Medium - and large - sized compressors usually use closed - type crossheads. The small end of the connecting rod is located inside the crosshead body, featuring a compact structure that can effectively transmit force and motion. They are connected by couplers, which are reliable in use and convenient for adjustment, enabling easy alignment of the piston rod and the crosshead. However, the structure is complex and heavy, and it is mostly used in large - scale compressors. In a compressor, the crosshead mainly serves to connect the piston and the connecting rod, and it also has a guiding function to ensure the accurate reciprocating motion trajectory of the piston and the smooth operation of the compressor. The electric motor drives the crankshaft to rotate. The big end of the connecting rod is installed on the crankpin of the crankshaft, and the small end is connected to the crosshead. The crank drives the crosshead to reciprocate in the slideway through the connecting rod, and then the crosshead drives the piston assembly to reciprocate in the cylinder to achieve gas compression and transportation. Measurement and inspection: Use turning gear to place the crosshead in different positions, measure the clearance between the slipper and the slideway, the alignment of the piston rod, etc., and check whether the slipper, coupler, etc. are damaged. Repair of the crosshead pin: The tapered surfaces at both ends of the crosshead pin and the tapered holes of the crosshead body are ground together to ensure good contact, check whether the oil holes are aligned, and handle problems such as cracks. Repair of the crosshead: Check whether the crosshead has cracks, scrape and grind the slipper to ensure that the contact surface meets the requirements, and at the same time, check the alignment of the crosshead in the slideway and adjust the slipper shims.