerland lnventor Appl. No. Filed Patented Assignee Priority HYDRAULIC ELEVATOR DRIVE 10 Claims, 8 Drawing Figs.

U.S.Cl. 192/3 R, 60/53 WW, 91/461 187/17, 254/150 Fl-l Int. Cl. ..F 16d 43/28, Fl6d 43/286 F leld 01 Search 60/53 WW; 91/461; 11/433; 187/17; 254/150 FH; 192/3 R [56] References Cited UNITED STATES PATENTS 2,104,780 1/1938 Vickers 60/53 WW 2,416,801 3/1947 Robinson 60/53 WW 2,986,884 6/1961 Smith 60/53 WW 3,120,880 2/1964 Jaseph 187/17 Primary Examiner-Edgar W. Geoghegan Attorriey-Kelman and Berman ABSTRACT: The hydraulic drive motor for the cable drum of an elevator is supplied with pressure fluid through a pressure control valve, a reversing valve, and a brake valve. The pressure control valve adjusts the liquid pressure in response to the torque transmitted between the motor and the cable drum, the reversing valve controls the direction of flow through the motor and also the flow rate, and the brake valve controls the return of liquid from the motor in response to the magnitude and the direction of the transmitted torque.

OUP- W4) 1141- 4 I C041- "al P24255028 Con T204 Vat r 1g HYDRAULIC ELEVATOR DRIVE -This invention relates to elevators, and particularly to a hydraulic elevator drive.

- Elevators having cages or platforms suspended from cables were operated heretofore by electric motors if the vertical life height was relatively great. The controls required with an electric drive motor'for uniform acceleration and deceleration and for a uniform elevator speed independent of the lifted or lowered load are complex and require costly maintenance.

Electric elevator motors, moreover, normally must be coupled to the cable drum of the elevator by a stepdown transmission rangement with a hydraulically operated motor to which a cable drum is connected'for transmission of torque between the drum and the motor, the drum being adapted to be connecte'd to the elevator cage or platform for simultaneous movement. A pressure control valve is interposed between a source of liquid under pressure and the motor for supplying liquid to the motor, and responds to torque transmitted between the motor and the drum the transmitted liquid.

A reversing valve having a plurality of outletsis interposed for varying the pressure of between the pressure control valveand the motor for varying a the direction of flow and the flow rate of the transmitted liquid from the source to the motor. A brake valve is operatively interposed between the motor and the source of pressure liquid. lt controls the return of the liquid from the motor to the source in response to the direction and magnitude of the torque transmitted betweenthedrum and the motor.

Because-of the use of a slow-movinghydraulic motor, the outputshaftof the motor, which rotates in response to flow of liquid through the motor, maybe fixedly fastened to the cable rum Thebrake valve has two bores and apair of spaced ports in each bore. Valve members axially movable in the bores vary the :effeetivefloyv seetions of the bores between the ports. The

terminal portions of a firstoperating conduitcommunicate respectively with one of the fluid connections of the motor and with an outlet of the reversing valve. A second operating conduit has two terminal portions which respectively communicatefwith the. other fluid connection of the-motor and another outlet of the reversing valve; Check valves between the terminal portions of the operating conduits prevent liquid flow; from the motor connections to the reversing valve. The two parts of a first one of the valve bore communicate with the terminal portions of the first operating conduit, and the ports of thesecond valve bore with the terminal portion of the second operating conduit. Springs. bias the valve members toward a position in which they block flow through the associated bores. Valve-actuating devices shift the valve ment shifts'the valve member between aneutral position and two operativ e positions. In its neutral position, the valve member of the reversing valve prevents liquid flow between the liquid source and the motor. In the two operative positions The pressure control valve has a valve member which moves in a bore of the valve between a plurality of positions. Portions of the bore respectively communicate with a pressure line of the liquid source which is supplied with liquid under pressure from a pump, and with a return line for returning liquid to the pump. In its several positions, the valve member defines respective flow paths of different flow sections between these lines. The valve member is moved in the valve bore in one'direction in response to the magnitude of the torque transmitted by the motor to the cable drum, and in the opposite direction in response to the liquid pressure in the pressure line Other features, additional objects, and many of the attendant advantages of this invention will readily become apparent from the following detailed description of a preferred embodiment when considered in connection with the appended drawing in which:

