Helical path conveyor

Claim 1

In a conveyor system of the type in which an endless conveyor belt formed of pivotally joined links is helically wrapped in series over a plurality of axially parallel uniformly rotating drums with the plane of the belt generally transverse to the axis of rotation of the drums, the improvement comprising: power means for rotating said drums about their central axis with the last drum in the series having a surface speed of the order of two per cent less than that of the preceding drums in the series, a first motive power supplying assembly for said belt including a rotatable member having non-slip engagement with the conveyor belt adjacent to and upstream of the initial engagement of the belt with the first of said drums and a constant torque power source adapted to drive said rotatable member, a second motive power supplying assembly for the belt including a rotatable member having non-slip engagement with said conveyor belt adjacent to but downstream of the area of final engagement of the belt with the last drum of said series and a constant torque power source adapted to drive said last mentioned rotatable member, said first and second motive power supplying assemblies each taking the form of two pairs of coaxially mounted wheels, one pair of wheels being mounted for rotation overlying said belt with the wheels engaging the opposite side marginal areas on one face of the belt and the other pair of wheels mounted for rotation underlying said belt with said last mentioned wheels engaging the opposite side marginal areas on the other face of the belt, said last mentioned wheels being power driven, the output of said first motive power supplying assembly to said belt being such as to establish the belt tension as it engages the first of said drums at a relatively low value just sufficient to hold the inner edge of the belt against the drum surface, the output of said second motive power supplying assembly to said belt being such as to lock the inner edge of the belt against the surface of said last drum in the series so that said belt is driven without slippage by said last drum, wherebY said belt enters said drum series at relatively low tension, has a sliding frictional drive relation with all but the last drum in said series and has a non-slip drive relation with the last drum.