Question 209Motor Plants - Assistant Engineer

The correct answer is D) their position in the lubrication system. Wrist pin bearings are difficult to lubricate because they are located deep within the engine, away from the main lubrication system. The oscillating motion and small size of the wrist pin bearings make it challenging for the lubricating oil to reach and effectively coat these components, leading to increased wear and potential failure. The other options are incorrect because they do not fully explain the primary reason for the difficulty in lubricating wrist pin bearings. The free-floating design (A) and reciprocating motion of the piston (C) are factors that contribute to the challenge, but the key issue is the bearings' location within the engine, which makes them difficult to access and lubricate from the main system.