Air Compressor

[cletrac (RIP)]

Most of the stuff I've read says that the air compressors were only used on vehicles with two speed transfer cases. These articles state that they weren't used on the C8A HUPs but the C8A Personnel parts manual lists them as optional equipment. If the parts manual lists them as optional equipment why would these other articles be so definite that they weren't used here?

[Tony Smith]

Perhaps it means they were capable of being fitted if required, as these vehicles shared the same gearbox with the larger vehicles.
The Ford parts books list a Thornton-Welles locking differential being available as optional, but I have never heard of any vehicles being so equipped.

[Rod Diery]

Originally posted by cletrac
Most of the stuff I've read says that the air compressors were only used on vehicles with two speed transfer cases. These articles state that they weren't used on the C8A HUPs but the C8A Personnel parts manual lists them as optional equipment. If the parts manual lists them as optional equipment why would these other articles be so definite that they weren't used here?

The air compressor could be fitted to a C8A but the compressor needs the gearbox to to be engaged in a forward gear to operate.
Since the C8A's single speed transfer case does not have a neutral position, the air compessor would only be able to be used if the vehicle were in motion or if it had it's driving wheels jacked off the ground.

Cheers
Rod

[cletrac (RIP)]

Maybe they put the compressor on the transmission on C8As. I got one that a farmer had installed on the trans on a civilian 46 Chev that he converted to a spray truck.

[Tony Smith]

Originally posted by Rod Diery
The air compressor could be fitted to a C8A but the compressor needs the gearbox to to be engaged in a forward gear to operate.
Cheers
Rod

No, the PTO air compressors that hang off the side of the gearboxes on Fords and Chevs are driven off the countershaft of the gearbox and work with the GEARBOX in neutral, irrespective which transfer case is fitted or what gear the transfer case is in. The PTO will also work with a transmission gear engaged but you keep the engine revs below 900rpm. Being in a gear will not reduce the PTO speed as it is directly meshed with the G/box input gear and then the engine. Pic below is of a Ford T98 PTO with helical constant mesh gears, but the principal is the same as CMP boxes. Source

[Rod Diery]

Originally posted by Tony Smith
No, the PTO air compressors that hang off the side of the gearboxes on Fords and Chevs are driven off the countershaft of the gearbox and work with the GEARBOX in neutral, irrespective which transfer case is fitted or what gear the transfer case is in.

Oops! Tony, you are absolutely right. Sorry about that, temporary? brain fade

Cheers
Rod