US 7,516,613 B2
Hydraulic drive system
George Kadlicko, Rockford, Ill. (US)
Assigned to Haldex Hydraulics Corporation, Rockford, Ill. (US)
Filed on Dec. 01, 2005, as Appl. No. 11/291,753.
Claims priority of provisional application 60/677103, filed on May 03, 2005.
Claims priority of provisional application 60/632178, filed on Dec. 01, 2004.
Claims priority of provisional application 60/632176, filed on Dec. 01, 2004.
Prior Publication US 2006/0156713 A1, Jul. 20, 2006
Int. Cl. F15B 11/00 (2006.01); E02F 9/22 (2006.01)
U.S. Cl. 60—414  [60/428; 60/464] 40 Claims
OG exemplary drawing
 
1. A hydraulic drive system comprising an actuator having a pair of chambers separated by a drive member and disposed to apply a motive force in opposite directions to said drive member, each chamber being connected to a respective one of a pair of variable capacity machines, at least one of which is operable in a pumping mode to supply fluid to a chamber and at least the other of which is operable in a motoring mode to consume fluid expelled from the other of said chambers, each of said machines having a pressure compensating control to condition said machine to maintain a respective predetermined pressure in said chambers and an external control operable to modulate said predetermined pressure in at least one of said machines and thereby vary the motive forces acting on said drive member.