| 摘要 |
PURPOSE:To certainly prevent the lock of a motor under a high pressure by balancing each pressure on the inside and outside of an internal gear by forming a passage which communicates to the inside and outside of the internal gear in the radial direction of the internal gear. CONSTITUTION:In the space 16 of a housing 11, an internal gear 20 is fitted in rotatable ways, and a shaft 30 is rotatably supported. An output gear 40 is fitted onto the spline shaft 301 of the shaft 30. An introducing groove 114 and a leading-out groove 115 for supplying and discharging the high pressure fluid for a working chamber are formed onto the edge surfaces 112 and 113 of the housing 11. With such constitution, a plurality of pressure balance holes 21 which penetrate in the radial direction are drilled at equal intervals in the circumferential direction on the internal gear 20. Therefore, each pressure on the inside and outside of the internal gear 20 is balanced, and the internal gear 20 is prevented from being applied with an eccentric load.
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