US3907120A

US3907120A - Hydrostatic system for overhead crane trolley

Info

Publication number: US3907120A
Application number: US463471A
Authority: US
Inventors: Robert R Johnston; Walter Arnold Paulssen
Original assignee: Dresser Industries Inc
Current assignee: FIELDSTON ACQUISITION Inc
Priority date: 1974-04-24
Filing date: 1974-04-24
Publication date: 1975-09-23
Anticipated expiration: 1992-09-23

Abstract

An oil filled hermetically sealed tank reservoir is supported overhead at the trolley level and is connected via conduit to the trolley side truck which includes enclosed portions forming an integral part of the reservoir. The tank contains essentially all hydraulic and electrical operating components as well as the high pressure hydraulic piping for operation of the hoisting and traverse functions of the overhead crane trolley. Oil within the tank is free to circulate between the tank and the enclosed portion of the trolley side truck making full use of peripheral wall surface to dissipate heat for maintaining temperature of the oil within allowable limits.

Description

United States Patent 1191 Johnston et al.

[ 1 Sept. 23, 1975 HYDROSTATIC SYSTEM FOR OVERHEAD CRANE TROLLEY [75] inventors: Robert R. Johnston, Muskegon; Walter Arnold Paulssen, Spring Lake, both of Mich.

[73] Assignee: Dresser Industries, Inc., Dallas, Tex.

[22] Filed: Apr. 24, I974 [21] Appl. No: 463,471

[52] US. Cl. 212/26; 60/404; 60/D1G. 10 [51] Int. Cl. B66C 17/00 [58] Field of Search 212/10, 11, 26, 32, 124;

60/477, 403, 404, DIG. 10; 254/150 FH; 303/10; 188/170 [56] References Cited UNITED STATES PATENTS 2,631,431 3/1953 Grebe 60/477 2,940,608 6/1960 Underwood et al. 212/124 3,035,414 5/1962 Smith 254/150 FH 3,279,172 10/1966 Kudo et al. 60/484 Gourlay et al. 60/463 Terry 60/398 [57] ABSTRACT An oil filled hermetically sealed tank reservoir is supported overhead at the trolley level and is connected via conduit to the trolley side truck which includes enclosed portions forming an integral part of the reservoir. The tank contains essentially all hydraulic and electrical operating components as well as the high pressure hydraulic piping for operation of the hoisting and traverse functions of the overhead crane trolley. Oil within the tank is free to circulate between the tank and the enclosed portion of the trolley side truck making full use of peripheral wall surface to dissipate heat for maintaining temperature of the 011 within allowable limits.

3 Claims, 5 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of3 3,907,120

US Patent Sept. 23,1975 Sheet 2 of3 3,907,120

FIG. 3

FIG. 4

US Patemt Sept. 23,1975 Sheet 3 of3 3,907,120

FIG. 5

HYDROSTATIC SYSTEM FOR OVERHEAD CRANE TROLLEY CROSS REFERENCE TO RELATED APPLICATIONS Application Ser. No. 463,500 entitled Crane Bridge Trolley co-filed herewith in the name of Paulssen and Chapin.

BACKGROUND OF THE INVENTION 1. The field of art to which the invention pertains includes the art of Traversing Hoists" and more particularly to hydraulic actuating systems therefor.

2. Various forms of hydraulic operated cranes have been developed over the years, as for example disclosed in US. Pat. Nos. 497,216; 2,984,191 and 2,906,143. Despite existence of the technology, the hydraulic crane has not met with any large measure of commercial success, at least not on a commercial scale even remotely comparable with those cranes utilizing components that are driven electrically. In a typical prior art installation for a hydraulic actuated crane trol ley, long exposed hydraulic conduits extend about the trolley frame to each of the individual components operable thereby. While various objections to those systems are known to exist among crane customers as, for example high noise level, etc., reluctance to purchase is principally attributed to a dislike for the hazard of likely oil leakage from burst lines or poor joints in the system and the combustion risk contemplated by such leakage. The objections can be readily reconciled such that when given a choice the customer would just as soon avoid the problem. Notwithstanding recognition of the commercial deterrents associated with hydraulically operated crane trolleys of the prior art, a ready solution has not heretofore been available.

SUMMARY OF THE INVENTION This invention relates to an improved system for operation of overhead crane trolleys and more particu larly to an improved hydrostatic system therefor. Unlike previous hydrostatic systems utilizing long exposed conduit having a multiplicity of joints for supplying the individual hydraulic components remotely scattered about the crane trolley, the system in accordance herewith completely encloses and submerges all high pressure hydraulically operated components and all high pressure piping that operationally control the hoisting and traverse functions of the crane. Enclosure of the components and piping is within a hermetically sealed oil filled tank reservoir supported overhead at the trolley elevation and which utilizes its available exterior walls as a thermally conductive surface by which temperature of the contained oil is maintained within allowable temperature limits. Within this arrangement, a novel holding brake mechanism is provided by which to operate the brake normally associated with positioning and holding of the crane hook. By virtue of the hydrostatic system being almost entirely contained within a sealed tank reservoir, the previous problems of conduit dripping and/or combustion hazards have been substantially, if not completely, eliminated.

