US3188106A - Industrial truck - Google Patents

Description

June 8, 1965 B. l. ULINSKI INDUSTRIAL TRUCK V 5 Sheets-Sheet 1 I 33 54 Lr rg e,

23 B. (Jar/ski June 1965 B. ULINSKI 3,l88,106

INDUSTRIAL TRUGK Filed Dec. 18, 1961 5 Sheets-Sheet 2 'HIM I NVEN TOR. B. UL/us K) 42%&

A rroge/VO' June 8, 1965 4 a. ULlNSKI &188,106&

INDUSTRIAL muon Filed Dec. 18. 1961 5 Sheets-Sheet s INVENTOR. B. I. ULIN$KI June 8, 1965 3. ULINSKI INDUSTRIAL TRUCK 5 Sheets-Sheet 4 Filed Dec. 18, 1961 m m a 97 mm %m r F W m n m ..N NM x w vm mm 3 3 a 3 m i-, V nm om mm I Pm I s wa 3 I Jon mmw U. AM 5 %me E &own 5 o June 8, 1965 B. uLNsK INDUSTRIAL TRUCK 5 Sheets-Sheet 5 Filed Dec. 18, 1961 I-NVENTOR. 5. UL/YSKI Arrow/ey I I I 1 I I I l p 188396 ENBUTEHAL TRUCK Bronislaus I. Utrinski, Flossnoor, Ill., assignor, by masne assignments, to Yale & Towne, Inc., New York, NK., a company of Ghio Filed Dec. 18, 1961, Ser. Ne. 160,@72

' 3 Cisms. (Ci. 28tl-t3.23)

i This invention relates to an industrial truck of the type utilizing a load platform which is mounted at its forward end for vertical movement on a wheel-supported lifting head and is supported at its rear end by downwardly pivoting wheels. and transport pallets, the pivoting Wheels entering spaces in the pallets to permit transport of the pallets.

Trucks of this type have been used for many years, and while various changes in the Construction outlined have been suggested and proposed, these trucks still incorporate complicated mechanical linkage systems for pivoting the rear wheels downwardly as the front end of the platform,

is raised relatively to the lifting head. Because of these r complicated mehcanical linkage systems, such trucks are necessarily costly to manufacture. Fur-ther, such mechanical linkage'systems do not lend themselves readily to variations in width or length of the truck. Accordingly, in order to provide a range of truck sizes and lengths, linkage systems of various sizes must be manufactured and stocked, with attendant problems of production and inventory.

The purpose of this invention is to provide a simplified truck Construction that eliminates the necessity of prior complicated, costly mechanical linkage systems for pivoting the rear wheels as well as the problem inherent in the manufacturing and stocking of mechanical linkages of various sizes for trncks of various widths and lengths. To this end, the truck of my invention incorporates first hydraulic ram means for raising the front end of the load platform relatively to the lifting head, and second hydraulic ram means, horizontally disposed and mounted adjacent the rear end of the load platform, for pivoting the rear wheels. By this arrangement, the necessity of costly mechanical linkage systems and the problems of manufacturing and stocking linkages of various sizes are eliminated, as the same size and shape of ram means may be used in trucks or various widths and lengths merely by shortening or lengthening the hydraulic lines which connect therams to the source of hydrau-lic pressure.

In a preferred form of the invention, the rams means for lifting the front end of the platform and the ram means for pivoting the rear wheels are connected hydraulically in series, with the fluid fiowing from the first ram means to the second ram means to effect simultaneous operation of the ram means, regardless of load distribution. As a feature of my invention, the dimensions of the ram means and the mounting structure for the pivotally mounted rear wheels are so related that the front and rear ends of the platform are raised the same amount through the simultaneous operation of the ram means.

To balance the hydraulic system in the event of some leakage or entrance of air, valve means are provided for periodically connecting all of the ram means in parallel with the source of hydraulic pressure whereby fluid flows 'to all the rams independently to fill the hydraulic system so that it will operate satisfactorily.

