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Publication numberUS3735958 A
Publication typeGrant
Publication dateMay 29, 1973
Filing dateNov 15, 1971
Priority dateNov 15, 1971
Publication numberUS 3735958 A, US 3735958A, US-A-3735958, US3735958 A, US3735958A
InventorsHollingsworth E E
Original AssigneeGray Manufacturing Comp Inc St
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
High rise transmission jack
US 3735958 A
Abstract
A high rise lifting jack, for use in handling transmissions or the like, having a pair of vertically extensible members telescopically received within a housing, one of the members being pneumatically actuated and the other being hydraulically actuated. Means secured to the housing at ground level control pneumatic raising during a first stage of operation,and means disposed adjacent and traveling with a load-carrying station at the upper end of the jack control hydraulic raising of the load station during a second,subsequent operating stage. Locking means secure the pneumatic member to the housing to positively support the load station during hydraulic raising.
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[4 1 May 29,1973

limited States Patent [191 Hollingswortli [54] HIGH RISE TRANSMISSION JACK Primary Examiner-Othell M. Simpson Inventor: Elmont E. Hollingsworth, St. Joseph, Atwmey s0hmldt Johnson Hovey & Wllhams [73] Assignee: Gray Manufacturing Company, Inc.,

[57] ABSTRACT A high rise lifting jack, for use in handling transmis- St. Joseph, Mo.

' Nov. 15, 1971 sions or the like, having a pair of vertically extensible members telescopically received Within a housing, one

Filed:

[21] Appl. No.: 198,922

of the members being pneumatically actuated and the other being hydraulically actuated. Means secured to the housing at ground level control pneumatic raising during a first stage of operation,and means disposed adjacent and traveling with a load-carrying station at the upper end of the jack control hydraulic raising of the load station during a second,subsequent operating stage. Locking means secure the pneumatic member 254/93 R, 93 HP; 91/4 References Cited to the housing to positively support the load station during hydraulic raising.

UNITED STATES PATENTS 3,329,403 7/1967 ....254l93 R 18 Claims, 2 w g Figures Patented May 29, 1973 v 3335,58

IN VENTOR.

llllGllil SE SMISSKON JACK This invention relates to lifting jacks and, more particularly, to a jack capable of moving a heavy load through a substantial vertical distance.

High rise lifting jacks are particularly suited for use in conjunction with repair or replacement work at the undercarriage area of elevated vehicles or the like. When installing or removing relatively heavy transrnissions, for instance, the vehicle is normally elevated a substantial distance above the ground support surfacein order to present a convenient working station for the mechanic at the undercarriage of the vehicle. Jacks of the type hereinafter described are particularly useful in supporting the transmission during installation thereof by raising and lowering the transmission to position the same in correct alignment with the mating components of the vehicle. By moving the jack and adjusting its height, the mechanic is able to properly locate the transmission for subsequent mounting thereof to the vehicle. The jack is also quite useful in removing the transmission from the vehicle and permitting controlled lowering thereof.

Completely manually operated jacks of the type described must inherently raise the heavy transmission rather slowly, regardless of whether or not the jack is directly mechanically operated or hydraulically actuated by a manual input force. Great mechanical advantage must necessarily be incorporated in the design of the jack actuator in order to permit manual operation of the jack and, as a result, the manual jack can be shifted upwardly only in short, incremental steps at a rather slow pace.

While pneumatic power is normally available at garages to provide an inexpensive power source for operation of such a jack, difiiculties inherent in pneumatic power have heretofore precluded its efficient use in operating high rise lifting jacks. Due to the inherent compressibility of air and the consequent sponginess and generally poor control of an air cylinder, it has been impractical to utilize an air cylinder to lift and position a transmission in its installation position with the precision required.

It is, however, highly desirable to utilize the readily available pneumatic power for operating the jack instead of operating it manually, in order to speed up the installation work as well as reduce the manual labor required. It is important at the same time, however, that the jack be of simple, inexpensive and very rugged design, and it is particularly important that the jack incorporate easily accessible controls for the mechanic while working under an elevated vehicle for safety purposes.

it is, therefore, a primary object of the present invention to provide a jack of the class described having a pneumatically operated member for raising a load supporting-head of the jack in order to quickly raise and position the head near an installation or removal station disposed a substantial distance above the ground support surface, and a hydraulically operated member for precisely positioning the load supporting head at a desired location subsequent to the initial pneumatic power raising operation. Separate hydraulic and pneumatic control means are disposed on the jack for controlling the respective pneumatic and hydraulic operations of the jack, the hydraulic control means being located adjacent and traveling with the load supporting member for ready accessibility.

