| 摘要 |
<p>A rotatable drum for reeling in and releasing a cable has drive means which includes a normally disengaged drive input clutch, a normally engaged brake and a normally engaged disconnect clutch which may be used to uncouple the drum from the drive system so that it may be turned manually to withdraw cable. The input clutch may be selectively engaged and the brake and disconnect clutch may each be selectively disengaged by fluid pressure from a control valve connected to a source of fluid pressure. The valve has a Hold or Brake-On position at which each of the clutches and the brake are unpressurized, a Reel-In position at which the input clutch and the brake are pressurized, a Brake-Off position at which only the brake is pressurized and further has a Free-Spool position at which the disconnect clutch is pressurized to free the drum from the resistance or drag of the drive system. Centering springs resist movement of the control valve away from the Brake-On position. To facilitate manual control of the valve, additional resilient means are arranged to create added resistance to further movement of the control valve as it approaches the Free-Spool position to assist the operator in avoiding overshifting to that position when it is not desired.</p> |
