The belt should be supported by means of flat impact idlers at a pitch (p) of at least 400mm. Impact idlers could be steel or rubber discs on steel tube. These idler brackets are adjustable to ensure correct belt tracking. Idlers are generally 127mm in diameter or 152mm discs.
The return idlers comprise pairs of finger rollers with rounded end caps, which run on the outer edges of the belt as indicated. These idlers are set at a pitch of between approximately 1,0m and 2,0m depending on the width of the belt, belt tensions, etc. The rounded end caps prevent damage to the sidewalls in the event of belt misalignment.
These rolls are usually 89mm diameter or 50mm diameter, steel tube idlers mounted onto individual adjustable brackets. The idlers are usually adjusted down by up to 5 degrees to cater for the deflection in the unsupported centre section of the belt as indicated in the sketch. Roll length depends on the width of the landing (between sidewall and belt edge) but should allow for belt misalignment without fouling the structure or falling off of the idler.
The clearance between the tip of the finger rolls and the edge of the belts' sidewall should be approximately ____mm when the belt is running centrally aligned in the structure.