Brake device

Abstract

A wrap spring moves from a relaxed state to an energised state for braking rotation of the output shaft in a vehicle transmission. The wrap spring may constrict for engagement on the shaft or expand for engagement with an adjacent ground member. Two wrap springs, concentric (Figure 13) or axially spaced, provide bi-directional braking. A split ring energises both wrap springs, e.g. using an epicyclic differential arrangement to move opposing ring portions in opposite directions (Figure 11A). The wrap spring may be mounted in a relaxed state for rotation with the shaft, with a mechanism for inducing drag torque to energise the spring for a braking operation (Figure 12). Means is provided preventing an actuator from energising the wrap spring, e.g. if the shaft is rotating above a predetermined speed.

Description

technical field [0001] The present invention relates to a brake device, more specifically but not exclusively to a vehicle anti-rollback device and / or parking brake device. Background technique [0002] Vehicle rollback typically occurs when attempting to launch the vehicle from a standstill on an incline, especially if the vehicle has a dry clutch drivetrain. Pawl brakes are known to prevent movement of vehicles when parked, and these pawl brakes are used to prevent vehicles from rolling. However, these detents are not particularly durable during frequent part-load transitions, such as when launching on an incline. Contents of the invention [0003] It is an object of the present invention to provide an improved braking arrangement which reduces or prevents rolling back of the vehicle. [0004] According to one aspect of the present invention, there is provided a braking device comprising an output shaft and a wrap spring mounted around said shaft, wherein the wrap spri...

AI Technical Summary

Problems solved by technology

However, these detents are not particularly durable during frequent part load transitions, such as when launching on an incline

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