I have a Funk 33000 HMD transmission in a 5-ton underground truck. It's in a transverse configuration rather than the normal drop configuration. After buying the machine, I drained and replaced the transmission oil as it had experienced water contamination through the breather. It was opaque but not truly "milky" compared to some I've seen. At slow speeds the transmission occasionally feels like it's slipping for a quarter- to half-second at most. It's not serious and doesn't really happen when tramming at full throttle so I can live with it but I wouldn't mind fixing it. I'm wondering if a clutch disc was water-damaged. Unfortunately I haven't tracked down a parts manual for the thing yet so I don't know much about it besides for what I got from the 8-page operation booklet (calling it a manual is a stretch. Does anyone here have experience with this model transmission and what might be going on?
I have no experience with this transmission. Checking the transmission pressure would be first step. The pressure could be low at lower rpm s and increase when at throttle from a worn pump or regulator valve. As a general specification the transmission pressure should be around 300 psi. Water contamination can cause some clutch disc to delaminate from the steel or swell.
So I may have spoke out if school, after looking up the HDM 33000 ( also only found in the dropbox configuration) This transmission appears to be just a multiple speed gear box, with a hydraulic motor to turn it.
Appreciate the information, that helps me narrow things down. Upon further examination, it looks like the driveline disc brake is dragging pretty badly which mimicked transmission slippage. I had trouble getting the truck to take off (was using it while clearing accumulated tumbleweeds from equipment in our yard) and after dumping the load and parking, found that brake rotor to be extremely hot. The axle brakes and transmission drum brake were cool. I'll call up the manufacturer and order a replacement caliper.