Question 435Motor Plants - Assistant Engineer

A) is the correct answer. The reason for knurling the piston skirt in an auxiliary diesel engine is to improve skirt lubrication. The knurling, or small grooves cut into the piston skirt, helps distribute the lubricating oil more evenly on the cylinder wall, reducing friction and wear between the piston and cylinder. This improves the overall lubrication of the engine. The other answer choices are incorrect - B) allows for heat expansion, but is not the primary reason for knurling; C) transmits forces evenly, but is not directly related to the knurling; and D) improves the piston seal, which is a different function not related to the knurling.