It is, therefore, an object of the invention to provide an improved system for operation of an overhead crane trolley.

It is a further object of the invention to provide a novel hydrostatic system for operation of an overhead crane trolley able to substantially, if not completely, eliminate the prior hazards ofoil leakage previously associated with similar purpose systems of the prior art.

It is a still further object of the invention to effect the foregoing objects with a hydrostatic system operably controlling both the hoisting and traverse operations of 'an overhead crane trolley with an arrangement that is economically virtuous as compared to such similar purpose constructions of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view, partially in section, of an overhead crane trolley employing the hydrostatic system in accordance herewith;

FIG. 2 is an end elevation;

FIG. 3 is a side elevation as viewed substantially along the lines 3-3 of FIG. 1;

FIG. 4 is a side elevation, partially in section, as viewed substantially along the lines 4-4 of FIG. 1; and

FIG. 5 is a schematic diagram of the operable hydraulic circuitry employed herein.

Reference is now made to the drawings in which there is illustrated an overhead, top running crane trolley designated of a type with which the invention hereof can be utilized. Crane trolley 10 is more completely disclosed in the above mentioned copending application cross referenced herewith. Briefly, trolley 10 is a 3-point support trolley adapted for traversal operation on

parallel rails

12 and 14 in turn supported on bridge girders (not shown). Comprising the trolley is a truck that includes a partially enclosed frame 21 supported on rail 14 by means of a drive wheel 26 and a longitudinally displaced trailer wheel 22. Laterally extending in a T-like formation from a support in frame 21 is a cylindrically elongated rope drum 32. The distal end of drum 32 is supported within the hub of a third fiangeless wheel 36 adapted for traverse movement over guide rail 12. Formed in the periphery of the drum are right hand rope guides 38 and left hand rope guides 40 between which the drum supports rope sheave's 42. Beneath sheaves 42, reeved rope 43 supports a block 44 carrying a load hook 46. Rotation of the drum effects required raising and lowering of load hook 46 while a spring biased holding brake mechanism 50 is operative as will be described for securing the load hook at any set position.

Comprising the hydrostatic system for operating trolley 10 in accordance herewith is an electric motor 52 operably attached at opposite ends to

hydrostatic pumps

54 and 56. All of these components are contained in an elongated hermetically sealed tank 58 comprised of side, top and bottom walls 62 formedof corrugated steel approximately /8 inch in thickness. The tank is supported at or about the trolley elevation and together with the enclosed portion of frame 21 forms the reservoir for system oil 60. Exterior wall surface of the reservoir is predetermined to at least provide adequate heat transfer sufficient to conductively maintain temperature of oil within allowable limits not to exceed about 180F. Each of the motor and pumps are of the type commercially available from Sundstrand Hydro-Transmission of Ames, Iowa. The level of oil 60 within tank 58 is at least sufficient to submerge the aforementioned components. Volume output of

pumps

54 and 56 and the direction of hydraulic flow to

hydraulic motors

64 and 66 are individually controlled electrically by remotely located

joy sticks

65 and 67 through which crane trolley operation is governed. Joy stick 67 acts to operate the hoisting functions while joy stick 65 acts to operate the traverse functions.

Incorporated into the operation hereof are three individual braking systems for safety and control of the hoisting operation. The first of the systems is the dynamic braking hydraulically afforded by the closed hydraulic loop formed by

conduits

76, 78 and 80 between motor 66 and pump 56. Being a closed loop, inoperability or significantly curtailed operability of the pump inherently brakes the system. The second braking system is provided by the pilot operated counterbalance valve 70 connected between

conduit

78 and 80 serving to trap oil in conduit 80 between it and the load side of hoist motor 66. When oil is trapped in that manner, the hoist motor is prevented from rotating in the lowering direction until pilot pressure is applied from pump 56 via

conduits

76 and 82 for releasing counterbalance valve 70. Providing the third braking system is a spring set normally closed, shoe brake 50 having a hydraulic operating cylinder 84. Cylinder 84 is in turn supplied via conduit 88, solenoid valve 90, conduit 92 and flow control valve 94 by a charge pump 86, integrally part of hoist pump 56. In the absence of or loss of charge pressure, line 92 is open to the tank and spring 74 operates to close brake 50. Solenoid 90 is energized by controller 67 being moved slightly toward hoist or lowering position to actuate brake cylinder 84 for opening brake 50 in opposition to spring 74. Flow control valve 94 operates to introduce a predetermined time delay so that under normal operation the hoisting and/or lowering motion is arrested before closing brake 50, thereby avoiding undue wear on the brake lining.

