Thanks, Chris,
The C&S had engine-only air brakes in addition to train air, to which was added the tender triple valve.
I don't know of a seperate triple valve on the engine brakes, but on #74, I do recall the same type of device as found on the rear cistern air tank attached to one of the tanks under the engineer's side of the cab. That device is what I have been told is the actual triple valve, the setting lever on the tender is located behind the engineer's side of the cab at the front of the tank. So you may be correct, there may be a seperate engine only triple valve on C&S engines.
I think it would take someone who knew what they were looking at a month to decipher the air systems on a C&S narrow gauge engine. It is incredibly complex.