It is another object of the present invention to provide, in a jack as described, locking means for selectively securing the hydraulically actuated member on the fixed housing of the jack in order to present rigid, solid support for the hydraulic member during actuation thereof.

It is another important object of the present invention to provide a jack wherein the locking means is operatively connected with the pneumatic control means so as to be automatically released whenever air is exhausted from the actuating chamber which operates the pneumatic member, in order to permit retraction of the pneumatic member and lowering of the load supporting head upon the exhausting of air from the pneumatic actuating chamber.

It is another object of the present invention to provide a high rise lifting jack having a stand including first and second, relatively reciprocable members which are pneumatically operated; a hydraulically operated third member which is reciprocable relative to the stand; locking means for securing the first and second members so that the stand presents a rigid support for the third member upon the reciprocation of the latter; ground-engaging and load-engaging support stations for respectively supporting and shifting a load relative to the ground during relative reciprocation between said members, said support stations being disposed at remote ends of the stand and the third member; and separate pneumatic and hydraulic control means for respectively controlling pneumatic and hydraulic operation of the jack, said pneumatic control means being located at the ground support station associated with the stand and the hydraulic control means being located at the load support station associated with the third member so that both the pneumatic and hydraulic control means are readily accessible throughout the entire operation of the jack.

It is yet another object of the invention to provide a high rise lifting jack of the class described having an upstanding housing engaging a ground support surface; hydraulic and pneumatic members telescopically received with the housing to define hydraulic and pneumatic fluid chambers, said members being shiftable in combination in response to pneumatic flow to the pneumatic chamber, and the hydraulic member being supported upon the pneumatic member to shift individually relative thereto in response 'to delivery of motive flow to the hydraulic chamber, the hydraulic member presenting a load supporting station at the upper end thereof; locking means for selectively securing the pneumatic member to the housing in order to present positive support of the hydraulic member upon the ground station during said individual shifting; and separate pneumatic and hydraulic control means respectively operatively coupled with the pneumatic and hydraulic chambers for controlling motive flow thereto, the pneumatic control means being mounted on the housing adjacent the ground and the hydraulic control means being operatively mounted upon the hydraulic member adjacent the load station.

These and other objects and advantages of the present invention are set forth or will become apparent from the following detailed description of a preferred embodiment of the invention when read in conjunction with the accompanying drawing, wherein:

FIG. 11 is a perspective view of the jack positioned at the end of its pneumatic stroke, the fully raised and fully lowered positions of the jack being shown in dashed lines; and

FIG. 2 is a fragmentary, elevational view of the jack, when located near its fully lowered position, with portions being broken away and in cross section to reveal details of construction.

Referring now more particularly to the drawing, the jack generally comprises an upstanding, cylindrical housing which has a base assembly 12 located at the lower end thereof. The base assembly illustrated has horizontally extending legs 14 provided with swivel wheel-type casters 16. The base assembly presents solid footing and support for the jack upon a ground support surface, the casters 16 permitting the jack to be easily maneuvered to desired locations. A towing handle 11 is pivotally mounted upon housing 10 to facilitate easy maneuvering of the mobile jack upon casters 16.

The housing 10 presents a hollow interior chamber, generally referred to by the numeral 18, closed at the lower end of the housing. The upper end of housing 10 is open and receives members 20 and 22 in telescoping relationship with housing interior 18. Operatively secured to the outer end of member 22 is a load-carrying and positioning head 24. The form of the head 24 as illustrated is of the type shown and described in detail in pending US. application Ser. No. 828,071, filed May 1, 1969, and entitled Load Carrying And Positioning Head, the aforesaid application and the present application having a common assignee.

