Roller Conveyor Service Manual: Bearing Condition, Roller Alignment, and Drive Chain Tension

1. Scope and purpose

This practical guide is designed for technical personnel who perform scheduled or unscheduled maintenance of roller and belt conveyors in industrial enterprises. It covers the critical aspects of assessing bearing condition, ensuring correct roller alignment and correct tensioning of drive chains. The goal is to prevent equipment failures, increase the service life of components, and ensure uninterrupted operation of production lines. Adherence to these recommendations helps to reduce operating costs and increase the overall reliability of conveyor systems.

2. Precautions

ATTENTION: Before starting any maintenance work on the conveyor system, be sure to perform the LOCKING/MARKING (LOTO) procedure in accordance with the company's internal instructions and the requirements of DSTU EN 1037:2018 (Safety of machines. Prevention of unexpected start). Failure to do so could result in serious injury or death.

MANDATORY: Use personal protective equipment (PPE): safety glasses (according to DSTU EN 166:2017), strong gloves, protective shoes with a metal toe (DSTU EN ISO 20345:2016) and protective clothing. When working in areas of high noise, use hearing protection.

DANGER: Beware of hot surfaces (bearings, motor housings, gearboxes), moving elements (chains, sprockets, rollers, belts) that can catch clothing or body parts.

3. Necessary tools and materials

4. Pre-release inspection checklist

Perform a visual inspection and initial check of the system before starting detailed work. Write down all detected deviations.

5. Step-by-step service procedure

5.1. Preparation for work and ensuring safety

1. Obtaining a work permit: Before starting work, coordinate with the responsible engineer or shift supervisor and obtain the appropriate permit.
2. Executing the LOCKOUT/TAGING (LOTO) procedure:
   1. Disconnect the conveyor from all sources of electrical energy. Use the main switch, disconnectors.
   2. Lock the switches in the OFF position with padlocks and install the identification tags.
   3. ACTION: Using a multimeter (in AC 400V voltage measurement mode), make sure there is no voltage at the motor terminals and in the distribution cabinet. Common mistake: Trusting the circuit breaker indication without actually checking that there is no voltage.
3. Establishing protective fences: Install portable fences and DANGER warning signs. WORK IN PROGRESS!" around the work area.

5.2. Assessment of the condition of the bearings

1. Visual inspection: Inspect the bearing assemblies for external damage, cracks in housings, traces of grease leakage or heavy contamination.
2. Aural check: When rotating the roller by hand (after unlocking, if possible, or during a short test run under supervision), listen for extraneous noises: grinding, rustling, humming, clicking. Common mistake: Ignoring minor noises that are the first signs of initial wear and tear.
3. Temperature control: Measure the body temperature of each bearing using an infrared thermometer (pyrometer).
   • Criterion: The normal operating temperature should not exceed +70°C. The temperature difference between similar bearings on the same conveyor should not be more than 10°C.
   • ACTION: Record readings and compare with previous measurements. Elevated temperature indicates excessive friction, lack of lubrication or initial wear.
4. To check for backlash: Grasp the end of the roller and try to rock it in the vertical and horizontal planes. Perceptible backlash indicates bearing wear.
   • Criteria: The permissible radial backlash for standard roller bearings is no more than 0.1 mm for diameters up to 50 mm and 0.2 mm for diameters over 50 mm. Measurements can be made using an indicator watch.
5. Bearing lubrication: If the bearings have oilers (melting nipples), lubricate according to the equipment lubrication map.
   • ACTION: Use a grease gun and grease of the type specified by the manufacturer (eg NLGI 2 lithium grease).
   • Visual indicator: Grease should appear from under the seal.
   • Common mistake: Excessive lubrication, which leads to overheating and damage to seals; insufficient lubrication, which accelerates wear.
6. Bearing replacement: If there is significant backlash, constant overheating or loud noises, the bearing must be replaced.
   • ACTION: Use the bearing puller. Clean the seats. Install the new bearing using even force (such as with a mounting sleeve and a press) to avoid damage. Grease the new bearing.

