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A valve mechanism for use in a hydrostatic transmission including a closed porting system for hydraulic fluid and a sump is provided. The valve mechanism includes a valve body mounted to the hydrostatic transmission whereby the valve body is open to the closed porting system at one end thereof and o

A valve mechanism for use in a hydrostatic transmission including a closed porting system for hydraulic fluid and a sump is provided. The valve mechanism includes a valve body mounted to the hydrostatic transmission whereby the valve body is open to the closed porting system at one end thereof and open to the sump at the other end thereof. The valve body has a first open position whereby hydraulic fluid is pulled into the closed system from the sump when the pressure of the fluid in the closed system is below a first pressure, a second open position whereby hydraulic fluid exists the closed system to the sump when the pressure of the fluid is at a second pressure higher than the first pressure, and a closed position when the pressure of the hydraulic fluid in the closed system is at a third pressure higher than the second pressure.

대표청구항 ▼

[ I claim:] [1.] A hydrostatic transmission comprising:a housing forming a sump for storing a quantity of hydraulic fluid;a center section mounted in said housing and having a hydraulic circuit;a hydraulic pump mounted in said housing;a hydraulic motor mounted in said housing and drivingly linked to

[ I claim:] [1.] A hydrostatic transmission comprising:a housing forming a sump for storing a quantity of hydraulic fluid;a center section mounted in said housing and having a hydraulic circuit;a hydraulic pump mounted in said housing;a hydraulic motor mounted in said housing and drivingly linked to said hydraulic pump through said hydraulic circuit;a plate secured to said center section; anda valve secured in said center section by said plate and disposed between said sump and said hydraulic circuit, said valve being movable between a first position whereby said hydraulic fluid is allowed to flow from said sump into said hydraulic circuit, a second position whereby said hydraulic fluid is allowed to flow from said hydraulic circuit into said sump, and a third position whereby no hydraulic fluid flows through said valve.