Heavy Equipment & Diesel Mechanics
Mechanics work under raised trucks and machines, around stored hydraulic pressure, and with huge tires that can explode. Most fatal incidents involve something falling or releasing energy unexpectedly.
- Construction
- General Industry
Top hazards
- Crushed under vehicles, raised dump beds, buckets and blades
- Multi-piece and split rim wheel explosions during inflation
- Hydraulic injection injuries from pinhole leaks and stored pressure
- Unexpected machine movement and engine start-up
- Diesel exhaust and carbon monoxide in shops
- Battery explosions and acid
Key practices
- Never work under a load supported only by a jack or hydraulics. Use rated stands, cribbing, and the manufacturer’s locks and props.
- Lock out and tag the machine; remove keys; relieve hydraulic pressure.
- Inflate tires in a restraining cage with a clip-on chuck and remote valve, standing out of the trajectory. Get trained on multi-piece rims.
- Never use your hand to search for hydraulic leaks. Use cardboard.
- Use exhaust extraction hoses indoors.
Field service
Mechanics who repair equipment on jobsites often work alone, on uneven ground, near traffic and other equipment, and in bad weather. Set up a safe work zone, chock and block the machine, and tell someone where you are. See Working Alone.
Stored energy to control
| Energy | Examples | Control |
|---|---|---|
| Gravity | Raised beds, booms, buckets, blades | Lower to the ground or block with rated stands and props |
| Hydraulic | Cylinders, accumulators, lines | Relieve pressure per the manual; bleed accumulators |
| Springs and tension | Track tensioners, spring brakes, suspension | Use the manufacturer’s tools and procedures |
| Air | Air brakes, tires | Drain tanks; deflate tires before removing wheels |
| Electrical | Batteries, high-voltage on hybrid and electric machines | Disconnect batteries; follow high-voltage procedures |
See Lockout/Tagout.
Shop checklist
- Machine parked on level ground, brake set, wheels chocked
- Key removed and a lockout tag on the controls
- Articulation lock installed where applicable
- Raised parts blocked with rated stands or cribbing
- Hydraulic pressure relieved
- Exhaust extraction connected for running engines
- Tire cage and remote inflation set up for tire work
- Eye protection, gloves and hearing protection on
Standards & references
- 29 CFR 1910.177: Servicing multi-piece and single-piece rim wheels
- See also: Battery Safety
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