Chain Selection made Easy

How to select the proper chain for your application

by Mildred Cahulogan.

Knowing the compatibility of Sprockets to the Chain is essential.  Roller Chain are used to connect two Sprockets together and transfer torque.

In order for the sprockets and chain to be compatible with each other they must both have the same thickness and pitch. All sprockets should be on parallel shafts with their corresponding teeth on the same plane.

Fig. 01. Sprocket Aligment


Choosing the right sprocket and chain will depend on its usage. Sprockets are designed for use with a specific chain.  Once you determine the chain pitch, you have to take note the number of chain strands used in the application.

Fig. 02. Chain Dimensions


Step by Step guide to choose the correct sprocket

1. Identify the chain type and pitch.

Pitch, refers to the measurement from one roller-pin center to the next roller-pin center of a given chain. In the U.S all chains are made to a given standard- with ANSI (refer to the table below).

Chart. 01. ANSI Standard Chain Sizes


2. Identify the sprocket hub type

Hub, indicates the core of the sprocket. Determine if the sprocket is Type A, Type B, Type C or Type D

Fig. 03. Sprocket Type

3. Identify the number of sprocket teeth or sprocket diameter.

The simplest way to identify the number of teeth is by simply counting the teeth around the sprocket. However, if the teeth are worn out we can use Caliper Diameter.

Caliper Diameter, is the dimension measured from the sprocket tooth valley to the sprocket tooth valley on the opposite side of the sprocket.  For a sprocket with an odd number of teeth, it is the distance from the bottom of one tooth gap to the bottom of the nearest opposite tooth gap.

Fig. 04. Sprocket Dimensions


4. For Type B and Type C sprocket we have to identify the Hub diameter.

Hub diameter, is the outside diameter.

5. Identify the LTB (length through bore)

LTB, is the inside hub diameter and the length to which it is machined.

6. Identify the sprocket bore

Sprocket bore, refers to the inside diameter of the sprocket to accommodate the shaft diameter. Plain bore sprockets usually require additional machining before installation.

7. Identify the keyway dimensions and set-screw locations

Keyway and setscrew are used to hold the sprocket in place. Sprockets are secured to the shaft using an ANSI standard dimensioned keyway and one or more set screws.

Chart. 02. Keyway dimensions