FIG. 1 diagrammatically illustrates an elevator hydraulically operated according to this invention;

FIG. 2 shows a unit of the apparatus of FIG. 1 consisting of a pressure control valve and a four-way valve, the unit being shown in elevational section;

FIG. 3 illustrates the four-way valve of FIG. 2 in section on the line IlI-III and in a different operating position;

FIG. 4 shows the valve of FIG. 3 in the position of FIG. 2 on a smallerscale together with its actuating mechanism;

FIG. 5 shows a brake valve of the apparatus of FIG. 1 in front elevation;

FIG. 6 illustrates the brake valve of FIG. 5 in front elevational section;

FIG. 7 shows the brake valve in section on the line VII-VII in FIG. 5; and

FIG. 8 is a sectional view of the brake valve taken on the line Vlll-Vlll in FIG. 5.

Referring initially to FIG. 1, there is seen a tank or sump 1 from which hydraulic fluid is withdrawn by a rotary pump 3 driven by an electric motor 2. The fluid is driven by the pump through a check valve 4 into a main pressure line 5 leading to a pressure control valve 6. As will presently be shown in more detail, fluid may be returned by the valve 6 through a main return line 7, a check valve 8, and a filter 9 to the sump 1.

A section 10 of the main pressure line leads beyond the pressure control valve to a four-way control or reversing valve 11, and

branch return lines

12,13 from the four-way valve 11 directly communicate with the main return line 7 in the pressure control valve 6. Depending on the position of the fourway valve 11, fluid under pressure is discharged from the valve through an operating conduit 14 and returned to the valve 11 through another operating conduit 15 or vice versa. Electromagnetically operated

pilot valves

16,17 shift the four-way valve 11 between its several positions, and are energized by electric current supplied by relays, rheostats, and the like in the housing 18 of the electrical elevator controls, not themselves relevant to this invention and known in the art. They are operated by pushbuttons under the control of an operator and by limit switches along the path of the elevator, as is conventional and not shown.

The

operating conduits

14,15 are connected through

check valves

19,20 with the connecting

nipples

22,23 of a rotary hydraulic motor 21, the

valves

19,20 permitting fluid flow from the valve 11 to the motor 21 only. Conduits 25,26'

respectively connect the

nipples

22,23 to a brake valve 24 for fluid flow from the nipple 22 to the conduit 15 by way of a return duct 27, and a check valve 30 bypassed by an adjustable throttle 29, and fluid from the nipple 23 may flow to the conduit 14 by way of a return duct 28, and a check valve 32 bypassed by an adjustable throttle 31. Fluid also may be supplied to the

nipples

22,23 from the main return line 7 through check valves l9',20' respectively, an arrangement which permits leakage losses of hydraulic fluid in the motor 21 to be made up.

The illustrated hydraulic motor 21 has an output shaft 33 which normally rotates at about rpm. and carries a cable drum 34. The two ends of a cable 35 trained over the drum 34 in several turns in a conventional manner carry the elevator cage or platform 36 and a counterweight 37 respectively. The shaft 33 also carries a drum 39 of a brake 38, the drum being normally held stationary by brake shoes 40 biased toward engagement with the brake drum 39 by a strong spring 42. A reciprocating hydraulic motor 41 can release the brake shoes when supplied with fluid under the pressure of the main lines 5 through an adjustable throttle 43. A check valve 44 bypasses the throttle 43 and permits fluid flow away from the motor 41. The brake shoes 40 thus may be disengaged from the brake drum 39 as long as the pump 3 operates and stop the elevator when the hydraulic drive fails.

