Concepts of roller and impact bar beds were considered; however, impact frames like those currently installed mounted on torsion springs were selected. This presents advantages as the length of the load zone has increased design freedom and components are cheaper to replace. However, this design required the use of a sway bar to maintain rigidity.
Sizing of the torsion spring was based on static mass of the roller frame assembly, belt mass and full conveyor load of product to “activate” the torsion spring. Further impact force due to product flow and large lumps was considered and found to be within the specification range for the selected torsion spring.
Data obtained throughout the trial project found design changes were required to counter the torsion spring sag. An additional system was added such that shims could be placed to conserve the original installed height of the trough, maintaining skirt gaps.
Further engineering analysis will determine how related factors influence impact force, particularly how “dynamic” a transfer system is due in part and/or in addition to torsion springs, frame deflection, belt compression, impact idler/bar compression and burden deflection.
It was shown by Swinderman et al  that a high failure rate to plant in belt conveyor systems is likely to occur in the transfer area. Burden being accelerated due to fall and changes in direction from one system to the next prevents steady state flow and requires additional thought into supporting the belt to improve the life of the belt and transfer components.
Conveyor Equipment Manufacturers Association  showed that the conveyor belt is considered one of the highest cost components over the life of a belt conveyor system. In some cases, it has been found by Vogel and Roberts  to be the most expensive per tonne conveyed per kilometre. Given the belt is capital intensive, all opportunities to protect it should be considered to extend the life and reduce the required planned and unplanned maintenance activities, where the system is not producing any payback.
It was shown by Gupta  that keeping the belt sufficiently supported and tracked, whilst minimising irregular belt tensions through correctly designed transitions, damage caused to the conveyor belt in the transfer is likely to be impact or abrasion related. Conveyor Equipment Manufacturers Association  showed that whilst abrasion wear occurs over the life of the belt in a relatively even manner, impact damage to the top cover is sporadic and can begin to affect the carcass; an alarming symptom given the carcass is designed to carry the tension forces that move the belt.