Hydrostatic transmission noise question

[Gene Davis (Ga.)]

Hey guy, some of you hydrostat guys like Allen in Ne or some of the rest of you, I need to ask a question. I have a 198 series Dig-It,(really is the name),made by Yazoo/Pug Power Corp in Misissippi TLB backhoe and loader with a 2 cyl 18 hp opposed Kohler engine and hydrostatic transmission. The question I have is every time it travels in forward or reverse direction I get a loud squalling sound like a relief valve bypassing. It does it in forward or reverse and it seems to have equal power either way, not sure if it has all the power it is supposed to as it has been doing this since I got it. Do hydrostats always make a noise like this as they are used? If not, any suggestions? Changed oil and filter in the transmission soon after I got it. The hydraulics are a seperate system, and use 15-40 engine oil instead of the Dexeron II ATF that the hydrostat uses.

 

[Allan in NE]

I don't have the first clue, Gene.

But, you don't 'spose the machine has a tranny bearing talkin' out loud, do ya?

Does it have a gearbox downstream of the hydro? If so, does it do it in neutral as well when you throw the control?

Also and just for what it is worth, anytime you have a hydraulic leak (o-ring, gasket, etc) it can set up a squealing noise when pressure is applied.

Dunno, hope you get it handled.

Allan

 

[Joe(TX)]

Hydrostatics tend to whine to some degree. What you have may not be a true hydrostaic system with a variable displacement pump. I have seen some using a gear pump setup with a control valve. These generaly are noisy.

 

[RodinNS]

Does the engine direct drive the 'stat or does it have a belt drive?
The reason I ask is because many of those small hydro's are belt driven. I've got one in a small feed cart that's belt driven by a 9 hp Honda. The hydro part is fine but the belts do slip and require changing from time to time.... Just a thought.

Rod

 

[Gene Davis (Ga.)]

Guys, this one is shaft driven from the engine and the hydraulic pump is on the other end of the crankshaft. Think maybe it is an Eaton brand(will have to look at that)unit that is direct coupled to the pinion shaft of the differential. We had one of those cussed, aggrevating belt driven hydrostats at the golf course where I work, and it was always giving trouble, a good foggy day would make the belts slip. Allen, are you talking about a hydraulic hose or fitting leak? I add very little fluid to it. If there was a leak I think it should show up in a puddle on floor or ground when running or parked overnight on shop floor. This appears to be a one case self contained unit. Will have to do some digging and find more info. Thanks for the help guys. Gene

 

[Anonymous-0]

See if there is a filter on the trans. that could be changed. Also check oil level. Some hydrostatic transmissions just make a lot of noise. Dave