Agco Corporation

Massey-ferguson Services N.v.

Roger Michael Weyman

John R Barton

Paul David Eames

Steven Bromley

John Graham Willacy

A system for accelerating the front wheels of a vehicle, eg an agricultural tractor, on turning a corner, comprises steering angle sensors (21) which, via a control unit (22) enable or disable drive to the front wheels from a hydraulic motor (11). The drive from the hydraulic motor from the front wheels is via a one-way clutch (14). The hydraulic motor (11) is powered by a pump (6) driven either directly from the vehicle engine or from the main transmission.

Vehicle front wheel speed change apparatus

A transmission, particularly an agricultural tractor transmission, has a creep gear facility whereby speeds under 0.5 km per hour are possible without slipping a clutch. Planocentric gearing (20) is used for the creep gear, selectively clutchable into the transmission by means of a dog clutch (31). The planocentric gearing comprises an input eccentric (32) which runs inside an inner ring member (33) carrying external gear teeth (34). The inner ring (33), in use, oscillates within an outer ring (36) having interior gear teeth (35) with which the exterior teeth (34) mesh at one point at any given time. Pins (38) are mounted on the inner ring (33) which are received in apertures (47) in a stationary reaction member (44). The oscillating motion of the inner ring (33) is transferred to the outer ring (36) as rotation, at a reduced speed from the input, giving a reduction ratio of 10:1 or higher in a single stage. The direction of the drive is preserved from input to output.

Transmission with creep gear

Gearbox selector forks are commonly mounted for axial movement on a supporting rail which is rigidly mounted in the gearbox casing. When the fork is moved axially along the rail to move a coupling sleeve it can tilt and jam on the rail if it experiences excessive actuation loads which may inhibit or at least delay the operation of the associated synchromesh unit and engagement of the required gear. The present invention overcomes this problem by providing a support rail 14 which is itself axially displaceable against the action of a resilient means 32 thereby ensuring that the required selector fork 16 movement for gear engagement may be achieved even when the fork 16 is jammed on the support rail 14.

Gear change mechanism

A gear coupler for coupling a gear to a shaft includes a first coupling member which is connected for rotation with the shaft and a second coupling member which is connected for rotation with the gear and engageable by the first coupling member. The second coupling member is capable of limited circumferential movement relative to the gear to allow the first and second coupling members to engage each other without the need to rotate the gear. The advantage of this arrangement is that gears can be engaged without the operator needing to exert excessive actuation force on any actuating system which controls the movement of the coupler.

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Coventry, United Kingdom

Roger Michael Weyman