Patent ID: 6530218
Filing Date: 2003-03-11
Classification: F16H

Abstract:
A hydrostatic continuously variable transmission comprising:a hydraulic pump including a pump cylinder and a plurality of pump cylinder bores; a hydraulic motor including a motor cylinder and a plurality of motor cylinder bores; a cylinder block having an output shaft, wherein said pump cylinder and said motor cylinder form the cylinder block; a high pressure oil passage disposed between the hydraulic pump and the hydraulic motor, said high pressure oil passage sending hydraulic oil to the hydraulic motor from the hydraulic pump during a normal operation of the transmission; a low pressure oil passage disposed between the hydraulic pump and the hydraulic motor, said low pressure oil passage sending hydraulic oil to the hydraulic pump from the hydraulic motor during the normal operation, and wherein said high and low pressure passages, said hydraulic pump and said hydraulic motor form a hydraulic closed circuit having a hydraulic pressure; a first pressure regulating valve for relieving the hydraulic pressure in the low pressure oil passage to the high pressure oil passage when the hydraulic pressure in the low pressure oil passage exceeds a predetermined value; and a second pressure regulating valve for relieving the hydraulic pressure in the high pressure oil passage to the low pressure oil passage when the hydraulic pressure in the low pressure oil passage exceeds a predetermined value, wherein the first and the second pressure regulating valves are formed in the cylinder block in parallel with the pump and motor cylinder bores.