# Can I use a newer Hydrostatic Riding Mower??



## RKM (Jun 9, 2008)

Short description

A hydrostatic transmission is the combination of a variable displacement hydraulic piston pump coupled to a hydraulic motor or motors. 

Longer description

The variable displacement pump typically has many small pistons arranged in a revolving barrel (much like that of a revolver hand gun) that will pump hydraulic fluid at a rate of zero to a maximum depending on the position of the "swash plate". The swash plate is a disc inside the pump that can be varied in angle relative to the piston barrel. Each piston has a "shoe" that rides against the swash plate. If the plate is at a 90 degree angle to the barrel, the pistons will not displace any fluid as the barrel revolves. When the swash plate angle is changed from 90 degrees, the pistons will begin to pump fluid because they will travel within their cylinders as the shoes follow the surface of the swash plate. The further the hydrostatic lever controlling the swash plate angle is pushed in either direction, the greater the volume of fluid that will be pumped in either direction.

The motor may be integrated with the pump and even with the differential on some units or the pump and motor (connected to the diff) may be separate. The zero turn lawn mowers usually use two pumps and two motors, one for each drive wheel. This is why each drive wheel can turn in opposite directions. 

This is my understanding of the basic function of a hydrostatic tranny. They are a really neat device, I use lots of them in manufacturing. I wasn't able to find a good cut-away drawing for you. I'm sure this would have helped to clarify my description.

This address may help some.

Rob

http://www.hydraulicspneumatics.com...sM/Article/True/6450/TechZone-HydraulicPumpsM


----------



## DavidDymaxion (Dec 1, 2008)

If you can find a small shunt motor, it'll be even easier. A shunt motor spins a steady rpm, and you change vehicle speed via the transmission, and the shunt motor will give you regen down hills.


clone477 said:


> Hello everyone,
> I have been reading the couple threads about converting riding mowers to electric, and have seen the hydrostatic drives might be hard to do.
> 
> I have found a 2007 MTD Yard Machines riding mower with a blown motor for $150, and wanted to use it for a conversion. Can someone tell me, as I didnt have success online looking for specs, if this machine does have a hydostaic drive. And maybe if someone could really explain what hydrostatic drive is, I know it it the way the tranmission works, through hydraulic pressure but that is it. Why would it be hard to convert?
> ...


----------

