Long Hydraulic Hoses Cause Trencher Fire

Heavy equipment used on construction sites are subject to all kinds of conditions.  Those conditions include, bad weather, rocky terrain, and remote locations.  All of these factors can play a part in determining whether a vehicle will ignite and burn.  We were recently asked to examine a trenching machine that was destroyed by fire.  The machine that was examined is shown below.

One of the most common causes of heavy equipment fires is hydraulic fluid leaks.  It is well known that hydraulic fluid is flammable and will ignite with the correct mixture of air and an ignition source.  Such sources can include engines and transmissions as well as electrical devices.  Although these are some of the more common factors, sometimes unusual circumstances can also lead to a piece of equipment being destroyed.  In the case of the fire damaged trencher, one of the findings included hydraulic hoses being long enough to reach the ground.  As a result, while the trencher was in operation, dirt was actually burying the hoses.  At the same time, the movement of the machine, as the trench was dug, was pulling the hoses through the dirt and causing the hoses to tear.  Hydraulic fluid leakage was not only inevitable but, so was the possibility of fire.  When hydraulic hoses have to be replaced, the lengths of the hoses are a maintenance issue.  It is extremely important that hoses of correct length are installed,  If the hose is short and fits tight between connections, the stress imposed by forcing the hose to stretch coupled with the stress of pressurization, can cause premature failure.  Likewise, a hose that is longer than necessary will move around and possibly make contact with solid objects that can wear or cut the hose jacket, weakening the wall.  As in this case, the dirt and rocks contributed to the weakening of the hoses found beneath the conveyor section, on the ground, and the subsequent release of hydraulic fluid that ultimately ignited and destroyed the trencher.  The hoses that were found are also shown below.