| 摘要 |
PROBLEM TO BE SOLVED: To prevent a leak of hydraulic fluid certainly as reducing the working manhours and the number of part items by forming taper groove part, extended with an inner diameter toward the outside, at the body internal side of a seal groove, and engaging a projecting part, installed on the circumference of an oil seal, with the taper groove. SOLUTION: Back pressure to be added to an oil seal 20 due to something wrong with a drain passage 18 installed toward a suction hole from a shaft hole 10, goes up, and if this back pressure goes up further beyond the extent of frictional force to be produced by a cylinder part, the oil seal 20 slides on an inner surface of a seal groove 11 and it intends to be displaced toward the outside of a body 1. However, since a projecting part 21 of the oil seal 20 is interpenetrated into a taper groove 13 of the seal groove 11, therefor this projecting part 21 is engaged tight with a wall surface of the taper groove 13 according to the displacement in the axial direction of the oil seal 20, whereby such a possibility that the oil seal 20 might be slipped out of the body 1 is thus preventable. |
