Hydro Speed Question

[71_Bronco 1,072]

Working on my '71 Bronco 14, with the stock Sundstrand hydrostatic "transmission". Have a question on using it.

 

I know the K321 Kohler should be run at full speed for the whole oil splashing / lubrication, and the hydro allows you to run the motor at full speed while driving at variable speed.

 

My question though, is regarding the hydro unit. Is it better to run the tractor at "full speed" like the motor? Or does the hydro unit not really care what you run it at? I'd hate to run it at half-speed when it should be at full-speed, and have an issue down the road.

 

Am I over thinking it?

[pfrederi 17,886]

All the WH hydro owners manual specify you run the engine wide open.  Cooling of the hydro with its fan turning slowly can be an issue. (MY Johne Deere Hydro also says run at full throttle....)

[lynnmor 7,354]

Running a hydro at high RPM is not just about heat.  I'll try to explain an example.  Let's say you are climbing a steep grade and want to go 3 MPH, with the engine running at half speed each component in the hydro will be subjected to double the torque that it would at full engine speed.  Some may remember the good old days when a stick shift car would slip a bad clutch in high gear but work to get you home in second, same principle.

[953 nut 55,836]

5 hours ago, 71_Bronco said:

Am I over thinking it?

[71_Bronco 1,072]

I looked through the manual for my Bronco like 3 times. It does say that you should run the motor at full throttle to get attachments like a mower deck to run at the proper speed, and that the hydro allows you to have variable ground speed while maintaining the motor at full RPM. It does mention that moving slower up a grade will essentially be like using low gear (vs trying to go fast up a grade), but does not give any recommendations as to using "full speed" whenever possible or anything like that.

[WVHillbilly520H 10,374]

I don't run WOT for anything except running PTO engaged attachments(deck tiller snow thrower) when I'm doing blade woek (front or rear) usually 1/2-3/4 throttle, no issues as of yet, bought it new in 1998, I believe you are over thinking it, Jeff.