| 摘要 |
The system is operated by a pressure release switch 4 which, when activated, completes the circuit sounding the alarm sounder 3, the alarm set switch 2 having previously been set. The switch is designed to fit in a pad (5, Figs 2 + 3, not shown) on which the foot of the jack of the caravan rests, in use. Alternatively, the switch can be set beneath a hitch lock. The switch can, alternatively, be set beneath a wheel of a vehicle. <IMAGE> |
