US2560146A - Lift truck - Google Patents

Description

July 10, 1951 N. WARSHAW ET AL LIFT TRUCK Filed April 2'7, 1946 Patented July 10, 1951 LIFT TRUCK,

Nathaniel Warshaw, Brookline, and Richard E. Jeffery, Maiden, ;Mass., assignorsto Market Forge Company, Everett, Mass., a corporation of Massachusetts ApplicationApril 27, 1946, Serial No. 665,468

2 Claims.

skid and to lift the load, with the skid, in

preparation for transferring the load to another location.

The primary object of our invention is to provide a lifting truck of the type described which, because of its general assembly and arrangement of parts, offers the maximum in efficiency of operation, not only in lifting and lowering but also in transporting a load from one place to another. Another object of our invention is to provide a lifting truck which affords a maximumloadcarrying surface commensurate with retaining the highest efiiciency of operation, an important feature in view of the restricted overall length of a device of this type made necessary by limited storage space, narrow corridors and standard size elevators in factories and buildings. Other objects of our invention are to provide a lifting truck which is extremely easy to operate, even in the most confined places, which is simple and economical to manufacture, and which is easily and economically maintained. Still a further object is to provide a lifting truck which is durable in construction and safe to. operate, advantages so important to lifting and handling of heavy objects. I

In one aspect our invention involves a lift truck comprising a chassis, rear wheel and front wheel supports therefor, swivel means for mounting the latter supports at the front end of the chassis to permit steering, and a lifting plat-form mounted upon said chassis for movement to elevated and lowered positions, the forward edge ing platform. A hydraulic ram connects the platform with means for mounting the rear wheel support at the rear of the chassis, and means are provided for transferring liquidfrom the pump to theram. The ram is disposed in inverted inclined position with the axis of the ram extending rearwardly and downwardly relative to the platform. A relatively resilient tube is provided for transferring the liquid from the pump to the ram and includes an intermediate coiled portion for absorbing the slight angular Y 2- motion of the ram with respect to the lifting platform when the latter is elevated or lowered. The pump has an operating handle projecting from its top and adapted for oscillation transversely relative to the lifting platform, and the pump mechanism includes acontrol valve lever disposed at the frontof the pump forcontrolling the rate and amount of platform lowering... In a further aspect of our invention the swivel means comprises an extension above the chassis and a. steering and pulling handle pivotally mounted on said swivel. extension, the handle comprising an intermediate shoulder, an axially slidable collar encircling the handle, means forwardly offset relative to the swivel extension for pivotally connecting the slidable collar to the swivel extension, and a spring disposed along the handle having one end abutting said shoulder and its opposite end. abutting the slidable collar whereby the expansion force of the spring normally holds the handle in upright position.

For the purpose of illustration a preferred embodiment is shown in the accompanying drawings in which Fig. 1 is a perspective view of the improvedtruck with the lifting platform in fully lowered position; and 1 Fig. 2 is a side elevation with parts broken away and with the lifting platform in fully elevated position.

Referring to the drawings, the numeral l represents a chassis comprising a pair of spaced side frame members 2, a rear frame member 3 and a front bridge 4, the sides, of the-bridge constituting upward extensions 5 of the forward ends of said side frame members 2. A skirt 6 is mounted on the inner faces of the rear frame member 3 and the side frame members 2 at their rear end portions, and extends downwardly below said frame members as shown in Fig. 2. The chassis-issupported at its rear end by rear wheels I mounted upon anaxle 8, the axle being supported by the downwardly extended side portions of skirt 6. The chassis-is supported at its front endby front wheels 9 mounte d upon the axle l0, the portion of the axle intermediate the. front wheels 9 passing through an open ing provided at the lower end. of a vertical steering post H and being locked to the steering post by suitable means such as a cotter pin I2. The vertical steering post H extends upwardly through an openingprovided in the top of the chassis bridge to provide an extension [3, the upper endof said extension being formed with a tongue IA. The vertical steering post withits extension are mounted in the chassis bridge 4 for free swivel movement relative to the chassis in any well known and conventional manner. A collar [5 is fixedly mounted on the extension l3 between the tongue 14 and the top of the chassis bridge, and is provided with a forwardly extending ear IS.

