Vehicle Movement
An unsecured vehicle can be very dangerous to person and property. Never assume the parking brake on the vehicle works. Always test it to make sure its operating properly. A vehicle will roll under its own weight on minor slopes. Never assume it will not move. Wheel chocks are required when a vehicle is parked on a slope, when a mechanic is working on it, or anytime a vehicle’s parking device is in question or in for repairs.
Hydraulic/Fuel Pressure
Exposure to hydraulic/fuel fluids that may be hot and under very high pressures can be dangerous to the skin, eyes or body. Always assume that hydraulic systems are under pressure either from the system pressure, or the resistance to weight creating the pressure. When working with cylinders make sure the load it is moving is supported with blocks or jack stands.
Air Pressure (Including Tires)
Always assume air components are under pressure either from the system pressure or the resistance to weight creating the pressure. Unexpected air pressure releases may cause harm to skin or body. Never work on any fitting or hose while the truck is running or under any pressure. All pressures must be removed from system prior to service or repairs to the system.
Batteries
A dead battery is as dangerous as a charged battery. Hazards pertaining to batteries include electric shock and burns, sulfuric acid, hydrogen gas, and weight. If working on an electrical system, disconnect the battery from the system until the repairs are made and ready for testing.
Cooling Systems
Vehicle cooling systems are designed to operate under pressure as heat builds. The fluid is hot enough to severely burn anyone that is near the hot fluid as it comes out of the system. When working with cooling systems, allow the temperature of the fluid to decrease on its own. This may take a few hours. If working with hot cooling fluids is necessary, wear proper PPE equipment including safety glasses, face shield and heavy rubber gloves that cover hands and arms. Slowly bleed off any pressure and do not open or pull a hose on a pressurized cooling system.
Spring Brakes
The parking spring in a spring brake chamber, when compressed, is holding thousands of pounds of energy that could kill or severely injure personnel. When working on an air brake chamber, the spring will need to be caged using a special caging tool. Never remove the spring brake clamp or try to repair the spring brake side of this chamber. Replace the entire assembly, or only the parking brake side of the brake chamber. Be careful of rusted chambers. Be very careful when handling a spring brake chamber. Do not drop it or toss into an iron dumpster. The spring may come out. A special tool can be purchased to contain the chamber and allow cutting of the spring for proper disposal.