A crawler is a crane mounted on an undercarriage with a set of tracks (also called crawlers) that provide stability and mobility.
A mobile crane with the necessary equipment to travel at speed on public roads, and on rough terrain at the job site using all-wheel and crab steering.
A crane mounted on a truck carrier provides the mobility for this type of crane. This crane has two parts: the carrier, often referred to as the Lower, and the lifting component which includes the boom, referred to as the Upper. These are mated together through a turntable, allowing the upper to swing from side to side.