We're sorry, but OSHAcademy doesn't work properly without JavaScript enabled. Please turn on JavaScript or install a browser that supports Javascript.

726 Introduction to Machine Guarding
Skip to main content

Mechanical Energy Hazards

The image shows safety blocks being used as an additional safeguard on a mechanical power press, even though the machine has been locked out. The safety blocks prevent the ram from coming down under its own weight.

Safety Block
A safety block being inserted into a machine.

Pneumatic and Hydraulic Energy Hazards

The second image shows a lockout valve. The lever-operated valve used during repair or shutdown to keep a machine or its components from operating can be locked open or shut.

Valve Lockout
Image of locking out a valve

Before the valve can be opened, everyone working on the machine must use his or her own key to release the lockout.

A sliding-sleeve valve exhausts line pressure at the same time it cuts off the air supply. Valves used to lock out pneumatic or hydraulic-powered machines should be designed to accept locks or lockout adapters and should be capable of "bleeding off" pressure residues that could cause any part of the machine to move.

Knowledge Check Choose the best answer for the question.

6-4. Which of the following is used as an additional safeguard to protect against a mechanical energy (gravity) hazard even though the machine has been locked out?