The pressure control valve 6, four-way valve 11, and brake valve 24 will be described hereinbelow in more detail. The apparatus shown in FIG. 1, as described so far, operates as follows:

As long as the

pilot valves

16,17 do not receive energizing current, the valves 11 and 4 interact in such a manner that the four-way valve 11 receives circulating fluid from the pressure control valve 6 at a pressure of about 45 p.s.i.g. and returns the fluid directly to the main return line 7 and the sump l. The pressure in the main pressure line 5 is too low to cause release of the brake shoes 40.

When an operating signal from the controls in the housing 18 energizes the pilot valve 16 for upward travel of the cage 36, and the combined weight of the cage and load exceeds the pull of the counterweight 37, the four-way valve 11 is shifted and reduces the direct return flow of fluid to the sump 1. The fluid pressure in the main pressure line 5 and in its section rises sharply as fluid is being fed to the arrested motor 21 through the operating conduit 14, and the brake shoes 40 release the brake drum 39. The fluid discharged from the motor 21 passes from the conduit 26 through the brake valve 24 which is set by the pressure in the conduit 14 to discharge the returning fluid to the operating conduit 15 from which it is led into the main return line 7 by the four-way valve 11. The motor 21 accelerates the cage or platform 36 to a constant speed which is a direct function of the fluid supplied to the motor 21. The controls in the housing 18 may include a speed governor, such as an electric tachometer coupled to the shaft 33 and connected in circuit with the

pilot valves

16,17 to maintain a desired elevator speed.

When the flow of current to the pilot valve 16 is reduced by the controls in the housing 18, the four-way valve 11 is shifted to decrease the rate of fluid flow to the motor 21, and the motor 21 is slowed while at first the brake 38 remains disengaged and the brake valve 24 is unaffected. When the valve 11 is returned to its original position, the flow of fluid to the motor 21 is stopped, and the brake shoes 40 engage the drum 39. The pressure in the

conduits

14, 15, 25, 26 is gradually released and the brake valve returns to its starting position.

When the cage 36 is empty or lightly loaded, a signal for upward travel received by the pilot valve 16 causes the motor 21 to be supplied with pressure fluid and the brake 38 to be released as described above. The oil released from the motor nipple 23 is directed through the conduit 26 to the brake valve 24 which throttles the return flow of fluid to the operating conduit in a manner to maintain the desired speed of the cage 36.

The three valves 6, ll, 24 are shown in detail in FIGS. 2 to 8. The pressure control valve 6 and the four-way valve 11 are contiguously juxtaposed so as to form a unitary structure when assembled. The valve 6 has a generally cylindrical straight bore passing through two enlarged chambers which communicate with the main pressure line 5 and the main return line 7 respectively, and provide permanently open connections between the main pressure line 5 and the pressure line section 10, and between the main return line 7 and the branch return line 12.

A generally cylindrical valve member 51 is axially movable in the bore and normally held in the position shown in FIG. 2 by a helical compression spring 52 interposed in the bore between the valve member 51 and a pressure relief valve 63. A blind axial end portion 61 of the bore permanently communicates with the main pressure line 5 through a channel 62 in the valve member. When the valve member 51 is shifted by fluid pressure in the bore portion 61 against the restraint of the spring 52, a wide circumferential groove 53 in the valve member connects the two chambers of the valve for direct return of fluid from the pressure line 5 to the sump 1.

The four-way valve 11 is shown in its nonnal or neutral position in FIGS. 2 and 4, and in one of its operative positions in FIG. 3. It has a generally cylindrical main bore which passes through five chambers respectively communicating with the pressure line section 10, the

return branch lines

12,13, and the operating

conduits

14,15 The return lines 12,13 are permanently connected by a manifold 55, and other connections between the several chambers in the valve 11 can be established by a valve member 54 of circular cross section having two axially spaced, wide,

circumferential grooves

56,57. In the operative position of FIG. 3 the groove 56 provides a throttling passage from the main pressure line section 10 to the operating conduit 14, and the operating conduit 15 is similarly connected to the return branch line 13 by the groove 57.

