Pin shaft with automatic limiting structure

The utility model provides a pin shaft with an automatic limiting structure, which comprises a pin shaft body, a maintenance cover plate is bolted at the center of the front surface of the pin shaft body, a pin shaft disc is integrally formed at the top end of the pin shaft body, and a pin shaft end part is integrally formed at the top end of the pin shaft disc. A sliding rail strip is transversely connected to the center of the bottom of an inner cavity of the pin shaft body in a bolted mode, a first sliding sleeve is embedded in the center of an inner cavity of the pin shaft disc, second sliding sleeves are embedded in the bottoms of the two ends of the inner cavity of the pin shaft body, and limiting structures are arranged in the inner cavities of the pin shaft body, the pin shaft discand the end portion of the pin shaft. Through the structural cooperation of the adjusting rods and the trapezoid seats, the trapezoid blocks on the two sides can be pushed outwards, through the cooperation of the sliding rai