| 摘要 |
A hydraulic jack including a bleed port for permitting the flow of fluid from the ram cylinder when the head portion of the ram moves to a position adjacent one end of the cylinder so as to prevent the ram head portion from being forced and the sealing means against the end of the cylinder. The bleed port means comprises a bore formed by a laser beam and extending through the cylinder wall, the bore having a diameter of less than approximately 0.015 inches along substantially its entire length.
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