Selecting Motor Roller Speed Code

You can always contact Pulseroller for assistance in properly selecting the right motor roller for your application, but here are some basic guidelines and calculations you can make to get good idea of what roller speed code to select.

You need to know the following about your application:

Load Weight
Load Material
Conveyor Speed
Number of idler rollers in your conveyor zone
Interlocking method between motor roller and idlers

Required Tangential Force

We will use the Required Tangential Force method to calculate the force needed based upon your data. The total force is equal to the sum of the force required to move the load plus the force required to drive the idler rollers

The basic equation is: F_Total = F_Load + F_Idlers

Calculate Force Required for the Load

To calculate the force (in N) for the load: F_Load = m x g x μ_r

Where:
m = Mass of Load in kg
g = Gravitational Constant = 9.8 m/s²
μ_r = Coefficient of Rolling Resistance of Load Material

Coefficient of Rolling Resistance (μ_r) for materials are typically ranges of values that vary depending on the particular quality of the material. The greater the value, the more force required, so using the higher value in the range is “worst case” scenario and should be used. Common materials and their values are:

Wood	Steel	Cardboard	Plastic	Rubber
0.02 ~ 0.05	0.01 ~ 0.02	0.05 ~ 0.1	0.02 ~ 0.04	0.1

Calculate Force Required for the Idlers

To get F_Idlers in N, we will use a formula that takes idler roller quantity multiplied by a force required per idler constant based upon the interlocking method:

Interlocking Method	Formula
Two Groove with standard O-Bands¹	F_Idlers = Qty of Idlers x 0.85
Micro-V with 2-Rib Belts²	F_Idlers = Qty of Idlers x 1.2
Micro-V with 3-Rib Belts²	F_Idlers = Qty of Idlers x 1.8

Calculate an Example

For an example, let’s use the following application data:

Load Weight	35 kg
Load Material	Cardboard
Conveyor Speed	0.67 m/sec
Qty of Idlers	7
Interlocking Method	Two Groove with standard O-Bands

Let’s assume the worst case for μ_r for cardboard = 0.1

F_Load = 35 × 9.8 × 0.1 ≅ 34N

F_Idlers = 7 × 0.85 ≅ 6N

F_Total = 34 + 6 ≅ 40N

To select the speed code, we need to first find the speed code whose maximum speed matches closest to our desired speed and
then examine its Rated Tangential Force value to see if it meets our requirement.

We need 0.67 m/sec, so from the Performance Data Chart; a 35 Speed Code has a maximum speed of 0.81 m/sec.
The Rated Tangential Force for a 35 Speed Code is 49.7N. A 35 Speed Code motor roller should work for this application³.

¹ O-Bands lose their transmission ability as the quantity increases. You should limit the number of O-Band idlers to 10 or less.
² Various factors including load weight determine whether you need to use a 2-Rib or 3-Rib Micro-V belt. Contact Pulseroller details of your application if you are not sure.
³ Factors other than required force and speed can affect the proper speed code selection. Contact Pulseroller with details of your application.