| 摘要 |
<p>The two way hydraulic jack for a bar-bending machine comprises a cylinder (1) in an oil reservoir with a cased single action pump (17) and a head (3) at each end. The pump has a ball distributor with one flow valve and one return valve. A lip seal (9) fits between the cylinder and the piston rod (6) at the head, its eventual non effectiveness being used as a stop to forward movement. A rear chamber (13) and a high pressure forward chamber (8) are fed via the distributor and a pipe (16) from the pump casing respectively. A stop ring (12) mounted on the rod is sited to the rear of a taper (29) and a second lip type piston seal (10) acts in a similar manner to the first to limit movement to the rear. A forward stop ring (7) has sufficient play on the piston to permit a laminar oil flow when the adjacent seal (9) becomes ineffective.</p> |
