Sprockets & Chain

Sprocket & Chain Basics

Common Terms

Pitch

Pitch is the measurement from one roller chain pin to another. Popular chain sizes used throughout FRC are the #25 and #35, which have their respective pitches of 0.25" and 0.375"

Pitch Diameter

Pitch Diameter also known as PD is the circle that is formed while the chain and sprocket are meshed together and which the chain rotates around. If you wish to find the PD, reference the formula below.

Pitch ÷ sin(180°/Tooth Count)

Chain Clearance Diameter

The Chain Clearance Diameter is the outer diameter of the sprocket while it is meshed with the chain. Knowing this is crucial when placing sprockets in tight places to ensure that no interference is being created. If you wish to find the Clearance Diameter, reference the formula below, along with an example equation for the sprocket shown above.

Pitch Diameter + Pitch

24T - #25 Sprocket

1.915 + 0.250 = 2.165

Outside Diameter

The Outside Diameter also known as OD refers to the size of the actual sprocket.

Calculating Center to Center

When deciding the placement and spacing of your sprocket and chain it is important to keep in mind that the Center to Center distance can be a fully custom measurement to ensure compatibility in your system, or can be decided through a pre-determined chain length.

The basic rule of thumb when deciding on a custom Center to Center distance is that it should be anywhere from 30-50 times the pitch of the desired chain for optimal usage and should not exceed 80 times the pitch.

Proper Tension

Ensuring that proper tension is present in a sprocket and chain system is crucial for the sake of system integrity and performance. Achieving proper tension is a fairly simple task to do when using a chain breaker tool and tensioner offered through WCP. Such as the Spartan Chain Tensioner or the Chain TurnBuckle.

Adding Chain Tensioner

Implementing our chain tensioners into your system is a an easy task due to them having the necessary clearance holes for the roller pins. Use the chain breaker tool to partially remove the pin from the chain and lay your selected chain tensioner in place, then simply reset the pin back into place.

Idlers

Idlers are yet another way to ensure proper tension is present in a chain and sprocket system as they can be placed either on inside or outside of the chain loop to provide more contact with the sprocket and decrease slack. Adding an idler to the chain loop does not affect the ratio and can actually benefit performance if placed near the driving sprocket as it allows for more meshing.

Recommended Applications

#25 Chain

• Intakes

• Conveyors

• Turrets

#25H Chain

• Drivetrains (wheels under 6")

• Intakes

• Conveyors

• Turrets

• Elevators

#35 Chain

• Drivetrains (wheels 6" and up)

• Wrists/arms

Load Rating

Chain Type	Max Working Load	Avg. Tensile Strength
#25	154 lbs	1058 lbs
#25H	209 lbs	1146 lbs
#35	419 lbs	2601 lbs

#25 Sprockets and Chain

Using this popular combination to transfer power or torque is a great alternative from other solutions due to the light footprint it has on your robot.

• Plate sprockets are 6061-T6 aluminum

• Hub sprockets are 7075-T6 aluminum

All #25 Sprockets will now be clocked and engraved. An alignment notch has also been added to help with clocking multiple items together during assembly.

#25 Engraving Example

#25 and #25H Chain (Product Page)

Roller Chain in 10 foot lengths for use with any #25 sprocket

• Available in #25 Standard and #25H

• ANSI standard

• Master Link included with 10 ft purchase

• Chain Break Tools available to easily separate chain

• Additional Master and Half Links sold in packs of 5

Motor Pinions (Product Page)

Bore	# of Teeth
8mm Spline XS	10, 12
8mm Key/Falcon	10

Double Hub Sprockets (Product Page)

Bore	# of Teeth
1/2" Hex	12*, 14*, 16*, 17, 18, 20, 22, 24

*12T and 14T sprockets are only available in steel. The 16T is available in steel and aluminum.

Chain in Tube Sprockets (Product Page)

Bore	# of Teeth
1/2" Hex	16, 17, 18

Single Hub Sprockets (Product Page)

Bore	# of Teeth
3/8" Hex	16, 18, 22
1/2" Hex	18

Plate Sprockets (Product Page)

Depending on the size, the Plate Sprockets will now have the MotionX Pattern and as many additional holes as possible following the 1" pitch.

Bore	# of Teeth
SplineXL	24, 30, 36, 42, 48, 54, 60, 66, 72, 84

#35 Sprockets and Chain

Using this combination to transfer power or torque is a great alternative from the #25 solutions as it can sustain double the working load and tensile strength.

• Plate sprockets are 6061-T6 aluminum

• Hub sprockets are 7075-T6 aluminum

All #35 Sprockets will now be clocked and engraved. An alignment notch has also been added to help with clocking multiple items together during assembly.

#35 Sprocket Engraving Example

#35 Chain (Product Page)

Roller Chain in 10 foot lengths for use with any #35 sprocket

• ANSI standard

• Master Link included with 10 ft purchase

• Chain Break Tools available to easily separate chain

• Additional Master and Half Links sold in packs of 5

Double Hub Sprockets (Product Page)

Material	Bore	# of Teeth
Aluminum	1/2" Hex	12, 15, 18
Steel	1/2" Hex	9, 12, 15, 18

Plate Sprockets (Product Page)

Depending on the size, the Plate Sprockets will now have the MotionX Pattern and as many additional holes as possible following the 1" pitch.

Bore	# of Teeth
SplineXL	18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 84