US 7,320,217 B2
Load controller for hydrostatic transmission in work vehicles
Toshifumi Yasuda, Amagasaki (Japan); Shigenori Sakikawa, Amagasaki (Japan); and Kazuhiko Ohtsuki, Amagasaki (Japan)
Assigned to Kanzaki Kokyukoki Mfg. Co., Ltd., Amagasaki-shi, Hyogo (Japan)
Appl. No. 10/553,099
PCT Filed Apr. 14, 2004, PCT No. PCT/JP2004/005287
§ 371(c)(1), (2), (4) Date Oct. 13, 2005,
PCT Pub. No. WO2004/102043, PCT Pub. Date Nov. 25, 2004.
Claims priority of application No. 2003/109359 (JP), filed on Apr. 14, 2003; and application No. 2003/356052 (JP), filed on Oct. 16, 2003.
Prior Publication US 2006/0254268 A1, Nov. 16, 2006
Int. Cl. F16D 31/02 (2006.01)
U.S. Cl. 60—468  [60/431] 15 Claims
OG exemplary drawing
 
1. A load controller provided in a hydrostatic transmission for a work vehicle, wherein power supplied from an engine is branched to drive an implement system and a traveling system, and a hydrostatic transmission is provided in the traveling system; the hydrostatic transmission connecting, in an oil-hydraulic closed circuit, an oil-hydraulic pump driven by the engine and an oil-hydraulic motor driven by the oil-hydraulic pump; the load controller comprising:
a bypass oil line for bypassing an oil line that has high pressure during forward movement in the oil-hydraulic closed circuit to reach an oil line that has low pressure during forward movement or an oil tank; a first opening/closing valve for opening or closing the bypass oil line;
an opening/closing valve controller that detects a load applied to the engine while traveling during working and opens the first opening/closing valve when the load exceeds a predetermined level;
a second opening/closing valve on the valve-outlet side of the first opening/closing valve that opens or closes the bypass oil line by external operation; and
a flow control valve between the first opening/closing valve and the second opening/closing valve.