The crosshead has a body formed of solid, metal plate, and of substantially U-shape. It comprises a pair of spaced-apart parallel limbs which are bridged between by an integral transverse member, and the latter is bored through to receive a piston rod therein. Shoe plates are joined to the limbs to guide the body in reciprocation. In the combination with a connecting rod assembly and a piston rod, an end of the piston rod is directly fastened to the connecting rod assembly, and the crosshead is coupled to an intermediate portion of the piston rod.