US1786643A - Lifting jack - Google Patents

Description

H. W. CLARK Dec. 30,1930.

LIFTING JACK F-iled .Aug. 19, 1927 Patented Dec. 30, 1930 UNITED STATES PATENTOJFFECE HAROLD W. CLARK, F ALLIANCE, OHIO, ASSIGNOR TO, THE BUCKEYE JACK MANUFAC- TURING COMPANY, OF ALLIANCE, OHIO LIIETING JACK Application filed August 19, 1927. Serial No. 2141154.

This invention relates to improvements in lifting jacks, with special reference to an improvement in the form of structure of the jack frame and frame base.

In order to obtain the maximum strength with the least possible weight of material, it has been the custom to make the base or lower part of the frame of the jack either of a single web section or of open box section. The disadvantage of the single web section for base is that when loads are applied eccentrically, the base has a tendency to bend at the edges and take a permanently curved form, so that thereafter the base of the jack will not rest securely upon any level surface but will have a tendency to tilt or tip when a vertical load is applied especially where the load is applied to the foot of the lifting rack. lVhere the base is made of the open boX section, while the edges are supported by the diagonal walls yet the curve where this wall joins the hori- Zontal bottom plate presents a weak point and the bottom of the jack will have a tendency to bend upwards and dish. a This distorts the bottom member and renders the jack ineflicient when set on a flat bed.

In order to overcome the bending of the edges which occurs when the single web section is used, and in order to strengthen the bottom plate against the dishing action, I make the edges of the lower plate of single web section and then core the inside of the base out so as to make flaring upward extending walls to meet the lower member of the casting, and it's-enforcing the opening at the top of the section with two vertical walls to further assist in preventing any bending of the base. I further insert vertical walls or webs in the front or toe of the base and also at the rear to strengthen the same and to prevent any bending or curving of the same under load either at the toe or at the rear of base.

The object of the present invention is to provide an improved base for jack frame, providing an economical distribution of the metal therein so as to provide great strength against distortion, at the same time keeping the weight of the metal as small as possible.

F ig. 1 is a side elevation of a j ask frame and base, showing the projecting foot of the lifting rack.

Fig. 2 is a horizontal section on line a@ of Fig. 1 with rack omitted.

Fig. 3 is a front elevation showing section of base taken on line 6-4) of Fig. 1, with rack omitted.

Referring to the drawing, 4 represents the hollow central standard of the jack frame in which the lifting rack 5 with its outwardly projecting foot 6 is slidably mounted being guided by vertical guides 7 cast as part of the frame. The rear wall of the frame is strengthened by rib 8 which is provided with opening 9 to serve as a hand grip for the jack. The outer flange of rib 8 is strengthened by flat oval shaped section 10, which can be easily gripped as a handle.

The base instead of being either cored out to form a hollow section or being of single web or solid section, is made of the form shown which is best shown in plan in Figure 2. The central part is cored out hollow, and

the flaring side walls 10 and the front and back walls 11 and 12 respectively join with the bottom member 13 along a line 14 which is considerably within the outer edge 15 of the base. The back and side walls are curved inwardly and upwardly from the bottom to meet the vertical members of the frame 4:. The front wall 11 extends diagonally upward from the bottom and is supported by internal rib or web 16 to strengthen the toe of the base against bending. Vertical strengthening rib or web 17 is provided in the rear of the base to strengthen that part against bending and to stiffen the bottom plate 13 from dishing.

The bottom member 13 of the base is of uniform thickness and is cut out at 18 in approximately rectangular form to permit of the insertion. or withdrawal of the lifting rack 5 with its projecting foot 6. This opening may vary in shape or in size depending upon the shape and size of the lifting rack. In order to supply the necessary strength to prevent breaking or bending of the toe or front 19 of the base, I increase the section of the metal at 20 and reinforce the opening 21 with two heavy horizontal members gradua-lly increasing in thickness from the part of the toe 22 to where the front wall meets the main vertical frame at 23.

With the base as I have shown it, there is a heavy single web flange extending complete- 1y around the base, supported against bendng by the front rear and side walls, my ob ject being: to provide a base properly designed to prevent bending at the edges and at the same time to keep the weight of metal as small as possible and to prevent the bottom plate from dishing or becoming concave under loads.

I have provided on the vertical body of the frame reinforcing ribs 24 on both sides of the frame, cast integrally with the frame and extending from the inside of the wall, inwardly. These ribs are just high enough to clear the rack which operates up and down in the center of the frame. The purpose of these reinforcing ribs is to strengthen the frame casting against breaking transversely at the central part of the body where side strains are usually encountered.

I have shown my base in connection with what is known in the trade as a trip ack but it will be obvious that the same type of base can be used with any of the other kinds of jacks commonly used for railroad construction, automobile, & etc.

What I claim is A frame for a lifting jack comprising an oblong base of cored out section, a single web bottom plate with an opening formed therein, an oblique front wall, a toe formed by the junction of the oblique front wall and the bottom plate, and a rib formed within the toe and integral with the bottom plate, the said rib being located approximately in the center of the toe and in the plane of the opening in the bottom plate.

In testimony whereof, I have signed this specification.

HAROLD IV. CLARK.

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