A handle I! is pivotally attached to the tongue l4 of the steering post extension by means of a connecting member [8 comprising at one end a hollow tubular portion l9 adapted to receive one.

end of the handle, and having a fork at its opposite end comprising the spaced fingers adapted to receive the tongue M of the steering post therebetween. Nut and bolt means 2| are provided for securing the handle to the hollow tubular portion 19 of the connecting member and for pivotally securing the tongue M to the fingers 20 of said connecting members.

The handle I! is provided intermediate its ends with a shoulder 22, and a collar 23 is slidably disposed on the handle below said shoulder, the collar having an arm 24 forwardly offset from the extension "l3 and formed with a bifurcated lower end pivotally secured to the ear l6 of the steering post extension collar [5 by suitable means such as a pintle 25. A helical spring 26 is disposed about the handle I! with one end abutting the shoulder 22 and the other end abutting the collar 23, the parts being so arranged that the expansion force of the spring normally holds the handle in a substantially upright position, as shown in Figs. 1 and 2. The handle I! is further provided at its free end with the usual crossbar 21.

The lifting platform 28 comprises a load-suporting floor 29 of substantially rectangular shape and a forward extension 29 of a width slightly greater than the width of the chassis bridge 4 and projecting above the load-supporting floor 29. The platform has downwardly directed side flanges 30 and a rear flange 3 I. The platform is mounted upon the chassis l for movement to elevated and lowered positions, the forward edge 32 of the platform extension 29 being rearwardside 5 of the chassis bridge 4, and a rear pair of links 35, parallel to the links 34, each rear link being secured at one end to a corresponding end of the rear axle 8 and its opposite end to an opposite downwardly extended side portion of the skirt 33, as shown in Fig. 2.

Mounted on the upwardly offset top wall 29 of said lifting platform and aligned with the forward edge 32 thereof is a hydraulic pump 36 of conventional type having a control valve lever 31 conveniently located at its front and an actuating handle 38 projecting from the top of the pump casing, the pump being so mounted on the platform, as aforesaid, that oscillation of the pump handle will be transverse relative to the lifting platform so as not to interfere in any way either with the load carried by the lifting platform or with the steering handle IT.

A hydraulic cylinder or ram 39 (Fig. 2) having a piston 40 and piston rod 4|, adapted to be extended and retracted by fluid pressure generated in the pump 36, has one end formed with a tongue 42 adapted to be received between two spaced lugs 43 fixed to the under side of the platform, said tongue being there pivotally secured by suitable means such as a pintle passing through openings formed in the lugs 43 and the tongue 42. The ram end of the piston rod 4| is connected to the rear axle 8 intermediate the wheels 1, said ram end being formed with an opening through which said axle passes. A relatively flexible tube 44 is connected at one end to the pump 36 and at the other end to the hydraulic cylinder 39 for transferring hydraulic fluid from the pump to the cylinder, the tube extending along the bottom face of the platform and having an intermediate coiled portion 45 for absorbing the slight angular motion of the hydraulic cylinder with respect to the lifting platform when the latter is elevated or lowered. From the foregoing it will be noted that by mounting the pump on the lifting platform, the hydraulic cylinder may be arranged in an inverted position which pre= vents foreign matter from working into the hy= draulic cylinder and permits the em loyment of a continuous, relatively flexible tubing, such, as for example, copper tubing.

As shown in Fig. 2, a pair of spaced supports 46 is carried by each side frame member 2 intermediate the rear and front wheels, to provide a rest for the lifting platform 28 when it is in fully lowered position.

