312000283 - 1028H PISTONS AND CONNECTING RODS
CONNECTING RODS
CONSTRUCTION SPECIFICATIONS
The connecting rods are made from ductile cast iron. The piston pins are fixed and counter-matched with the connecting rod.
COMPOSITION
The connecting rod comprises a casing or shank, with a rectilinear axis, which rigidly connects the small end, hinged to the gudgeon pin with a copper alloy bush in between and the big end, hinged on the crank pin with bearings in between. .The big end is divided into two sections for fitting reasons: the fixed part is in one piece with the casing and the moving part is connected to the former by studs. The two sections are divided by fracture lines to guarantee correct matching. This technique combines simple construction with low production costs.Since the connecting rod is subjected to compression and combined compressive and bending stress forces it tends to become distorted; as a result the connecting rod body should be made in such a way as to combine lightness with maximum resistance and is therefore constructed with a double T section.The connecting rod is the main element connecting the piston with the crankshaft.PISTONS
CONSTRUCTION SPECIFICATIONS
The aluminium alloy and silicon pistons have a graphite layer on the skirt; the crown has a letter indicating the class to which it belongs and an arrow which should be facing the direction of rotation of the engine (timing side) when the individual pistons are fitted in the cylinders.
COMPOSITION
The piston comprises two parts:
- Head (1) or area of the piston rings, with a diameter slightly smaller than that of the cylinder to allow the thermal dilation of the metal.
- Skirt (2) or guide pad for the small end that supports the side thrust. The skirt contains two hubs or bosses that house the piston pin.
OPERATION
It is the component that receives the engine impulse directly from the pressure of the combustion gas, via the connecting rod, transmitting the drive force to the crankshaft.It should meet the following requirements:
- high mechanical resistance that allows it to support the explosion pressures (~35 kg/cm2) and the dynamic stresses;
- good resistance to heat and to wear;
- good thermal conductivity, to transmit the heat from the hot area to the cold area underneath;
- lightness and quiet operation when hot and when cold.