Engine mechanism — piston-to-rod connection In a reciprocating internal combustion engine, the connecting rod is attached to the piston by which component?

Introduction / Context:
The piston-to-connecting-rod joint must transmit high alternating forces while allowing oscillation as the rod swings on the crankpin. Knowing the correct component name avoids confusion during overhauls.

Given Data / Assumptions:

• Piston has a pin bore (gudgeon-pin boss).
• Connecting rod has a small-end eye with a bush or bearing.
• Retainers (circlips) may prevent axial pin movement.

Concept / Approach:
The cylindrical member passing through the piston bosses and the small-end eye is called the piston pin (also gudgeon pin or wrist pin). It provides a journal for oscillation and transmits gas and inertia loads.

Step-by-Step Solution:
Identify joint type: pin joint between piston and rod small end.Name of load-carrying member: piston pin (gudgeon pin).Select the option that correctly names this member.

Verification / Alternative check:
Workshop manuals and parts catalogs label this as piston pin/wrist pin; circlips or spirolocks retain but do not form the primary joint.

Why Other Options Are Wrong:
Cap bolt and rod cap belong to big-end assembly at the crankpin, not the piston end.

Cap roller bearing is not the standard term nor the correct location.

Circlips are retainers, not the joint component itself.

Common Pitfalls:
Installing pins without correct clearance or lubrication causes scuffing; incorrect circlip seating risks catastrophic pin walk.

Final Answer:
piston pin