US2518251A

US2518251A - Industrial truck

Info

Publication number: US2518251A
Application number: US3853A
Authority: US
Inventors: George F Quayle
Original assignee: Yale and Towne Manufacturing Co
Current assignee: Yale and Towne Manufacturing Co
Priority date: 1948-01-23
Filing date: 1948-01-23
Publication date: 1950-08-08
Anticipated expiration: 1967-08-08

Description

-5 Sh eet's-Sheet 1 h I l I I l I I l l I I l 1 I l G. F. QUAYLE INDUSTRIAL TRUCK LOAD CARRIAGE RAM CYLINDER SUPPORT 0N MOVABLE UPRIGHTS FLUID PRESSURE SOURCE DOWN RAM INVENTOR Gan/ 7e BY Aug. 8, 1950 Filed Jan. 23, 1948 MOVABLE UPRIGHTS Aug. 8, 1950 a. QUAYLE INDUSTRIAL 'mucx 5 Sheets-Sheet 3 Filed Jan. 25, 1948 avx ag fz INVENTOR rye G ATTORNEY Aug. 8, 1950 e. F. QUAYLE INDUSTRIAL mucx 5 Sheets-Sheet 4 Filed Jan. 23, 1948 2 2 4 z 6 MN m m RM b or E T JWN m f v/ m 2%..

0 Ema .7 I B Aug. 8, 1950 a. F, QUAYLE INDUSTRIAL TRUCK Filed Jan. 23, 1948 5 Sheets-Sheet 5 ill/111114. Zr/l/l/l/Il/l ATTORNEY .i atenie Aug. 8, 1950 INDUSTRIAL TRUCK George F. Quayle, Philadelphia, Pa., assignor to The Yale & Towne Manufacturing Company, Stamford, Oonm, a corporation of Connecticut Application January 23,1948, Serial No. 3,853 I This invention relates to an industrial truck of the type in which a load elevating carriage is moved vertically with respect to a main frame for lifting and lowering a load.

In trucks of the particular class, it is customary to mount the load elevating carriage for lifting movement on a pair of secondary uprights, the secondary uprights being in turn mounted for vertical movement on primary uprights. For lifting the carriage on the secondary uprights, and for further lifting the secondary uprights on the primary uprights, it is customary in one type of truck to use a hydraulic ram, comprising a cylinder within which operates a ram that takes the form of a sleeve or solid piston.

Asthose skilled in the art will fully appreciate, it is exceedingly important that the load elevating carriage be capable of some lifting movement prior to the movement of the secondary uprights, so that the overall height of the truck shall not be increased when the carriage is lifted 27 Claims. (Cl. 187-9) the primary uprights and the secondary uprights to lift the secondary uprights together with the carriage relatively to the primary uprights. This truck has been very successful commercially, as those skilled in the art fully appreciate.

It is the object of my invention to improve the prior art trucks of the particular class described by contributing a more effective and emcient mechanism.

A feature of my invention resides in the utilization of a pair of hydraulic rams, with one ram preferably pressing upwardly to lift the carriage relatively to the secondary uprighw, while the other ram presses vertically downwardly to lift the secondary uprights relatively to the primary uprights. By mounting the two rams on the secondary uprights, and by directing their operation as indicated, I am able to effect a considerable saving in hydraulic connections while utilizso ing to the very minimum a flexible hose conneca limited amount. This arrangement is especially necessary where a truck is used for moving loads in and out of freight cars, it being there essential that the overall height of the truck be maintained at a minimum, while the load elevating carriage moves to stack the load within the freight car or to remove a load from a stack in the car. It'is also essential in trucks of the particular class that the elevating ram itself be not unduly exposed, and that it shall not extend above the primary or secondary uprights during the lifting movement of the elevating carriage.

In one form of prior art truck, the elevating ram is adapted to raise the elevating carriage through means of a chain, while adapted to elevate the secondary uprights through direct physical contact between the ram piston and v the said secondary uprights. This direct physical contact is not made until after the ram has moved a predetermined degree to-lift the elevating carriage a relatively short distance from the ground. Because the distance the carriage may move prior to the movement of the secondary uprights is limited, the particular form of prior art truck cannot be used successfully in many load handling installations.

