Pistons And Connecting Rod Assemblies; General Information - Perkins 2800 Workshop Manual

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Pistons and connecting rod assemblies

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General information

The pistons fitted to the 2800 Series engines consist of two parts: a forged steel crown (A1) and a cast
aluminium skirt (A2). The two parts are retained on the connecting rod by the gudgeon pin (A4). The pistons
each have three rings fitted to grooves in the crown. The top ring is keystone shaped and its face is plasma
coated. The second ring has a tapered face which has a chrome finish. The third ring is an oil control ring and
also has a chrome finish on its face. The oil control ring contains a coil spring which expands the ring. Small
holes in the piston groove allow oil from the oil control ring to drain back to the sump.
The connecting rods are of a conventional design. The small end is wedge shaped and the big end bearing
cap is retained by two special bolts. A split type shell bearing is fitted at the big end and a single piece bearing
is pressed into the small end.
Piston squirter jets provide a supply of oil to cool the piston crown. An oil cooling chamber is formed by the lip
at the top of the piston skirt and the cavity behind the ring grooves in the piston crown. The oil returns to the
sump through the clearance gap between the crown and the skirt.
Workshop Manual, TSD3450E, Issue 1 57