virabrequim

Virabrequim, known in English as a crankshaft, is a primary rotating component in most internal combustion engines. It converts the reciprocating motion of pistons into rotational motion that can drive a vehicle or machine. The crankshaft is housed in the engine block and supported by main bearings, with connecting rods attached to crankpins along its throws.

Construction elements include main journals, crankpins (throws), counterweights, and oil passages. It is commonly made from cast iron, forged steel, or billet steel. Depending on design, it may be a single-piece component or built from multiple pieces in some engines. The crankshaft also provides attachment points for timing gears or a belt pulley and often incorporates balancing features to reduce vibration.

Operation occurs as each piston moves and its connecting rod exerts a force on a crankpin. The offset of the crankpin from the main axis (the crank radius) converts the vertical motion into rotation. This rotation delivers torque to the engine’s crankshaft gear or flywheel; its balance and the engine’s firing order influence vibrations. Crankshaft design must withstand bending, torsional, and fatigue stresses.

Maintenance and issues involve ensuring adequate lubrication of bearings, correct alignment of main bearings, and proper heat treatment. Worn bearings, scoring of crankpins, cracks, or bending can lead to loss of lubrication, misalignment, and engine failure. Balancing during manufacture and sometimes dynamic balancing during maintenance help minimize vibrations.

Applications encompass nearly all piston engines, including automobiles, trucks, motorcycles, aircraft, marine, and industrial machinery. Advances in materials, precision machining, and balancing continue to improve engine efficiency, durability, and performance.