In an application for patent flled by Bronisla I. Ulinski, Ser. No. 692,465, there is disclosed an ingenious solution for the problem in which two rams are utilized for lifting the load elevating carriage and the secondary uprights. One of the rams operates between the secondary uprights and the load elevating carriage to lift the carriage, while the other ram operates between tion between the fluid pressure source on the main frame and the rams on the moving secondary uprights. Moreover, I am able to obtain a full lift of the load carriage prior to any lift Sli of thesecondary uprights. These contributions are of exceeding importance, as those skilled'in the art will understand.

. As a further feature of the invention, the two rams may be telescoped for operation, thereby requiring only a single cylinder, the larger of the two rams pressing upwardly to lift the carriage relatively to the secondary uprights, while the smaller of the two rams presses downwardly to lift the secondary uprights relatively to the primary uprights. As a further feature of this part of the invention, no control means are utilized for directing the fluid against either of the rams, the fluid moving inherently against the larger ram because it has a larger area than the smaller ram and also carries the lighter load. The smaller of the two rams naturally operates last to raise the secondary uprights relatively to the primary uprights. Actually, I have found selves.

A further feature of the invention resides in the utilization I of an extremely short flexible hose connection between the fluid pressure source on the main frame and the rams. As a still further feature of this part of the invention, the ram assembly of my invention is arranged so that the fluid from the pressure source enters the ram cylinder or cylinders through the downwardly pressing ram, making possible thereby an extremely short flexible hose connection, all aswill be very clear after a reading of the specification.

A further feature of my invention resides in the eflicient utilization of flexible members such as chains for lifting the secondary uprights by downward pressure of a ram.

I have thus outlined the general nature of my invention and its relation to the prior art in order that the description thereof that follows may be better understood, and in order that my contribution to the art may be better appreciated. There are, of course, additional features of my invention that will be described hereinafter and which will form the subject of the claims appended hereto. appreciate that the conception on which my disclosure is based may readily be utilized as the basis for the designing of other structures for carrying out the several purposes of my invention. It is important, therefore, that the claims to be granted me shall be of sufiicient breadth to prevent the appropriation of my invention by those skilled in the art. v Referring now to the drawings, Fig. 1 is a vertical elevation and partial section of the load lifting end of a truck of the particular class described. Fig. 1a is a perspective diagrammatic sketch illustrating the functional operation of my two rams. Fig. 2 is a section taken along lines 2-2 of Fig. 1. Fig. 3 is a view looking downwardly on the structure of Fig. 2. Figs. 4, 5, and 6 are sections taken respectively along lines ll, 5-5, and 6-6 of Fig. 2. Fig. '7 is a vertical section through the telescopic ram assembly. Fig. 8 is a view of the structure of Fig. 1, showing the elevating carriage in its fully elevated position relatively to the secondary uprights. Fig. 9 is a view along the same lines as Fig. 8, showing the secondary uprights raised relatively to the primary uprights. Fig. 10 is a view similar to that of Fig. 1, but showing a modification in which two cylinders are utilized for the two rams. Fig. 11 is a view showing the modification of Fig. 10, with the elevating carriage raised relatively to the secondary uprights. Fig. 12 is a view similar to that of Fig. 11, but showing the secondary uprights raised relatively to the primary uprights. Figs. 13 and 14 are sections taken respectively along lines l3-l3 and il-ll of Fig. 10.

Referring now more particularly to the drawings, and more especially to Figs. 1, 8, and 9, the main frame of a standard industrial truck is designated by reference numeral 10, the particular truck being of that type which is electrically propelled and which is equipped with an electrically operated pump for generating hydraulic pressure that is supplied through a flexible hydraulic line. H to suitable rams. The truck is supported at one end by wheels l2 mounted on an axle IS, the other end of the truck being not shown, but being of the-usual class well known in this art. Since my invention relates particularly to the mounting and movement of the elevating carriage and secondary uprights, I think it unnecessary to describe in further detail the truck per se.

Referring now more particularly to Fig. 2, considered with relation to the remaining Figs. 1 to 9 showing my first modification, the main Those skilled in the art will frame Ill of the truck is equipped with side plates l0a to which are welded a pair of vertical primary fixed uprights B. These primary fixed uprights l3, as shown in Fig. 3, are reinforced by a transverse bar I4 and are otherwise braced relatively to the truck by structural frame members l5, l6, and I1 best illustrated in Fig. 1. A pair of secondary uprights i8 is equipped with upper and lower rollers IQ for vertical movement relatively to the primary uprights i3. Secondary uprights l8 are braced at their upper ends by a cross assembly 20, and are further reinforced at an intermediate point by ram supporting casting 2|, probably best illustrated in Fig. 1a, where it is shown in perspective.

