Hydraulic Presses
Hydraulic presses form, punch, straighten and assemble parts with tons of force. The ram can come down when you don’t expect it, either because someone hits a control or because hydraulic pressure leaks away and gravity takes over. Guarding, blocking and lockout keep hands and bodies out from under it.
- General Industry
- Manufacturing
- Maintenance
Which rules apply
OSHA’s mechanical power press rule (1910.217) doesn’t cover hydraulic presses, but OSHA’s general machine guarding rule (1910.212) and lockout rule (1910.147) do. The industry standard is ANSI B11.2. See Machine Guarding.
Point-of-operation guarding
The point of operation is where the die closes on the part. Your hands must not be able to reach it while the ram moves. Common safeguards:
- Fixed barrier guards with openings too small for fingers
- Interlocked gates that stop the press when opened
- Light curtains that stop the stroke when a hand breaks the beam, mounted far enough away that the ram stops before you reach the die
- Two-hand controls placed so both hands must stay on the buttons until the danger is past
Hand tools for loading and unloading help, but they aren’t guards on their own. See Safeguarding Devices.
- Never tie down a two-hand button, tape over a light curtain or bypass an interlock.
- Never reach in to straighten a part while the press can cycle.
Ram drift and safety blocks
A hydraulic ram can slowly drift down or suddenly fall if a valve or seal fails, even with the power off. Whenever anyone works in the die area, for die changes, repairs or cleaning:
- Lower the ram onto the die or blocks, or put safety blocks under it, rated for the weight.
- Use blocks with interlocks if your press has them, so the press can’t run with a block in place.
Stored hydraulic energy
- Turning off the pump doesn’t remove the pressure. Accumulators and trapped oil can still move the ram.
- Lockout means shutting off and locking the power, bleeding pressure, blocking the ram and testing that nothing moves. See Lockout/Tagout.
- A pinhole leak in a hydraulic hose can inject oil through your skin. That’s a surgical emergency even if it looks small. Never check for leaks with your hand. See Hydraulic Hazards.
Daily press check
- Guards and gates in place and interlocks working
- Light curtain stops the stroke when tested with the test rod
- Two-hand controls require both hands and release stops the ram
- Emergency stop works
- No hose leaks, damaged fittings or low oil
- Ram doesn’t drift when stopped at the top
Report any problem and tag the press out of service until it’s fixed.
Other hazards
- Parts or broken dies can be ejected. Wear safety glasses.
- Heavy dies need hoists or die carts to move.
- Oil leaks make floors slippery. Clean them up right away.
Standards & references
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