GB2240838A

GB2240838A - Cocking mechanism

Info

Publication number: GB2240838A
Application number: GB9102171A
Authority: GB
Inventors: John Richard Spencer
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-02-01
Filing date: 1991-02-01
Publication date: 1991-08-14
Anticipated expiration: 2011-02-01
Also published as: GB9102171D0; GB9002288D0; GB2240838B

Abstract

A cocking mechanism for use on an air weapon of the type having a piston slidable in a cylinder to compress air into a reservoir comprises a cocking arm 10 pivotally mounted at 12 on the cylinder, a connecting rod 14 pivotally connected at one end 16 to the piston and at the opposite end 18 to a sledge or slide 20 which is slidably movable on the cocking arm against the action of a spring 28 within a range limited by a recess 30 and a block 32, so that the position of the point of pivotal connection 18 varies during the arcuate pivotal movement of the cocking arm to increase the mechanical advantage of the mechanism during the final part of the compression stroke of the piston. <IMAGE>

Description

"An Improved Cocking Mechanism" This invention relates to a cocking mechanism and nore particularly, but not exclusively, to a cocking mechanism for use on an air weapon.

Air weapons such as the air rifle described in U.K.

Patent No. 2,193,562 comprise a piston slidable in a cylinder for compressing air into a reservoir from which the compressed air is released by a trigger-operated valve mechanism into a barrel of the rifle to fire a projectile therefrom.

The piston of this known air rifle is movable in the cylinder by a cocking mechanism comprising a cocking arm pivotally connected at one end to the rifle and at a point between the ends of the arm to one end of a connecting rod whose other end is pivotally connected to the piston.

Although this known type of cocking mechanism operates satisfactorily on air rifles of larger bore types, on smaller bore rifles, where it is necessary to achieve higher pressures of compressed air in the reservoir to obtain the required power output, it is found this known cocking mechanism suffers from the disadvantage that the force which has to be applied to the cocking arm1 particularly during the final part of the compression stroke of the piston, reaches an undesirable value.

The object of this invention is to provide an improved cocking mechanism in which this disadvantage is alleviated.

According to one aspect of this invention, a cocking mechanism for use on an air weapon of the type having a piston slidable in a cylinder to compress air into a reservoir comprises a cocking arm pivotally mounted on the weapon, a connecting rod pivotally connected at one end to the piston and at the opposite end to the cocking arm at a point between the ends thereof, wherein the position of the point of pivotal connection of the connecting rod to the cocking arm varies during the arcuate pivotal movement of the cocking arm to increase the mechanical advantage of the mechanism during the final part of the compression stroke of the piston.

Preferably, the end of the connecting rod remote from the piston is pivotally connected to a sledge or slide which is slidably mounted on the cocking arm.

Preferably, also, stop means is provided for limiting the range of sliding movement of the sledge or slide relative to the cocking arm.

The stop means is, preferably, adjustable to adjust the position of the sledge or slide in the weapon loaded position thereby adjusting the pressure of the air in the reservoir and the output power of the weapon.

Preferably, the sledge or slide is movable against the action of resilient means in the direction towards the pivotal connection of the cocking arm to the weapon.

Preferably, also, the point of pivotal connection of the sledge or slide to the connecting rod is movable to an over-centre position with respect to the point of pivotal connection of the connecting rod to the piston and the point of pivotal connection of the cocking arm to the cylinder when the cocking arm is moved to the weapon loaded position to retain the piston in position in the cylinder at the end of the compression stroke thereof The cocking arm is, preferably, pivotally connected to the cylinder of the weapon.

According to another aspect of this invention, an air weapon comprises a cocking mechanism according to said one aspect of this invention.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing which is a diagrammatic side elevation of the cocking mechanism.

Referring now to the drawing, a cocking mechanism for an air weapon of the type described in U.K. Patent No.

2,193,562 comprises a cocking arm 10 pivotally connected at 12 to a cylinder (not shown) of the weapon.

A connecting rod 14 is pivotally connected at one end 16 to a piston (not shown) of the weapon. The other end of the connecting rod 14 is pivotally connected at 18 to a sledge or slide 20.

The sledge or slide 20 is provided with a bore 22 in which a rod 24, secured by a bolt 26 to the cocking arm 10, is a sliding fit. The sledge or slide 20 is therefore capable of sliding movement longitudinally of the cocking arm 10 on the rod 24 and a helical compression spring 28 is mounted on the rod 24 and confined endwise between the sledge or slide 20 and the cocking arm 10 thereby urging the sledge or slide 20 away from the pivotal connection 12 of the cocking arm 10 to the cylinder (not shown).

The sledge or slide 20 is provided with a recess 30 and a block 32 mounted on the rod 26 and secured in position thereon by a screw 34 extending through a bore 36 in the cocking arm 10, is located in the recess 30 to limit the extent of sliding movement of the sledge or slide 20.

A screw-threaded stop member 38 is screwed into the screw-threaded end of the bore 22 in the sledge or slide 20 and engages the end of the rod 24 to limit the movement of the sledge or slide 20 in a direction towards the pivotal connection 12 of the cocking arm 10 to the cylinder (not shown). A locking nut 40 is mounted on the stop member 38 to secure the member 38 in adjusted position.

In operation, the cocking mechanism is shown in the drawing in the position where the weapon is loaded and the piston (not shown) has completed its compression stroke in the cylinder (not shown).

