Jump to content
Sturgeon's House

Compressed Air gear change systems


Walter_Sobchak
 Share

Recommended Posts

I always knew the Pz 35 used a compressed air system for changing gears, this has been written about in several books and said to have been rendered inoperable by the Russian Winter.  I didn't know until watching the new "Matilda Diaries" episode on youtube that the Matilda II infantry tank also used compressed air to change gears.  Anyone know if any other WW2 tanks used compressed air systems?  Any records of the Soviets having issues with this system in their Lend Lease Matilda tanks in the winter?

Link to comment
Share on other sites

The original pilot Covenanter had a pneumatically-operated transmission. According to Knight, the MEE report on the tank noted, "It is pointed out however that since the vehicle steering is entirely dependent on the air supply, any failure of the engine or compressor renders the salving of the vehicle a most difficult proceeding." The next pilot and production tanks switched to cables...

Link to comment
Share on other sites

They're still packed away but I have some older books that mention automotive pneumatic gearchange (and automatic/semi-automatic clutching) systems.  Most (damn near all) incorporated some form of reservoir for a few shifts (and/or clutchings) if the supply failed.

 

As far as cold weather, there were all kinds of dryers (chemical and mechanical) to make sure the supply to the system was as dry as possible.   "pure" Ethyl Alcohol was one of the chemical means.

 

Let that sink in a moment, especially in a "Joe is a hell of a guy" circumstance.

Link to comment
Share on other sites

I don't know of any other tanks that use the system specifically, but it is possible that the Germans were fooling around with it.

 

The Germans, and most other WWII tank-building nations weren't able to make loads and loads of planetary gears.  Planetary gears were usually restricted to the final drives (and sometimes not even then, as in the disastrous case of the panther).  This is significant because automatic transmissions are essentially a big stack of planetary gears back to back to back:

 

Automatic_transmission_cut.jpg

 

 

Whereas manual transmissions don't use any planetary gears at all, they have two parallel layshafts:

 

qIoTdgl.jpg

 

But manual transmissions are harder to use, especially non-synchronized manual transmissions where one must master the arcane art of double-clutching, no small feat in a vehicle as clunky as a tank.  So German tanks generally featured a transmission where the actual act of shifting gears was done automatically, once the driver had selected the gear they wanted to go into and activated a gear change control.

 

But the act of changing gears in a layshaft transmission is considerably more complex than in a planetary transmission, so there would need to be some system of actuators to engage the clutch, shift the gears to the appropriate position, then disengage the clutch.  In a planetary transmission it's a far simpler matter of simply applying or releasing band brakes to the planetary gear sets.  This is where the pneumatic system comes in handy.

 

All the German systems I've heard of are electrically actuated, but there might be some pneumatic ones too.

Link to comment
Share on other sites

  • 2 weeks later...

I don't know of any other tanks that use the system specifically, but it is possible that the Germans were fooling around with it.

 

The Germans, and most other WWII tank-building nations weren't able to make loads and loads of planetary gears.  Planetary gears were usually restricted to the final drives (and sometimes not even then, as in the disastrous case of the panther).  This is significant because automatic transmissions are essentially a big stack of planetary gears back to back to back:

 

Automatic_transmission_cut.jpg

 

 

Whereas manual transmissions don't use any planetary gears at all, they have two parallel layshafts:

 

qIoTdgl.jpg

 

But manual transmissions are harder to use, especially non-synchronized manual transmissions where one must master the arcane art of double-clutching, no small feat in a vehicle as clunky as a tank.  So German tanks generally featured a transmission where the actual act of shifting gears was done automatically, once the driver had selected the gear they wanted to go into and activated a gear change control.

 

But the act of changing gears in a layshaft transmission is considerably more complex than in a planetary transmission, so there would need to be some system of actuators to engage the clutch, shift the gears to the appropriate position, then disengage the clutch.  In a planetary transmission it's a far simpler matter of simply applying or releasing band brakes to the planetary gear sets.  This is where the pneumatic system comes in handy.

 

All the German systems I've heard of are electrically actuated, but there might be some pneumatic ones too.

 

Matilda (II) had an air assist, IIRC.

Link to comment
Share on other sites

  • 1 year later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...