US2259421A

US2259421A - Lifting jack

Info

Publication number: US2259421A
Application number: US264326A
Authority: US
Inventors: Jackson Alexis
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-03-27
Filing date: 1939-03-27
Publication date: 1941-10-14
Anticipated expiration: 1958-10-14

Description

0d. 14,1941. A JACIKSON 2,259,421'

, LIFTING JACK Filed March 27; 1959 AL Ex/s cv/(s 0N INVENTOR.

BY I I QUA M0/muy ATTORNEY.

Patented Oct. 14, 1941 PATENT OFFICE LIFTING JACK Alexis Jackson, Bayside, Y., assignor to Vadim S. Makaroff, New York, N. Y.

Application March 27, 1939, Serial No. 264,326

19 Claims.

My invention relates to lifting jacks and has particular reference to jacks for lifting automotive vehicles at one end in order to render accessible the under side of such vehicles for repairs, etc. My invention has further reference to pneumatic or air operated jacks.

In an ordinary pneumatic jack of this type the lifting power is furnished by a motor consisting of an air cylinder with a piston, the piston being pivotally connected to a frame or base of the jack, the cylinder being mounted on the lifting arms pivotally connected at the lower ends to the frame, the free ends of the arms being used for raising a vehicle. Such jacks have a disadvantage in that the cylinder must be mounted entirely `above the lifting arms as otherwise it will interfere with their lowering to the ground. The high cylinder forms an obstruction for the end extension of a vehicle such as rear bumpers, trunks, etc., so that the jack must be sufliciently long to extend under the axle while the cylinder remains outside the bumper or trunk. It is also necessary to shift the cylinder as far as possible to the rear of the jack, thereby increasing the leverage and making necessary a corresponding increase inthe lifting force,i. e., diameter of the cylinder. The high cylinder, moreover, interferes with the work around the lifted end of the Vehicle.

My invention has for its object, therefore, to provide a jack in which the air cylinder is placed horizontally so that the jack can be moved under the rear bumper of an automobile. With the horizontal mounting of the cylinder it is possible to increase the stroke of the piston, so that the cylinder can be correspondingly reduced in diameter, still further reducing the height of the jack.` The horizontal mounting of the cylinder makes it possible to build the frame of the jack' around the cylinder, the latter Contributing to the stiffness of the frame so that less metal is needed for the frame with a corresponding reduction in the total Weight of the device and its cost.

Another disadvantage of ordinary lifts is that the lifting force remains practically constant while the arm is being raised, although the moment of resistance considerably varies, being the greatest at the start and rapidly decreasing as the arm approaches the vertical position. It becomes necessary therefore to provide an air cylinder of a relative large diameter as determined by the initial torque only. In my improved lift I provide a mechanism whereby the leverage between the cylinder and the lifting arm varies,

being the greatest at the start when the moment 55 rollers in such' a manner that the angle of the` surfaces varies with the raising ofthe arm, being the smallest at the start. As a result, the arm 15T represents a leverfwith a variable position of its middle fulcrum, the lower" end of the arms having supporting rollers under the frame of the jack. The arm is therefore directly supported on the rollers, relieving the strain from the rear por- 20' tion of the frame.

Still another object of my invention is to provide a locking mechanism for the jack in order to retainlthearm in the raised position regardless of the air pressure in the cylinder. I also 2.5provide an improved manual control mechanism, preferably operated by a pedal, for releasing the locking device simultaneously withthe release of air from the cylinder when it is desired to lower the arm.

My invention is more fully described in the accompanying specification and drawing in which-- Fig. 1 is a sectional elevationof my jack showing the arms in theV rai-sed position, the lowered Bposition being shown in dotted lines;

