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Our Expert Takes Your Questions: What is an Overspeed Shut-Off Device?

November 28, 2017


An overspeed shut-off device increases operator safety by reducing the risk of accidents.

Pneumatic grinders are widely used in the manufacturing industries, in particular in metal working sectors such as foundries, casting plants and fabrication. In such industries, safety is of utmost importance. The overspeed shut-off device, a feature available in a pneumatic grinder, maximizes the operator safety by reducing the risks of abrasive related incidents caused by air pressure fluctuations (above 90 PSI / 6.3 bars).

How does it work?

In the unlikely event of overpressure (or external factor affecting the tool speed), this device stops the tool, preventing the abrasive from overspeeding and causing possible accidents.


The air flow is continous from air inlet, through motor and to the exhaust. 

Overspeed shut-off open


A steel sphere blocks the air stopping the motor rotation: the air flow is interrupted.

overspeed shut-off closed

“When the overspeed shut-off device is released, the tool is blocked. It is highly recommended to do a diagnostic first to determine the cause that led to the activation of the device, and only then reset the tool. Always refer to the tool’s manufacturer instructions when doing so.”

Lucas Bryk , Global Product Marketing Manager - CP Material Removal
Chicago Pneumatic Experts - what gives power to an impact wrench - how does a pneumatic grinder work

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