Click here to skip to content
Where the world turns for couplings

Belt & Chain Tensioners

Rubber Tensioner
  • Maintenance-free; easy to install
  • Transmits a constant torque, ensuring longer belt or chain service life
  • Improves efficiency, decreases energy costs
  • Available in 7 standard sizes, with a wide range of accessories

Chain & Belt Tensioning - Roller chains are power transmission components with positive transmission which, by virtue of their design are subject, depending on quality, to elongation as a result of wear of 1 to 3% of their total length. In spite of this elongation due to aging, a roller chain transmits the occurring torques effectively providing it is periodically re-tensioned.

Without tension adjustment, the slack side of the chain becomes steadily longer, oscillates and reduces the force transmitting wrap angle of the chain on the chain wheels. The chain no longer runs smoothly off the teeth of the chain wheels, producing uneven running of the entire drive and supporting wear (polygon effect).

The service life of the chain drive can be extended considerably by the use of an automatic chain tension adjuster. The Lovejoy ROSTA tensioning element prevents the slack side of the chain from “sagging” or “slapping” by its automatic operation and very wide tensioning range for compensating this given elongation.

The Lovejoy ROSTA tensioning element is based on the ROSTA rubber spring principle. According to application it is supplemented with the appropriate sprocket wheel or chain rider set for chain drives or with the belt roller or pulley in belt tensioner applications. Assembling of the sprocket wheel and chain rider sets or the belt roller on the tensioning element is carried out on the customer’s side.

Pretensioning - With the Lovejoy ROSTA tensioning element the necessary travel and simultaneously the corresponding initial tension force can be accurately adjusted by a torsion angle scale and indicating arrow. Excessive initial pretensioning of the chain should be avoided in order to reduce the tensile force and surface pressure on the links.

Vibration Damping - The Lovejoy ROSTA tensioning element, based on a system of rubber springs, absorbs considerably the chain vibration due to internal molecular friction in the rubber inserts. The rubber spring effectively absorbs the vibrations, resulting from the polygon effect, which also positively influences the noise level of the complete chain drive.

Installation - The sprocket wheel or chain rider is installed in arm position “normal” or “hard” in the required position and secured with the supplied nuts. The laterally adjustable bearing on the thread permits simple and rapid adjustment of the wheel or rider to the chain track. The central fixing of the tensioning element with a single screw saves a great deal of time in installation. In addition, only one fixing hole is required on the “machine side”. On smooth, clean and torsionally rigid surfaces the resistance of the frictional contact between the tensioner housing and the machine element is a multiple of the maximum initial tensioning torque at 30°. In almost all applications therefore, any additional securing of the tensioner housing can be dispensed. Only with rough, uneven or highly corroded mounting surfaces could the torsional resistance be insufficient on account of the point application nature of the frictional contact. In these exceptional cases we recommend the mounting of a locking pin through the positioning notch on to the machine structure.

Please download catalog for sizing and dimensional data.