The description of head 24 will not be set forth in detail as reference may be made to the aforementioned application for further understanding of the construction and operation of the head 24. Briefly, however, the head 24 includes a platform 26 for engaging and supporting a load such as an automobile transmission, and the head 24 is shiftable in a plurality of planes so that the load carried by the platform may be precisely positioned as is necessary, for instance, when a transmission is to be removed from or replaced in a vehicle. Through utilization of a leveling link assembly 28, the entire head 24 may be rotated in' a fore-and-aft tilting direction about a shaft 32; the platform 26 may be rotated in a complete 360 circle.

Plate mounts 36 are affixed to a hydraulic mounting block 38 which is secured to the upper end of member 22 in order to operatively couple head 24 to the upper end of member 22. Hydraulic control means, including a pump 40, are carried by mounting block 28 and hydraulically interconnected with the interior of member 22 for purposes set forth in detail hereinafter.

Member 20 includes an elongated, hollow cylinder 42 having a gland 44 disposed at the lower, inner end thereof. A bearing 46, carried by gland 44, engages the inner wall of housing 10 during reciprocation of member 20 relative to housing 10. Also disposed at the inner end of cylinder 42 is a piston shoulder 48 having a pneumatic seal 50 disposed therebelow in sealing relationship with the inner wall of housing 10. The shoulder 48, seal 50 and gland 44 cooperate to present a movable piston barrier extending transversely across the interior of housing 10 in sealing relationship with the inner wall thereof so as to define a pneumatic working chamber 52 disposed between the lower end of housing 10 and the piston barrier. A spacer 54 in the form of an annular ledge, is rigidly fixed upon the exterior wall of cylinder 42 in order to define a space 56 between it and piston shoulder 48. The upper surface of spacer 54 is engageable with a bearing 58 afiixed at the upper end of housing 10 to limit upward extension of member 20 out of housing 10.

The innermost member 22, which is telescopically received within the hollow interior 43 of cylinder 42, includes a centrally disposed ram 60 having a lower end in contact with gland 44 and extending in sealing relationship through a piston 62. The upper end of ram 60 is disposed within the interior 64 of a concentrically arranged cylinder 66 whose upper end is firmly secured to hydraulic mounting block 38. A hydraulic seal 68 cooperates with ram 60 and the lower end of cylinder 66 which is received by piston 62, in order to form interior 64 as a hydraulic motive fluid chamber.

Member 22 also includes another hollow cylinder 70 disposed concentrically and intermediate cylinders 66 and 42. Cylinder 70 is substantially of the same length as cylinder 66, having an upper end affixed to hydraulic mounting block 38, and a lower end sealingly attached to piston 62. Cylinder 70 thereby cooperates with inner cylinder 66 in order to form an annular fluid reservoir chamber 72 between the cylinders 66 and 70 of member 22. An elongated reservoir suction tube 74 extends downwardly within reservoir chamber 72 to present a low pressure fluid supply duct extending into mounting block 38 to which the upper end of tube 74 is secured.

Piston 62 carries a circular bearing 63, and a spacer 71 is snugly, but loosely, carried between the outer surface of cylinder 70 and the interior surface of cylinder 42. Bearing 63 presents a relatively low friction contact surface with the interior surface of cylinder 42 so as to facilitate reciprocation of member 22 relative to cylinder 42 during such relative reciprocation, the upper surface of spacer 71 being cooperable with a bearing 45 disposed at the upper end of cylinder 42 in order to limit vertical extension of member 22 out of cylinder 42.

Pneumatic fluid inlet and exhaust control valve elements 76 and 78 are mounted upon base portion 12 at the ground support station presented thereby and are respectively interconnected with pneumatic chamber 52 via ports 80 in housing 10. A pressurized air inlet conduit is mounted upon housing 10 to interconnect with the inlet side of valve 76 and to present an inlet port 82 conveniently positioned for interconnection with an air compressor (not shown). A foot pedal 84 is pivotally mounted upon base portion 12 and operates inlet valve 76 when depressed to direct pressurized air from cylinder port 82 into pneumatic chamber 52 to thereupon effect extension of member 20 relative to housing 10. A second foot pedal 86 is also pivotally mounted upon base portion 12 and cooperates with a control valve spool 88 of exhaust valve 78 to permit the exhausting of air from pneumatic chamber 52 when depressed to thereupon permit retraction of member 20 back into housing 10. The jack thereby presents pneumatic retraction and extension control elements disposed at base portion 12 which are respectively operable to permit extension and retraction of member 20.