Fig. 2 is a top plan View of the same; Fig. 3 isa rear end view of the same ;v My lifting jack consists of an air cylinder I mounted' Ona frame formed of two angle iron 4Q beams 2. The front ends of the beams support a shaft 4 with supporting wheels 5 at the ends. Brackets 6 are mounted at the sides of the beams 2 for a transverse shaft 1 having rollers 8 at the ends. The rollers engage inner sides of arms S 4 made of channel bars joined together at the mid'- dle by a bridge plate II). The lower ends of the arms are joined by a shaft II with wheels I2 at the ends. Tubular rollers I3 are provided on the shaft I I to facilitate the sliding movement of the 50 shaft under the beams 2. The arms are bent at the middle so that their free ends occupy a low position indicated in dotted lines in Fig. 1 when the arms are lowered. The wheels I2 recede to the rear of the cylinder when the arms are lowered'as shown in dotted lines in Fig. 1. The

shaft I2 is also connected by links I4 with the ends of a cross-bar I5 resting on the upper edges of the beams 2, rollers I6 being provided to reduce the friction at the points of contact. The cross-bar I5 is connected at the middle by a bolt Il to the end of a rod I8 extending from a piston I9 in the cylinder I. The rod I8 is made of two channel bars welded together at the edges.

A valve nipple 20 is provided for admitting compressed air into the cylinder, the valve being preferably of the type used with automobile tires. A pressure gauge 2I may be provided for indicating air pressure in the cylinders. provided at the sides of the beams 2 for removable handles 23 for moving the jack.

The operation of my jack is as follows: y l

The front end of the jack is moved under the axle of a vehicle until recessed grippers or forks Sleeves 22 areV 24 on the ends of the arms register with the axle.v I

An air hose (not shown) is then fitted on the valve nipple'Zii and the air is turned on. As the pressure in the cylinder builds up, the piston will be moved outward, "carrying the cross-bar I5 and pulling the Vlinks Ill.'v As a result, the shaft II will' bemo'ved forward, the wheels I2 sliding on the floor. The resistance to thismovement is reduced by the provision of the vtubular rollers I3 on the shaft II and by the fact that the load is supportedl on the ends ofthe arms near the front wheels 5 so that a very small fraction of this load rests on the'rear wheels I2 before the arms are sufficiently raised. The arms move on the rollers 3', the edges of the channel bars of the arms forming cam surfaces inclined at a small angle tothe direction vof the pull so that a relatively `small force is required to raise the' arms. The arms,

Ywliilesliding over the 'rollers 8, are also rotatedv on the shaft I I, the rotation being relatively small at the'start. It is gradually increased, however, as the arms are being raised, until at the end the sliding movement almost disappears, being replaced by a simple rotation on the rollers 8. The leverage will be then also reduced, resulting in a more rapid movement of the lifting arm. The

torque of the load on the arm will be then correspondin'gly decreased, however, because of the A shortening of the distance between the free ends of the arms and the wheels 8. By properly selecting therelative dimensions of the moving parts Vit is possible to' obtain a practically 'constant torque for the lifting motor.

A locking mechanism is provided in order to hold the arm in the raised position even if the air should escape from the cylinder. This mechanism comprises a dog 25 keyed on a shaft 26 journaled at the ends in Ythe-sides of the brackets 6. The dog slides over the upper side of the rod 18 provided with, a series of rectangular holes .21. The dog, when falling in one of the holes, engages the front edge ofthe hole as shown in Fig.

1, thereby locking the rod and preventing its inward movement under pressure of the load on thearms 9. A fork'28 is also keyed on the shaft 25 and is engaged 'at the lower end by a compression spring 29 thereby urging the dog against the rod AIii'. A mechanism is provided for releasing the dog from the piston rod, consisting of a lever 30 pivotally'supported on brackets 3| at the rear of the cylinder I and having a pedal 32. The end of the lever is connected by a bar 33 with the end of the fork 21, the bar sliding between the shaft I IY and the 'cylinder I', the rollers I3being spaced apartto provide room for-the bar 33. The dog 25 israised by stepping on the pedal 32, thereby turning thevlever 30 and moving the fork 28 against the pressure of the spring 29. An air exhaust valve 34 is tted in the bottom of the cylinder and connected with the lever 3i) in such a manner that the air is released from the cylinder when the pedal is depressed and the dog raised, the arms being then released for their downward movement under the load of a vehicle.

It is understood that my jack may be further modied within the scope of my invention vas set forth in the appended claims.

I claim as my invention:

1. A lifting jack comprising a frame, lifting arms, means to slidably and rotatively support the arms on the frame at their intermediate portions, means to support an object on the front 4ends of the arms, means to slidably support the rear ends of the arms, and means to move the rear ends of the arms forward thereby causing the arms to slide and to rotate on the supporting means at their intermediate portions so as to raise the front ends of the arms.

