“The main cause of peak torques, and hence a major torque amplification contributor, is backlash in gears and couplings” Torque amplification is a measure of the peak torque in the driveline compared to the steady working torque. In all torsional applications, the driveline (including motor, shafts, gearbox, pinions etc) must be designed to withstand the maximum torque over a given duration, or premature failure of the system is a certainty!

Many drivelines are over engineered to compensate for transient peak torques. The main cause of these, and hence a major torque amplification contributor, is backlash in gears and couplings. When a shock load occurs, such as when a billet of steel hits the mill rolls the driven object will try to absorb the inertia of the impact resulting in a slowing of the system. The impact winds up the driven train transmitting the torque back to the driving motor.

In the case of a back driven system, as this torque passes each backlash gap there is virtually no resistance as the gear teeth shift to the opposite side of the gap. This results in a “hammer blow” due to the fact that the load has accelerated across the backlash gap and is then abruptly decelerated back to the operating speed generating a dynamic torque which is transmitted along the driveline. The Renold Hi-Tec coupling is backlash free by virtue of the pre-compressed rubber blocks which not only eliminates clearance but incorporate hysteretsis damping as the rubber deflects. Where torsional vibration problems exist the coupling can be tuned with different types of rubber block to change the natural frequency of the system to avoid resonant frequencies.

Contact your nearest Renold Branch for more information.