A narrow conduit 58 provided partly in the valve 6 and partly in the valve 11 connects the manifold 55 with the space in the terminal bore portion of the valve 6 partly occupied by the spring 52, and its flow section may be adjusted by means of a threaded throttling member 68 in the valve 6.

Branch conduits

59,60 lead from the portion of the conduit 58 in the valve 6 to the operating

conduits

14,15 respectively when opened by the valve member 54. In the position of the valve member 54 seen in FIG. 2, the two terminal parts of the conduit 58 are connected by a narrow circumferential groove in the valve member 54 while the

branch conduits

95,60 are interrupted by the portion of the valve member 54 which blocks fluid flow from the main pressure line section 10 to the operating

conduits

14,15. In the position of the valve member 54 seen in FIG. 3, the

conduits

58,60 are blocked, and the conduit 59 communicates with the operating conduit 14, and thus also with the main pressure line section 10.

The aforementioned pressure relief valve 63 near the spring 52 of the pressure control valve 6 has a conical valve member 65 which normally blocks fluid flow through the orifice of a conduit 66 to the main return line 7. The valve member 65 is held against its seat by a spring 64 whose force can be adjusted by means ofa screw 67.

The aforedescribed main bore of valve 11 communicates with respective chambers 71 in two identical caps or covers 70, only one cover 70 and associated structure being shown in detail in FIG. 4. The covers respectively carry the

identical pilot valves

16,17 only the valve 16 being seen in detail in the drawing. Springs 72 in the chambers 71 normally hold the valve member 54 of the four-way valve 11 in the neutral position seen in FIGS. 2 and 4.

The pilot valve 16 has a solenoid coil 73. The associated armature 74 moves toward the right, as viewed in FIG. 4, and inward of a pressure chamber when the coil 73 is energized, and correspondingly moves a valve member 75. The valve member controls fluid flow from the pressure line section 10 through a duct 76 to the chamber 80, and from the chamber 80 through a duct 78 to the return branch line 12. The chamber permanently communicates with a control conduit 77 leading to the chamber 71. The flow section of the conduit 77 can be controlled by a throttling screw 82. The stroke of the valve member 54 inward of the chamber 71 may be controlled by a threaded abutment 81.

In the illustrated position of the pilot valve 16, the chamber 71 is vented to the main return line 7 by the pilot valve 16 so that the two springs 72 hold the valve member 54 in the position seen in FIG. 2. When the pump 3 is started, pressure fluid from the main pressure line 5 cannot enter the blocked

conduits

14,15. As the pressure in the line 5 increases, the fluid in the terminal bore portion 61 of the pressure control valve 6 shifts the valve member 51 against the restraint of the spring 52while fluid is discharged through the conduit 58 into the return line 7. A throttling passage is formed in the groove 53 between the

lines

5 and 7, and the pressure drop across the throttling restriction balances the spring 52. In the illustrated embodiment, the spring 52 is selected to make the pressure drop 45 p.s.i.

When the solenoid 73 is energized, pressure fluid can flow from the pressure line section in the valve 11 through the pilot valvechamber 80 into the chamber 71, and the valve member 54 is shifted into the position seen in FIG. 3 in which fluid can flow from the main pressure line section 10 through the operating conduit 14 to the hydraulic motor 21.

. The resulting pressure drop in the

main pressure line

5,10

I causes the valve member 51 of the pressure control valve 6 to move toward the position seen in FIG. 2 to restrict the fluid flow through the groove 53 until the pressure drop at the lower flow rate balances the spring 52 and the pressure of the fluid surrounding the spring and communicating with the conduit.14 through the conduit 59, the conduit 58 being blocked rent in the coil 73. A bore 79 in the valve member 75 connects theblind end of the chamber 80 remote from the armature 74 with the conduit 77 so that fluid pressure may oppose the force of the energized solenoid coil.

The partial closing of the bypass connection from the line 5 to" the line 7 in the groove 53 of the valve member 51 results in a sufficient pressure increase at the reciprocating brake motor 41 to cause lifting of the brake shoes 40 from the drum 39.

The motor 21 can start rotating at a speed determined solely by the energizing current in the coil 73.

