ANSI/ASME B18.8.1 Cotter Pin and Application Table Chart

ANSI/ASME B18.8.1 Cotter Pin Application Size Table Chart

Cotter Pins per ANSI/ASME B18.8.1

A cotter is a pin or wedge passing through a hole to fix parts tightly together. In British usage cotter pin has the same meaning, but in the U.S. it refers to a different fastener .

Typical applications are in fixing a crank to its crankshaft , as in a bicycle, or a piston rod to a crosshead , as in a steam engine. Note: the angle of the wedge determines the position of the parts being held, therefore on a bicycle the pedal arms will only be at 180 degrees to each other if the angle of the cotter pin's wedge is the same on both pins.

NOMINAL SIZE	A Diameter	C Head Diameter	D Prong Length	LENGTH
.03125	0.032	0.060	0.010	0.125 to 3 by 1/8
.046875	0.048	0.090	0.020	0.125 to 3 by 1/8
.0625	0.060	0.120	0.030	0.25 to 3 by 1/8
.078125	0.076	0.160	0.040	0.25 to 3 by 1/8
.09375	0.090	0.190	0.040	0.375 to 3 by 1/8
.109375	0.104	0.220	0.050	0.375 to 3 by 1/8
.125	0.120	0.250	0.060	0.5 to 3 by 1/8
.140625	0.134	0.280	0.060	0.5 to 3 by 1/8
.15625	0.150	0.310	0.070	0.625 to 3 by 1/8