SMQ500A 50T telescopic crawler crane is our own developed products, which maximum load capacity is 50T, and maximum load moment is 171 T·M. The total weight of this type crane is 57.8T and length is 14.386m. When under working condition, the width is 4.76m, while 3.3m for transportation. Crane’s height is 3.02m with 10.8-38m length boom and 7.5m jib. Whole crane is composed by three parts, carriage, turntable and arm. The carriage is welded as a closed box by plates with different directions to increase construction stability. The turntable is a combination structure of closed box and single web plates. The arm frame is adopted with hexagon section, which has good stretch proof ability.