Shifting device for a clutch

1. A shifting device for a positively engaging clutch having complementary first and second positively engaging coupling elements; comprising:

a housing;

an actuator rod which is axially movable within the housing by means of an associated rod actuating mechanism, the rod actuating mechanism comprises a spring which urges the actuator rod against a first end stop and a ram which is operable to move the actuator rod axially in opposition to said spring against a second end stop;

a clutch shift fork engaged with the first coupling element and being mounted on the actuator rod for axial movement of the first coupling element into and out of engagement with the second coupling element in response to axial movement of the actuator rod;

a fork position adjuster for axially adjusting position of the clutch shift fork on the actuator rod, the clutch shift fork being mounted on the actuator rod by a threaded connector forming the fork position adjuster such that the clutch shift fork is axially movable on the actuator rod; and

an access port in a side wall of the housing to allow operation of the fork position adjuster from an exterior of the housing.

2. The shifting device as claimed in claim 1 , wherein the access port is aligned with an end of the actuator rod to allow engagement of an adjusting tool with the end of the actuator rod for rotation of the actuator rod within the housing.

3. The shifting device as claimed in claim 1 , wherein the clutch shift fork has a hub with a threaded bore which engages a complementary threaded portion of the actuator rod such that rotation of the actuator rod in the bore of the hub causes axial movement of the clutch shift fork along the actuator rod.

4. The shifting device as claimed in claim 1 , further comprising a fork stroke adjuster for adjusting the displacement of the clutch shift fork between a fully engaged position and a fully disengaged position, the fork stroke adjuster comprises an adjustable stop which is provided on the housing to limit axial movement of the actuator rod within the housing.

5. The shifting device as claimed in claim 4 , wherein the fork stroke adjuster is operable from an exterior of the housing.

6. The shifting device as claimed in claim 4 , wherein the adjustable stop is an adjusting screw rotatably mounted on the housing adjacent one end of the actuator rod.

7. The shifting device as claimed in claim 1 , further comprising fixed stops within the housing which cooperate with the actuator rod to limit axial movement of the actuator rod within the housing.

8. The shifting device as claimed in claim 1 , wherein the ram comprises a piston on the actuator rod which is slidably received in an associated cylindrical bore in the housing and forms with the housing a chamber for reception of pressurized fluid which acting on the piston opposes said spring bias.

9. A differential assembly incorporating the shifting device as claimed in claim 1 .

10. A gearbox incorporating the shifting device as claimed in claim 1 .

11. A shifting device for a positively engaging clutch having complementary first and second positively engaging coupling elements comprising:

a housing;

an actuator rod which is axially movable within the housing by means of an associated rod actuating mechanism, the rod actuating mechanism comprises a spring which urges the actuator rod against a first end stop and a ram which is operable to move the actuator rod axially in opposition to said spring against a second end stop;

a clutch shift fork engaged with the first coupling element and being mounted on the actuator rod for axial movement of the first coupling element into and out of engagement with the second coupling element in response to axial movement of the actuator rod; and

a fork position adjuster for axially adjusting position of the clutch shift fork on the actuator rod, the clutch shift fork being mounted on the actuator rod by a threaded connector forming the fork position adjuster such that the clutch shift fork is axially movable on the actuator rod, the clutch shift fork has a hub with a threaded bore which engages a complementary threaded portion of the actuator rod such that rotation of the actuator rod in the bore of the hub and relative to the housing causes axial movement of the clutch shift fork along the actuator rod.

12. A shifting device for a positively engaging clutch having complementary first and second positively engaging coupling elements comprising:

a housing;

an actuator rod which is axially movable within the housing by means of an associated rod actuating mechanism, the rod actuating mechanism comprises a spring which urges the actuator rod against a first end stop and a ram which is operable to move the actuator rod axially in opposition to said spring against a second end stop;

a clutch shift fork engaged with the first coupling element and being mounted on the actuator rod for axial movement of the first coupling element into and out of engagement with the second coupling element in response to axial movement of the actuator rod; and

a fork position adjuster for axially adjusting position of the clutch shift fork on the actuator rod, the clutch shift fork being mounted on the actuator rod by a threaded connector forming the fork position adjuster such that the clutch shift fork is axially movable on the actuator rod; and

a fork stroke adjuster for adjusting the displacement of the clutch shift fork between a fully engaged position and a fully disengaged position, the fork stroke adjuster comprises an adjustable stop which is provided on the housing to limit axial movement of the actuator rod within the housing, the fork stroke adjuster being operable from an exterior of the housing.