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| Illustration 1 | g01204879 |
(1) Piston (2) Compression rings (3) Oil ring (4) Pin retainer (5) Piston pin (6) Connecting rod (7) Connecting rod bearing (8) Connecting rod cap (9) Bolt | |
Aluminum pistons (1) have three rings. The rings include two compression rings (2) and one oil ring (3). All the rings are located above the piston pin bore. The top two compression rings are rectangular. The oil ring is a two-piece ring. Engine oil returns to the crankcase through holes in the oil ring groove.
Note: Earlier designs of the pistons had a cast iron band for the top two rings in order to help reduce wear on the compression ring grooves. The newer design has a band for the top ring only.
The piston is attached to connecting rod (6) with piston pin (5) and with two pin retainers (4). The connecting rod has a taper on the pin bore end. This taper gives the connecting rod and the piston more strength in the areas with the most load. Four bolts (9), which are set at a small angle, hold connecting rod cap (8) to the connecting rod. This design keeps the connecting rod width to a minimum, so that a larger connecting rod bearing (7) can be used and the connecting rod can still be removed through the cylinder liner.