The optimal arrangement of a chain drive depends on a number of parameters such as the length of the chain, the force to be transmitted and the space available. In general, a horizontal position of the sprocket axes is preferable, with the loaded strand at the top and the slack strand at the bottom. In this configuration, the longitudinal load from the chain's own weight has a positive effect and ensures good engagement with the sprockets. A slack strand on top is only acceptable for short centre distances and minimal sag.
with top-mounted load strand (favourable)
from horizontal (favourable)
of sprockets (unfavourable)
An inclined arrangement of the sprocket axis up to a 60° inclination from the horizontal is also considered a favourable position. Larger angles or a vertical arrangement, on the other hand, are considered unfavourable drive arrangements due to poor engagement of the lower sprocket. In such cases, auxiliary means are required to ensure sufficient chain tension. Often, the theoretically most favourable sprocket position in theory cannot be realised in practical chain drive designs.
The correct position in the chain drive
By correctly positioning the chain tensioner, wear-induced elongation can be minimized, thereby maximizing the service life of the chain drive. A chain tensioner should always be installed on the slack strand. The optimal position for mounting chain tensioning wheels and tensioners is directly behind the drive sprocket in order to keep the length of the slack strand to be tensioned as short as possible.
Chain weight
The weight force of the chain in the slack strand to be tensioned should not exceed the force of a spring already relaxed by 50%.
Chain tensioner on the slack strand, positioned directly behind the drive sprocket. In combination with slide rails. Provides optimal and highly efficient chain support and tensioning.
The Omega Spann-Box® assembly provides twice the tensioning travel thanks to its double redirection. This solution is ideal for use with long chain strands with significant sag, ensuring reduced vibrations and a longer service life for the chains.
To the Tensioning Station
Two Spann-Box® units near the drive. For alternating directions of rotation, we recommend using two chain tensioners near the drive, since the load and slack strands switch when the drive direction is reversed. For optimal guidance and increased robustness, we also recommend using a deflection profile.
Challenge in reversing operation
Power transmission takes place exclusively in the load strand. This is where the maximum tensile force occurs, meaning there is no sag in this section of the chain and it is always fully tensioned. The resulting force acting perpendicularly on the chain tensioner is always greater than the maximum tensioning force of the Spann-Box®. Therefore, the chain tensioner located in the load strand is completely compressed, eliminating any spring-back effect. If the force acting on the Spann-Box® is too great, avoidable wear can occur on both the chain tensioner and the chain itself. Optimal positioning of the Spann-Box® is therefore especially critical in reversing operation.
The Mini-Spanner, Spann-Boy®, and Spann-Box® chain tensioners operate with a spring action or free oscillation. To avoid increased surface pressure and the resulting excessive wear of the sliding profile, the chain tensioner should always have a minimum spring travel of 5 mm.
The chain tensioner should be aligned parallel to the chain. Otherwise, irregular and one-sided wear may occur.