gallery 36 through its open bottom some of the oil is captured by the cups 54 so as to provide a u201c cocktail shaker action u201d which redirects the captured oil back into the cooling gallery 36 during rapid reciprocating movement of the piston assembly 10 during operation the cups 54 are partitioned from one another such they form discrete reservoirs according to the invention the skirt 14 is further fitted with an oil deflector 56 which operates at least during a portion of the stroke of the piston assembly 10 to direct all or some of the jet of cooling oil issuing from the spray nozzle 38 onto the wrist pin and pin boss portion 40 of the assembly 10 so as to cool the wrist pin 16 and the pin bosses 40 particularly in the vicinity of the pin bores 42 so as to cool the bearing surface between the pin bosses and wrist pins 16 in the illustrated example the pin bores 42 are fitted with bushings 44 and the deflected oil serves to cool the bushings during operation the deflector 56 is similar in construction to the oil cooling cups 54 but is generally wider and oriented on the skirt 14 so as to lie in the path of the jet of cooling oil issuing from the spray nozzle 38 over a portion of the stroke s of the piston see fig5 the deflector 56 presents a deflector wall 58 projecting radially inwardly from the inner.