The rate at which the valve member 54 is shifted by fluid entering or leaving the chamber 71 can be controlled by means of the throttle screw 82, and the rate of movement of the valve member 51 may be similarly adjusted by means of the throttling member 68.

It will be noted that the pilot valve 16 does not require a spring for returning the armature 74 to its inoperative position whenthe coil 73 is deenergized. The armature is quickly returned by the pressure of fluid in the chamber 80, but the entire force of the magnet is available for quickly shifting the valve member 75 into the operative position while the chamber 80 is vented to the return line 7.

The brake valve 24 which controls fluid flow from the motor 21 to the sump through the four-way valve 11 is shown in detail in FIGS. 5 to 8. The valve body or casing 83 is a brickshaped block of metal provided with two spacedly parallel bores 85,86 of generally cylindrical shape and axially closed by two plates 84 fixedly attached to opposite faces of the block 83 in a manner not shown in detail.

Valve members

87,88 are axially movable in the

bores

85,86 respectively, and

are each provided with a wide circumferential groove.

Paired, axially spaced

ports

89,90 and 91,92 respectively lead from the

bores

85,86 to the

conduits

14, 25, 15, 26.

Springs

93,94 in the

bores

85,86 normally hold the valve members in the positions best seen in FIG. 6 in which they block fluid flow between the

ports

89 and 90, and between the

ports

91 and 92. Axially elongated, tapering notches 95 in the

valve members

87,88 can provide restricted flow channels between the ports when the valve members are moved against the restraint of the

respective springs

93,94, the effective flow section of each channel varying with the axial position of the valve member. a

The axial end portions of the

bores

85,86 receiving the

springs

93,94 are connected by a duct 98 to each other and to a drain opening 99 for fluid leaking past the

valve members

87,88. The opposite

axial end portions

96,97 of the

bores

85,86 communicate with the

aforementioned throttles

29,31

and

check valves

30,32 which are arranged in the block 83.

A duct 100 (FIGS. 5 and 7) leads from the port 89, and thus from the operating conduit 14, to the check valve 30 which consists of a spring loaded ball 30' cooperating with a shoulder in the duct 100. A branch of the duct 100 leads to the throttle 29 which is threadedly adjustable, and thence by way of a duct 101 to a duct 102 also connected to the check valve 30 and terminating in the terminal bore portion 97.

correspondingly, the port 91 and the operating conduit 15 are connected by a duct 103 to the check valve 32 having a spring loaded ball 32'. A branch of the duct 103 leads to the adjustable throttle 32, and ducts 104,105 ultimately lead to the bore portion 96.

As partly described with reference to FIG. 1, the brake valve 24 operates as follows:

When the motor 21 is operated to lift the weight of the loaded cage 36 not compensated by the counterweight 37, or to lift the counterweight 37 when the latter is heavier than the lightly loaded or empty cage 36, the fluid pressure in the conduit 14 and in the port 89 is increased beyond the pressure set by the spring 52 in the valve 6 according to the unbalanced load which is to be lifted. The high fluid pressure applied to the valve member 88 in the bore portion 97 can shift the valve member against the spring 94 until fluid can flow practically unimpeded between the

ports

91,92 from the motor 21 to the sump 1 through the wide groove in the valve member 88.

When the motor rotates in the same direction in which a difference in the weights of the cage 36 and the counterweight 37 tends to turn the shaft 33, the fluid pressure in the conduit 14 is insufficient to shift the valve member88 to the end of its stroke against the spring 94, and the return flow of fluid from the motor 21 to the sump l is throttled in the notch 95. The valve member 88 is held in an equilibrium position in which as much fluid can flow from the motor 21 to the sump 1 as is necessary to provide enough pressure at the motor 21 for the desired constant motor speed set by means of the controls in the housing 18 and the four-way valve 14. The position of the valve member 88 thus varies with the magnitude and the direction of the load applied to the shaft 33 of the motor 21.