The load elevating carriage is designated generally by reference numeral 22 and is here shown equipped with forks 23, each having vertical portions 24 carried by plate 25 best illustrated in Figs. 5 and 6. Plate 25 has welded thereto rearwardly extending brackets 26 carrying upper and lower rollers 21 through which the load elevating carriage 22 is adapted to move vertically relatively to the secondary uprights 18. As thus far described, my truck resembles closely the trucks of the prior art.

In the first modification of my invention to be here described, I use a pair of rams operating within a single ram cylinder through the telescoping of the said rams. Thus, referring now particularly to Fig. 7 taken with relation to Fig. 2 and the remaining figures showing the first modification, the cylinder used by me is designated generally by reference numeral 28. Cylinder 28 comprises an outer sleeve 29 having a lower cap 30 screwed thereto at 3| and an upper cap 32 screwed thereto at 33. The inner telescoping ram is termed by me the down ram and is designated generally by reference numeral 34. Down ram 34 is formed of a head casting 35 and a sleeve portion 35a welded together as is clearly illustrated and adapted to move downwardly for actuating a cross bar 36 onwhich is rotatably mounted a pair of opposed sprockets 31.

The outer telescoping ram is called by me the up ram and is designated generally by reference numeral 28. Up ram 38 is formed of a head casting 39 and a sleeve portion 40 mounted as illustrated best in'Fig. '7 for vertical sliding movement. A cross bar 4| is carried by the up ram 38 and is formed with stub shafts l2 relatively to which are mounted sprockets 43 through means of ball bearings 44. It isv well at this point to indicate that the sprockets 31 are mounted on the down ram 34 in the same manner as the sprockets 43 are mounted on the up ran.

'38. It will be well also to indicate that I utiliz certain spacer and sealing sleeves within the ram cylinder in addition to various hydraulic seals, all as shown in my drawings. but which I do not believe need be described in detail as they are customary in the art and per se form no part of my invention herein claimed.

The ram cylinder 28 is adapted to be carried and supported by the secondary and movable uprights l8 through the casting 2i best illustrated in Figs. 1a and 5, and to be further supported relatively to uprights l8 by a cross assembly 49, best seen in Fig. 4, through a U-bail 49a. Preferably, the ram assembly will be welded to the casting 2|, but it may be otherwise secured thereto, if desired. For the purposes of my invention, it merely need be appreciated that the ram cylinder 28 will be fixed to the secondary uprights for movement bodily therewith.

Referring now more particularly to Figs. 1, la, and 2, a pair of sprocket chains, each designated by reference numeral 45, is utilized for lifting the load carriage 22 relatively to the secondary or movable uprights l3. Eachchain 45 is secured at 48 to a bracket 41 welded to the plate 25 of the load carriage 22, as best illustrated in Fig. The other end of each chain 45 is secured at 48 relatively to the reinforcing cross assembly 49 welded to the secondary or movable uprights l8 as probably best shown in Fig. 2. Chains 45 are maintained in an upwardly extending vertical bight with each chain in engagement with a sprocket 43 of the up ram 38. Obviously, movement of the up ram 38 w'ill'act on the chains to lift the load carriage relatively to the secondary uprights, the rate of movement being twice the speed of movement of the. ram itself.

For lifting the secondary uprights l8 relatively to the primary or fixed uprights I3, I utilize a pair of chains each designatedby reference numeral 58. One end of each chain 58 is secured at 5l' to the ram cylinder supporting casting 2|,

as is best seen in Figs. 1a and 5. The other end of each chain 58 is secured at 52 to a bracket 53 that is an integral part of the main frame, as

probably best illustrated in Figs. 1, 8, and 9.-

Each of the chains 58 is reeved to form a downwardly extending bi'ght passing around sprockets 31 moving with the down ram 34. Upon downward movement of thedown ram 34 relatively to the ram cylinder 28, since brackets 53 of the main frame are stationary, it followsthat the ram cylinder 28 will be moved upwardly. Therefore, the

casting 2| will also move upwardly and will carry into the ram cylinder for operation against the head casting 35 of the down ram 34 and the head casting 38 of the up ram 33. v

