Excavators are heavy construction equipment consisting of a boom, dipper, bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression from the steam shovels and often mistakenly called power shovels. Excavators are typically used for digging excavations and for trenching purposes. Their versatility and effectiveness make them vital at construction sites in industries as varied as mining, forestry, construction, pipeline industries, and much more. The operator of the excavator uses pedals and levers to steer the equipment and to move backward and forwards. Tracks, similar to tank tracks, are activated by the diesel-powered engine, and hydraulic motors control the arm of the excavator.