Operating Engineers are also heavy-duty mechanics who repair equipment on the job site and in the shops of contractors. They repair just about every type of construction equipment. Being a heavy-duty repair mechanic requires advanced mechanical aptitude and the ability to lift heavy weights. Much of what is true for the construction equipment operator holds true for the heavy-duty repair mechanic. The major portion of the mechanic's job in the construction industry is on the job site. Mechanics are required to stay on the job until equipment that has broken down is repaired and put back into service. This often means working under the lights at night in the dirt or mud. Mechanics buy and use their own tools. It is not uncommon to have several thousand dollars invested in tools.