A safety pawl or locking device 90 is pivotally mounted upon housing 10 at a support bracket 92 disposed on the exterior thereof generally adjacent the upper end of housing 10. Pawl 90 freely extends through an opening 94 in the wall of housing 10 to the interior thereof at a location disposed in the path of travel of spacer 54 associated with member 20. A crank portion 96 of safety pawl 90 has a generally vertically extending bar link 92 secured to one end thereof. The lower end of bar link rests upon retraction foot pedal as to be displaced vertically thereby upon depression of pedal W5. The weight of crank 96 and link 94 biases safety pawl 9b to its normally disposed position illustrated in FIG. 2, wherein the inner end of pawl 94 is in interfering relationship with the path of travel of spacer 54.

it is to be noted that opening 94 acts also as a vent hole for communicating with the atmosphere the upper portion of housing interior 18 disposed above air cylinder seal 50. In this respect, it is also to be noted that cylinder 42 is provided with an aperture 41 for interconnecting its interior 43 with the portion of housing interior lib disposed above air cylinder seal 5% so as to also vent to atmosphere the interior 43 of cylinder 42.

The hydraulic pump 4% illustrated is a manually operated, plunger-type pump secured upon the lower surface of hydraulic mounting block 3%. A reciprocating plunger lllb depends from the body of pump 40 for interconnection with an operating handle ltl2 pivotally secured upon the body of pump 40. The pump is interconnected with hydraulic chamber 64 and suction tube 74 through conventional circuitry schematically illustrated, which circuitry may include one-way check valves 1104 disposed in the fluid conducting paths between the pump and the chamber 64 and tube 74. Upon stroking of handle W2, fluid is drawn from reservoir 72 to the pump, then positively displaced under pressure to the chamber 64, pressure in chamber 64 thereupon acting against member 20 through ram 64 so as to effect vertical extension of member 22 relative to member 2 0. Head 24 shifts upwardly with member 22 to raise the load, and the hydraulic control means also shift upwardly and remain at the load-supporting station presented at the outer end of member 22.

The hydraulic control means also includes a conventional release valve assembly, the operating knob 14b of which is illustrated in FIG. 2 of the drawing, which release valve assembly is operatively mounted within block 38 and interconnected with reservoir chamber 72 and hydraulic chamber 64. The release valve is operable when moved to a clearing position to permit direct discharge of hydraulic fluid flow from chamber 64 back into annular reservoir chamber 72 in order to permit subsequent retraction of member 22 back into the interior 43 of member 2%. Conventionally, the release valve assembly is operable in a blocking position to prohibit direct interconnection of chamber '64 with reservoir chamber 72 so as to permit normal operation of pump 460.

When the jack is fully retracted with head 24 located at its lowermost position, member 20 will be fully retracted within housing 110 with its associated lower gland 44 disposed adjacent the lower end of housing ll). Also, member 22 will be fully retracted within member 201) with its associated lower piston 62 in abutting relationship with the upper surface of gland 44. Both the pneumatic chamber 52 and the hydraulic chamber 64 are consequently of minimum volume in this fully retracted position. When so positioned, the jack is adapted to permit easy maneuverability of large, bulky items such as automatic transmissions of automobiles, into and out of disposition underneath elevated vehicles.

During operation, such as upon installing a transmission in a vehicle, the jack is rolled underneath the elevated vehicle with the transmission carried upon head 24. Cylinder port 22 is interconnected with an air compressor or like source of pneumatic air supply. Extension foot pedal 44 is depressed by the operator to effect pneumatic fluid flow into chamber 52. Member 241) thereupon extends or rises rather rapidly until the upper surface of spacer 54 engages bearing 54, the retracted member 22 being carried with member 20 so as to raise head 24 and the transmission carried thereupon. The jack is illustrated in FIG. l with member 24b in the outermost, extended end of its stroke relative to housing 10.

While shifting upwardly in response to delivery of motive flow to pneumatic chamber 52, the spacer 54 will engage safety pawl 94) as the member 20 nears its stroke end and will easily force pawl 94) to shift outwardly upon its pivoted interconnection with support bracket 92 in order to permit spacer 54 to pass over and above pawl 9 h. The inner end of pawl subsequently drops back into the interior of housing 10 and into space 56. Though shown in exaggeration in the drawing for clarity, the space 56 snugly accepts pawl 94) in order to substantially prevent subsequent upward or downward movement.

