Fan clutch thermal or air???

works the same way as on a car, only ever seen them on the older cummins though

 

Question: How is it driven? By a water pump shaft too?

 

same way as on a car, temp rises in rad, internal clutch senses it and it locks up as an air clutch would.

 

Some of them have the air line routed up against the inside of the radiator core and connecting to the center of the fan hub (very hard to see, but you can feel it with your hand). If it's strictly thermal, it will sound like an airplane all the time and the fan will never stop completely.

 

never seen that on an ntc cummins, only on a CH Mack with an E7 motor. but they really dont work or sound any different from an air ooperated fan

 

I know how they operate, just curious what it's connected to. Does the engine have the water pump in the front like a car?

 

The water pump is in the front of an ntc Cummins but no way it could carry a fan, it's too low on the engine, so it would have an alternative style fan hub for the viscous fan drive to mount to and the fan.

 

Mounted the same way as a traditional fan would be, with fan shaft and bearings and drives off of crank. Will not sound any different than a traditional fan would, you just have no control over it.