| 摘要 |
PURPOSE: A hydraulic pump control system of a small excavator is provided to prevent the lowering of the speed on a front work by swivel and to prevent unnecessary output loss by outputting the appropriate flow for swivel. CONSTITUTION: The hydraulic pump control system of a small excavator comprises a front working unit containing a boom cylinder(1), a bucket cylinder(2) and an arm cylinder(3), hydraulic pumps(P1,P2) for primary, secondary variable capacities supplying pressure oil to traveling motors(M1,M2), a pump regulator(4) controlling a swash angle of the hydraulic pumps(P1,P2), a swivel motor(M3), a third hydraulic pump(P3) supplying oil pressure to the swivel motor(M3) only, a swiveling direction control valve(7) installed on a discharge hydraulic line(5) of the third hydraulic pump(P3) to change the direction of oil pressure supplied to the swivel motor(M3), a pair of oil grooves(6a,6b) connected to the inlet/outlet of the swiveling direction control valve(7) and the swivel motor(M3), check valves(8a,8b) installed on the oil grooves(6a,6b) to restrain the supply of oil pressure and to allow the discharge of oil pressure, parallel oil grooves(9a,9b) detouring each check valve(8a,8b), swiveling input flow control valves(12a,12b) installed on each parallel oil groove(9a,9b) and communicated when the pressure of pressure oil supplied to the swivel motor(M3) goes over than the appointed pressure, an input flow sensor of a swivel motor connected to each oil groove(9a,9b) of the swiveling input flow control valves(12a,12b) to select the high pressure of the pressure oil on the passages(6a,6b), and an oil groove(10) connecting the detected oil pressure with the pump regulator(4).
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