OIL-PRESSURE CIRCUIT FOR CIVIL ENGINEERING AND CONSTRUCTION MACHINERY

摘要

PURPOSE:To equalize the left and right-side running forces without any zig- zagged motion during the multi-purpose operation period while running by connecting the inlet ports of the left or right-side running switching valve of the first oil-pressure pump and also of the other running switching valve of the second oil-pressure pump. CONSTITUTION:The first oil-pressure pump 20 is connected in parallel with a bucket switching valve 21, a turning switching valve 26, and a boom switching valve 22 in order, and in tandem with a left or right-side running switching valve 23 downstream of the boom switching valve 22. The second oil-pressure pump 24 is connected in tandem with an arm switching valve 25 and the other running switching valve 27 in order. The inlet ports of the running switching valves 27 and 23 are connected by a connection tube 30. Thus, lateral running forces can be equalized without causing any zig-zagged motion during the multi- purpose operation period while running.