Cross-shaped large-torque loading device

A cross-shaped large-torque loading device comprises a base, an output shaft and a line-shaped key spring assembly, a circular ring is arranged in the middle of the base, four mounting plates are evenly arranged on the outer edge face of the circular ring, two inserting holes are formed in the tail ends of the mounting plates, an inner hole of the circular ring is correspondingly connected with the tail end of the output shaft in an inserted mode, and an inserting groove connected with a testing platform is formed in the tail end face of the output shaft; a positioning block is arranged at the head end of the output shaft, the four side faces of the positioning block correspond to the four mounting plates one to one, each side face is provided with a U-shaped clamping block, and mounting holes are formed between the U-shaped clamping blocks and the corresponding side faces of the positioning block. Each linear key spring assembly is composed of two key springs, adjacent spring rods of the two key springs are