Safety pawl 9% thereby effects rigid, mechanical securing of member 20 with respect to housing it) upon the positioning of member 20 substantially at its outmost, extended position. It will be apparent that the member 249 and housing lb thereby present a stand comprising relatively reciprocable members which are selectively intersecurable, the stand representing a rigid, solid support column extending upwardly from base assembly 112 when the member 20 is secured to housing 10.

During this first pneumatic power stage of jack operation, the load carried by head 24 is displaced upwardly a substantial distance and preferably to a location near the installation position thereof. Though jack operation in this pneumatic stage is not precisely controllable due to the sponginess of the compressible, pressurized air in chamber 52, the jack permits the transmission or like load to be quickly and easily positioned in the general area of the installation position required.

To effect further raising of head 24 and to position the load precisely at the installation position, the jack is operated in a second, hydraulic stage. Handle 102 is manually stroked to displace a quantity of motive fluid into hydraulic chamber 64 and shifts the load up wardly. In particular, the cylinders 6b and 74D operatively secured to head 24, shift vertically upwardly an infinitely variable amount with reaction support being provided by ram b ll and the gland 44 affixed to member 20. The rigid support stand presented by the intersecured member 2% and housing 10 thereby transmit the load experienced by member 22 to base assembly 112 in order to present a solid footing for member 22 during individual extension thereof relative to member 2t). It is important that safety pawl 94 be disposed in space'fih to effect intersecurement of member 20 with the housing in order to dispel the sponginess characteristics of the pneumatically operated member 20. The rigid support presented by intersecured member 20 and housing 110, along with the inherently noncompressible characteristics of the hydraulic motive fluid delivered to chamber 64, permit positive, repeatable infinitely variable, upward shifting of the head 24. Pump4ll is operated manually until head 24 and the transmission are raised to the precise installation location desired.

In conjunction with this precise vertical positioning of the head and the load carried thereby, the head may be adjusted in a plurality of planes in order to perfect precise alignment of the transmission with the mating parts of the vehicle to which the transmission is normally affixed upon installation. As noted before, the aforementioned application, which is incorporated herein by reference thereto, may be referred to for a complete description of such operation of head 24 itself.

Member 22 may be individually retracted back into member 20 by operating release knob 106 so as to clear a path of direct communication between hydraulic chamber 64 and annular reservoir chamber 72. The weight of head 24 and any load carried thereupon will effect displacement of fluid from chamber 64 back into the low pressure reservoir 72 so as to permit retraction of member 22. It will be apparent, of course, that by manual operation of the pump handle 102 and the release valve knob 106, member 22 may be precisely extended and retracted relative to the intersecured member 20 and housing 10 in order to locate head 24 at the desired vertical position.

The members 20 and 22 may be retracted in combination back into housing 10 by depressing foot pedal 86 in order to permit valve 78 to exhaust air from pneumatic chamber 52 to the atmosphere. Simultaneously with exhaust of air from chamber 52, depression of foot pedal 86 also shifts safety pawl 90 out of space 56 so as to release the pawl and disengage member 20 from housing 10 in order to permit retraction of member 20 relative to housing 10 in response to the weight presented upon member 22. Member 22, of course, simultaneously retracts with member 20 due to the supporting engagement of member 22 upon member 20.

To effect retraction of the jack, the member 22 may be first fully retracted back into member 20 and then the members 20 and 22 may then be retracted in combination back into housing 10. The pneumatic and bydraulic control means are totally separate in operation however, permitting the members 20 and 22 to be retracted in combination by depression of foot pedal 86 before individual retraction of member 22 back into member 20, if so desired. When effecting extension of the jack on the other hand, it is important that the members 20 and 22 be fully extended in the pneumatic power stroke and the safety pawl secured with member 20 prior to hydraulic actuation of member 22 relative to member 20. This sequence of extension operation of the jack assures a solid footing for the jack during manual, hydraulic extension thereof.

