PNEG-2116
Bucket Elevator
35
5. Operation
Initial Belt Tracking
IMPORTANT: This procedure is to be performed with the elevator empty. Should any problem be
discovered, it will be much more difficult to correct if the elevator is full of material.
1. When the belt has been spliced, shift the belt laterally on the head pulley so it is centered on the
pulley.
a. If the elevator has a screw take-up,
, adjust the screws evenly downward
at both ends of the take-up pulley shaft. Continue adjusting the screws until the belt can be seen
to wrap snugly around the take-up pulley.
b. If the elevator has a posi-guide take-up,
, then simply remove the
temporary support so the weight of the take-up is exerted on the take-up pulley. If the loaded
elevator, when tested, is found to need more belt tension, that can be accomplished by adding
ballast to the weight box.
2. Establish a firm, level, horizontal reference plane common to both ends of the take-up or boot pulley
shaft. Measure from the reference plane to the pillow block mounting surface at each end of the
pulley shaft. If the distances are not equal, adjust the take-up screws,
, or the
alignment adjusting screws,
until the pulley shaft is level.
3. Establish a firm, level, horizontal reference plane common to both ends of the head pulley shaft.
Measure from the reference plane to the pillow block mounting surface at each end of the pulley
shaft. See
a. If both mounting surfaces and hence both pillow blocks are not at the same height, loosen the
mounting bolts for the pillow block on the low end of the head shaft.
b. Turn the jack screws evenly to raise the pillow block until both ends of the head shaft are level.
Shim between the pillow block and its mounting surface. Shims should be as nearly equal to the
area of the pillow block base as possible so as not to concentrate stress on a small area of the
bearing housing , causing it to fracture. Slotted shims are suitable and easy to use.
c. After the pillow block has been shimmed to level the head pulley, back off the jack screws so the
full weight of the pillow blocks rests on the shims. Tighten the mounting screws.
4. If it has not already been done, lubricate all components requiring initial lubrication. This includes,
but is not limited to, the drive reducer. Reducers are usually shipped dry, without lubricant. Refer to
the manufacturer data, which should have been saved when the components were unpacked or
consult the manufacturer or a local supplier of the component.
5. Start the elevator. Observe the belt as it passes around the pulleys. If the belt appears to be “walking”
towards the edge of the pulley, be ready to shut down the elevator drive. Several complete
revolutions of the belt will be required before the belt reaches a steady-state tracking condition.
6. If the belt steadily tracks on or near the center of both pulleys, no further action is necessary. If,
however, the problem is that the elevator structure is significantly out of plumb, the remedy is going
to be more complex. The elevator will have to be plumbed
NOW
after all the guying and/or bracing
has been installed. Study the diagrams in
. Try to correct belt tracking first by
adjusting the boot take-up pulley and then by shimming the head pulley pillow block bearings. If
altering pulley alignment has no effect, run the elevator until the belt splice is accessible through the
inspection door. Use a long straightedge (10' or longer) or taut line to see if the belt was spliced
squarely. If necessary, resplice the belt.
