Guard mechanical sensing

Careful design of guards is vital. An ineffective guard can be worse than none at all, as it can give rise to a false sense of security. Emergency shutoff devices may be needed, in addition to electrical and mechanical guarding. 

Electric field transducers can also be used. They generate a capacitive field in a hazard area. Any grounded object in the field can he detected. Operators working in that area are grounded and can he sensed by this method to stop the machine before its activation. These are different guards and safety devices that are normally used to avoid mechanical hazards. 

Mechanical-power presses are required to have switches and brakes that are operator proof The size of some presses makes it imperative that they are switch-guarded as well as mechanically guarded. This section describes what actions must be taken to produce the most failsafe device possible. Minimum braking action and the proper brakes that must be installed on presses of differing specifications are outlined. Criteria for the use of presence-sensing devices and their proper utilization is described. 

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