Locomotive screw-jack.

Application filed April 27,1914. Serial No. 834,570.

To all wjiom it may concern:

Be it known that we, Clement A. Hardy and Ralph H. Bourne, residing at Chicago, Cook county, Illinois, both citizens of the 5 United States, have invented a certain new and useful Improvement in Locomotive Screw-Jacks, of which the following is a specification.

This invention relates to screw jacks for 10 lifting heavy objects, but it is particularly applicable to the general class of devices used for lifting heavy locomotives from a railroad track for repair and other purposes. One form of these devices is illustrated in 15 Patent No. 1,085,734 to C. A. Hardy, February 3rd, 1914, and another is shown in an application now pending, Serial No. 665,082.

The object of the invention is to provide means whereby when the lifting bar oper20 ated by the lifting jacks of apparatus of this class reaches a stationary support, either temporary during its movement, or permanent in its lowest position, the control of the screws upon the bar will be auto25 matically disconnected without stopping the screw or breaking the apparatus ; that is to say, the lifting screws then automatically cease to further lower the lifting bar with consequent danger of injury to the machine. 30 A further object is to, in combination with the above, provide means whereby the lifting bar will be automatically taken up by the lifting screws when their direction of motion is reversed, from lowering to 35 raising.

The invention consists in a device capable of carrying out the foregoing objects, which can be easily and cheaply made and installed, which is satisfactory in operation, 40 and is not readily liable to get out of order and consists in details and features of construction which will be hereafter more fully described and claimed.

Referring to the drawings, Figure 1 is 45 _a vertical sectional detail view taken on the line 1—1 of Fig. 2 of a locomotive screw jack having the device of this invention in its preferred form incorporated therein. Fig. 2 is a vertical sectional detail view on ⁵⁰ the line 2—2 of Fig. 1. Fig. 3 is an enlarged sectional detail view on the same line showing certain details. Fig. 4is a detail plan view on the line 4—4, of Fig. 3.

As is more fully shown in the above men55 tioned patent and application, devices of this general class are applied to ordinary railroad tracks 10 (Fig. 2). They comprise, in general, one or more pairs of trucks 12 traveling along supplementary tracks 14 parallel to the main track 10, each truck 60 being equipped with a power or lifting shaft 16 controlling one end of a lifting cross bar 18 extending across the track 10 and under the locomotive to be lifted, said bar in some instances carrying also rail por- 65 tions 10^a adapted in certain positions of the device to aline with the rails 10. Each shaft is rotatable at the will of the operator in either direction by means well known in the art illustrated, for instance, in the above 70 patent and application⁴. These trucks 12 may be hand or power driven along the tracks 14, one hand mechanism which may be used comprising the lever 20 operated by a ratchet wheel 22 connected to a shaft 24 75 of the truck.

The cross beam or bar 18 which will be hereafter referred to at various places as a “load bearing member” and “load support”, is supported upon a pair of nuts 26 screw 80 threaded as shown in the figures upon screw threads 15 of each main shaft 16 so that as each shaft 16 is rotated this nut travels upon the threads 15 and correspondingly supports the bar 18. 85

The nut 26 is made of noncircular cross section, as clearly appears in Fig. 2, and slidably but nonrotatively fits into the block or hub 30 extending from the lower side of the adjacent end of beain 18 which ⁹⁰supports, bears, or carries the load, so that if the beam 18 be supported at any point desired and the shafts 16 are rotated to cause the nuts . 26 to travel downward thereon, said nuts will be thus withdrawn ⁹⁵from the beam 18 without either crushing the temporary support for the load or breaking the lifting mechanism and the same advantage exists when permanent supports 32 are provided for the beam 18 in the low- ¹⁰⁰est normal position of the beam 18 in which the rail sections IO register with the main rails 10.

The screw threads 15 upon the screws 16 are omitted at the bottom of each shaft for ¹⁰⁶a distance above the collar or base plate 34 greater than the height of the nuts 26 so that there is opportunity for each nut 26 to temporarily rest in this portion of its shaft 16 above the worm wheel 36 which drives ¹¹⁹

1,176,751 the screw, and below the screw threads 15 thereon; or in other words, in which the rotating shaft has no effect upon these nuts to move them farther downward and conse5 quently to move the beam 18 below its fixed supports, for instance, the rests 32.

Under each nut 26 is a spring mechanism 40, in the particular case here illustrated a coil spring, of sufficient strength to lift the 10 adjacent nut 26 and hold it in engagement with the lower end of the screw threads on shaft 16 so that when the shaft is rotated in lifting direction, the nut 26 will be readily taken up by the screw.

From the foregoing description of this mechanism is will be seen that when the parts are in the position of Fig. 2 and the shafts 16 are rotated, the bar 18 will be given motion upward or downward accord20 ing to the rotation of the shafts 16. When, now, the shafts are rotated in the proper direction to lower beam 18 and said beam has reached the position where it rests upon the supports or rests 32, further rotation of the 25 shafts 16 in this direction withdraws the nuts 26 out of the hubs 30 and the nuts 26 continue to move downward until they have traveled off from the screw threads 15 of the shafts 16 and rest quietly upon the 30 springs 40, in which position the load beam is carried at rest upon the supports 32; the nuts 26 exert no control upon the beam, and consequently any neglect of the operator in allowing the screws 16 to continue 35 to rotate in the direction just described, causes no damage whatever to any of the mechanism. When, however, the direction of rotation of the shafts 16 is reversed, the nuts 26 being held in proximity to the lower 40 ends of the screw threads 15 by the springs 40, the screws immediately take up the nuts 26, move them up into engagement with the beam 18 and then they begin to lift the load and move it up to and through the position 45 of Fig. 2.

It is entirely obvious that the screw threads 15 may be omitted at the top of the shaft as well as at the bottom thereby preventing the nuts 26 from either traveling 50 off from the upper end of the shaft if there is no top support or into engagement with any supporting members which are provided at that point.