The pivotal connection 18 of the connecting rod 14 to the sledge or slide 20 has moved to an over-centre position relative to the line joining the pivotal connection 16 of the connecting rod 14 to the piston (not shown) and the pivotal connection 12 of the cocking arm 10 to the cylinder (not shown), thereby retaining the piston (not shown) at the end of the compression stroke.

The position of the piston (not shown) in the cylinder (not shown) at the end of the compression stroke is adjusted by screwing the stop member 38 into or out of the bore 22 thereby enabling the pressure of the air in the reservoir of the weapon (not shown) at the completion of the next compression stroke and thus the power output of the weapon to be adjusted.

After discharge of the weapon, the weapon is loaded by first moving the cocking arm 10 pivotally in a clockwise direction about the pivot point 12 from the position shown in the drawing through an angle of approximately 180 degrees.

During this first pivotal movement of the cocking arm 10, the sledge or slide 20 is moved by the spring 28 to the position remote from the pivotal connection 12 of the cocking arm 10 to the cylinder (not shown) until the block 32 contacts the end of the recess 30 adjacent to the connection 12, thereby ensuring the piston (not shown) reaches the outer end of the cylinder (not shown) and can thus perform a full compression stroke.

It will be appreciated this movement of the sledge or slide 20 by the spring 28 enables a greater length of compression stroke of the piston to be achieved than would otherwise be possible in a cocking mechanism where the connecting rod is pivotally connected at a fixed position on the cocking arm.

The pivotal movement of the cocking arm 10 about the connection 12 is then reversed and the cocking arm 10 is moved in an anti-clockwise direction back to the position shown in the drawing, to effect the compression stroke of the piston (not shown) in the cylinder (not shown) and load the weapon.

During this movement of the cocking arm 10, the spring 28 is fully extended and the point of pivotal connection 18 of the connecting rod 14 to the sledge or slide 20 is at the maximum distance from the pivotal connection 12 of the cocking arm 10 to the cylinder (not shown) so that the mechanism has the lowest mechanical advantage during the initial part of the compression stroke of the piston (not shown) when the load thereon is at the lowest level.

As the cocking arm 10 moves to the position where the position of the connecting rod 14 relative thereto is approximately as shown in broken lines in the drawing, the force exerted by the compressed air on the piston (not shown) increases and the load transmitted by the connecting rod 14 onto the sledge or slide 20 is sufficient to overcome the pressure of the spring 28. The sledge or slide 20 is then moved slidably on the rod 24 into the position shown in the drawing where the pivotal connection 18 of the connecting rod 14 to the sledge or slide 20 is closest to the pivotal connection 12 of the cocking arm 10 to the cylinder (not shown).

In this position of the sledge or slide 20, the mechanical advantage of the mechanism is at its greatest thus enabling the final part of the compression stroke of the piston (not shown), when the greatest loads are encountered, to be completed with the minimum effort being applied by the user to the cocking arm 10, In a modification, the stop member 38 and locking nut 40 are replaced by providing the bore 22 with a closed end and means on the cocking arm 10 for adjusting the length of the rod 24.

In another modification, the sledge or slide 20 is slidably mounted on a track formed on the cocking arm 10 and adjustable stops for adjusting the position of the sledge or slide 20 are also provided on the cocking arm 10, thereby enabling the rod 24 and the stop member 38 and locking nut 40 to be replaced.

Although the above described cocking mechanism is particularly suitable for use on air weapons, it will be appreciated this type of mechanism can be used on other equipment where a variable mechanical advantage is required such as, for example, grease guns or the like without departing from the scope of this invention.

Claims

What I claim is:

1. A cocking mechanism for use on an air weapon of the type having a piston slidable in a cylinder to compress air into a reservoir comprising a cocking arm pivotally mounted on the weapon, a connecting rod pivotally connected at one end to the piston and at the opposite end to the cocking arm at a point between the ends thereof, wherein the position of the point of pivotal connection of the connecting rod to the cocking arm varies during the arcuate pivotal movement of the cocking arm to increase the mechanical advantage of the mechanism during the final part of the compression stroke of the piston.

2. A cocking mechanism according to Claim 1, wherein the end of the connecting rod remote from the piston is pivotally connected to a sledge or slide which is slidably mounted on the cocking arm.

3. A cocking mechanism according to Claim 2, wherein stop means is provided for limiting the range of sliding movement of the sledge or slide relative to the cocking arm.

4. A cocking mechanism according to Claim 3, wherein the stop means is adjustable to adjust the position of the sledge or slide in the weapon loaded position thereby adjusting the pressure of the air in the reservoir and the output power of the weapon.

5. A cocking mechanism according to any one of Claims 2 to 4, wherein the sledge or slide is movable against the action of resilient means in the direction towards the pivotal connection of the cocking arm to the weapon.

6. A cocking mechanism according to any one of Claims 2 to 5, wherein the point of pivotal connection of the sledge or slide to the connecting rod is movable to an over-centre position with respect to the point of pivotal connection of the connecting rod to the piston and the point of pivotal connection of the cocking arm to the weapon when the cocking arm is moved to the weapon loaded position to retain the piston in position in the cylinder at the end of the compression stroke thereof.

7. A cocking mechanism according to any one of the preceding claims, wherein the cocking arm is pivotally connected to the cylinder of the weapon.

8. An air weapon comprising a cocking mechanism according to any one of the preceding claims.

9. A cocking mechanism constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawing.

10. An air weapon constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawing.