The invention relates to the technical field of
petroleum drilling and production equipment, in particular to an automatic clearance adjusting oil cylinder and a hydraulic
disc brake, which comprise a cylinder body, one end of the cylinder body is closed, the other end of the cylinder body is open, a main
piston and a compensation
piston are arranged in the cylinder body, and a compensation oil cavity is arranged between the compensation
piston and the inner wall of the closed end. A
brake oil cavity is formed between the main piston and the compensation piston, and a one-way valve is arranged on the compensation piston. A containing groove is formed in the middle of the end, facing the inner wall of the closed end, of the compensation piston, the
peripheral wall of the T-shaped end of the pull rod is in sealed sliding connection with the inner wall of the containing groove, the other end of the pull rod is fixedly connected with the main piston, and a
brake gap is formed between the T-shaped end of the pull rod and the groove bottom of the containing groove. The automatic clearance adjusting oil cylinder has the following advantages: the
brake response time is ensured; the
automatic control is realized; the automatic clearance adjusting oil cylinder is compact in structure, economical, practical and stable in brake clearance control, the stability of equipment during operation is guaranteed, and production requirements and quality requirements are finally met.