In operation, the lift truck in fully lowered position, as shown in Fig. 1, may be backed under an elevated load, for example a load resting on a load-skid until the front of the skid abuts the upstanding forward extension 29 of the lifting platform. The pump handle 38 is then oscillated, transferring hydraulic fluid under pressure to the hydraulic cylinder to cause the piston rod to move downwardl and rearwardly relatively to the cylinder 39. The resultant increase in distance between the pivot 42 and axle 8 is translated through the sets of links 34 and 35 to cause the lifting platform to swing upwardly and forwardly to elevated position, as shown in Fig. 2. It will be noted that in this elevated position a very compact arrangement of lifting and steering means has been achieved, yet, even in this elevated position, the pump and forward edge of the lifting platform are rearwardly offset from the axis of swivel of the steering post and handle, thus leaving the handle and front whels free to swivel more than to either side of the longitudinal axis of the truck independently of the pump and lifting platform and free from any interference therefrom. The load now being off the floor, the readily accessible control valve lever 31 may be shifted to holding position and the lifting truck with its load may be freely rolled to any desired new location by means of the handle l1. It will be further noted that the pivot point of the handle is relatively high and above the chassis of the truck which is a definite advantage to the ease of pulling and steering the truck to the new location. At the new location, the lifting truck may be left with its load, in which case the handle I! will assume a convenient and safe upright position due to the aforesaid expansion force of the spring 26 tending to hold the handle normally upright. It it is desired to store the load skid at the new location, the control valve lever 31 is manipulated to release the hydraulic pressure in the cylinder 39 at a desired rate and to a desired amount which permits the piston rod to retract into the cylinder, causing the lifting platform to lower until the skid again rests on the floor. Further lowering of the latform separates the top of the lifting platform from the skid, at which time, the lifting truck may be withdrawn from under the skid in readiness for a new task.

It should be understood that the present .disclosure is for the purpose of illustration only and that this invention includes all'modifications and equivalents which fall within the scope of the appended claims.

We claim:

1. A lift truck comprising a chassis, rear wheel supports therefor and means for mounting said supports at the rear end of the chassis, front wheel supports therefor and swivel means for mounting said front wheel supports at the front end of the chassis to permit steering, a lifting platform mounted upon said chassis for movement to elevated and lowered positions the forward edge of the platform being rearwardly offset from the axis of swivel when the platform is in either position, a hydraulic pump mounted at the front end of the platform and aligned with said forward edge of the platform, a, hydraulic ram connecting the rear wheel support mounting means with the platform, the ram being disposed in inverted inclined position with the axis of the ram extending rearwardly and downwardly relative to the platform, and a relatively flexible tube for transferring liquid from the pump to the ram including an intermediate coiled portion for absorbing the slight angular motion of the ram with respect to the lifting platform when the latter is elevated or lowered, whereby operation of the pump will elevate or lower the lifting platform.

2. A lifting truck comprising a chassis, rear wheel supports therefor and means for mounting said supports at the rear end of the chassis, front wheel supports therefor and swivel means for mounting said front wheel supports at the front end of the chassis to permit steering, a steering and pulling handle pivotally secured to the upper end of the swivel means for movement about a substantially horizontal axis, a lifting platform mounted upon said chassis for movement to elevated and lowered positions, a hydraulic pump mounted on the front of the platform in alignment with the forward edge thereof and having a manually-operated pump-actuating handle projecting from its upper end and operatively movable transversely relative to the platform for elevating the platform, a hydraulic ram underneath the platform and connecting the rear wheel support mounting means with the platform, and means for transferring the liquid from the pump to the ram, said hydraulic pump, actuating handle and forward edge of the platform being rearwardly spaced from the swivel means and steering and pulling handle and free from connection therewith when the platform is in either position, so that lifting and lowering of said platform may be effected independently of said steering and pulling handle.

NATHANIEL WARSHAW. RICHARD E. JEFFERY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,841,673 Raymond Jan. 19, 1932 2,161,660 Shepard et al June 6, 1939 2,217,704 Quayle 1 Oct. 15, 1940 2,280,104 Stuebing Apr. 21, 1942 2,325,396 Hastings July 27, 1943 2,372,585 Klumb et a1 Mar. 27, 1945 2,388,864 Page Nov. 13, 1945 2,422,538 Framhein June 17, 1947 2,423,703 Henderson July 8, 1 947

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