Patent ID: 6510779
Filing Date: 2003-01-28
Classification: F04B

Abstract:
A bore pressure optimization mechanism for a hydrostatic unit including a rotatable cylinder block assembly having a cylinder block with a sealing surface thereon in fluid communication with a plurality of pressurizable piston bores, the mechanism comprising:an end cap including separate first and second working pressure passages therethrough terminating respectively at corresponding first and second ports on a block mounting surface directed toward the sealing surface of the cylinder block, the ports having opposite ends separated or spaced apart by at least a pair of walls; at least one wall of at least a pair of walls having and encircling a bleed passage formed therethrough, the bleed passage extending from the block mounting surface to one of the first and second working pressure passages; a variable orifice valve having a variable orifice disposed in the bleed passage of the end cap for metering fluid from one of the piston bores to one of the first and second working pressure passages in the end cap; and means for generating a control signal to the valve so as to adjust the size of the variable orifice based upon the control signal wherein a swashplate operatively associated with the cylinder block has a tilt angle which is free from moveable influence from the change of size of the variable orifice.