The placement of the pneumatic controls at the ground station assures convenient and easy accessibility to the foot-operated pedals 84 and 86 thereof during all stages of jack operation. Placement of the hydraulic control means adjacent the head 24 or load-support station of the jack, conversely assures that these hydraulic, manually operated controls will always be disposed in a convenient, accessible position to the operator. In particular, when installing automobile transmissions or the like, the general working area for the operator will, of course, be at head 24 and the arrangements of components offered by the present jack always locates the hydraulic controls substantially at this working area.

The present invention thereby presents a jack having a pneumatically operated member 20 that performs the majority of the work in lifting a transmission to the installation position, thereby reducing manual labor required. The manual, hydraulic stage of operation of the present jack is used to do only a small portion of the lifting in the critical area where positive movement of the transmission in minute increments is necessary in order to properly position the transmission. During the manual hydraulic stage, the intersecurement of member 20, with housing 10 eliminates the undesirable characteristics of air-operated cylinders and presents solid footing for the hydraulically operated member 22 to permit gentle and positive urging of the transmission into the installation position. Accordingly, the jack combines the advantages of air power in greatly reducing amount of manual labor required, with the advantages of manual hydraulic power in precisely controlling jack operation during the final stages of the transmission installation.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is: 1. In a high rise lifting jack for raising a load relative to a supporting surface:

a housing member having a base assembly at one end thereof adapted to engage said supporting surface;

hydraulic and pneumatic operated members each having inner ends received within said housing for defining spaced, variable volume, hydraulic and pneumatic fluid chambers, said hydraulic and pneumatic operated members being shiftable in combination relative to said housing in response to delivery of pneumatic motive flow to said pneumatic chamber, said hydraulic member being supported by said pneumatic member for shifting individually relative to said housing and said pneumatic member in response to delivery of hydraulic motive flow to said hydraulic chamber, said hydraulic member having a load-carrying head at the outer end thereof adapted to engage said load;

pneumatic control means located on said housing member and operatively coupled with said pneumatic chamber for controlling pneumatic motive flow thereto; and

hydraulic control means located adjacent said loadcarrying head and operatively coupled with said hydraulic chamber for controlling hydraulic motive flow thereto.

2. A jack as set forth in claim 1, there being locking means for selectively intersecuring said housing and said pneumatic member, whereby to provide solid support structure for said load-carrying head and said hydraulic member during said individual shifting of the hydraulic member.

3. A jack as set forth in claim 2, wherein said locking means is releasable to permit combined retraction of said hydraulic and pneumatic members relative to said housing.

4. A jack as set forth in claim 3, wherein said pneumatic control means includes a retraction control element secured to the housing member and operably connected with said pneumatic chamber, said retraction control element being shiftable to a release posi tion to permit exhaust flow from said pneumatic chamber and thereby permit said combined retraction of said hydraulic and pneumatic members when said locking means is released.

5. A jack as set forth in claim 4, wherein said pneumatic control means also includes an extension control element secured to the housing member and operably connected with said pneumatic chamber, said extension control element being shiftable to a position for directing pneumatic motive inlet flow to said pneumatic chamber to effect combined extension of both said pneumatic and hydraulic members relative to said housing.

I 6. A jack as set forth in claim 4, wherein said locking means includes a pawl, said pawl being interengageable with said housing and said pneumatic member upon shifting of the latter to its outermost, extended position relative to said housing, whereby to intersecure said housing and said pneumatic member in said outermost position.

7. A jack as set forth in claim 6, wherein said locking means also includes a link extending between and operatively engaging said pawl and said retraction control element, said link being operable to release said pawl in response to shifting of said retraction control element to said release position, whereby to permit said combined retraction of the hydraulic and pneumatic members.

8. A jack as set forth in claim 1, said head being shiftably secured to said hydraulic member and presenting a lifting surface adapted to engage the load.

9. A jack as set forth in claim 8, wherein said hydraulic control means includes a motive fluid supply pump carried by said head and operatively connected with said hydraulic chamber for delivering hydraulic motive flow thereto when operated to effect individual extension of said hydraulic member from said pneumatic member.

10. A jack as set forth in claim 9, wherein said hydraulic control means further includes a release valve operatively carried by said head and operatively connected with said hydraulic chamber, said release valve being shiftable to a clearing position to permit exhaust flow from said hydraulic chamber and thereby permit individual retraction of said hydraulic member into said pneumatic member.

