Crankshaft (engine number 146091 onward) Fiat 500 F/L/R/126

Crankshaft (engine number 146091 onward):

This product fits the following models:

• Fiat 500 F (1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972)
• Fiat 500 L (1968, 1969, 1970, 1971, 1972)
• Fiat 500 R (1972, 1973, 1974, 1975)
• Fiat 126 (1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987)

The Crankshaft

During the combustion of the fuel-air mixture in the combustion chambers of the cylinders of an engine, energy is converted into motion; the pistons in the cylinders move up and down. The crankshaft's task is to redirect the up-and-down motion of the pistons into a rotational movement. The rotational movement is transmitted to the flywheel, which, in turn, passes the motion through the clutch and gearbox to the axles and wheels.
The pistons are connected to the crankshaft via the connecting rods (conrods). Together, the three components—pistons (with piston pins), connecting rods (with bushings and bearing shells), and crankshaft—form what is known as the crank mechanism.

Parts of the Crankshaft:

• Journal Bearings:
  The journal bearings of the crankshaft define the axis of rotation and are housed in the main bearings in the engine block.
• Crankpins:
  The crankpins are offset from the axis of rotation of the crankshaft and are arranged between the main bearings. The offset ensures that the crankpins move in a circular path around the axis of rotation of the crankshaft. The connecting rods are mounted on the crankpins. The distance of the crankpins from the center of the crankshaft defines the piston stroke (keyword: displacement).
• Crank Webs:
  The crank webs are located between the crankpins and are typically designed to balance the offset rotating mass of the crankpins and their connecting rods. This prevents an "out-of-round" motion of the crankshaft and resulting vibrations.
• Optional: Counterweights:
  If the crank webs are not designed as counterweights, they have the option to accommodate additional weights.

Types of Crankshafts:

• Crankshafts can be cast or forged.
  Forged crankshafts are more labor-intensive to manufacture and, consequently, more expensive, but they have the significant advantage of being more resistant to stress and therefore more durable. Forged crankshafts use alloyed tempering or nitriding steel as the starting material. The journal bearings are also surface-hardened.
• Crankshafts can be designed with integrated or bolted counterweights.
• The design of the crankshaft is determined, among other things, by the number of cylinders in the engine, the required stroke, the firing order of the cylinders, and the engine type.
• There are hollow crankshafts to allow engine oil to be directed to the main and connecting rod bearings for lubrication. There are also solid crankshafts that are equipped with rolling bearings (instead of plain bearings) supplied with sufficient lubricant solely through the oil mist in the cylinder-crankcase.
• Crankshafts can be height-adjustably mounted – for example, through an eccentrically mounted crankshaft bearing. This allows for variable compression, with the advantage of up to 25 percent lower fuel consumption in partial load conditions.