The operation of my invention will now be summarized through reference to Figs. '1, 1a, 8 and 9. In the position of the parts in Fig. 1, the two rams are fully telescoped and the secondary or movable uprights 13 are in their fully lowered position relatively to the fixed or primary uprights l3. Let us say that fluid under pressure pressure will be developed within the ram cylinder 23 and this pressure will now actuate the down ram 34. .Upon' movement of the down ram 34 relatively to the cylinder 28 from the position of Fig. 8 to the position of Fig. 9, the chains 50 will be moved from the position of Figs. 1a and 8 to the position ofjFig. 9. Since, as earlier described, brackets 53 cannot move, the relative movement between the down ram 34 and the ram cylinder 28 will effect the upward movement of thecylinder and, the movable or secondary uprights l8 to the position of Fig. 9. Thus, it will be appreciated that the introduction of fluid into the ram cylinder 28 will effect a lifting of the load carriage relatively to the secondary uprights andv thereafter a lifting of the secondary uprights relatively to the primary uprights.

It will be interesting to note by reference .to

Figs. 8 and 9 that the flexible hose II has very will be extremely small with relation to the movement of the load carriage 22. This is of extreme importance, as those skilled in the art will understand. Moreover, it is important to appreciate that my invention requires the utilization of but the single short hose H rather than the rather extensive movable hose connections of the prior art.

Referring now to Figs. l0't0'14 inclusive, I show there a modified form of my'in-vention'in which the down ram and the up ram are mounted in separate cylinders. The functional operation of the two rams is identical in every way, however, with that of the two rams of the first modification.

is now introduced into the ram cylinder 23 through bored passages 54 of down ram 34. Be-

cause the up ram 38 has a larger cross sectional area than the down ram 34, and because the up ram is required to lift a lighter load than the down ram 34, it is obvious that the fluid will act first 'on the up ram 38 to move it from the position of Fig. 1 to the position of Fig. 8. This movement of the up ram 33 effects, through the sprockets 43, the movement of the chains 45 from the position of Fig. la'to the position of Fig. 8. Thus, in the position of Fig. 8, the relatively lim-' ited movementof the-up ram 38 has, through the chains 45, efiected a lifting movement of the The fixed or primary uprights of my second modification are designated by reference numeral 68 and mount for movement relatively thereto movable secondary uprights 6| through suitable upper and lower rollers 62 supported by brackets 63 extending from the secondary uprights 6| as best illustrated in Fig. 14. The load carriage of my second modification is designated by reference numeral 84, and it is adapted for movement through upper and lower rollers 85 relatively to the secondary or movable uprights 6|.

Secondary uprights 8| have secured thereto a lower ram supporting casting 68 similarin many respects'to'the casting 2| of the first modification, except that it, is adapted to support an up ram cylinder 81 and a down ram cylinder 68. Preferably, i utilizekan additional upper ram supporting casting for bracing and otherwise securing in positionthe two

ram cylinders

61 and 68. A flexible-hose 18 extends, as does the flexible hose ll of the first modification, to the down ram H this down ram being bored as isthe down ram 34 of the first'modification, so that fluid load carriage 22 that is double the movement of the ram 38.

With the load carriage 22*now fully elevated,

inder 88. Fluid is then conducted from the upper end of the down ram cylinder 68 through a. pipe 12 to the lower end of the up ram cylinder 61- v for action against the up ram 13. v

Up ram 'l3 is equipped withsuitable sprockets acting against a pair of chains I4 similar to chains45 of my first modification. One end'of each of the chains 14 issecured at '|5 to the castuprights. Each chain is secured at its other end at ll to a bracket 11 forming part of the load elevating carriage 64. The movement of up ram other ram pressing upwardly when hydraulic 13 will obviously lift carriage 54 just as the carriage 22 of the first modification is lifted by its up ram ll.

Down ram 1 l' operates through a pair of sprockets 18 against a pair of chains 19. One end of each of the chains-I8 is secured at 80 to a bracket ll forming part of the main frame as in the case of the first modification. Each chain 19 has its other end secured at 82 to the ram cylinder sup,- porting casting 66 forming part of the secondary uprights 6|. The movement of down ram II will lift the secondary uprights 6| just as the movement of down ram 34 lifts the secondary uprights 22 of my first modification.

