The 2:1 Rule of Linear Bearing Motion System

The 2:1 Rule of Linear Bearing Motion System

You must pay attention to the 2:1 rule when you using plastic linear bearings: If the distance from the driving force to the fixed bearing is greater than double the distance between the two bearings, the bearing can theoretically bind or cause vibration static friction coefficient in any case greater than 0.25.

The farther the driving force is from the guide bearing, the greater the wear rate and the higher the driving forces required. The 2:1 principle is not the result of load or driving force; instead, it is the product of friction of sliding elements. There are many ways to ensure that the design follows this rule, including adding bearings, increasing the distance between bearings or using a larger linear system.

 CSB-LIN® Eccentric forces

● Maximum 2:1 ratio
● 1x =bearing separation on same shaft

● 2x =distance from shaft to load or force

 ●CAUTION: uneven motion or even system blockage will occur if the 2:1 ratio is exceeded !
This principle is NOT load dependent! It is NOT due to edge loading. It is also NOT dependent on the driving force used! The greater the distance between the drive and guide bearings, the higher the degree of wear and required drive force.

There may be other factors that add to the braking effect, but the coefficient of friction is the main cause.

NOTE: The Rule(2:1) is based on the static friction value of 0.25 theoretically, However, Additional lubrication can help to drop friction and extend the 2:1 ratio.
If you have any questions on design and/or assembly, please contact our application engineers.