2. A lifting jack comprising a frame, lifting arms, means to slidably and rotatively support the arms on the frame at their intermediate portions, means to 'support an object on the front ends of the arms, means to slidably support the rear ends of the arms, and means to move the rear ends of the arms forward thereby causing the arms to slide and to rotate on the supporting means at their'intermediate portions so as to raise the front ends of the arms, the arms being bent in themiddle so as to bring the front ends below the first-mentioned supporting means when the arms are in the lowered position.

3. A lifting jack comprising a frame, lifting arms, means to slidably and rotatively support the arms on the frame at their intermediate portions, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms on the ground, and means to move the rear ends of the arms forward thereby causing the arms to slide and rotate on the supporting means at their intermediate portions so as Vto raise the front ends of the arms.

e. A lifting jack comprising a frame, lifting arms, means to slidably and rotatively support the arms on the frame at their intermediate portions, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms comprising rollers thereon adapted to slide under the frame, and means to move the rear ends of the arms forward thereby causing the arms to slide and to rotate on the supporting means at their intermediate portions so as to raise the front ends of the arms.

5. A lifting jack comprising a frame, lifting arms, means to slidably and rotatively support the arms on the frame at their intermediate portions, means to support an object on the front ends of the arms, rollers on the rear ends of the arms adapted to slide in engagement with the frame, and means to move the rear ends of the arms forward thereby causing the arms to slide and to rotate on the supporting means at their intermediate portions so as to raise the front ends of the arms.

6. A lifting jack comprising a frame, lifting arms, means to slidably and rotatively support the arms on the frame at their intermediate portions, means to support an object on the front ends of the arms, a shaft connecting the rear ends of the arms passing under the frame, wheels on the shaft for supporting the arms on the ground, rollers on the shaft for supporting the frame on the shaft, and means to move the rear ends of the arms forward thereby causing the arms to slideand to rotate the supporting means at their intermediate portions so as to raise the front ends of the arms.

7. A lifting jack comprising a frame, lifting arms having cam portions', means to slidably and rotatively support thearms on the frame at their cam portions, means to support anfobject on` the front ends of the arms, means to slidably support the rear ends of the arms on vthe `ground, and means to slidably rotate the armson their cam supporting means and to move the rear ends forward thereby raising thefrontends of the arms.

8. A lifting jack comprising a frame, lifting arms having cam portions, means to slidably and rotatively support the arms on, the frame at their cam portions, the supporting` means forming fulcrums for the arms, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms on the ground, and means to rotate the arms on their fulcrums and to cause the rear ends to slidably move forward thereby causing the arms to slide by the cam portions on the fulcrum points so as to raise the front ends of the arms.

9. A lifting jack comprising a frame, wheels supporting the front end of the frame, brackets in the middle of the frame, rollers rotatively supported on the brackets above the frame, lifting arms at the sides of the frame, longitudinal grooves in the arms slidably engaging the rollers, means to rigidly join the two arms together, means on the front ends of the arms for supporting an object, a shaft joining the rear ends of the arms under the frame, wheels on the ends of the shaft for supporting the arms on the ground,`

means on the shaft supporting the frame, and means to move the shaft with the rollers forward thereby sliding and rotating the arms on the rollers for raising the frontends of the arms.

10. A lifting jack comprising a frame, wheels supporting the front end of the frame, brackets in the middle of the frame, rollers rotatively supported on the brackets above the frame, lifting arms at the sides of the frame made of channelshaped bars facing each other with their flanges, the flanges slidably engaging the rollers, a member rigidly joining together the arms, means on the front ends of the arms for supporting an ob- `iect, a shaft joining the rear ends of the arms Ig under the frame, wheels on the ends of the shaft for supporting the arms on theground, means on the shaft supporting the frame, and means to move the shaft with the rollers forward thereby sliding and rotating the arms on the rollers for raising the front ends of the arms.

11. A lifting jack comprising a frame, lifting arms having cam portions, means to slidably and rotatively support the arms on the frame at their cam portions, the supporting means forming fulcrums for the arms, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms on the ground, a cross member slidably supported on the front portion of the frame, bars hingedly connecting the rear ends of the arms with the cross member, and means to move the cross member forward thereby moving forward the rear ends of the arms, causing the arms to slide and to rotate on the fulcrums thereby raising the front ends of the arms.