The two

ram cylinders

68 and 61 may actually be made the same size and will operate sequentially because ram cylinder 61 is adapted to lift through its ram 13 a smaller load than is to be lifted by ram H of cylinder 68. However, in the drawings, I show the ram II to be smaller in size than the ram 13 in order to better emphasize the invention.

, It will now be quite clear that when fluid is first introduced through the flexible hose 10 into the cylinder 68, it will flow through the pipe 12 .against the relatively larger ram 13 to lift the load carriage. to its position of Fig. 11 on the secondary-uprights 6i. As soon as this is accom- "plished, the pressure will be increased so as to act on the smaller ram H, and to lower that ram relatively to its cylinder 68. This movement willoperate through the chains 19 relatively to the fixed points 80 so as to raise the secondary uprights together with the primary uprights and the carriage to the position of Fig. 12. As I have I believe that the considerable merits and thegreat simplicity of my invention will now be understood and appreciated by those skilled in the art.

I now claim: 1. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic rams mounted on said secondary uprights for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, and means whereby said rams lift said carriage relatively to said secondary uprights and said secondary uprights relatively to said primary uprights.

2. In a truck of the class described, primary uprights, secondary uprights, .means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic rams mounted on said secondary uprights for movement relatively pressure is applied thereto, means whereby one of said rams lifts said carriage relatively to said secondary uprights, and means whereby the other of said rams lifts said uprights relatively to said primary uprights.

3. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic rams mounted on said secondary uprights for movement relatively thereto, means whereby one of said rams lifts said carriage relatively to said secondary uprights, and means whereby the other of said rams lifts said uprights relatively to said primary uprights.

4.- In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprightsfor movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic rams mounted on said secondary uprights for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, means whereby the upwardly moving ram lifts said load carriage relatively to said secondary uprights, and means whereby the downwardly-moving ram lifts said secondary uprights relatively to said primary uprights.

5. In a truck of the class described, primary uprights, secondary uprights, means, mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic rams mounted on said secondary uprights for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, a flexible member secured, at one end to said secondary uprights and at the other endto said load carriage, means whereby said upwardly moving ram applies pressure to said flexible member whereby to move said carriage upwardly relatively to said secondary uprights, a second flexible member secured at one end to said primary uprights and at the other end to said secondary uprights, and means whereby said downwardly moving ram upplies pressure to said flexible member to lift said secondary uprights relatively to said primary uprights.

6. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively'to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, 'a pair of hydraulic rams mounted on said secondary uprights for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, a flexible member secured at one end to said secondary uprights and at the other end to said load carriage while forming an moving ram applies pressure to said flexible member whereby to move said carriage upwardly relatively to said secondary uprights, a second flexible member secured at one end to said primary uprights and at the other end to said secondary uprights while forming a downward bight, and means whereby said downwardly moving ram applies pressure to saidflexible member to lift said secondary uprights relatively;torsaidwpri mary uprights. I 'E a '7. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pairot hydraulic rams mounted on said secondary uprights for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, a chain secured at one end to said secondary uprights and at the other end .to said load carriage, a sprocket whereby said upwardly moving ram applies pressure to said chain 5 to move said carriage upwardly relatively to said secondary uprights, a chain secured at one end to said primary uprights and at the other end to said secondary uprights, and a sprocket whereby said downwardly moving ram applies pressure to- 0 said chain to lift said secondary uprights relatively to said primary uprights.

8. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair or hydraulic rams mounted on said secondary uprights for move- 40 ment relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto, a chain secured .at one end to said secondary uprights and at the other end to said load carriage while forming an upward bight, a sprocket whereby said upwardly moving ram applies pressure to said chain to move said carriage upwardly relatively to said secondary uprights, a chain secured at one end to said primary uprights and at the other end to said secondary uprights while forming a downward bight, and a sprocket whereby said downwardly moving ram applies pressure to said chain to lift said secondary uprights relatively to said primary uprights.

9. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load cariage for movement vertically relatively to said secondary uprights, a pair of hydraulic rams mounted on said secondary uprights for movement relatiively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, a chain secured at one end to said secondary uprights and at the other end to said load carriage while forming an upward bight,

ward bight, and a sprocket whereby said downwardly moving ram applies pressure to the bight relatively to said primary uprights.

