GB2296302A

GB2296302A - A trigger mechanism

Info

Publication number: GB2296302A
Application number: GB9425975A
Authority: GB
Inventors: Roland Graham Whiteing
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-22
Filing date: 1994-12-22
Publication date: 1996-06-26
Also published as: CN1125299A; ES2122886A1; CZ33495A3; ES2122886B1; ITMI950599A1; GB9425975D0; IL116453A0; WO1996019709A1; ITMI950599A0

Abstract

A trigger mechanism comprises a trigger 10 with a protuberance 14, shaped in the general form of a epicycloid, which engages recess 15, shaped in the general form of a hypocycloid, in a rocker 20. The trigger 10, when pulled, pivots about pin 11, thereby pivoting rocker 20 about pin 31 which allows a cut-out (34, fig 2) to engage with a sharp nosed portion 35 on the rocker 20. This ensures that there is no movement of the trigger 10 and lock pin 33 at the moment of firing. A sear spring 30 is retained in its upper position by sear spring 25 which is located in slide 27 the top of which is angled and engages tail 29 on the rocker 20. The mechanism, when applied to guns, allows the cartridges to be ejected without the risk of the gun being fired. It is possible to employ the mechanism in latching, locking, gearing or driving applications. <IMAGE>

Description

DRIVING MECHANISM This invention relates to a driving mechanism for causing movement of one member with respect to another member in which the members are each rotatable about an axis.

According to the present invention in such a driving mechanism one of the members has at least a portion thereof shaped in the general form of an epicycloid whilst the other has a portion shaped in the general form of a hypocycloid which said portions are interengageable with one another so that movement of one member causes movement of the other member.

Preferably the portions shaped as an epicycloid moves around the inside of the hypocycloid.

The hypocycloid portion may be of parabolic hyppocrepian or other non linear shape.

In one preferred arrangement the member having the epicycloid portion is driven by the member having the hypocycloid portion.

The terms epicycloid and hypocyclqid have been used generally but the curves traced by the members according to the present inventions do not correspond exactly to the curves of these terms.

The positions of the axes of movement of the respective members may be variable. For example, where the hypocycloid member drives the parabolic hypocycloid member, depending upon the position of the axes the hypocycloid can cause the extremities of the hypocycloid to describe opposite but greater or smaller movements. Similarly by varying the position of the axes of the epicycloid then again the movement of the hypocycloid can be caused to be non linear.

By driving either the epicycloid or hypocycloid can either a horizontal or opposing vertical movement be caused. By varying the axes positions of either cycloid in relation to each other, or the shape of the hypocycloid or epicycloid, can the effective movement at each extremity be varied.

The system can be used in many latching, locking, gearing or driving applications particularly where fine tolerances are required. As mentioned earlier either cycloid can be driven.

In one application of the invention it may be incorporated into the trigger mechanism of a gun.

In such a trigger mechanism there may be included a trigger and a rocker device and in this case the trigger may include the member having the hypocycloid portion and the rocker mechanism includes the member having the epicycloid portion.

Such a trigger mechanism may also include a lock up device and in this case means may be provided for ensuring that there is no movement of the lock up device and trigger mechanism at the moment of firing.

In this case the lock up device may incorporate a member adapted to engage in the trigger mechanism and the lock up device and a sharp nosed projection may be provided on one member which engages a cut out device on the other. In a preferred arrangement the sharp nosed projection may be mounted on the lock up mechanism and the trigger is provided with a cut out.

The present invention also includes within its scope a gun including a driving mechanism as set forth and particularly a trigger mechanism as similarly set forth above.

The present invention is particularly useful in a gun of the kind described in European Patent Specification No. 0 280 685. The general operation of the gun is as set forth in that specification but the operation of the trigger mechanism which will now be described by way of example with reference to the accompanying drawings is completely different.

It is to be understood that this trigger mechanism and the movemments described are only one specific way of putting the driving mechanism into effect.

In the drawings: Figure 1 - is a general view of a gun including a driving mechanism according to the present invention, and Figure 2 - is an enlarged view of part of the firing mechanism The firing mechanism comprises in essence a trigger 10 which constitutes one of the members and a rocker 20 which constitutes the other member. The trigger 10 is pivoted about a pin 11 which constitutes one axis which passes through a bore 12 near its upper end. The trigger has a shaped finger grip 13 on its lower portion. Above the pivot pin there is a protuberance 14 constituting the hypocycloid adapted to engage in a recess 15 constituting the epicycloid in the rocker mechanism 20 and which will be described in more detail later.The trigger also has a bore 16 in its rear portion in which is received a trigger spring 17 the other end of which is received in a recess 18 in a member 21 located above a trigger guard 22.

Located in a further recess 23 in the top of the member 21 is one end of a sear spring 25 the other end of which is located in a slide 27 the top of which is angled and shown at 28 and engages the underside of a tail 29 on the rocker 20.

A sear 30 is normally retained in its upper position by means of the sear spring.

