"Wet Clutch" ?

[1958 F.W.D.]

I saw the term "wet clutch" in the Convoy thread....What is it??? Is it a hydraulic clutch??? Esplain Lucy......Thank you!!!

[b61fred]

I have had some hudson cars that had a wet clutch and they were quite a bit different. The clutch disc was saturated in oil looked kinda like a torque converter. The cluch disk looked like a metal disk with several cork plugs in it. If you let it leak all the oil out it would grab too quickly and rip the little corks right out of the disk. I don't know if thats how mack trucks did it but thats what I know. The most modern aplication of a wet clutch is a motorcycle, I think almost all motercycles have a wet clutch.

[39 Baby Mack]

I don't really know that much about how they operated.

The Mack Co. called them Dynamax clutches and U.P.S. used a bunch of them for awhile in there "F" models.

They used a special flywheel housing that was sealed because it was filled with A.T.F. fluid.

They were operated by a treadle valve located where the clutch pedal would be.

I can remember seeing these trucks leave the toll booths and if you noticed when they left they didn't jump around like normal trucks did when the driver

engaged the clutch---they just plain flat took off sort of like they had an on & off clutch with no in-between.

I think that was the idea of it especially with slip seat trucks, so the clutches would always engage the same way and therefore should last longer.

Ron

[kscarbel]

Exactly. The Mack Dynamax wet clutch (designated CL-72 and CL-721) was an option available to all customers but it actually came to be because UPS demanded it, initially in the F-model from 1970 and later in the MH (in those days, when UPS spoke, Mack listened). Produced by Rockford Clutch Corp., they lasted almost forever. Clutch engagement took some getting used to but I wish more customers had tried it. The long life more than offset the added purchase cost. Mack basically worked with Rockford to very successfully adapt their wet clutch technology for off-highway construction machinery to the heavy truck application. I recall it being available at least thru 1985.