US1946242A

US1946242A - Lifting jack

Info

Publication number: US1946242A
Application number: US576512A
Authority: US
Inventors: Frank H Schwerin
Original assignee: DUFF NORTON Manufacturing Co
Current assignee: DUFF NORTON Manufacturing Co; DUFF-NORTON MANUFACTURING Co
Priority date: 1931-11-21
Filing date: 1931-11-21
Publication date: 1934-02-06
Anticipated expiration: 1951-02-06

Description

Feb. 6, 1934. F. H. SCHWERIN LIFTING JACK Filed Nov. 21, 1931 m r z w alum/$2 ATTORN E Patented Feb. 6, 1934 The invention relates t STAT-ES; PATENT OFFICE LIFTING JACK Frank H. Schwerin,

Bell'evue, Pa., assignor to- Application November 21, 1931 Serial No. 576,512

2 Claims. (Cl. 254108) rack or ratchet jacks.

An object of the invention is to provide an improved jack having a simple and compact forcemultiplying mechanism including a compound lever system and an operating handle" connected to the lever system in a relation which obtains the most desirable operation of the force-multiplying mechanism. The invention is particularly adapted for use in making the inspections of the journals of railway cars conveniently and quickly. Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

The embodiment of the invention illustrated in the accompanying drawing is shown partly in elevation and partly in ver tical section.

The jack frame comprises a base 2 and standard 3 rising from the base and formed tangular passage for the which is formed with ratchet teeth 5.

with a recjack bar 4, the back of At the back of the frame and extending upward from the base is a rib 6, and above largement 7 containing The top of the jack this there is an enthe pawl mechanism.

bar is preferably provided with a lifting head 8, but the load rest which is more the purpose of raising the particularly useful for cars is a long toe-lift 9,

truck-frames of railroad which projects at the say at the side opposite 'mechanism. The front front of the jack, that is to from all the operating wall of the standard is accordingly formed with a vertical slot 10 through which the toe-rest, secured to the lower end of the rack bar, extends.

Fulcrumed in the enlargement 7 on a pin 11 is these pawls vention the lever 12 is not front of the fulcrum, is

. A holding pawl 14 is enlargement on a pin 15. The arand of the lever 12 may of the mechanisms of known cordance with this inthe operating lever socketed to receive the handle but is a secondary lever of a compound leve The operating lever located below the lever 12.

the handle 17, and its forward for reception of r system.

19 of the present jack is It has the socket 16 portion is connected to the rib 6 by a fulcrum pin 18. The two pair of links 20, constituting levers are interconnected by a the equivalent of a single link. The lower ends of these links are pivoted on a pin 21, which is carried by the primary operating lever at a point between its fulcrum 18 and the socket are pivoted to a pin 22 ;;secondary lever 12, this ar 16. Their upper ends on the rear end of the m of the secondary lever much longer than the forward arm which distance between the centers of the fulcrum 11 and the pivot of the pawl 13.

The socket 16 extends at an angle to a plane through the axes of the

pivotal connections

18 and 21 so that the operators end of the handle 1'7 is higher above the ground or floor on which the jack stands than it would be if the axis of the socket and handle were in line with these

pivotal connections

18 and 21. In the drawing the pivot 21 is shown in a pos'tion higher than the pivot 18. The angular relation of the handle 1'! permits the operating lever 19 to be oscillated to bring the pivot 21 well below the level of the pivot 18 before the operators end of the handle 17 79 strikes the ground or floor.

The mechanical advantage of ratchet lifting jacks is not uniform. As the handle 17 moves downward the lifting force of the jack decreases somewhat because of changes in the effective lever arms. For example, the leverage effect of the operating lever 19 reaches a minimum when the axes of the

pivots

18 and 21 are in a substantially horizontal plane at right angles to the plane of the

pivots

21 and 22. The most uniform mechanical advantage, and the greatest pawl travel, are obtained when the power stroke of the handle 1'? is such that the plane through the axes of the

pivots

18 and 21 becomes horizontal when the handle is at the midpoint of its stroke.

The angular position of the socket 16 permits the use of a long handle 1'7 and the most desirable stroke for the lever 19 with the axes of the

pivots

18 and 21 in a substantially horizontal plane at the mid-stroke position of the lever 19. Thus, the invention provides a jack having a minimum change in mechanical advantage during a stroke of the operating lever.

This mechanism is a very simple and inexpensive means of increasing the power advantage of the jack. It also possesses other distinct advantages. The mechanism is all at the back of the jack and involves no overhang or projection at the front which would keep the jack from being placed close to the face of a load to be raised on the toe-lift; consequently, the toe-lift can project from the front of the jack, and when this toe is used the operating lever and handle are away from the load. In geared rack jacks, in which multiplication of force is obtained by gearing, the mechanism necessitates some projection beyond the front or toe face of the jack, which increases the distance from the center of the jack bar to the load face, unless the toe is arranged to 1 being is measured by the project at one side :of the jack, as is sometimes done. In the latter event, however, the operating lever and handle must operate in a plane adjacent and'parallel with the load face, which in some work, such as journal work, would interfere with the side of the car or other body.

In order to provide the jack with a larger base and to facilitate moving the jack from point to point, a base plate 23 is attached to the base of the jack, upward rear extensions 24 of this base plate carrying two wheels 25, which when the jack is erect are clear of the ground. A catch 26 pivoted on one of the links 20, or on a part of the jack frame, and engageable with a Stud 27 on the socket lever enables the handle to be used for tilting the jack and the 'base plate onto the support of the wheels for trundling.

It will be understood that jacks embodying the invention include means for reversing the pawl i action to secure automatic lowering of the load.

Known reversing provisions are applicable directly to the jack shown in the drawing and it has been thought unnecessary to illustrate such provisions.

The jack of this invention is well adapted, and has been specially devised, for the inspection and repair of journals of railroad cars. Periodic inspection of all journals is compulsory, and a speeding up of such inspections is greatly to be desired. The present jack is to be applied to the truck frame between the journals, so that both journals are raised and can be inspected at the same time. The force-multiplying linkage is such as to give ample power for this purpose with cars of maximum weight.

However; the invention is not confined to this use, and the jack may be readily modified for other specific purposes.

I claim:

1. In a lifting jack, the combination with a the end of the long arm of the lever; a second lever fulcrumed at one end on the frame and pivotally connected intermediate its ends to the link at a point which is higher than said fulcrum when the second lever is at one end of its stroke; and a handle-receiving socket in the end of the second lever remote from the fulcrum, said socket extending upwardly at an angle when the parts are in such position that the fulcrum of the second lever and the axis of its pivotal connection to the link are in a common horizontal plane.

2. In a lifting jack, the combination with a frame, of a ratchet bar guided for vertical movement in the frame; force-multiplying mechanism comprising a lever pivoted between its ends to the frame; a lifting pawl carried by one end of the lever and engaging the teeth of the ratchet bar; a link pivotally connected to the other end of the lever; an operating lever fulcrumed at one end on the frame and pivotally connected to the link at a point which is higher than the fulcrum when the mechanism is at one end of its stroke; and a handle connected to the operating lever and extending at such an angle to a plane through the fulcrum and the axis of the pivotal connection of the operating lever to the link that the handle has a substantial upward slope when the operating lever is moved into position where said fulcrum and axis are in a common horizontal plane.

FRANK H. SCHWERIN.