OCR

Increasing the capacity of the conveyors. The increase in capacity from 1260 LTPH to 2000 LTPH will not require a change in belt speed. The change will be only in conveyer cross section loading. Each drive has a 300-hp wound rotor induction motor, direct- connected through a parallel shaft double reduction herringbone gear reducer. The drive pulleys are lagged with a ceramic material which has the property of retaining its coefficient of friction in the presence of moisture. The lagging material is riveted to a curved steel plate which, in turn, is bolted to the pulley. Three curved plates or sectors comprise a shell to encase the drive pulley. The input and output shafts of the speed reducers are coupled to their respective components through a rubber insert-type coupling. These inserts shroud the coupling bolts, and the flexibility of the rubber absorbs shock loads and misalignment. Brakes: During normal operation, the 300-hp motors provide a continuous braking force. This regenerative braking is converted to usable electrical energy, which is fed continuously into the electrical network. For an idea of the magnitude, of energy that is converted, the first seven month period of 1963 is tabulated below: Long Tons Kilowatt Hours Period Conveyed Produced January 435,760 443,680 February 392,510 414,810 March 400,540 396, 840 April 454,680 438,990 May 484,580 470, 620 June 422,680 427,400 July 530,890 486,610 TOTAL 3,121,640 3,078,950 The regenerative, braking is supplemented by quick acting, compressed air operated, adjustable, double shoe brakes, of the type used for many years on hoisting equipment. These mechanical brakes combine three important features: 1) A controllable compressed air operated brake; 2) An adjustable, compressed air operated safety brake; 3} An emergency falling-weight brake.