The preceding description of the mode of operation of the apparatus is limited to the effects of control signals received by the pilot valve 16. In view of the symmetrical construction of the apparatus, a separate description of the manner in which rotation of the motor 21 in the opposite direction is controlled by the pilot valve 17 and associated elements is unnecessary.

Conventional electrical controls in the housing 18 permit the illustrated elevator arrangement to be operated at an inching speed which may be reduced to zero when the cage 36. reaches a desired position. The apparatus automatically compensates for varying loads and permits the rate of acceleration or deceleration of the cage 36 and the constant cage speed to be selected as may be needed. The cage is braked in accordance to electrical signals produced in accordance with the position of the cage, and is braked mechanically in the event of a power failure or a failure in the hydraulic system.

The apparatus is relatively simple and accordingly reliable in its operation and requires only minimal maintenance work. As is partly indicated in FIG. 2, all three

valves

6, 11, 24 can be combined in a structural unit having only four external fluid connections and three electrical terminals.

It should be understood, of course, that the foregoing disclosure relates only to a preferred embodiment of the invention, and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

1. In a hydraulic drive arrangement for an elevator having a cage or platform, in combination:

a. a hydraulically operated motor (21 b. drum means (34) connected to said motor for the transmission of torque between said drum means and said motor and adapted to be connected to said cage or platform for simultaneous movement;

c. a source (3) ofa liquid under pressure;

d. pressure control means (6) interposed between said source and said motor for supplying sad liquid to said motor and responsive to torque transmitted between said motor and said drum means for varying the pressure of the transmitted liquid;

e. reversing valve means (11) having a plurality of outlets and interposed between said pressure control means and said motor for varying the direction of flow and the flow rate of the transmitted liquid from said source to said motor; and

f. brake valve meaNs (24) interposed between said motor and said source for controlling the return of the transmitted liquid from said motor to said source in response to the direction and magnitude of said torque.

2. In an arrangement as set forth in claim 1, said motor having an output member rotating in response to flow of said liquid through said motor, said drum means being fixedly fastened to said output member.

3. In an arrangement as set forth in claim 1, said brake valve means (24) including 1. means defining first and second valve bores (85,86) having respective axes and respective pairs of spaced ports (89,90; 91,92);

2. first and second valve members (87,88) axially movable in said bores respectively for varying the effective flow sections of said bores between said ports thereof,

3. said motor including first connecting means (22) and second connecting means (23), each connecting means being operative for admitting said liquid to said motor, and for releasing from said motor liquid admitted by the other connecting means;

4. a first operating conduit (14) having two terminal portions respectively communicating with said first connecting means and with an outlet of said reversing valve means;

5. a second operating conduit (15) having two terminal portions respectively communicating with said second connecting means and with another outlet of said reversing valve means;

6. two check valve means (19,20) respectively connecting the terminal portions of said operating conduits and preventing liquid flow therethrough from the associated connecting means to said reversing valve means;

7. the ports of said first valve bore respectively communicating with said terminal portions of said first operating conduit;

8. the ports of said second valve bore respectively communicating with said terminal portions of said second operating conduit;

9. yieldably resilient means (93,94) axially biasing said valve members in respective directions;

[0. first valve actuating means (96) responsive to liquid pressure in said second operating conduit for moving said first valve member against the restraint of the associated yieldably resilient means; and

l 1. second valve actuating means (97) responsive to liquid pressure in said first operating conduit for moving said second valve member against the restraint of the associated yieldably resilient means.

4. In an arrangement as set forth in claim 3, a check valve and a throttle arranged in parallel between each of said valve actuating means and the associated operating conduit.

5. In an arrangement as set forth in claim 3, each of said valve members being formed with an axially tapering recess, the ports of each pair being axially spaced for simultaneous communication with respective axial portions of the recess in the associated valve member.

