US2212051A - Lifting jack - Google Patents

Description

Aug. 20, 1940.

w. s. SAUNDERS LIFTING JACK Fild May 15, 1959 2 Sheets-Sheet l II T FIG.4.

L 1 .r ukrl INVENTOR. WALTER S. SAUNDERS 8 y TORNEY LIFTING JACK Filed May 15, 1939 2 Sheets-Sheet 2 INVENTOR. WALTER SSAUNDERS ATTO Ys Patented Aug. 20, 1940 UNITED; srarss PATNT FFICE LIFTING JACK Application May 15, 1939, Serial No. 273,609

Claims.

This invention relates to lifting jacks, and is particularly concerned with the improvement and simplification of jacking devices for motor vehicles.

In the jacking of automobiles, it has become common practice to provide lifting jacks adapted to engage the front or rear bumper, to lift the car by forcing the bumper upwardly. Where rotatable screw shafts have been employed, difficulty has been encountered in the construction of such jacks, for the reason that where the thread of the screw is of sufficiently high pitch to provide the quickest feasible jacking, friction between the lower end of the screw shaft and its pedestal or other bearing must be relatively great, otherwise the weight of the car will rotate the shaft in reverse direction, and the jack will not hold. Practical considerations require that the pedestal and screw shaft be separable, to permit storage of the jack in a small space, and this further complicates the difficulty of providing sufiicient controlled friction between the shaft and pedestal. The present invention aims to provide an improved jack of the character indicated, having a screw shaft and a separable pedestal constituting the lower bearing therefor, incorporating means whereby adequate friction is maintained at all times to prevent unwanted backing of the shaft under the weight of the car or other load.

A further object is to provide an improved combined pawl and ratchet mechanism, handle support and casing, of improvedand very simple and inexpensive yet rugged construction.

Still another object is to provide improved stop means limiting the upward movement of the traveller and lifting arm which serve to raise the load, yet allowing fuller use of the length of the screw than has heretofore been possible.

Other objects and advantages will be apparent from the following description, wherein reference is made to the accompanying drawings illustrating preferred embodiments of my invention and wherein similar reference numerals designate similar parts throughout the several views.

In the drawings: Figure 1 is a side elevational view of a lifting jack incorporating the present invention, the :screw shaft being centrally broken away.

Figure 2 is a central cross section of the combined pawl and ratchet mechanism, casing, and handle support, fragmentarily showing the adiacent portion of the screw shaft.

Figure 3 is a transverse section taken substantially on the line 33 of Figure 2, and lookingin the direction of the arrows.

Figure 4 is a vertical sectional view taken substantially on the line 4-4 of Figure l, and looking in the direction of the arrows. 5

Figure 5 is aperspective view of the ratchet element.

Figure 6 is a View partly in side elevation and partly in substantially central vertical section of the lower portion of a jack of somewhat modi- 10 fled construction.

Figure 7 is a transverse section thereof. taken substantially on the line 1l of Figure 6, and looking in the direction of the arrows, and;

Figure 8 is a perspective view of the ratchet i element of the modified construction.

Referring now to the drawings:

Reference character Ill designates the screw shaft which comprises the main lifting element and is adapted to be rotated by means of a 20 handle l2 through the agency of a pawl and ratchet mechanism housed in a casing l5, positioned upon the shaft against longitudinal movement but. rotatable thereabout.

.The ratchet element consists of a bushing I1 25 fast upon the shaft and having radially projecting teeth 18 at its upper edge. The teeth are inclined with respect to the axis, to a degree conforming to the inclination of the handle l2 and its supporting socket portion E6. The socket portion will be seen to constitute an integral extension of the casing l5, the casing and socket portions being formed in upper and lower halves held together by overbent tongues 89 and a rivet 2!, the latter also serving as a bearing and support for the pawl 21!. The bushing il will be seen to substantially fill the casing 55, to maintain alignment between the pawl and ratchet teeth. The pawl is provided with a pointed detent portion at each end, these being adapted to act in reverse directions. An integral extension 22 of the pawl extends through a slot 23 inthe side of the casing, constituting a finger piece by which the pawl may be swung by hand to throw either detent end into engagement with 5 the ratchet, two oppositely acting positions being thereby provided, as indicated in Figure 3. The rear edge of the pawl is provided with a pointed extremity 26 adapted tolie on either side of the oppositely pointed central portion of a leaf spring 25, which thereby urges the pawl into engagement with the ratchet teeth in whichever direction may be desired. The spring is retained at its ends in the casing upon ears 26, and the movement of its central portion is sufficient to allow the pawl to be moved to either side by merely manipulating the finger piece 22.

