US1397869A - Self-lowering jack - Google Patents

Description

J. C. KOPF.

SELF LOWERING JACK. APPLICATION HLED FEB. 4. 1921-.

1,397,869, Patented Nov. 22, 1921.

6 4 SHEETSSHEET l.

(June/M500 393. @Mozwe 1. c. KOPF.

SELF LOWERING JACK.

APPLICATION FILED rzs.4. 1921..

1,397,869. PatentedNov.22,1921.

n 4 SHEETS-SHEET 2.

v ammo/mime c? 74 3& attozm J. C. KOPF.

SELF LOWERING JACK.

APPLICATION FILED FEB. 4. 1921.

1,397,869, Patented Nov. 22, 1921-.

EETS-SHEET 3- 3g at 002w J. C. KOPF.

SELF LQWERING JACK.

APPLICATXON man FB.4.192|.

1,397,869, Patented Nov; 22, 1921.

4 SHEETS-SHEET 4.

UNITED STA'I:

RATENT OFFICE.

JOHN C. KOPIF, OF BELLEVUE BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE DUFF MANUFACTURING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION 01 PENNSYLVANIA.

SELF-LOWERING J'ACK.

Specification of Letters Patent.

Patented Nov. 22, 1921.

To all whom it may concern:

Be it known that I, JOHN G. Kerr, a citizen of the United States, and a resident of the borough of Bellevue, in the county of Allegheny andVState of Pennsylvania, have invented a certain new and useful Improvement in Self-Lowering Jacks, of which the following is a specification.

In a copending application, Serial No. 419,694, filed Oct. 26, 1920, I have disclosed a self lowering screw-jack having a manually-controlled mechanical holding device and a double-acting daslrpotgeared to the rotary run-down screw, as therein more particularly set forth. The present invention is specifically an improvement within this type of jack, affording certain features of advantage having to do with the general purpose of providing a simple, safe and citicient jack mechanism.

In the accompanying drawings, forming part hereof:

Figure 1 is a vertical section through a jack embodying the invention, taken in the plane of the axes of the screw and main operating shaft, which are seen in elevation;

Fig. 2 is a vertical section on a larger scale taken on the line 22 of Fig. 1, showing a portion of the interior mechanism partly in elevation and partly broken away and in section;

Fig. 3 is a horizontal section on the line 3--3 of Fig. 2, with interior parts in elevation;

Fig. 4 is a vertical section on the line 4-4: of Fig. 2; and

Fig. 5 is a vertical section on the line 55 of Fig. 2.

The jack has a base 1, provided with a hollow standard 2 and an annex chamber 3 toward the bottom. The vertically movable load member is preferably in the form of a ram 4 slidably guided in a bearing 5 in the top of the stationary standard of the base, the top of the ram having a head 6 to act upward against the jacking point of the part to be raised. The ram is held against turning by a key 7 held in the upper part of the standard and projecting into a vertical groove 8 in the side of the ram.

The ram is hollow and its lower portion holds, or is formed as, a nut 9, or non-rotary screw member. A male screw 10 is supported rotatably on the base upon a ballv movement of the screw in one direction, the

lifting direction, is produced by oscillatory movement of a removable bar.

The threads of the screw, meaning thereby the two screw members, are to be understood as being of steep pitch, that is to say,

beyond the angle of repose, so that the jack will run down by itself under load, if not held. At such time, through the relative vertical movement of the rotary and nonrotary screw members, the screw 10 is rotated by the load in the direction reverse to that of lifting, and this in turn rotates the shaft 12 in the run-down or lowering direction.

An auxiliary shaft 18, for holding and lowering is journaled in bearings 19, 20 in the annex chamber, transversely to the main operating shaft; and fixed on this shaft and held against longitudinal movement by the bearings is a worm 21, which meshes with a worm-wheel 22 fixed to the main shaft. The worm-wheel and worm are also of comparatively steep pitch, so that the worm will be rotated by the worm-wheel.

The invention includes a closed singlecylinder and double-acting piston device marked generally23, which is shown contained in a barrel 2 1, forming an extension of the annex chamber 3. The said barrel is preferably provided with an enlarged inner portion which is bolted or otherwise separably secured to the main body of the annex casing. As thus constructed, a rotary member 26 is rim-journaled, coaxial with the shaft 18, in a bearing-ring 27 inserted in the enlargement 25, and in a bearing 28 in the mouth of the annex body. The portion of said member which is held against displacement between these bearings constitutes a brake-drum 29, while the portion or element which extends within the barrel'is formed with a cam-groove 30. A circular series of ratchet-teeth 31 on the inner face of the member, and a collar 32 with cooperative teeth, slidably keyed on the end ofthe shaft 18 and pressed-by a spring 33, constitute an embodiment of one-way-acting clutch or driving Connection.

