Machine Design

Piston-rod brake needs no air pressure

The motion-control industry's first round-line pneumatic rod lock prevents piston rods from moving when air pressure is lost.

It can help hold stationary loads at machine shutdown and prevent tool drift. The Rod Lock from Bimba Manufacturing Co., Monee, Ill. (, uses a cam-and-pin design to activate the brake. When there is compressed air, the piston presses a spring down and dowel pins follow a cam to their open position. As the pins move to the open position, they also open a clamp to let the rod travel freely. When air pressure is lost, the spring forces the piston up, the dowel pins follow the cam to the closed position, and the clamp closes.

The Rod Lock holds up to 40 lb on a 3/4-in. bore and up to 700 lb in a 3-in. bore. Maximum operating pressure is 125 psi, and it takes at least 50 psi to release the clamp. It operates in temperatures ranging from -20 to 200°F. Expected service life is 5 million cylinder actuations and 1 million lock actuations.


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