6. In an arrangement as set forth in claim 1, said reversing valve means (11) including 1. means defining a va ve bore having an axis, first and second conduits (10,12) connecting said bore to said source, and third and fourth conduits (14,15) connecting said bore to said motor;

2. a valve member (54) axially movable in said bore and formed with a plurality of recesses; and

. pilot means (16,17) for shifting said valve member between a neutral position and two operative positions, said valve member in said neutral position preventing liquid flow between said source and said motor, said recesses in one of said operative positions respectively connecting said first and third conduits, and said second and fourth conduits, and said recesses in the other operative position connecting said first and fourth conduits and said second and third conduits.

7. In an arrangement as set forth in claim 6, electrical control means 18) for controlling said pilot means.

8. In an arrangement as set forth in claim 1, said pressure control means including means defining a valve bore, a valve member (51) movable in said bore between a plurality of positions, said source including a pump (3), a pressure line (5,10) supplied with liquid by said pump, and a return line (7) for returning liquid to said pump, respective portions of said bore communicating with said pressure line and said return line, said valve member in said positions thereof defining respective flow paths of different flow section between said lines, means (59,60) responsive to the magnitude of said torque for moving said valve member in said bore in one direction, and means (61,62) responsive to liquid pressure in said pressure line for moving said valve member in a direction opposite to said one direction.

9. in an arrangement as set forth in claim 1, said drum means being rotatable, brake means (38) engageable for arresting said drum means, and brake-operating means (41,42) for disengaging said brake means and for engaging the brake means in response to changes in the pressure of said liquid of said source.

10. in an arrangement as set forth in claim 9, said brakeoperating means including a hydraulic-brake-operating motor, said source including a pump and a pressure line supplied with sad liquid by said pump, a check valve and a throttle connecting said pressure line to the brake-operating motor.

Claims

1. In a hydraulic drive arrangement for an elevator having a cage or platform, in combination: a. a hydraulically operated motor (21); b. drum means (34) connected to said motor for the transmission of torque between said drum means and said motor and adapted to be connected to said cage or platform for simultaneous movement; c. a source (3) of a liquid under pressure; d. pressure control means (6) interposed between said source and said motor for supplying sad liquid to said motor and responsive to torque transmitted between said motor and said drum means for varying the pressure of the transmitted liquid; e. reversing valve means (11) having a plurality of outlets and interposed between said pressure control means and said motor for varying the direction of flow and the flow rate of the transmitted liquid from said source to said motor; and f. brake valve meaNs (24) interposed between said motor and said source for controlling the return of the transmitted liquid from said motor to said source in response to the direction and magnitude of said torque.

3. pilot means (16,17) for shifting said valve member between a neutral position and two operative positions, said valve member in said neutral position preventing liquid flow between said source and said motor, said recesses in one of said operative positions respectively connecting said first and third conduits, and said second and fourth conduits, and said recesses in the other operative position connecting said first and fourth conduits and said second and third conduits.

3. In an arrangement as set forth in claim 1, said brake valve means (24) including

6. In an arrangement as set forth in claim 1, said reversing valve means (11) including

7. In an arrangement as set forth in claim 6, electrical control means (18) for controlling said pilot means.

8. In an arrangement as set forth in claim 1, said pressure control means including means defining a valve bore, a valve member (51) movable in said bore between a plurality of positions, said source including a pump (3), a pressure line (5, 10) supplied with liquid by said pump, and a return line (7) for returning liquid to said pump, respective portions of said bore communicating with said pressure line and said return line, said valve member in said positions thereof defining respective flow paths of different flow section between said lines, means (59,60) responsive to the magnitude of said torque for moving said valve member in said bore in one direction, and means (61,62) responsive to liquid pressure in said pressure line for moving said valve member in a direction opposite to said one direction.

10. In an arrangement as set forth in claim 9, said brake-operating means including a hydraulic-brake-operating motor, said source including a pump and a pressure line supplied with sad liquid by said pump, a check valve and a throttle connecting said pressure line to the brake-operating motor.

10. first valve actuating means (96) responsive to liquid pressure in said second operating conduit for moving said first valve member against the restraint of the associated yieldably resilient means; and

11. second valve actuating means (97) responsive to liquid pressure in said first operating conduit for moving said second valve member against the restraint of the associated yieldably resilient means.