| 摘要 |
PROBLEM TO BE SOLVED: To vary constant power characteristics of a swash plate type variable displacement pump without remarkably varying a structure. SOLUTION: A tilting angle of a variably swash plate is adjusted based on balance between energizing force of a spring mechanism which energizes the variably swash plate in a tilting direction, and cylinder inner pressure for energizing the variably swash plate in a standing direction, for performing constant power controlling. In such a variable displacement piston pump of a large amount flow, a plurality of discharge side through-hole lines 32, 33, 34 are formed on a valve plate 3 which distributes oil discharged from the cylinder. Among the through-hole lines, a notch 37 of an aperture 34a of the through-hole line 34 is shortened, through which line 34 oil is supplied to a swing system of a shovel. Influence of the swing system on a running system is reduced by decreasing a high pressure area of the through-hole line 34 for supplying oil to the swing system.
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