Normally, elevators have the screw - type take - up on the foot or boot shaft unless space does not permit. If it is necess ary to place the screw - type take-up on head shaft, the centers of the bucket elevator should not exceed 90 feet, because the total weight of chain (or belt) plus buckets and load in buckets on up or carry side, is hanging on the take-up screw intension. Wherever a head take-up is used, the next larger sized head shaft from that recommended should be used, as the vibration is transferred to the head shaft through the pickup in the boot. Gravity take-ups are used on many elevators,
particularly on powdery or aerated material such as cement, lime, and gypsum. A softening effect is encountered at the pickup which must be absorbed by this floating take-up. The frame supporting the shaft and wheel simply rides up and down in angle or channel guides, attached to the inside of the casing. This mechanism was also avoided here.