The upper end of the shaft will be seen to be provided with a screw thread, which is preferably of the buttress type. A traveller nut 30 rides upon the threads and is trapped in an opening as 32 in a sheet metal cage 35, which is shaped to encircle the shaft and provided with a laterally projecting arm 31, notched, as at 40, to under engage the bumper or other part to be lifted. The threads are deformed near the end of the shaft, as indicated at 44 and such deformed portion. limits the upward movement of the traveller. Due to the downward extension of the portion of the cage which encircles the shaft, the nut may thus be allowed to move to a point near the upper end of the shaft, without danger of injury to or displacement of the cage.

The lower end of the shaft is beveled as indicated at 5B and adapted to fit in a socket, 52, having conical walls of similar pitch, formed as a depression in a sheet metal base plate 55, the central, socketed portion of which may be somewhat raised, as shown in the drawing. The socket is so shaped that the shaftmust ride upon the beveled surface near its periphery, a predetermined minimum of friction being thereby insured.

In the somewhat modified construction shown in Figures 6, 7 and 8, the ratchet is formed as a sleeve HA having circumferentially spaced perforations l8A which act as abutment teeth for the pawl 20A, disposed centrally of the casing I 5A and at right angles to the shaft.

The portion of the shaft to which the pawl sleeve is to be applied is knurled as at 23A, and. the sleeve is of such size that when forced onto the knurled portion, it is firmly held against turning with relation to the shaft. The lower endof the shaft is somewhat rounded and adapted to ride in a cup, 52A, the bottom of which is curved upon a shorter radius, to provide clearance between the end of the shaft and the bottom of the cup except around the periphery of the shaft. The side walls of the cup are somewhat conical in shape, to allow a certain amount of tilting of the shaft with relation to the base. Again it will be noted that the presence of a minimum amount of friction is insured by the fact that the shaft and the bearing cup may only engage along a surface near the periphery of the shaft. Other portions of the modified embodiment corresponding to parts already described have been given like reference characters, distinguished by the addition of the letter A to each, and require no detailed redescription.

. I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiments to be considered in all respects as illustrative and not restrictive; reference being had to the appended claimsrather than to the foregoing description to indicate the scope of the invention.

I claim:

' 1. In a lifting jack, in combination with a base and a screw shaft adapted to be rotatably supported thereby, a traveller threaded on the screw shaft and adapted to move therealong to lift or lower a desired load when the screw shaft is turned, and means for turning the screw shaft, comprising a tubular sheet metal ratchet portion fast upon and projecting from the surface of the shaft having an integral flange provided with ratchet teeth extending circumferentially thereof, each tooth being tapered on both sides, a sheet metal combined casing and handle supporting portion encircling and rotatable with respect to the shaft and enclosing said ratchet portion and held thereby against unwanted longitudinal movement with respect to the shaft, a pawl housed in said casing and cooperating with said ratchet element and having a manually operable portion extending from said casing, a pair of nose portions spacedly carried by said pawl, each nose portion having an abrupt face and a sloping face, the abrupt and sloping faces of the two nose portions facing in opposite directions, means pivotally securing the pawl to the casing at a point behind and approximately midway between said nose portions, the positioning of said pivotal securing means being such as to permit swinging of either of said nose portions into engagement with said ratchet teeth, the sloping face of each of said nose portions being so inclined as to slide over said ratchet teeth, and the abrupt face being adapted to engage and hold said teeth, and over-center spring means tending to urge either of said nose portions into engagement with said ratchet teeth.

2. Means as set forth in claim 1 in which said pawl is provided with oppositely acting detent portions engageable with the ratchet portion by rocking the pawl to either of two extreme positions, and spring means having an overcenter portion engageable with the pawl in either of two directions and tending to move the pawl toward either of said extreme positions in accordance with the direction of such engagement between the pawl and said overcenter portion.

3. Means as set forth in claim 1 in which said pawl is provided with two oppositely acting detent portions, overcenter spring means tending to urge the pawl yieldably toward either of two extreme positions to which it may be thrown, to engage either of said detent portions with the ratchet portion, and a finger portion connected to the pawl and extending from the casing to allow the pawl to be swung to either of said extreme positions.

4. Means as set forth in claim 1 in which said ratchet portion comprises a plurality of teeth projecting from the shaft at an acute angle to the axis, said casing having a portion projecting from'the shaft at an angle conforming to that of the teeth, and means for supporting said pawl element at a corresponding angle.

5. Means as set forth in claim 1 in which said ratchet portion comprises a sleeve fast upon the shaft and having teeth projecting therefrom at an acute angle to the axis, said casing having a portion projecting from the shaft at an angle corresponding to that of the teeth and substantially aligned therewith, means for rockably supporting said pawl element at a corresponding angle, said projecting portion of the casing also being provided with a handle supporting portion disposed at a similar angle.

WALTER S. SAUNDERS.

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