As a further feature of the invention, the horizontally disposed ram means at the rear end of the load platform for pivoting the rear wheels, are mounted at one end in a seat and normally held assembled against the seat by spring mean without actual attachment of the ram to the seat or load platform. This arrangement facilitates removal and replacenent of the ram means and also allows &llh Patenta& June &1965

a the ram means to move bodily off its seat against the Generally, trucks of this type are used to lift resistance of the springs if its pivotally mounted rear wheel should strike an obstruction. This bodily movement of the ram means prevents vacuum being developed in the hydraulic system and air ante-ring the system as would result if there were movement of the ram piston relatively to the ram cylinder without flow of fluid to the ram cylinder. The spring means also serve to return the pivotally mounted rear wheels to raised position when fluid is released from the ram means.

I have thus outlined rather broadly the more importan features of my invention in order that the detailed description thereof that follows may be better understood, and in order that my contribution to the art may be better appreciated. The-re are, of course, additional features of myiinvention that will be described hereinafter and'which will form the subject of the claims appended hereto. Those skilled in the' art will appreciate that the conception on which my disclosure 'is based may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of my invention. It is important, therefore, that the claims be regarded as including such equivalent Construction as do not depart from the'spirit and scope of my invention, in order to prevent the appropriation of my invention by those skilled in the art. i i

Referring now to the drawings:

FIG. 1 is a perspective view of a truck in which my invention is enbodied, showing the load platform in a raised position;

i FIG. 2 is a side elevational Viewof the truck shown in FIG., 1, showing the load platform in a lowered position; i

PIG. 3 is a rear view taken in the direction of the arrows 3--3 of FIG. 2;

FIG. 4 is a perspective View of the lifting head of the truck as disassembled from the truck;

FIG. 5 is a skeletonized view of the truck shown in FIG. 1, showing the position of the rams and the hydraulic circuit for the rams;

FIG. 6 is a sectional view taken on the line 6--6 of FIG. 2;

FIG. 7 is a sectional view taken on the line 7--7 of FIG. 6; v

FIG. 8 is a View, partly in section, showing the mounting of the traction unit on the main f'ame.

Referring to the drawings and in particular'to FIG. 1, the invention is shown applied to a pallet truck incorporatng a lifting head lil const-ructed in accordance with my co-pending application Serial No. 160,073, filed December 18, 1961, entitled Lifting Head for Industrial Truck. While the invention is described hereafter in connection with a truck incorporating this particular lifting head, it will be appreciated that this is for the purpose of illustration and that the invention may be applied to trucks incorporating various different lifting head structures for mounting the front end of the load platform for vertical movement.

It is sufi icient to an Understanding of the invention to point out that the lfting head 10 is formed by a simple, horizontal plate 11 and a pair of elongated, vertically extending tubes 12, which are Secured to and eXtend through the plate 11 adjacent the rear edge, as best shown in FIG. 4. The tubes are suitably braced by plate gussets 13 which are welded or otherwise Secured to the plate 11 and the sides of the tubes 12.

The plate 11 is provided with a central opening 14 in which a combined steering and traction unit 15 is mounted for Steer-ing rot-ation by means of a suitable hearing assembly 16, as shown in FIG. 8. The unit 15 is of the general type shown in my United States Patent No. 2,950,- 773, dated August 30, 1969, and includes a steerable traction wheel 17 and an electric drive motor 18 which drives the wheel 17 through suitable gearing. The combined steering and traction unit 15 is adapted to be rotated by means of a pivotally mounted handle 19, to eifect Steering movement of the wheel 17. Handle 19 is provided with suitable switch means 20 for controlling the electric drive motor 18.

The load platform, generally designated by reference numeral 21, includes tr ansversely spaced, horizontal, channel-shaped legs 22 which are adapted to be extended through a pallet. The legs 22 are welded or otherwise rigidly secured at their front ends to a transversely extending, horizontal plate 23. A transversely and vertically extending plate 24 in turn is secured at'its lower edge to the plate 23 and is reinforced, or stiffened, at each side by Vertically extending channel members 25 which are Secured at their lower ends to the plate 23. A second transversely extending, horizontal plate 26 is secured to the upper ends of the channel members 25 and to the transversely extending vertical plate 24. A suitable battery housing 27 is mounted on the rear of vertical plate 24 and supported on the transverse plate 23. Batteries, not shown, for driving the electric motor 18 are enclosed within the housing 27.

