Equal length remaining method of rear-tensioning device, transition support and crane

The invention provides an equal length remaining method of a rear-tensioning device, a transition support and a crane. The equal length remaining method includes that one end of the rear-tensioning device is connected with a free end of a super-lift mast of the crane, the other end of the rear-tensioning device is connected with a first end of a connecting piece in pivoting mode, a second end of the connecting piece is connected with a boom or a rotary table of the crane in pivoting mode, so that an included angle formed by a connecting line between the first end of the connecting piece and a hinged point of the super-lift mast and the boom and an extending direction of the super-lift mast is 90+/-3 DEG C during swinging within a swinging angle of the super-lift mast. When a field angle of the super-lift mast is changed, the length of the rear-tensioning device is approximately equal. On the one hand, a phenomenon that manual multi-time adjustment of the length of the rear-tensioning device when hoisting performance under a super-lift working condition is calculated is avoided, and on the other hand, a problem that calculating accuracy of the hoisting performance under the super-lift working condition is affected due to the fact that the calculated length of the rear-tensioning device and the actual length of the rear-tensioning device are not uniform.