Hetzer preselect gearbox compared to Ferret

[David Herbert]

Ok,
From the above it can be seen that each side functions separately. Slowing one side does not speed up the other so there is no regeneration unlike a controlled differential (Sherman / Stuart) or Merit Brown (Centurion / Cromwell etc).

The two outer bands are simply brakes to stop that track.
Each side has a clutch which is spring engaged like a car clutch. If engaged with no brakes applied that track is in high gear (normal for straight running).

Clutch disengaged with no brakes gives neutral which if the other side is still in high, will result in a gentle turn towards the side in neutral depending on road conditions. However on a down slope the vehicle will turn the other way which can be exciting.

Clutch disengaged and the inner brake band applied will give low gear to that track resulting in a geared turn (if the other track is in high) of a radius depending on the gear ratios.

It is possible to design the controls so that it is possible to have one track in neutral with the brake applied and the other in low, resulting in a pivot turn with one track locked but it seems from Malcolm's earlier post that that has not been done here. On Crusader it was relatively easy as the brake bands were air operated so all that was needed was a rather ingenious valve block.

The Praga-Wilson main transmission I think is a five forward one reverse unit, very similar to those used in cars and buses in the UK.

I do not know what the units are on the front of the engine.

David