Vertically extending shafts 28 secured at top and bottom to the transversely extending horizontal plates 23 and 26 extend slidably through the tubes 12 to thereby support and guide the rear end of the load platform 21 for vertical movement relatvely to the lfting head lil. The front end of the load platform 21 is adapted to be raised relatively to the lifting head by means of a pair of hydraulic rams 29 which are att achedat their lower ends to seats or brackets 30, welded or otherwise secured to the sides of the tubes 12, and which are attached at their upper ends to the transversely extending horizontal plate 26. Admission of fluid to the rams 29 to extend them, as shown in FIGS. 1 and 5, serves to raise the front end of the load platform 21 relatively to the lifting head 10, while the front end is guided through sliding movement of the shafts 28 in the tubes 12.

The rear end of the load platform 21 is supported by wheels 31 which are mounted on links 32 pivotally secured to the legs 22 adjacent the rear ends of the legs by means of pivot pins 33. Pivotal movement of the links 32, therefore, serves to raise or lower the wheels 31 relatively to the legs 22 of the load platform 21 to raise or lower the rear end of the platform 21.

In accordance with the invention, and in contrast to the larrangements as used in trucks heretofore for pivoting the rear wheels downwardly, the rear wheels 31 are adapted to be pivoted downwardly by means of horizontally disposed hydraul-ic rams 34 which are mounted within the legs 22 adjacent the rear ends thereof. This arrangement eliminates the necessity of complicated, expensive linkage systems as heretofore used for pivoting the wheels downwardly.

u As best shown in FIGS. 6 and 7, the rear ends of the cylinders 34a of the rams 34 are provided with elongated projections 35 having convexed shoulders 36. As assembled in the leg 22, the projection 35 of each ram extends through an annular seat 37 and the shoulder 36 engagcs a `conoaved annular surface 38 on the seat 37 to allow pivoting of the ram. The seat 37 is can-ied in an opening 39 in a supporting member 40 which is secured to and extends between the sides 22a of the leg 22. Each ram 34 is held assembled in its seat 37 by means of a pair of extension springs 41 which are secured at one end to the ends of a cross pin 42, which is carried by the piston rod 34b of the ram 34, and are Secured at their opposite ends to the supporting member 40. The cross pin 42 also extends through the links 32 to thereby pivotally attach the piston rod 34b to the links 32 so that extension of the ram 34 serves to pivot the links 32 and the wheels 31 about pivot pin 33 from the raised position as shown in solid lines in FIG. 7 to the lowered position as shown in broken lines in FIG. 7. As the wheels 31 pivot downwardly, the springs 41 are stretched, and when fluid is released from the rams 34, the springs 41 serve to retract the piston rods 34b and pivot the links 32 in a counter-clockwise direction to raise the wheels 31 to the position shown in solid lines in FIG. 7. Engagement of flat portions 43 on the ends of the cross pin 42 with the upper surfaces of blocks 44 serves to limit the pivotal movement of the links 32 in each direction, as best shown in FIG. 7. The blocks 44 are Secured to the sides 22a of the legs 22, and the pivot pins 33, on which the links 32 are mounted, extend through the blocks 44 and are locked in position by set screws 45 which are threaded through the blocks and engage the pivot pins. As best shown in FIG. 6, the links 32 are held assembled to each side of the wheels 31 by means of a bolt 46.

