Hetzer preselect gearbox compared to Ferret

[Tobias Weibel]

Good day to all of you.

I work in the workshop of the Swiss Military Museum Full-Reuenthal. We are one of the largest military museums in Switzerland.
We have two G13 (petrol and diesel engine)

I can organize or scan a G13 manual.

Tobias

[James P]

Great to see another MLU member (Tobias) stepping up and offering assistance. Seriously if you are plonking down a load of cash for a vehicle you should buy all the manuals possible, it is really not all that difficult. Case in point............

https://www.ebay.com/itm/WW2-German-...-/391441687153

[Malcolm Towrie]

Originally Posted by Tobias Weibel

Good day to all of you.

I work in the workshop of the Swiss Military Museum Full-Reuenthal. We are one of the largest military museums in Switzerland.
We have two G13 (petrol and diesel engine)

I can organize or scan a G13 manual.

Tobias

Tobias, that would be very useful to us! We have no documentation to go with this very nice Hetzer we have just acquired. This is a Praga petrol-engined version.
Malcolm

[Tobias Weibel]

Here is a preview







The rest is in the works

[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

[Richard Farrant]

Originally Posted by David Herbert

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

David

Hi David,
I was intrigued to know what the two items were on the drive end of the engine. Using a german to english translation on Google, it seems one is flywheel (logical) and the other means 'sliding clutch'. No doubt some else knows more on this.

[David Herbert]

Centrifugal clutch possibly ?

Sorry, I could have googled it too but was too lazy !

If it is a centrifugal clutch it might be stuck from lack of use which might explain why it is necessary to engage neutral to avoid stalling.

Also I should have thanked Tobias for joining in.

David

[Richard Farrant]

Originally Posted by David Herbert

Centrifugal clutch possibly ?

Sorry, I could have googled it too but was too lazy !

If it is a centrifugal clutch it might be stuck from lack of use which might explain why it is necessary to engage neutral to avoid stalling.

Also I should have thanked Tobias for joining in.

David

David,
There is another word before before 'sliding clutch', which is Sicherheilts, which translates as Safety, so safety sliding clutch. I think centrifugal is most likely as it does not need a separate control.

Yes, thanks to Tobias for the interesting diagrams and welcome to the forum.