6-27.2. CONNECTING ROD - MAINTENANCE INSTRUCTIONS
a. Each connecting rod (trunk-type piston) is forged to an "I" section with a closed hub at the upper end and a
bearing cap at the lower end. The connecting rod is drilled to provide lubrication to the piston pin at the upper end and is
equipped with a nozzle to spray cooling oil to the underside of the piston head. An orifice is pressed into a counterbore
at the lower end of the oil passage to meter the flow of oil.
b. A helically-grooved bushing is pressed into each side of the connecting rod at the upper end. The cavity
between the inner ends of these bushings registers with the drilled oil passage in the connecting rod and forms a duct
around the piston pin. Oil entering this cavity lubricates the piston pin bushings and is forced out the spray nozzle to oil
the piston. The piston pin floats in the bushings of both the piston and connecting rod.
This paragraph also includes assembly of the piston onto a connecting rod.