In a two-stroke engine, what is a primary advantage of using a crosshead?

• A. Allows higher piston speeds and different lubrication demands
• B. Reduces engine displacement
• C. Increases crankcase pressure
• D. Eliminates need for lubrication

Answer: (A)

The benefit of a crosshead is that it decouples the piston's straight-line motion from the crankshaft and connecting rod. With a crosshead, the piston is driven through a piston rod to a crosshead that slides in guided straight lines, while the connecting rod attaches to the crosshead. This arrangement lets the piston reach higher speeds and longer strokes without imposing large angular forces on the piston and cylinder walls, reducing side thrust and wear in the bore. It also allows the lubrication systems to be specialized: the piston-cylinder region can have its own lubrication needs, while the crosshead and connecting rod bearings can be lubricated separately. The other options don’t address these benefits—crossheads don’t inherently reduce displacement, increase crankcase pressure, or eliminate lubrication.