12. A lifting jack comprising a frame, lifting arms having cam portions, means to slidably and rotatively support the arms on the frame at their cam portions, the supporting means forming fulcrums for the arms, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms on the ground, a cross member slidably supported on the front portion of the frame, bars hingedly connecting the rear ends of the arms with the cross member, a motor supported on the frame, and means to move the cross bar by the motor, causing the arms to slide and to'rotate on the fulcrums thereby raising the front ends of the arms.

13. A lifting jack comprising a frame, lifting arms having cam portions, means to slidably and rotatively support the arms on the frame at their cam portions, the supporting means forming fulcrums for the arms, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms on the ground, a motor on the frame, and means to rotate the arms on the fulcrums so as to raise the front ends of the arms by the motor while causing the rear ends of the arms to slide on the ground.

14. A lifting jack comprising a frame, a. cylinder horizontally mounted on the rear portion of the frame, lifting arms at the sides of the frame, means to rotatively and slidably support the arms at their intermediate portions on the frame, means to support an object on the front ends of the arms, means to slidablysupport the rear ends of the arms, a piston in the cylinder, a rod on the piston, operative connections between the rod and the rear ends of the arms, and means to admit a fluid under pressure into the cylinder for moving the piston with the rear ends of the arms thereby raising the front ends of the arms.

15. A lifting jack comprising a frame formed of two bars, a cylinder horizontally mounted on the rear portions of the bars and rigidly joining the bars together, lifting arms at the sides of the frame, means to rotatively and slidably support the arms at their intermediate portions on the frame, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms, a piston in the cylinder', a rod on the piston, operative connections between the rod and the rear ends of the arms, and means to admit a fluid under pressure into the cylinder for moving the piston with the rear ends of the arms thereby raising the front ends of the arms.

16. A lifting jack comprising a frame, a cylinder horizontally mounted on the rear portion of the frame, lifting arms at the sides of the frame, means to rotatively and slidably support the arms at their intermediate portions on the frame, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms, a piston in the cylinder, a rod on the piston, means to slidably support the front end of the rod on the frame, bars connecting the rod supporting means with the rear ends of the arms, and means to admit a fluid under pressure into the cylinder for moving the piston with the rear ends of the arms thereby raising the front ends of the arms.

1'7. A lifting jack comprising a frame, a cylinder horizontally mounted on the rear portion of the frame, lifting arms at the sides of the frame, means to rotatively and slidably support the arms at their intermediate portions on the frame, means to support an object on the front ends of the arms, means to slidably support the rear ends of the arms, a piston in the cylinder, a rod on the piston, operative connections between the rod and the rear ends of the arms, means to admit a fluid under pressure into the cylinder for moving the piston with the rear ends of the arms thereby raising the front ends of the arms, means to lock the rod in the operative position with the arms raised, a pedal at the rear of the frame, and operative connections between the pedal and the locking means for releasing the latter Whenv the pedal is depressed.

18. A lifting jack comprising a frame, a cylinder horizontally mounted on the rear portion of the frame, lifting arms at the sides of the frame, means to rotatively and slidably support the arms at their intermediate portions on the frame, means to support an object on the front ends of the arms, means to slidably support the rear'ends of the arms, a piston in the cylinder, a rod on the piston, operative connections between the rod and the rear ends of the arms, means to admit a uid under pressure into the cylinder for moving the piston with the rear ends of the arms thereby raising the front ends of the arms, means to lock the rod in the operative position With the arms raised, a pedal at the rear of the frame, operative connections between the pedal and the locking means for releasing the latter When the pedal is depressed, and means to release the uid from the cylinder when the pedal is depressed.

19. A lifting jack comprising a frame, a lifting member, means to slidablyand rotatively support the member at its intermediate portion, means to support an object on the front ends of the lifting member, means to slidably support the rear end of the lifting member, and means to move the rear end of the lifting member, thereby causing the lifting member to slide and to rotate on the supporting means at its intermediate portion so as to raise the front end of the lifting member.

ALEXIS JACKSON.