[AT] OT: hydrostat mowers

[Ken Knierim]

Interesting question. My armchair view is that it depends on how the unit
was designed. I would expect that the main heating on the oil would be from
the pump and that by turning the engine revs down you'd reduce the friction
losses in the pump. Running the engine slower might increase the operating
pressure though since you'll be asking for more torque, so reducing the
overall pressure may help with friction losses and internal wear. Also, do
you know if the motors have a variable flow design?

Maybe you could affix an engine coolant temperature gage to the side of the
unit and try it both ways and see what causes the least heating of the
housing?

Ken in AZ

On Fri, Jun 18, 2010 at 11:47 AM, Bill Bruer <bill_bru at bellsouth.net> wrote:

> I have a Cub Cadet 1330 with the hydrostat transmission - that is, an
> integrated pump and motor unit.  Also, my zero-turn mower has 2 IZT
> integrated pump and motor units.  Neither is recommended for hard pulling
> jobs, yet both have drawbars and I see others using these type of mowers
> for
> pulling various implements.  The main possible damage seems to lie in
> overheating the hydro units.
>
> So, when pulling an implement is it better for the hydro units to use full
> engine/pump rpm and reduce ground speed with the hydro motor controls or
> slow the engine/pump and open up the hydro motors?  I hope I've stated this
> fairly clearly.
>
> Bill Bruer
>
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