Pt 425 stump grinder

[rjy]

Can someone give me the exact RPM the grinder wheel spins at Full throttle. Please measure it with a shaft tachometer or a photo eye tach. Please be safe while doing this!! I don’t want a guess. I need to size a new motor. ( Shaft broke off mine today) or if someone knows the White hydraulic motor cross over number to the Power trac that would also work.

 

[agjones]

Terry will probably answer the rpm question.

 

[Gravy]

Can someone give me the exact RPM the grinder wheel spins at Full throttle. Please measure it with a shaft tachometer or a photo eye tach. Please be safe while doing this!! I don’t want a guess. I need to size a new motor. ( Shaft broke off mine today) or if someone knows the White hydraulic motor cross over number to the Power trac that would also work.

I can't exactly answer your question because mine is really old and came with a Char-Lynn motor (I bought mine well-used from davesisk a long time ago). But I can tell you that replacing the original motor with one of a larger displacement one made the whole thing work better.

I can also tell you that the Power-Trac part number P142-3 on a stump grinder in the PT showroom at least 10 years ago indicated a displacement of about 3 cubic inches. I believe the original Char-Lynn on mine was 2.8ci and the current one is about 4ci. The lower speed and higher torque make it much less prone to stalling. I still have to feed it into the wood pretty lightly, but the original was very nearly useless on hardwood that wasn't rotten. OTOH, that also puts more load on the shaft, so that might be a concern.