Do hydrostatic and hydraulic mean different units?

[rlee6]

Or are the terms used interchangeably? I have an HST tractor and I know I have a hydrostatic transmission. But do I have a separate hydraulic power unit? In other words, do I have to replace 2 filters or 1? (not counting engine oil filter, fuel filter, and air filters) Thanks for answering this newbie question.

 

[RonR]

Depends on the tractor, you could have one hydraulic unit that drives the hydrostatic transmission/pump or one that drives the HST and one for powersteering and/or remote hydraulics and 3 pt hitch.

ron

 

[beenthere]

My take, is that all tractors now have a hydraulic system. Pump or two to feed power steering and to feed the FEL or auxilary hyd. cylinders through control valves.
In addition, the transmissions come as gear or hydrostatic. If hydrostatic transmission, there will be pedals or lever to operate the direction and speed you will go. If gear, there will be a gear system of some sort.
For both tranny systems, the transmission fluid is the hydraulic fluid, and in one reservoir, and will have one filter most likely, plus maybe a screen to pass transmission hydraulic oil through for cleaning.
The engine will have its' own oil system separate from the tranny/hyd. system.

 

[rlee6]

Thanks for the answers. I just got the operator's manual by mail toady. I was reading up the maintenance section. I found only one hydraulic filter for the hydrostatic transmission. I was wondering if I missed something. Apparently, mine has one hydraulic power unit that drives everything.

 

[thcri]

</font><font color="blue" class="small">( T Apparently, mine has one hydraulic power unit that drives everything. )</font>

Your bio says you don't have a tactor yet. Did you buy something? And maybe more of us could help you if you told us what you bought.

murph

 

[ronjhall]

Looking at the Allmand 8435 HST specs. It appears that the tractor has a separate pump for Hydraulics and HST. There may be a screen on the Hydraulics.
Now that you have a tractor. /forums/images/graemlins/cool.gif How about posting some pictures and updating your profile? /forums/images/graemlins/grin.gif

 

[milkman]

Good question, I'm interested in the answer myself. Maybe someone will know.

 

[RalphVa]

I think my tractor has the same hydraulic pump for all services. Some other tractors use 2nd pumps for the power steering and lift hydraulics.

Ralph

 

[rlee6]

Sorry folks for not updating bio. I just bought a used Allmand 8435 HST. It is a TYM T330 HST with Mitsubishi 36 HP engine. Here is the specification. http://www.tym-usa.com/t330hst.htm

You were right about the screen. It seems to have transmission, hydraulics, and rear axle as one system.

 

[Partsman2]

According to the specs you have dual pumps and a hydrostatic tranny. 1 pump runs the PS (4.55 gpm flow rate)and the other pump runs the hyraulics and the hydro tranny (6.3 gpm). The total flow rate of both combined is 10.85 gpm.

The PS pump is dedicated only to PS so you don't get jerky steering when operating your hydraulics.

I have a JD with hydro tranny and I have a transmission filter, a separate hydraulic filter, and a filter screen in the return line. The filters and fluid are changed according to main. schedule and the screen is cleaned periodically.

I hope this helps. /forums/images/graemlins/smile.gif