Jack with Self-Adjusting Securement Mechanism

1 . A jack with a self-adjusting securement mechanism which automatically adjusts to a thickness dimension of a support member and which secures the jack to the support member as force is applied by the jack, the jack comprising:

. a base having first and second sides and a length defining an axis;

. a ram extendable from the first side of the base along the base axis;

. a ram-drive mechanism in power-transmission relationship with the ram operative to extend the ram to apply a pushing force; and

. a securement mechanism which clamps the jack to a support member, the securement mechanism having a pair of independently pivotable jaws

with generally facing gripping surfaces, each jaw being eccentrically pivotable mounted along the second side of the base on a pivot axis

approximately equidistant from the base axis and being biased to pivot so as to swing each gripping surface toward the other, thereby self-adjusting

the jaws to the thickness of a support member when between the jaws and clamping the jack to the support member as the pushing

force is applied by the jack.

2 . The jack of claim 1 wherein each jaw pivots bidirectionally in first and, alternatively,

second directions to swing the gripping surfaces toward or away from the other.

3 . The jack of claim 2 wherein each jaw pivots the gripping surface toward the other until

stopped by contact with a support member therebetween.

4 . The jack of claim 3 wherein each jaw is a cam.

5 . The jack of claim 3 wherein each jaw is biased to pivot by a spring.

6 . The jack of claim 5 wherein the spring is a torsion spring.

7 . The jack of claim 2 wherein each gripping surface is curved.

8 . The jack of claim 7 wherein each gripping surface includes a plurality of projections.

9 . The jack of claim 8 wherein the projections are teeth.

10 . The jack of claim 8 wherein a clamping force applied by the jaws to the support member

increases as the pushing force applied by the jack increases.

11 . The jack of claim 8 wherein the ram comprises:

. a bar having a distal end; and

. a pusher attached to the hair distal end.

12 . The jack of claim 11 wherein the ram-drive mechanism comprises:

. a rack along the bar;

. a pinion gear meshed with the rack;

. a lever which powers pinion gear rotation; and

. a one-way clutch which enables the lever to power pinion gear rotation in one direction to

extend the ram.

13 . The jack of claim 12 wherein operation of the lever in a first direction powers extension

of the ram and operation of the lever fully in a second direction releases the jaws from the support member.

14 . The jack of claim 13 wherein the ram-drive mechanism further comprises:

. a pawl which allows pinion gear rotation in a first direction to extend the ram and which

engages the pinion gear to limit rotation in a second direction to maintain the force: and

. a surface associated with the lever which contacts and releases the pawl from the pinion

gear.

whereby, release of the pawl with the ram applying force causes the base to move sufficiently to

release the jaws from the support member.