Patent ID: 6102829
Filing Date: 2000-08-15
Classification: B60W,F16H,Y10T

Abstract:
A vehicle gear change mechanism comprising:a prime mover or engine,a change speed gear box,clutch means through which drive is transmitted from the prime mover to the gearbox,a gearbox actuator for effecting a change of gear ratio in the gearbox, the actuator being pressure fluid operated,control means for controlling the operation of the actuator in accordance with a selected change of gear ratio, anda fluid supply for supplying pressurized fluid to the actuator at a first pressure, the fluid supply including:isolating means disposed between the fluid supply and the actuator, andvalve means disposed between the isolating means and the actuator;wherein the control means is arranged so that during a first part of the movement of the actuator the isolating means is operated to interrupt the supply of pressurized fluid from the fluid supply to the actuator and the valve means is operated to supply residual fluid, downstream of the isolating means, to the actuator at a second pressure;and wherein during a second part of the movement of the actuator the isolating means is operated so that pressurized fluid from the fluid supply communicates with the actuator and the valve means is operated to supply said fluid to the actuator at said first pressure, the operation of the actuator being such that over the first part of the movement of the actuator the force applied to the actuator to effect a gear change is less than over the second part of the movement of the actuator.