Transmission brake

Driver's manuals usually caution against using the transmission brake when driving, as it is neither powerful enough nor robust enough and so will not work effectively and may even be damaged by trying to stop a moving vehicle.

Drum brakes allow simpler adjustment with cable-actuated hand lever mechanisms.

The apparently undersized transmission brake thus has more holding ability than its small size might suggest, but is less suitable for driving loads.

However any differential action, either within an axle or front-to-back on an all wheel drive (permanent 4×4) vehicle can still allow movement.

A second advantage is that they remove the need to provide cable connections to the wheel brakes, on off-road vehicles where such may be prone to damage.