It will be noted that this arrangement for m'ounting the rams 34 allows the rams 34 to move bodily to the right as viewed in FIG. 7 off the seats 37 through Stretching of the springs 41. This bodily movement occurs without movement of the piston rods 3 51 7 relatively to the ram cylinders 34a. Thus, if the wheel 31 should strike an obstruction tending to rotate the links 32 in a clockwise direction, as viewed in FIG. 7, the rams 34 will move bodily to the right through stretching of the springs 41, rather than the piston rod 34b moving relatively to the ram cylinder 34a. This bodily movement of the ram cylinder 3451. This bodily movement of the ram 34 prevents vacuum being developed in the hydraulic system and air entering the system as would result if there were movement of the ram'piston relatively to the ram cylinder without flow of fluid to the ram cylinder. The projections 35 guide and support the rams 34 relatively to the seats 37 during such bodily movement.

In the preferred form of the invention, the rams 29 for r aising the front end of the load platform relatively to the liftin-g head 10 and the rams 34 for pivoting the rear wheels 31 downwardly are connect-ed hydraulically in series with the source of fluid pressure so that as fluid is admitted to the rams 29 on one side of the pistons thereof to extend the rams 29, fluid on the other sides of the pistons is forced out of the cylinders by the pistons of the nams 29 and flows to the rams 34 to eifect simultaneou's operation of the rams 34 regardless of load distribution.

This is illus'trated in FIG. 5 wherein one side of each of the rams 29 is connected to a combined electric pump and reservor unit 47 through a line 48 and a line 49, and the opposite side of each ram 29 is connected by a line 50, a va-lve 51 and a line 52 to a ram 34. Thus, when the pump and reservor unit 47 is operated to admit fluid pressure to the upper side of the pistons of the rams 29 to' extend the rams and raise the front end of the load platform 21, fluid flows from the lower sides of the pistons of the rams 29 through lines 50, valves 51 and lines 52 to the rams 34 to thereby operate the rams 34 simultaneously. The dimensions of the rams 34 and the links 32 are so selected that the front and rear ends of the load platform are raised the *same amount through :the simultaneous operation of the - rams 29 and 34. The valves 51 are bypass valves which normally close off bypass lines 53, but which may be opened periodica'lly to connect the rams 34 in parallel with the rams 29 through the bypass line 53 to allow fluid to flow from the pump and reservor unit 47 directly to both rams 29 and 34 to insure that the hydraulic system is completely filled so that it will operate satisfactorily.

As shown in FIG. 5, the cylinders 29a of the rams 29 and the combined pump and reservor unit 47 are secured to the plate 26. The cylinders 29a, pump and reservor unit 47, and rams 34, together with the connecting hydraulic lines and valves, therefore, move with the load platform 21 so that there is substantially no flexing of the hydraulc lines.

As shown in FIGS. 6 and 7, the end of each leg 22 of the load platform 21 is provided with pallet clamping' .t roller 54 which is mounted on levers 55. The levers 55 are pivoted to the leg 22 by means of a pivot pin 56 which is carried by a lug 57. The lug 57, in turn, is welded, or v otherwise -secured, to a cross plate 58 which extends be tween and Secured to the sides 22a of the legs 22. Each roller 54 is normally urged downwardly toward the position shown in full lines in FIG. 7 by a spring 59 which surrounds a bolt 60, bears at its upper end against a Washer V 61 carried by the bolt 60 and bears at its lower end against *a seat 62 which is pivotally Secured to the levers 55 through pivots 63. The bolt 6%) is anchored to the cross plateSS.

The spring pressed, pallet clamping rollers 54 serve to hold a pallet firmly against the ground until the wheels 31 move into proper position as the legs 22 are inserted through a pallet preparatory tolifting the pallet After the legs have been inserted through the pallet, the combined pump and reservoir unit 47 is operated to admit fluid pressure to the rams 29 and to thereby extend the rams 29 and rams 34 connected in series therewith to raise the load platform 21 and the pallet supported thereon a few inches from the ground. The pallet may then be transported through operation of the truck. The

platform 21 is lowered byreversing the direction of operation of the pump and reservoir unit 47.