10. In atrutk of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said';jprimary; ights loadfcarf- ""ns imoui iting saidiload""carriagemr exit ertically 'i'elatively to said secondary uprights, a hydraulic ram cylinder mounted on said secondary uprights, a pair of telescoping rams in said cylinder adapted for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, and means whereby said rams lift said carriage relatively to said secondary uprights and said secondary uprights relatively to said primary uprights.

11. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a hydraulic ram cylinder mounted on said secondaryuprights, a pair of telescoping rams in said cylinder adapted for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, means whereby the upwardly moving ram lifts said load carriage relatively to said secondary uprights, and means whereby the downwardly moving ram lifts said secondary uprights relatively to said primary uprights.

12. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondaryuprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a hydraulic ram cylinder mounted on said secondaryuprights, a pair of telescoping rams in said cylinder adapted for movement .relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, a flexible member secured atone end to said secondary uprights and at the other end to said load carriage, means whereby said upwardly moving ram applies pressure to said flexible member whereby to move said carriage upwardly relatively to said secondary uprights, a second flexible member secured at one end to said primary uprights and at the other end to said secondary uprights, and means whereby said downwardly moving ram applies pressure to said flexible member to lift said secondary uprights relatively to said primary uprights.

13. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relativelyto said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a hydraulic ram cylinder mounted on said secondary uprights, a pair of telescoping rams in said cylinder adapted for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto. and the other moving upwardly when'hydraulic pressure is applied thereto, a chain secured atone end to said secondary uprights and at the other end to said load carriage, a sprocket whereby said upwardly moving ram applies pressure to said chain to move said carriage upwardly relatively to said secondary uprights, a chain secured at one end to said primary uprights and at the other end to said secondary uprights, and a sprocket whereby said downwardly moving ram applies pressure to said chain to lift said secondary uprights relatively to said primary uprights.

14. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a hydraulic ram cylinder mounted on said secondary uprights, a pair of telescoping rams in said cylinder adapted for movement relatively thereto with one ram moving downwardly when hydraulic pressure is appliedtheretc and the other moving upwardly when hydraulic pressure is applied thereto, means whereby said rams lift said carriage relatively to said secondary uprights and said secondary uprights relatively to said primary uprights, said downwardly moving ram having a bore therethrough whereby fluid is transmitted into said hydraulic ram cylinder and against said rams, said bore extending to an outer lower surface of said ram, and means of connection between a source of hydraulic pressure and said bore.

15. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load car- 12 toanouterlowersurface ofsaidraimanda flexible hose connection between a source of hydraulic pressure and said bore.

17. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load car-. riage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic ram cylinders mounted on said secondary uprights, a ram in one or said cylinders moving downwardly when hydraulic pressure is applied thereto, a ram in the other of said cylinders moving upwardly when hydraulic pressure is applied thereto, and means whereby said rams lift said carriage relatively to said secondary uprights and said secondary uprights relatively to said primary uprights.

18. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic ram cylinders mounted on said secondary uprights, a ram in one of said cylinders moving downwardly when hydraulic pressure is applied thereto, a ram in riage, means mounting said load carriage for movement vertically relatively to said secondary said secondary uprights, a pair of telescoping rams in said cylinder adapted for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, means whereby the upwardly moving ram lifts said load carriage relatively to said secondary uprights, means whereby the downwardly moving ram lifts said secondary uprights relatively to said primary uprights, said downwardly moving ram having a bore therethrough whereby fluid is transmitted into said hydraulic ram cylinder and against said rams, said bore extending to an outer lower surface of said ram, and means of connection between a source of hydraulic pressure and said bore.

16. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movementyertically relatively to said secondary uprights, a hydraulic ram cylinder mounted on said secondary uprights, a pair of telescoping rams in said cylinder adapted for movement relatively thereto with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, means whereby said rams lift said carriage relatively to said secondary uprights and said secondary uprights relatively to said primary uprights, said downwardly moving ram telescoping within the upwardly moving ram and having a bore therethrough whereby fluid is transmitted into said hydraulic ram cylinder and against said rams, said bore extending uprights, a hydraulic ram cylinder mountedon the other of said cylinders moving upwardly when hydraulic pressure is applied thereto, means whereby the upwardly moving ram lifts said load carriage relatively to said secondary uprights, and means whereby the downwardly moving ram lifts said secondary uprights relatively to said primary uprights.

19. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic ram cylinders mounted on said secondary uprights, a ram in one of said cylinders moving downwardly when hydraulic pressure is applied thereto, a ram in the other of said cylinders moving upwardly when hydraulic pressure is applied thereto, a

flexible member secured at one end to said secondary uprights and at the other endto said load carriage, means whereby said upwardly moving ram applies pressure to said flexible member whereby to move said carriage upwardly relatively to said secondary uprights, a second flexible member secured at one end to said primary uprights and at the other end to said secondary uprights, and means whereby said downwardly moving ram applies pressure to said flexible member to lift said secondary uprights relatively to said primary uprights.

' 20. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage, for movement vertically relatively to said secondary uprights, a pair of hydraulic ram cylinders mounted on said secondary uprights, a ram in one of said cylinders moving downwardly when hydraulic pressure is applied thereto, a ram in the other of said cylinders moving upwardly when hydraulic pressure is applied thereto, a chain secured. at one end to said secondary uprights and at the other end to said load carriage, a sprocket whereby said upwardly moving ram applies pressure to said chain whereby to move said carriage upwardly relatively to said secondary uprights, a chain secured at one end to said primary uprights and at the other end to said secondary uprights, and a sprocket whereby said downwardly moving ram applies pressure to said chain to lift said secondary uprights relatively to said primary uprights.

21. In a truck of the class described, primary uprights, secondary uprights, means mounting rights and said load carriage relatively to said secondary uprights, means whereby a source of hydraulic pressure is connected to said cylinder for the flow of fluid against said' rams, one of said rams being larger than the other ram in relation to the loads accepted thereby to a degree sufllcient to direct the fluid pressure first to the relatively larger ram and then to the relatively smaller ram.

22. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a ram cylinder, a pair of telescoping hydraulic rams in said cylinder, means whereby a source of hydraulic pressure is connected to. a bore in one of said rams whereby to introduce fluid under pressure into said ram cylinder for action against both rams, means whereby one of said rams lifts said load carriage relatively to said secondary uprights while the other of said rams lifts said secondary uprights relatively to said primary uprights, and the load thus applied to one of said rams being lighter in proportion to its pressure area than the load thus applied to the other ram whereby one of said rams is actuated automatically in advance of the other ram.

uprights, load carrying means, means mounting said load carrying means for vertical movement on said uprights, a ram cylinder flxed on said load carrying means, a ram in said cylinder adapted for downward vertical movement relatively to said ram cylinder and load carrying means upon the application of fluid pressure to said ram, and means whereby downward movement of said ram lifts said load carrying means relatively to said pair of uprights,

24. In a truck of the class described, a pair of uprights, load carrying means, means mounting said load carrying means for vertical movement on said uprights, a ram cylinder fixed on said load carrying means, a ram in said cylinder adapted for downward vertical movement rela- 23. In a truck of the class described, a pair of tively to said ram cylinder and load carrying means upon the application of fluid pressure to said ram, a chain secured at one end to said pair of uprights and at the other end to said load carrying means, and means whereby the downward movement of said ram acts against said chain to lift said load carrying means relatively to said pair of uprights.

25. In a truck of the class described, primary uprights, secondary uprights. means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic rams mounted with one ram moving downwardly when hydraulic pressure is applied thereto and the other moving upwardly when hydraulic pressure is applied thereto, and means whereby said rams lift said.

carriage relatively to said secondary uprights and said secondary uprights relatively to said primary uprights.

26. In a truck of the class described, primary uprights, secondary uprights, means mounting said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary uprights, a pair of hydraulic rams positioned with one ram pressing downwardly when bydraulic pressure is applied thereto and the other ram pressing upwardly when hydraulic pressure is applied thereto, means whereby one of said rams lifts said carriage relatively to said secondary uprights, and means whereby the other of said rams lifts said uprights relatively to said primary uprights.

2'1. In a truck of the class described, primary uprights, secondary uprights, means mounting a said secondary uprights for movement vertically relatively to said primary uprights, a load carriage, means mounting said load carriage for movement vertically relatively to said secondary- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,320,600 Howell Junel, 1943 2,381,729 Dunham Apr. 7, 1945