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T R A N S I T I O N SRecommended MinimumTransition Distance(At terminal pulleys for troughed belts)A troughed conveyor belt changes from a troughedshape to a flat one in its passage from troughing idlersto a head pulley. Conversely, in its passage from a tailpulley to troughing idlers, it changes back into atroughed shape. At the area of change, the transitionmust occur over sufficient conveyor length in order toavoid excessive tension in the belt edges at a terminalpulley where the belt operating tension is high. At alow tension terminal, excessive edge tension will rarelybe encountered, but here sufficient transition distancemust be provided to keep the belt tension at thebottom of the trough great enough toavoid buckling and subsequent problemswith belt splices.impact idlerstancD t =Transition Distanced=Belt trough depthWhen required, belt support within the transitiondistance may be provided by using 20°, 271/2°, idlersbetween the pulley and the first (or last) 45° idler; or byusing transition idlers with adjustable concentrator rolls.Calculating Transition DistanceMultiplying the belt width (inches) by the tabletransition distance factor will give the minimumrecommended transition distance (inches).Long-center-roll idlers with unequal length rolls usefactors in table, but use constant B = 23 instead ofactual belt width.▲ Dt = Ft x b▲ Dt = Minimum Transition Distance, Inches▲ Ft = Transition Distance Factor▲ b = Belt Width, inchesD 1 =Transition Distanced=Belt trough depthstandardtroughingidlersD 1Condition 2dd3transitionidlers hereif necessaryline tangent totop of centerrollers10line tangent totop of centerrollersD 1Condition 1LEXAMPLE: on equal length 35° idlersunder Condition 1, a 36-inch USFLEXbelt at 80 - 90% of its rated tensionrequires a transition distance at least:Dt = 2.4 x 36 = 86.4" — thus,the 35° idler should be no closer than86.4" to the pulley. A 20° idler may beused at — Dt = 1.4 x 36 = 50.4"On long-center 35° idlers, the transitiondistance for this belt would be:Dt = 2.4 x 23 = 55.2"