Crosshead

Sliding organ in an engine design, guided so as to give a linear motion to the end of a piston rod, and to resist the deflection which the angularity of the connecting rod would cause if free to act. It may have one, two, or four guides. Where there is one guide, the cro head surrounds it on all four sides (it is usually rectangular); where two, it stands vertical, and the guides are over each other and in the IMG:content-1040.png:[blocks in formation] A, Cro head B , Piston rod. C, Loose collar. D , Key. E , Links. F. Beam gudgeon. G, Bearings for parallel bars. same vertical plane as the piston and connecting rods; where four, it is horizontal and a pair of guides is above and below it on each side of the plane in which the piston and connecting rods operate. The slipper cro head, applicable to engines which "throw over" on the outgoing stroke and are not reversed, has one wide bearing surface on the bottom, which can be kept thoroughly lubricated without attention. Where the end of the piston rod is guided by links, little remains of the cro head but the pin.