By the above description, there is disclosed a novel system for operation of an overhead crane trolley in which all the operating components are hydraulically actuated and all are submerged in a hermetically sealed tank supported at the trolley level. The tank comprises the oil reservoir and by its enclosing walls provides sufficient exterior surface area for conductively cooling of the oil in order to maintain oil temperature within allowable limits. By virtue of the entire drive system being submerged, the noise level normally associated with high pressure hydraulic systems of the prior art is substantially if not completely eliminated. At the same time, the system is able to operate the holding brake with a time delay that sets after all motion of the load hook stops thereby preventing excessive wear on the brake shoes as would otherwise be encountered. With the predominance of hydraulic piping and all high pressure piping likewise being contained within the oil tank reservoir, the entire system is substantially isolated against the possibility of hydraulic spray typical of failure occurring in a hose or other hydraulic pressure conduits of the prior art.

Since many changes could be made in the above conbodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. A hydrostatic system for operating an overhead crane trolley comprising in combination:

a. a crane trolley supported overhead and operable when actuated to effect traversal and hoisting functions;

b. a sealed tank supported at the general elevation of the crane trolley and adapted to contain a fill of hydrostatic oil;

c. a plurality of components supported in said tank adapted to be submerged beneath the oil level thereof, said components including:

1. an electric motor;

2. a pair of pumps operably connected to said motor;

3. a first hydraulic motor connected to one of said pumps and adapted to actuate the hoisting function of said trolley; and

4. a second hydraulic motor connected to the other of said pumps and adapted to actuate the traversal function of said trolley;

d. control means to independently actuate said first and second hydraulic motors for independently effecting operation of their respective actuating functions;

e. a plurality of braking systems operably controlled by said tank supported components and operably interacting with each other, one of said braking systems being hydraulically responsive to forming of an oil trap thereto, another of said braking systems being dynamically responsive to reduction in hydraulic supply pressure within a closed hydraulic loop thereto, and still another of said braking systems being mechanically operable and comprising a pair of brake shoes movable into and out of braking relation with a braking surface and a hydraulic unit operably connected to said brake shoes and effective when energized to actuate said shoes toward said braking relation; and i f. flow control means introducing a controlled time delay in energizing said hydraulic brake unit following occurrence of events requiring said mechanical braking system to be actuated.

2. A hydrostatic system according to claim 1 in which the exterior walls of said tank are thermally conductive to afford conductive cooling of said oil fill.

3. A hydrostatic system according to claim 2 in which said trolley includes a frame support at least a portion of which is enclosed and is located juxtaposed to said tank and the walls of said enclosed frame portion to- 'gether with the walls of said tank provide a predetermined surface area for conductively cooling said oil fill to within a predetermined limit of temperature rise.

Claims

1. A hydrostatic system for operating an overhead crane trolley comprising in combination: a. a crane trolley supported overhead and operable when actuated to effect traversal and hoisting functions; b. a sealed tank supported at the general elevation of the crane trolley and adapted to contain a fill of hydrostatic oil; c. a plurality of components supported in said tank adapted to be submerged beneath the oil level thereof, said components including: 1. an electric motor; 2. a pair of pumps operably connected to said motor; 3. a first hydraulic motor connected to one of said pumps and adapted to actuate the hoisting function of Said trolley; and 4. a second hydraulic motor connected to the other of said pumps and adapted to actuate the traversal function of said trolley; d. control means to independently actuate said first and second hydraulic motors for independently effecting operation of their respective actuating functions; e. a plurality of braking systems operably controlled by said tank supported components and operably interacting with each other, one of said braking systems being hydraulically responsive to forming of an oil trap thereto, another of said braking systems being dynamically responsive to reduction in hydraulic supply pressure within a closed hydraulic loop thereto, and still another of said braking systems being mechanically operable and comprising a pair of brake shoes movable into and out of braking relation with a braking surface and a hydraulic unit operably connected to said brake shoes and effective when energized to actuate said shoes toward said braking relation; and f. flow control means introducing a controlled time delay in energizing said hydraulic brake unit following occurrence of events requiring said mechanical braking system to be actuated.

2. a pair of pumps operably connected to said motor;

3. A hydrostatic system according to claim 2 in which said trolley includes a frame support at least a portion of which is enclosed and is located juxtaposed to said tank and the walls of said enclosed frame portion together with the walls of said tank provide a predetermined surface area for conductively cooling said oil fill to within a predetermined limit of temperature rise.

4. a second hydraulic motor connected to the other of said pumps and adapted to actuate the traversal function of said trolley; d. control means to independently actuate said first and second hydraulic motors for independently effecting operation of their respective actuating functions; e. a plurality of braking systems operably controlled by said tank supported components and operably interacting with each other, one of said braking systems being hydraulically responsive to forming of an oil trap thereto, another of said braking systems being dynamically responsive to reduction in hydraulic supply pressure within a closed hydraulic loop thereto, and still another of said braking systems being mechanically operable and comprising a pair of brake shoes movable into and out of braking relation with a braking surface and a hydraulic unit operably connected to said brake shoes and effective when energized to actuate said shoes toward said braking relation; and f. flow control means introducing a controlled time delay in energizing said hydraulic brake unit following occurrence of events requiring said mechanical braking system to be actuated.