Maintenance & Reliability · PM Log
Conveyor Belt Tracking Adjustment And Roller Replacement
Provides a standardized method for diagnosing and correcting conveyor belt tracking deviations and replacing damaged or worn return/idler rollers to prevent belt edge damage, material spillage, and structural wear.
Estimated Time
45 min
Difficulty
Advanced
Regulation
CSA Z432 / Z460
Version
1.0
Purpose
To establish a controlled, repeatable procedure for restoring and verifying conveyor belt alignment and idler roll condition. Proper tracking prevents catastrophic belt failure, minimizes spillage cleanup costs, and reduces unplanned downtime caused by structural contact or mistracking-induced edge fray. Roller replacement must achieve a specified Total Indicated Runout (TIR) to avoid introducing harmonic vibration into the belt carcass.
Scope
Applies to troughed belt conveyors with fabric or steel-cord belting in dry bulk material handling systems. Covers idler roll replacement on the carry side and return side, snub pulley alignment, crowned pulley inspection, and belt tensioning via screw-type or gravity take-up assemblies. Does not cover splice repair, pulley lagging replacement, or structural stringer modification.
Safety Precautions
- Complete isolation of all electrical, hydraulic, and gravitational potential energy sources. Lockout/tagout in accordance with CSA Z460. Verify zero energy state before approaching the belt path.
- Hard hat, safety glasses with side shields, high-visibility vest, steel-toed boots, cut-resistant gloves (ANSI A4+), and hearing protection if ambient noise exceeds 85 dBA.
- Never attempt to adjust tracking or reach into a pinch point while the belt is in motion. Maintain 3-point contact when accessing elevated stringers or walkways.
- If working inside a chute, skirt board enclosure, or return side tunnel, follow confined space entry protocol (atmospheric testing, standby attendant, retrieval equipment).
Required Tools & Materials
- Conveyor belt tracking gauge / precision straight edge (1.5m)
- Chalk line / rotary laser alignment tool (accurate to ±1mm)
- Full set of combination wrenches & sockets (metric & imperial, up to 46mm)
- Come-along or chain hoist (rated capacity > belt tension)
- Hydraulic roller puller / bearing separator
- Replacement idler roll assembly (verify TIR < 1mm)
- Pry bar / heavy-duty pinch bar
- Dead blow mallet (2kg / 4lb)
- Torque wrench (calibrated within the last 12 months)
- Thread-locking compound (Loctite 242 or equivalent medium strength)
- Grease gun with NLGI #2 EP grease
Procedure: Step-by-Step
1
Lockout & De-tension: Apply LOTO per CSA Z460. Confirm all belts, pulleys, and take-up weights are stationary and at zero energy state. Slacken the belt take-up to relieve tension on the belt path.
2
Empty Belt Inspection: Restore power for jogging only (or walk the belt slowly with a tugger). Observe the full circumference. Mark the leading edge of any mistracking on the belt edge with chalk. Categorize the deviation: loading zone, return run, or pulley drift.
3
Pulley Squareness Check: Using a laser aligner, project a line across the face of the head and tail pulleys. Measure the distance to the conveyor centerline string. Acceptable squareness is ±1mm across the pulley face. Record any offset for correction.
4
Idler Alignment & TIR Measurement: Place the tracking gauge across three consecutive idler rolls. Rotate each roll by hand. If the Total Indicated Runout (TIR) exceeds 2mm, or if the roll does not contact all three troughing idlers evenly, mark it for replacement.
5
Roller Replacement: Remove the retaining bracket or pin on the defective idler. Use the hydraulic roller puller to extract the bearing cartridge from the stringer slot. A dead blow mallet may be used to break initial corrosion. Install the new roller assembly. Ensure the snub angle is set between 5° and 10° to avoid belt slippage.
6
Thread Locking & Torquing: Apply Loctite 242 to all bracket fasteners. Torque to manufacturer specification (typically 80–120 ft-lbs, depending on stringer gauge). Do not over-torque to avoid crushing the roll bearing.
7
Empty Belt Tracking Adjustment: Slowly jog the belt. Turn the tail pulley bearing block adjustment bolts in 1/4 turn increments. After each adjustment, allow the belt to stabilize for 3 full revolutions. The belt should center within 25mm of the pulley centerline.
8
Crowned Pulley Check: If tracking drift persists under load, inspect the crown face profile. Using a straight edge, measure the crown height. If the crown apex has worn down by more than 3mm (or 50% of the original profile), schedule pulley re-crowning or replacement.
9
Loading Zone Optimization: Adjust skirt boards to ensure the incoming material stream is centered on the belt within ±10mm. Measure the horizontal velocity of the material at the chute opening. Material speed must be within 15% of belt speed to prevent belt wander.
10
Re-tensioning: Re-apply tension to the take-up system. For screw take-ups, torque both adjustment screws evenly. For gravity take-ups, add weight until the belt sag at the center roll span is between 2% and 3% of the span length.
11
Full Load Test & Documentation: Run the conveyor at full production load for 30 minutes. Re-measure tracking deviation at the head pulley. Maximum allowable deviation is 25mm from center. Complete the PM log: record final TIR, tracking offset, tension sag %, and technician notes.