Crosshead Forging

The crosshead is a component that connects the piston and connecting rod, and has a guiding effect. A large number of compressors use connecting rod small ends. The purpose of the crosshead is to translate reciprocating motion of the piston into the semi rotary motion of the con rod and so bearings are required. It is also necessary to provide guides in order to ensure that the side thrust due to the conrod is not transmitted to the piston. This also ensure the piston remains central in the cylinder thus limiting wear in the liner. Two faces are required as the thrust acts in opposite directions during power and compression stroke. Guide shoes positioned at the extreme ends of the crosshead pin provided a large area and minimise risk of twisting. The doxford engine uses a centrally positioned shoe because there is no room at the ends of the pin due to the side rod crossheads.