The thrust surfaces of a piston are positioned at what angle to the centerline of the crankshaft and piston pin?

The thrust surfaces of a piston are designed to be at right angles to the centerline of the crankshaft and piston pin. This configuration is crucial for the effective transfer of forces between the piston and the cylinder walls during the engine's operation.

When the piston moves up and down within the cylinder, the combustion forces acting on the piston create thrust that must be effectively managed to ensure smooth operation. Aligning the thrust surfaces at right angles helps in minimizing wear and maximizing the contact area for force distribution, which enhances engine efficiency and longevity.

In contrast, if the thrust surfaces were positioned parallel, acute, or obtuse to the centerline, it could lead to improper force management, increased friction, and higher chances of wear and tear on both the piston and cylinder walls. This would ultimately compromise the engine's performance and durability. Therefore, the perpendicular alignment is essential for optimal engine function.