Patent ID: 8658927

Claim:
A safety switch system with guard locking comprising a cam mechanism, a cam operated solenoid switch, an actuator and a locking mechanism, wherein the cam mechanism comprises a rotary cam biased towards a datum position and a cam plunger biased onto the cam, and the switch comprises a solenoid plunger biased out of a housing of the switch towards the cam plunger and in which position the switch enables a power supply, whereby in the datum position of the cam the cam forces the cam plunger towards the solenoid plunger which in turn forces the solenoid plunger into the switch housing and in which position the switch is enabled to disable a power supply, and in order to move the switch to the condition which enables power the cam is provided with at least one engagement means to accept the actuator, insertion of the actuator is adapted to drive the rotation of the cam away from its datum position and to enable the cam plunger to engage in a detent in a profile on the cams surface thereby allowing movement of the biased cam plunger away from the solenoid plunger which in turn allows the solenoid plunger to be biased out of the housing, the engagement means and actuator are designed such that rotation of the cam away from its datum position means that the actuator cannot be withdrawn until the cam is moved back to its datum position, removal of the actuator enables movement of the cam back to its datum position and for power to be disabled, and wherein the locking mechanism has means to lock the actuator in the engagement means to prevent its removal when said power is supplied by the switch until certain operating conditions have been met, characterised in that the locking mechanism comprises a moveable safety arm which extends between the solenoid and cam plungers such that the cam plunger only acts on the solenoid plunger via the interposition of the moveable safety arm, the locking mechanism having means to lock movement of its arm when the cam plunger is in the detent to trap the cam plunger between the arm and the cam thus preventing its movement towards the solenoid plunger and thereby locking the rotation of the cam back to its datum position.