Motor vehicle transmission including a hill holder device

Claim 1

A motor vehicle transmission including a rotary part for transmitting drive to at least one wheel of the vehicle, a fixed part, a hill holder device coupled to the fixed part and rotary part for inhibiting reverse movement of the vehicle, the hill holder device comprising in series unidirectional means and a fluid-operable control system for operating ratio selector actuators of a change-speed gearing and which is arranged to apply an increasing fluid pressure to the disengageable coupling to effect a rising rate of coupling engagement, the fluid operable control including a resiliently biassed member of one of said actuators which moves against its bias in response to pressure applied to the disengageable coupling whereby the rate of increase in fluid pressure is dependent on the movement of said member against its bias, the fluid operable coupling and an actuator for selecting a higher gear ratio than a starting gear ratio for the vehicle being fed with fluid simultaneously.