BS 3790-2006 pdf free download.Specification for belt drives — Endless wedge belts, endless V-belts, banded wedge belts, banded V-belts and their corresponding pulleys.
E.1 Because of the high power ratings of wedge and V-belts, it is neccsswy to be able to measure belt tensions with sufficient accuracy to avoid belt slip or overloaded bearings or to meet particularly arduous (Ondit ions.
The procedure described in E.2 to E.5 is revommen(led br drives coming within the normal range for each belt section as defined in this British Standard.
E.2 Check that the puLley centres are fixed. Rotate the larger pulley at least four complete revolution.s before making the following measurements. Use a matched set of belts (see 4.5) on a multi-belt drive.
Measure the length of the belt span between pulleys in millimetres. For a two pulley drive system the span may be calculated u.sing equation E.5. At the centre of the span apply a force with a spring balance in a direction perpendicular to the span, until the belt is deflected from its initial po.sft ion (position I in Figure E. I) by an amount (posItion 2 in Figure El) equal to either:
a) 0.02 mm for every millimetre of span length if the span length is 500 mm or less (see Figure E.l, condition 1);
b) 0.01 mm for every millimetre of span length if the span length exceeds 500 mm (see Figure E. 1, condItion 2).
Note the force applied and compare it with the appropriate value ofF given in Table E. 1. For a multi-belt drive carry out this procedure for each belt and compare the average value of the forces on all the belts with the specified values of F in Table E. 1. Adjust the belt tension as necessary so that the measured force falls within the values of F iii Table El.
NOTE Thw to th ntalur of handed hells ft might nt be p%.cihk! to d4fiecl the centre of the belt -pau as ins ujjlcient force can be applied. It might then be ?(‘(flJ Iti use ci ?u)ther nu’thod qf twit U9Lsioninq. 77u’ bell inan?(fact u #‘er hoidd be consulted.
E.3 A measured force below the lower value ofF in Table El indicates undertensioning, whilst a measure(l force above the higher value indicates overtensioning. However, when starting up a drive with new belts, tension the drive to the higher value of F since belt tension falls rapidly in the early stages of running in.BS 3790-2006 pdf free download.