Full details of the installation should be given to Fenner engineers for them to cross-check calculations and give the most economical and reliable belt recommendation. It is essential to have some information on the belt tensile requirement, belt length and width and the material being conveyed. Where the T1 figure (Tension at Drive Head) is known it should be used as the basis for initial belt selection. Otherwise, at least the following information should be given to enable this figure to be calculated:
1. Centre distance of conveyor (m)
2. Belt speed (m/s)
3. Peak loading (t/hr)
4. Belt width (mm)
5. Material carried
6. Angle of trough
7. Type of drive (number of drive pulleys, angle of the wrap, and whether steel or rubber lagged) and take-up arrangement (e.g. gravity, load sensed or fixed)
8. Net changes in elevation (rise or fall between loading point and delivery point in metres) and maximum gradient (degrees)
9. If known, details of idlers (the type of bearings, style of idlers, idler diameters, and pitch)
Alternatively, installed motor power can be used as a rough guide together with belt speed which must be provided. Actual power consumed whilst running fully laden is more relevant than installed power. Details of the material and general conditions are useful:
1. Size of material (maximum lump size, proportion fines to lumps)
2. Loading details (height of the drop, the direction of feed, etc.)
3. Condition of material (dry/wet, temperature, etc.)
4. Exact nature of the material (density, nature - sharp or rounded)
The correct belt selection must consider:
• Belt capacity
• Belt tensile strength
• Requirement due to load and conveyor structure
The Fenner formulae on these pages will give fairly accurate results through various other factors that can affect the total power requirement. For example in winter, additional power may be required to overcome initial friction in the idlers and transmission units. Poor chute design and seized idlers will also bring about the need for additional power, as well as promoting unnecessary belt wear. Similarly, if extensive skirt plates are fitted there may be a small additional power requirement, as there will on installations where a tripper exists. Wherever the above factors are likely to be significant Fenner should be contacted for advice.
Many similar formulae exist for calculating power requirements all of which are acceptable when correctly applied. It is important, however, that attempts are not made to transpose factors and constants from sources other than this brochure into the Fenner formulae, otherwise, inaccuracies are likely.
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