Machine Guarding: Devices

• It may stop the machine if a hand or any part of the body is inadvertently placed in the danger area;
• Restrain or withdraw the operator's hands from the danger area during operation;
• Require the operator to use both hands on machine controls; or
• Provide a barrier which is synchronized with the operating cycle of the machine in order to prevent entry to the danger area during the hazardous part of the cycle.

Presence-Sensing Devices 

Photoelectric (optical)

Uses a system of light sources and controls which can interrupt the machine's operating cycle.

Radiofrequency (capacitance)

Uses a radio beam that is part of the machine control circuit. When the capacitance field is broken, the machine will stop or will not activate.

Electromechanical

Has a probe or contact bar which descends to a predetermined distance when the operator initiates the machine cycle. If there is an obstruction preventing it from descending its full predetermined distance, the control circuit does not actuate the machine cycle.

Pullback

Pullback devices utilize a series of cables attached to the operator's hands, wrists, and/or arms. This type of device is primarily used on machines with stroking action. When the slide/ram is up between cycles, the operator is allowed access to the point of operation.

Restraint

The restraint (holdout) device utilizes cables or straps that are attached to the operator's hands at a fixed point. The cables or straps must be adjusted to let the operator's hands travel within a predetermined safe area. There is no extending or retracting action involved. Consequently, hand-feeding tools are often necessary if the operation involves placing material into the danger area.

Safety Trip Controls

Provide a quick means for deactivating the machine in an emergency situation. A pressure-sensitive bar, when depressed, will deactivate the machine.

 

Safety tripwire cables may also be located around the perimeter or near the danger area.

Two-Hand Controls

Requires constant, concurrent pressure by the operator to activate the machine. With this type of device, the operator’s hands are required to be at a safe location (on the control buttons) and at a safe distance from the danger area.

Two-Hand Trip

This device requires concurrent application of both the operator’s control buttons to activate the machine cycle, after which the hands are free.

Gate

A gate is a movable barrier which protects the operator at the point of operation before the machine cycle can be started. They are usually designed to operate with each machine cycle.

 

Source: http://www.oshatrain.org 

Webmaster, Earn Money Here!
@ Safety Information...ThinkSafe,WorkSafe