Hydraulic System Hazards & Injection Injuries

Excavators, loaders, lifts and many attachments run on hydraulic fluid at 2,000 to 5,000 psi or more. A pinhole leak can shoot fluid through your skin. A failed hose can drop a boom or bucket. And trapped pressure can make parts move when you least expect it.

• Equipment operators
• Mechanics
• Maintenance

Injection injuries

• A fine stream of fluid can pierce skin and gloves. The wound may look like a small pinprick and hurt very little at first.
• Fluid spreads under the skin and kills tissue. Without fast surgery, injection injuries often lead to amputation.

Finding leaks safely

• Use a piece of cardboard or wood to find leaks, never your hand or fingers.
• Wear safety glasses and gloves.
• Shut down and relieve pressure before tightening fittings or changing hoses.

Relieving pressure

1. Lower all attachments to the ground, or block them securely. See Blocking & Cribbing.
2. Shut off the engine and remove the key.
3. Move the controls through all positions to release pressure, as the maker’s procedure says.
4. Release pressure in accumulators, which can store pressure even with the engine off.
5. Loosen fittings slowly, with a rag over them, and stand to the side.

Follow lockout/tagout for maintenance. See Lockout/Tagout.

Other hydraulic hazards

• Falling loads: a hose or seal failure can drop a boom, bucket, blade or dump body. Never work under a raised part held only by hydraulics.
• Hot fluid: hydraulic oil can be hot enough to burn. Let the system cool before opening it.
• Hose whip: a hose that bursts or comes loose under pressure can whip and strike. Keep hoses and fittings in good shape.
• Slips and fire: leaked oil on steps and walkways, and oil spraying on hot engine parts.
• Unexpected movement: controls bumped by a jacket or tool can move the machine. Lower everything and engage the control lockout lever before leaving the seat.

Hose inspection

• No cracks, cuts, abrasion through the cover, or exposed wire reinforcement
• No bulges, blisters or kinks
• Fittings not corroded, cracked or leaking
• Hoses routed away from pinch points and hot surfaces, with guards and clamps in place
• Replacement hoses match the original pressure rating

Last updated: October 2, 2026