Thedrum is encircled by a brake-band, or relatively stationary brake element, 34, having perforated end lugs35, which are suspended on a rod 36 having bearings in the top of the annex, one of the end portions of the rod being a thrust-screw 37 engaging cooperative screw-threads in the wall, whereby the brake can be released and tightened by manipulation of an external lever handle 38 on the screw, a spring 89 tending to open the band when the screw is backed off. manually-controlled holding and stopping device is thus provided, the precise form, however, being susceptible of variation.

Fitting slidably in the, barrel 24, and coaxial with the parts which have been described, is a closed fluid-tight cylinder 40,

having an extension 41, which telescopes over the cam member 26 and is provided with cam-follower studs 42 working in the camgroove 30. The said cylinder is held against turning with the rotary cam by screw studs 43 in the wall of the barrel projecting inward into longitudinal grooves 44 in the exterior of the cylinder.

Within the cylinder is a relatively stationary double-acting piston 45, having a packing-ring 46 making tight sliding contact with the wall. As illustrated, this piston may be heldstationary in respect to the reciprocation of the cylinder by being connected with the rotary cam member 26, with which it may rotate. As thus arranged, the rod 47 to which the piston is secured passes through packing glands 48, 49 in the heads of the cylinder and is screwed into the cam member.

An opening 50 of predetermined size through the piston affords a restricted passage between the two chambers at opposite sides, through which the confined fluid in the cylinder, preferably a liquid, is obliged to flow as the cylinder and piston are relatively reciprocated.

In operation, the load is lifted in the usual way, by ratcheting the shaft 12. In this operation, the teeth of the member 30 of the automatic clutch ride idly over the teeth on the brake-drum and cam member 26, the said member and the reciprocatory part of the piston and cylinder device remaining.

stationary. At the end of each stroke, the effort of the load transmitted and reduced through the gearing, and tending to rotate the member 26 in the reverse direction, causesthe clutch to catch, and is thereby solidly sustained by the brake, which remains applied during lifting. In order to effect lowering, the brake-band is loosened by means of the handle 38, thus permitting the brake-drum to turn, whereupon the load member 4- starts to descend. Thereby, through the screw members, multiplying gears l6, 15, 22 and 21, and the clutch, the cam is rotated, and by it the parts of the coaxial piston and cylinder device are relatively reciprocated. This compels the fluid to make its way back and forth through the restricted passage 50, and thus restrains the load member to a safe speed of lowering. Theload can be stopped at any point withgutllnjurious shock by again putting on the ra re.

Other forms and aspects of the inVen tion will suggest themselves to the mechanic.

a vertically movable load member, vertical screw means for lifting comprising a screw which is rotated in one direction to efi ect lifting and in the opposite direction by the act1on of the load in lowering, and a holding devlce, in combination with a cam connected wlth the screw, and a single-cylinder double-acting dash-pot coaxial with the cam and operable thereby in lowering.

3. A self-lowering jack, having a base and a vertically movable load member, vertical screw means for lifting comprising a screw wh ch is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, and a holding device, in combination with a cam connected with the screw, 2. fluid-retarding device comprising a riciprocatory cylinder coaxlal with the cam and operatively related thereto, and a relatively stationary doubleacting piston in the cylinder.

4. In a self-lowering jack, a base and a vertically movable load member, vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the load in lowering, a main operating shaft geared to the screw and bearing a wormwheel, an auxiliary shaft bearing a worm meshmg said worm-wheel, a cam coaxial with said auxiliary shaft to be driven thereby, and-a fluid-cylinder and piston device coaxial with the cam and operable thereby in lowering.

5. A self-lowering jack, having a base and a vertically movable load member, vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, and a holding device, mechanism comprising a multiplying gearing and a one-way-acting clutch connected with said screw, a rotary part adapted to be driven through said mechanism in lowering and comprising coaxial brake and cam elements, a relatively stationary brake member cooperative with said brake element, and a coaxial double-acting single-cylinder dash-pot operable by the cam element.

6. A self-lowering jack, having a base and a vertically movable load member, and vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, in combination with a cam geared to said screw, and a device coaxial with the cam, comprising a closed fluid cylinder and a doubleacting piston therein, one of which is operatively related to the cam.

7. A self-lowering jack, having a base and a vertically movable load member, and vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, in combination with a cam geared to said screw, a barrel coaxial with the cam, a closed fluid cylinder contained in the barrel in operative relation to the cam to reciprocate without turning in the barrel, and a relatively stationary double-acting piston in the cylinder.

8. In a self-lowering jack, a base and vertically movable load member, vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, a holding device, and a single-cylinder and doubleacting piston dash-pot device geared to said screw in respect to lowering.

9. In a self-lowering jack, a base and a vertically movable load member, vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, an auxiliary shaft geared to said screw, a rotary member coaxial with said shaft, a one-way-acting connection between said shaft and rotary member, a manual brake cooperative with said rotary member, and a piston-and-cylinder retarding device connected with said rotary member.

JOHN C. KOPF.

Images