An adjusting screw is also provided and fitted within the sear spring thus allowing full adjustment of the travel of the sear which is operated by the tail of the rocker 20.

The rocker device itself is pivoted about a pin 31 constituting its axis in a bore 32. It comprises a lock-up pin 33 at its forward end and the tongue 28 at its rear. The protuberance 14 is shaped with its forward end as shown in Figure 2 with a cut-out 34. This is adapted to be engaged by a sharp nosed portion 35 on the rocker 20. This ensures that at the moment of firing there is no movement of the lock-up pin and the trigger.

The shape of the protuberance 14 and the recess 15 and the operation of the pivots of the rocker and trigger correspond to the two opposing cycloids in conjugation.

In this case the trigger acts as the epicycloid and moves around the inside of the hypocycloid which is the recess on the rocker and which may as stated earlier be of parabolic or hippocrepian or nonlinear shape, thus causing the hypocycloid to be moved.

As the parabolic hypocycloid is caused to rotate around an axle, the movement of the epicycloid, which is in congruence with the hypocycloid then, depending on the axle point of the hypocycloid causes the extremities of the hypocycloid to prescribe opposite but greater or smaller movements.

By varying the position of the pivot points of the epicycloid the movement of the hypocycloid can be caused to be linear or nonlinear. The same applies to varying the axle position of the hypocycloid.

By varying the axle positions of either cycloid or with relation to each other or the shape of the hypocycloid or epicycloid the effective movement at each extremity can be varied.

With particular reference to the example of the mechanism described with relation to the gun set forth in European Specification No. 0 280 685 it will be seen that the sear and rocker and trigger mechanism differ from that shown in the Patent Specification referred to. The original sear was a simple rocking bar and this did not lend itself easily to manufacture and did not allow an easy fitment of a bar safety catch and slow lock-up.

It will be seen that the mechanism which in the original was termed the H shaped rocker device which served as both sear and barrel lock, the new arrangement described here causes the barrel lock to rise and engage through the cylinder into the barrel and, at the same time, the tail section of the barrel lock moves in an opposite direction which causes the sear pin to disengage from the cocked cam to which the firing pin is attached thus causing the cam and firing pin to move forward driven by a spring in the firing pin cam housing.

This arrangement ensures that the barrel is locked to the sleeve and the receiver body by means of the barrel lock prior to the sear allowing the firing pin cam housing to move and the firing pin striking the cartridge thus activating the cartridge. Also it allows an adjusting screw to be fitted within the sear thus allowing full adjustment of the travel of the sear pin which is operated by the tail of the rocker.

This in turn allows the sensitivity of the firing action and the trigger pull to be adjusted. It will be seen from the Figure that the safety bar (catch) when depressed causes the safety bar to engage into a similiar groove in the sear thus locking the sear from any movement which disallows the firing pin cam housing any movement.

The safety bar (catch) can be placed in the locked position irrespective of the gun being loaded and cocked or uncocked.

Thus the action can still be operated but not fired and this allows a quick and easy method of emptying unfired cartridges from the gun by pumping the action and allowing the mechanism to eject the cartridges without risk of the gun being accidentally fired.

Thus with regard to the present invention the driving mechanism which has been described with particular reference to a gun can be used in a number of applications and as stated earlier in latching, locking, gearing or driving applications particularly where fine tolerances are required.

Claims

1. A driving mechanism for causing relative movement of one member with respect to another member in which the members are each rotatable about an axis, one of the members having at least a portion thereof shaped in the general form of an epicycloid whilst the other has a portion shaped in the general form of a hypocycloid which said portions are interengageable with one another so that movement of one member causes movement of the other member.

2. A driving mechanism as claimed in Claim 1, in which the portions shaped as an epicycloid moves around the inside of the hypocycloid.

3. A driving mechanism as claimed in Claim 2, in which the hypocycloid portion is of parabolic hyppocrepian or other non linear shape.

4. A driving mechanism as claimed in Claim 3, in which the member having the epicycloid portion is driven by the member having the hypocycloid portion.

5. A driving mechanism as claimed in any one of the preceding Claims, in which the positions of the axes of movement of the respective members are variable.

6. A driving mechanism as claimed in any one of the preceding Claims, which is incorporated into the trigger mechanism of a gun.

7. A trigger mechanism as claimed in Claim 6, including a trigger and a rocker device in which the trigger includes the member having the hypocycloid portion and the rocker mechanism includes the member having the epicycloid portion.

8. A trigger mechanism as claimed in Claim 7, in which a lock up device is included.

9. A trigger mechanism as claimed in Claim 8, in which a sharp nosed projection is provided on one member which engages a cut out on the other member.

10. A trigger mechanism as claimed in Claim 9, in which the sharp nosed projection is mounted on the rocker mechanism which includes the lock up device and the trigger is provided with the cut out.

11. A trigger mechanism including a driving mechanism as claimed in any one of Claims 1 to 6.

12. A gun including a trigger mechanism as claimed in any one of Claims 6 to 11.