As best shown in FIG. 6, the upper surfaces of the legs 22 are preferably provided with openings 64 through which the rams t, wheels 31, pallet clamping rollers 54 and associated structure may be serviced. The :openings .64 are normally closed by removable cover plates 65,

best shown in FIGS. 1 and 6. t

From the preceding description, it can be seen that there is provided a simple truck Construction which eliminates the necessity of the complicated, costly mechanical linkage systems as heretofore used for pivoting the rear wheels downwardly as the front end of the load platform is raised relatively to a lifting head. With the arrangement of the invention, the necessity of manufacturing and stocking linkages of various sizes are eliminated as the same size and shape of rams may be used in trucks of various widths or lengths by merely shortening or lengthening the hydraulic lines which connect the rams to each other and to the source of hydraulic pressure.

While one embodiment of the invention has been shown and described, it will be appreciated that this is 'for the purpose of illustration and that changes and modifications may be made therein Without departing from the spirit and scope of the inventon.

I now claim:

1. An industrial truck comprising,

(a) a wheel supported lifting head,

(b) aload platform, t

(c) means mounting the forward end of said load platform on said lifting head for vertical movement relatively to said liftiug head,

(d) ram means connected with said lifting head and said load platform for raising said forward end of said load platformtrelatively to said lifting head,

(e) wheel means, V V

(f) means mounting said wheel means on said load platform adjacent the rear end thereof' for downward pivotal movement relatively to said load platform to raise and support said rear end of said load platform, i

(g) horizontally disposed ram means mounted on said load platformadjacent said rear end, one end of said horizontally disposed ram means being operably connected to said wheel means, the other end of said horizontally disposed ram means being mounted on a seat Secured to said load platform and normally held against said seat by spring means connected bev tween the other end of said rammeans and saidload platform whereby said horizontally disposed ram means may move bodly ofl of said ram seat through extension of said spring without relative movement between the ends of said ram means, and

(h) means including a source of fluid pressure and hydrauliclines for applying fluid pressure to both said ram means to raise the front and rear ends of said load platform.

2. An industrial truck comprising,

(a) a wheel supported lifting head,

(b) a load platform,

(c) means mounting the forward end of said load pla-tform-on said lifting head for vertical movement relatively to said lifting head, i

(d) ram means connected with said lifting head 'and said load platform for raising said forward end of said load platform relatively to said lifting head,

(e) wheel means,

(f) means mounting said wheel means on said load platform adjacent the rear end thereof for downward pivotal movement relatively to said load platform to raise and support said rear end of said load platform,

(g) horizontally disposed ram means mounted on said load platform adjacent said rear end, said horizontally disposed ram means including a pisten rod and a cylinder, said piston rod being connected to said wheel means said cylinder being mounted on a seat secured to said load platform and normally held against said seat by spring means connected between said piston rod and said load platform whereby said ram cylinder may move off 'of said seat through eX- tension of said spring without :relative movement between said cylinder and piston rod, and

(h) means including a source of fluid pressure and hydraulic lines for applying fluid pressure to both said ram means to raise the front and rear ends of said load platform.

- 3. An industrial truck comprising,

(a) a wheel supported lifting head, (-b) a load platform,

(c) means mounting the forward end of said load plat- (f) means mounting said wheel means on said load platform adjacent the rear end thereof for downward pivotal movement relatively to said load platform to raise and support said rear end of said load platform,

(g) horizontally disposed ram means mounted on said load platform adjacent said rear end, one end of said horizontally disposed ram means being operably connected to said wheel means, the other end of said horizontally disposed ram means being mounted on a seat Secured to said load platform and normally held against said seat by spring means connected b tween end of said ram means and said load platform, Whereby said horizontally disposed ram means may move off of said ram seat without relative move-ment between the ends of said ram means, .said seat having an opening therethrough and said other end of the horizontally disposed ram means having a projection extencl-ing slideably through said opening for guiding said ram means when said ram means is moved off said seat, and u -(h) means including a source of fluid pressure and hydraulic lines for apply-ing fluid pressure to both said ram means to raise the front .and rear ends of said load platform. i

4. An industrial truck comprising,

(a) :a wheel supported lifting head,

(b) a load platform,

(c) means mounting the forward end of said load plat- 7 form on said lifting head for vertical movement relatively to said lifting head,

(d) r-am means connected with said lifting head and said load platform for raising :said forward end of said load platform relatively to said lifting head,

(e) wheel means,

(f) link means pivotally Secured to said load platform for downward pivotal movement `and supporting said wheel means adjacent to end thereof,

*(g) horizontally disposed ram means, one end of said horizontally dispo sed ram means being connected to said link means for pivoting said link means and wheel means downwardly and the other end of said horizontally disposed ram means being mounted on a seat Secured to said load platform .and normally held against said seat by .spring means connected be- -tween the other end of said ram means and said load platform, whereby said horizontally disposed ram means may move off of said seat Without relative movement between the ends of said ram means, and

(h) means including a source of fluid pressure and hydraulic lines for applying fluid pressure to both said ram means to raise the front and rear ends of `said load platform.

5. An industrial truck comprising,

(a) a wheel supported lifting head,

(b) a load platform,

( c) means mounting the forward end of said load platform on said lifting head for vertical movement relatively to said lifting head,

(d) ram means connected with said lifting head and said load platform for raising said forward end of said load platform relatively to said lifting head,

(e) wheel means,

(f) link means pivotally .Secured .to said load platform for downwardly pivotal movement and supporting said wheel means adjacent the end thereof,

(g) horizontally disposed ram means, one end of said horizontally disposed ram means being connected to said link means through a pivot pin and the other end of said horizontally disposed ram means being mounted on a seat secured to said load platform and normally held against said seat by spring means connected to the other end of said ram means and 'said load platform, whereby said horizontally disposed ram means may move off said seat through extension of said spring means without relative movement between .the end of sa-id ram means, said pivot pin extending outwardly from said link means .and engageable with a portion of said load platform to limit pivotal movement of said link means in each direction, and

(h) means including a source of fluid pressure and hydraulic lines for applying fluid pressure to both said ram means to raise the front and rear ends of said load platform.

6. An industrial truck comprising,

a) :a wheel supported lifting head,

(b) a load platform including transversely spaced,

channel shaped legs,

(c) means mounting the forward end of said load platform on said lifting head for vertical movement relatively to said lifting head,

(d) ram means on each side of said lifting head conneoted with said lifting head and said load platform for raising said forward end of said load platform relatively to said main frame,

(e) wheel means for each of said legs,

(f) means mounting one of said wheel means in each leg .adjacent `the rear end thereof for downward pivotal movement relatively to said leg to raise and support said rear end of said load platform,

(g) horizontally disposed ram means in each leg adjacent .the rear end thereof, one end of each of said horizontally disposed ram means being operably conr nected to said wheel means for that leg, and the other end of each of said horizontally disposed ram means being mounted on a seat Secured to said leg and normally held against said seat by spring-means connected between the other end'of said ram means and said leg, whereby each of said horizontally disposed ram means m-ay move off of said ram seat without relative movement between the ends of said rain means, and

(h) means including a source of fluid'pressure and hyi dr aulic lines for applying fluid pressure to said ram means on said lifting head and in said legs to Iaise the front and rear ends of said load platform.

7. :In an industrial hydraulic lift truck, a load supporting main frame having a pair of spaced legs at opposed sides of the truck and a forward transverse portion connecting said legs, a lifting head including a rear end portion juxtaposed to the forward portion of the main frame, a steeririg wheel and means mounting said wheel for rota tion in a vertical steering axis relatively to said lifting head, means extending between the forward portion of the frame and rear end portion of the lifting head and mounting said frame for bodily lifting movement in a straight line relatively to the lifting head, a pair of spaced hydraulic forward lift rams arranged one at each side of the truck and interconnected between said lifting head and said forward transverse frame portion, each forward ram having a lifting axis positioned parallel -to said :straight line lifting movement of .the main frame, a lifting link pivoted under each `of said legs, a floor wheel on one end of each of said lifting links, a hydraulic ram substantially horizontally mounted on each of said legs, means whereby each of said horizontally mounted rams actuates one of said lifting links, means for supplying fluid under pressure to said four hydraulic rams, including means placng one of said 'horizontally mounted rams hyd' aulically in series with the forward ram on the same side of the truck so that those rams by acting in predetermined relation to each other will contribute stability to the truck, and each of the horizontal rams on the legs being of such size with relation to the length of its link and the mountng of said link, and to the capacity of the 'forward ram with which it is in series `so that the link when actuated by its ram will move its wheel the same vertical distance that the related forward ram moves said forward transverse portion of the frame relatively to .said lifting head, the steering axis being held vertical incidental to that actuation of each link by its ram.

8. In an industrial hydraulic lift truck, a load supporting main frame having a pair of spaced legs at opposed sides of the truck and a forward transverse portion connecting said legs, a lifting head including a rear end portion juxtaposed to the forward portion of the main frame, a steerng wheel and means mounting said wheel for rot-ation in a vertical steering axis relatively to said lifting head, means extending between the forward pontion of the frame and rear end portion of the lifting head and mounting said frame for bodily lifting movement in a vertical straight line relatively .to the lifting head, a pair of spaced hydraulic forward lift rams arranged one at each side of the truck and interconnected between said lifting head and said forward transverse frame portion, each forward ram having a lifting aXis positioned parallel to said straight line lifting movement of the main frame, a lifting link pivoted under each leg and adapted to rotate downwardly rel-atively to the leg, a floor wheel on one end of each of :said lifting links, a hydraulic ram substantially horizontally mounted on each of said legs, means whereby each of said horizontally mounted rams rotates one of said lifting links .and its floor wheel downwardly, means for supplying fluid under pressure to said four hydraulic rams to 'lift said main frame simultaneously on said lifting head and floor wheels, including means controlling the fluid supplied to `said horizontally mounted rams and to the forward rams so that those rams will act in predetermined relation to each other whereby to move each floor wheel 9 10 by its link the same vertical distance that the forward 2,693339 :14/54 Quayle 254-8 ttansverse portion of the frame moves relatively to the 2,7 12,430 7/55 Steublng 254-2 lifiting head, the truck being stabilzed and .the steering axis 2,-893,747 7/5-9 Hamblin 2804323 v being held vertical incidental to that movement of the &901852 -9/59 Bottoms 60-53 !floor wheels. 5 2, 953,903 9/ 60 Skoog 60-97 References Cited by the Examiner A' HARRY LEVY, Prima Examiner.

UNITED STATES PATENTS PHILIP ARNOLD, Examner. 2,3-72,5'85 -3/45 -K1umb et al. 280-43.12

Claims (1)

1. AN INDUSTRIAL TRUCK COMPRISING, (A) A WHEEL SUPPORTED LIFTING HEAD, (B) A LOAD PLATFORM, (C) MEANS MOUNTING THE FORWARD END OF SAID LOAD PLATFORM ON SAID LIFTING HEAD FOR VERTICAL MOVEMENT RELATIVELY TO SAID LIFFTING HEAD, (D) RAM MEANS CONNECTED WITH SAID LIFTING HEAD AND SAID LOAD PLATFORM FOR RAISING SAID FORWARD END OF SAID LOAD PLATFORM RELATIVELY TO SAID LIFTING HEAD, (E) WHEEL MEANS, (F) MEANS MOUNTING SAID WHEEL MEANS ON SAID LOAD PLATFORM ADJACENT THE REAR END THEREOF FOR DOWNWARD PIVOTAL MOVEMENT RELATIVELY TO SAID LOAD PLATFORM TO RAISE AND SUPPORT SAID REAR END OF SAID LOAD PLATFORM (G) HORIZONTALLY DISPOSED RAM MEANS MOUNTED ON SAID LOAD PLATFORM ADJACENT SAID REAR END, ONE END OF SAID HORIZONTALLY DISPOSED RAM MEANS BEING OPERABLY CONNECTED TO SAID WHEEL MEANS, THE OTHER END OF SAID HORIZONTALLY DISPOSED RAM MEANS BEING MOUNTED ON A SEAT SECURED TO SAID LOAD PLATFORM AND NORMALLY HELD AGAINST SAID SEAT BY SPRING MEANS CONNECTED BE-

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