11. A jack as set forth in claim 2, wherein said pneumatic member includes a first, hollow cylinder having an inner end disposed in the interior of said housing member; and first piston means secured to said inner end of the first cylinder and positioned in sealing relationship with said housing member for defining said pneumatic chamber within the interior of said housing.

112. A jack as set forth in claim 11, wherein is provided a ledge on the external surface of said first cylinder, and wherein said locking means includes a pawl movably mounted upon said housing member and normally disposed to engage said ledge upon positioning of said first cylinder in its outermost, extended position whereby to thereupon prevent retraction of said first cylinder into said housing, said pawl being selectively movable away from said ledge to permit said combined retraction of the hydraulic and pneumatic members.

13. A jack as set forth in claim 12, wherein is provided a ram extending from said hydraulic chamber into engagement with said first piston means whereby to support said load-carrying head and said hydraulic member upon said first cylinder during said individual shifting of the hydraulic member.

14. A jack as set forth in claim 13, wherein said hydraulic member includes a second, hollow cylinder having an inner end received within the interior of said first cylinder and an outer end operatively secured to said head.

15. A jack as set forth in claim 14, wherein said hydraulic member further includes second piston means secured to said inner end of the second cylinder and positioned in sealing relationship with said ram for defining said hydraulic chamber within the interior of said second cylinder between said outer end thereof and said second piston means.

16. A jack as set forth in claim 15, wherein said hydraulic member further includes a third, hollow cylinder disposed intermediate said first and second cylinders and having an inner end secured to said second piston means and an outer end operatively secured to said head, whereby to define an annular, fluid reservoir chamber between said second and third cylinders.

17. A jack as set forth in claim 16, wherein said hydraulic control means is operably connected with said annular reservoir chamber for controlling hydraulic flow between the latter and said hydraulic chamber.

18. In a high rise lifting jack for shifting a load relative to a ground support surface:

a stand comprising first and second members positioned in a telescoping relationship and defining a pneumatic fluid chamber therebetween, said first and second members being relatively reciprocable in response to delivery of pneumatic motive flow to said pneumatic chamber;

locking means for intersecuring said first and second members upon locating same in a predetermined, relative position to prevent relative reciprocation therebetween;

a third member positioned in telescoping relationship with said second member, said third member defininga hydraulic fluid chamber, said third member and said stand being relatively reciprocable in response to delivery of hydraulic motive flow to said hydraulic chamber;

support stations disposed at opposite, remote ends of said first and third members whereby to reciprocate relatively in response both to delivery of said pneumatic flow and said hydraulic flow, one of said support stations being adapted to engage said ground support surface and the other being adapted to engage said load;

pneumatic control means positioned at said support station associated with said first member and operably connected with said pneumatic chamber for controlling pneumatic motive flow thereto; and

hydraulic control means positioned at said support station associated with said third member and operably connected with said hydraulic chamber for controlling hydraulic motive flow thereto.

i t i i

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3329403 *May 4, 1966Jul 4, 1967Milwaukee Hydraulic Products CCombination hydraulic and pneumatic jacks
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4072288 *May 17, 1976Feb 7, 1978Stabilus GmbhChair with pneumatically adjustable seat height and back support inclination
US4919234 *Nov 9, 1988Apr 24, 1990Pearson Theodore SPortable lift
US5192187 *Oct 23, 1991Mar 9, 1993Sweet Lawrence HAdjustable load bracing crossbar
US6273662Aug 31, 2000Aug 14, 2001Mark A. FleckensteinLifting device
US6378843 *Mar 9, 2001Apr 30, 2002Hong Wen-ChengJack device
US6581908 *Nov 1, 2000Jun 24, 2003Gray Automotive Products, Inc.Dual cylinder jack with interchangeable attachments
US7584973 *Dec 7, 2006Sep 8, 2009Steve BragerMultilevel tool tree
US8201805 *May 29, 2008Jun 19, 2012Filiberto CidHydraulic jack apparatus
Classifications
U.S. Classification254/2.00R, 254/93.00R, 91/4.00R
International ClassificationB66F3/24
Cooperative ClassificationB66F3/24
European ClassificationB66F3/24