Aug 2005

Small Heavy Duty Mobile Equipment

Heavy Duty Mobile Equipment (HDME) is widely used in mining, lumbering, road building and plant construction. Most HDME has high-pressure hydraulic systems. Smaller equipment, such as logging vehicles, front-end loaders and haulage trucks, are usually diesel powered. Some haulage trucks are electrically powered or have a diesel engine powering a traction motor through an alternator.

HDME are normally operated under hazardous conditions and are frequently remote from water supplies and public fire protection. Damage to the equipment can result in a costly replacement with serious interruption or reduction of operations for an extended period of time.

Smaller equipment is normally subject to hydraulic system fires through leaking or failure. The main damage has occurred due to the inability or failure of the operator to do one or more of the following steps: set the parking brakes, shut off the engine, manually actuate the fixed extinguishing system, use portable extinguishers, and/or summon help for manual suppression. During a fire, there is usually not enough time for an operator to perform all these procedures. Replacement of hydraulic fluids with less hazardous hydraulic fluids, where practical, can reduce the largest fire source. New HDME should also use the less hazardous fluid where practical.

An inspection program should be started to reduce the chance of leaks and failures to the hydraulic and fuel system. Lines should be visually checked and tested and fittings should be tightened. Flexible hydraulic lines should be replaced periodically on a programmed basis or when deemed by inspection or test.

Periodically clean HDME of all combustible materials. Preferably, noncombustible solvents should be used.

A manual engine shutoff switch should be installed which is accessible from the ground and in a location not exposed by the engine compartment.

Multipurpose dry chemical has proven to be the most effective extinguishing agent. The extinguishing system should be automatically actuated and discharge into areas where ignition of hydraulic fluid is possible. The extinguishing system should also discharge into the engine compartment regardless of hydraulic fluid type, to protect against leaking fuel fires. The extinguishing system should be capable of manual actuation from within the operator’s compartment and at an outside location readily accessible from the ground. Interlock the engine, braking and hydraulic systems with the actuation of the extinguishing system. A time delay between detection and extinguisher activation can be incorporated to allow operators time to drive the HDME away from hazardous locations, if necessary.

Risk Logic can provide assistance in helping to determine the degree of exposure to your HDME.