| 摘要 |
An integral barrel is provided with a cam (5) which may be rotated by a key. The cam has the form of a cylinder with a recessed platform (21) in one section. A microswtich (2) is positioned so that its pin (20) is normally forced inwards by the cam, when the switch is in the on position, but may drop into the recess to turn the switch off. A pawl (6) is mounted near the base of the lock mechanism so that its edge (6) comes into contact with the surfaces (7a,7b,7c) of a tooth in the cam cylinder. When the barrel is rotated in the normal direction, with the switch in the 'on' position, reverse rotation is prevented by engagement of the cam tooth with the pawl. The barrel is further rotated in the normal direction until a position is reached where the lock mechanism allows the withdrawal of the key. |
