| 摘要 |
A pawl and ratchet mechanism has a baulking member which may be set in a ratcheting condition, a pawl free condition, and a baulking condition. A thrust member, engageable with the baulking member, is movable in first and second directions in which the baulking member is respectively moved towards and away from the ratcheting condition. A solenoid valve is settable in first and second conditions in which thrust is imparted to the thrust member to cause the latter to move respectively in the said first and second directions and detector means detects when the baulking member has moved into or out of the baulking condition, and into the pawl free condition, the detector means controlling the setting of the solenoid valve to that when the baulking member is in the baulking condition, the solenoid valve is so set that the thrust moves the baulking member towards the pawl free condition, the solenoid valve is so set that the thrust moves the baulking member towards the ratcheting condition. |
