TL;DR
Belt slip reduces elevator capacity and can cause belt misalignment or buckets to jam. Check the belt tension and head pulley lagging condition before adjusting the take-up.
What you might see
- elevator capacity dropping without load change
- belt squealing at the head or boot pulley
- slippage alarm from the speed sensor
- belt tracking off to one side of the pulleys
Likely causes
Belt tension too low from take-up not adjusted after initial stretch-in
Head pulley lagging worn or contaminated, reducing friction coefficient
Belt elongation from heat or moisture reducing the effective take-up range
Overloading the elevator beyond rated capacity, exceeding the drive traction limit
Required tools
- Tape measure for take-up position
- LOTO kit
Safety first
- Grain dust inside elevator legs reaches explosive concentrations. No ignition sources. Belt slip generating heat or sparks is a direct explosion risk.
- Lock out before any belt, take-up, or pulley inspection. The belt runs continuously and pulls with high tension.
Procedure
- 1
Stop the elevator and lock out before inspecting the belt or take-up.
Warning: Bucket elevator legs contain grain dust at explosive concentration. No ignition sources. Sparks from belt slip against a pulley are a fire and explosion ignition hazard. Stop the elevator immediately if slip is occurring. - 2
Measure belt tension by checking the take-up position. Confirm the take-up has remaining adjustment range. A take-up at its limit indicates the belt has stretched beyond adjustment range and requires replacement.[1]
- 3
Inspect the head pulley lagging for wear or contamination. Worn lagging reduces the friction required to transmit drive torque to the belt.[1]
- 4
Adjust the take-up in small increments (5 mm) and recheck belt alignment after each adjustment. Uneven adjustment creates crown and causes belt tracking problems.
- 5
If lagging is worn, schedule head pulley re-lagging at the next outage. Temporary slip can be managed by increasing tension but worn lagging will continue to cause problems.
- 6
Review the feed rate into the elevator boot. Overloading causes the motor to require more torque than the drive traction limit, causing slip.
- 7
After adjustments, run the elevator empty and then at production rate. Confirm no belt squeal or slip before releasing to production.
Sources
Universal Industries Universal Industries Tapco Bucket Elevator / Drag Conveyor general technical documentation, Universal Industries
Bucket elevator belt tension and take-up adjustment, general bulk material handling practice (general)
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