What are Crankpins?
14 May 2019

A crankpin is the part of the crank of a crankshaft to which the connecting rod is attached. Crankpins transfer up-and-down motion between the crankshaft and connecting rod. The big end of the connecting rod is connected to the crankpin of the crankshaft by way of a bearing. Connecting rods typically have two-piece crankpin bearings for connecting the lower end of the rod to a crankpin of a crankshaft.

Crankpin meets the demands for high-performance engines, lightweight design, component reliability and low through cost manufacturing. The crankpins are subjected to shock and fatigue loads. Thus material of the crankpin should be tough and fatigue resistant. The crankpins are generally made of carbon steel, forged steel, and alloy steel. It also improves the strength of the component. The surface of the crankpin is hardened by case carburizing, nitriding or induction hardening.

There are two main types of NRB crankpins based on the oil hole configuration:

Cross Hole Type Crankpin

This crankpin has a lubricating hole which is drilled at an angle in such a way that the oil path opens in the crank-web oil passage. This crankpin although complex in its design has the advantage of single piece design

Straight Hole Type Crankpin

This crankpin has a lubricating hole which is drilled radially and opens in the central hole to which the oil is provided by the oil passage in the crank-webs. This crankpin is simple in design, however, requires a central oil hole to be covered from both sides by metal caps.

For more information on NRB Bearing visit: http://www.nrbbearings.com/