The ball transfer units consist of a metal or plastic body within which a main ball, supported by other smaller balls, facilitates the movement in any direction of loads applied on flat surfaces (e.g. conveyor belts).

Choice of the ball transfer unit

To choose the proper ball transfer unit for a conveyer track, both weight and dimension of the load to be carried must be taken into consideration.
The max distance “a2” between the ball transfer units (on a plane surface) is obtained by dividing the smaller load dimension to be conveyed (a1) by 2.5.
This calculation (based on an elementary geometry principle) guarantees that a load is always supported by at least 3 ball transfer units, thus preventing it from tipping over.
As far as the weight is concerned, as the load is supported by at least three different ball transfer units, each of them would bear a third of the total weight (the total weight divided by three).
It may be equal or lower than the max load capacity values showed in the table for every unit.

Speed and friction

The permissible conveying speed is 2 m/sec. With speeds higher than 1 m/sec., according to the dimensions of the ball transfer units, a rise in temperature, in proportion to the dimensions of them, could occur owing to the increase of the rotation speed of the support balls.

The friction value of the ball transfer units, at a speed of 1 m/sec., is 0.005 μ. This value depends, however, on the application and it could be subject to several variables.

Lubrication of the balls is recommended to prevent corrosion, even though some applications may not require it.

On the contrary, for the transfer elements with a plastic body, it is not necessary to use lubricants and greases because they are made of self-lubricating materials, resistant to corrosion.