TILT CYLINDER GROUP 7J9696 - Caterpillar

3400 Series Engines Equipped with Precombustion ChambersDescription of Change: The connecting rods and pistons now used in 3400 Series Engines equipped with precombustion chambers are a different design. See the Illustrations. As shown in the first Illustration, the sides of the new connecting rod around the piston pin bore are tapered. The inner part of the new piston is also tapered in the area of the piston pin bore. As shown in the second Illustration, the sides of the former connecting rod and the inner parts of the former piston were straight. The new piston is stronger than the former piston for two reasons. More of the piston pin is in the bore of the new piston. This causes a distribution of the stress in the piston pin bore over a larger area. Second, the material in the new piston is stronger than the material in the former piston.
Adaptable To: When used together, the new parts are adaptable to earlier engines as shown in the chart but a complete set of new pistons and connecting rods must be installed. Since the new pistons and connecting rods do not have the same weight as the former pistons and connecting rods, the new and former parts cannot be used together in an engine. If the new and former parts are used together in an engine, the result is added stress and vibration in the engine.
New connecting rod and piston with tapered joint.
Former connecting rod and piston with straight joint.