Combination valve including improved neutral valve for use in hydrostatic transmission

A hydrostatic transmission for receiving input from a vehicle engine and driving an output axle comprising:

• a pump receiving an input from said engine and a motor;
• a hydraulic circuit for operatively connecting said pump and said motor;
• and
• at least one valve operatively connected to said hydraulic circuit, said valve having a check flow position to allow hydraulic fluid to flow through said valve into said hydraulic circuit, a neutral position whereby hydraulic fluid flows out of said circuit through said valve, and a closed position whereby no fluid flows through said valve.

A hydrostatic transmission for receiving input from a vehicle engine and driving an output axle, comprising:

• a pump receiving an input from said engine and a motor;
• a hydraulic circuit in which hydraulic fluid flows for operatively connecting said pump to said motor;
• a check valve for allowing hydraulic fluid to flow into said hydraulic circuit;
• and
• a neutral valve for allowing hydraulic fluid to exit said hydraulic circuit;
• wherein said neutral valve comprises:
• a valve body having a hydraulic fluid passage therethrough;
• a spool slidable mounted in said valve body and movable between an open position wherein said hydraulic fluid passage is substantially open and a closed position wherein said hydraulic fluid passage is substantially blocked;
• and
• a chamber formed between said valve body and said spool in which a portion of said hydraulic fluid is disposed when said spool is in said open position;
• whereby said hydraulic fluid is forced from said chamber when said spool is caused to move from said open position to said closed position such that the rate of movement of said spool between said positions is controllable.