5.3. Checking and aligning rollers

1. Roller Inspection: Carefully inspect the surface of each roller for cuts, cracks, chips, abrasive wear, material sticking, or deformation. Check that all rollers rotate freely. Jammed rollers create excessive friction and can damage the belt or product.
2. Checking the perpendicularity of the rollers:
   1. ACTION: Using the laser alignment device, check the perpendicularity of each roller to the longitudinal axis of the conveyor.
   2. Criterion: The permissible deviation should not exceed ±1 mm for each meter of roller length. For example, for a roller with a length of 500 mm, the deviation should be no more than ±0.5 mm.
   3. ACTION: If the roller is not perpendicular, loosen its fasteners and adjust the position until the required accuracy is achieved. Tighten the mounting bolts with a torque of 45 Nm for M10 or 78 Nm for M12.
   4. Common mistake: Insufficiently accurate alignment, which leads to lateral overlap of the tape, increased wear of the edges of the tape and rollers.
3. Checking the parallelism of adjacent rollers:
   1. ACTION: Use the laser device to check the parallelism of the axes of two adjacent rollers.
   2. Criterion: Deviation from parallelism should not exceed 0.5 mm.
   3. ACTION: Adjust the position of the rollers as necessary as described above.
4. Replacement of damaged rollers: Rollers with significant defects or those that do not rotate must be replaced.

5.4. Checking and tensioning the drive chain

1. Inspection of chain and sprockets:
   1. Visually inspect the chain for wear of links, cracks, corrosion, jamming, lack of lubrication. Pay attention to chain stretching - this is the most common type of wear.
   2. Inspect the sprocket teeth. Tooth wear should be uniform; the presence of "hooks" or uneven wear indicates improper chain tension or wear.
2. Measuring chain tension:
   1. ACTION: Measure the center distance between the sprockets. Use a chain tension gauge or the sag method (pressing on a free branch in the middle of the span) to determine the amount of sag.
   2. Criteria: The optimal sag is 1-2% of the interaxial distance for a free branch. For example, for a wheelbase of 1000 mm, a sag of 10-20 mm is permissible. This parameter may vary depending on the recommendations of the chain manufacturer (for example, according to ISO 4347).
   3. Common mistake: Ignoring the manufacturer's recommendations for tension, resulting in rapid wear or slipping.
3. Regulating chain tension:
   1. ACTION: If the tension does not meet the norm, loosen the fastening bolts of the drive or tensioner.
   2. ACTION: Move the motor or tension roller until optimal tension is achieved.
   3. ACTION: Tighten the actuator or tensioner mounting bolts to the recommended torque. For M10 bolts - 45 Nm, for M12 - 78 Nm. Always check these values ​​with the manufacturer's technical documentation.
   4. Common Mistake: Over-tensioning, which places heavy loads on shaft and sprocket bearings, accelerating their wear.
4. Chain Lubrication:
   1. ACTION: Clean the chain of dirt and old grease with a brush and metal cleaner.
   2. ACTION: Apply special chain lube. Use a lubricant that penetrates the inside of the links, providing protection against wear and corrosion.
   3. Visual indicator: The chain should be evenly coated with a thin layer of grease.
5. Replacing Chain and Sprockets: If the chain has significant stretch (>3% of nominal length per 100 links), damaged links or sprockets have severely worn teeth, they must be replaced as a set.

5.5. Final inspection and cleaning

1. Checking all fasteners: Make sure all loosened and adjusted fasteners are tightened to the correct torque.
2. Installing protective covers: Install all protective covers and fences, making sure they are securely fastened.
3. Workplace cleanup: Remove all tools, materials, grease and dirt from the work area.
4. Removal of warning signs: Remove previously installed fences and warning signs.
5. Loto removal: Remove padlocks and marking tags from circuit breakers only after confirming completion of work and safe start-up.

6. List of checks after maintenance

After all work is completed and power is restored, perform a test run of the conveyor and complete this checklist.

7. Troubleshooting guide

This table contains typical malfunctions, their probable causes, and recommended corrective actions.

8. Recommended maintenance schedule

9. Directory of spare parts

To ensure smooth operation of the conveyor, the availability of the main list of spare parts is critically important. UNITEC-D offers a wide range of high quality components.

Visit our UNITEC-D E-Catalog to order original spare parts and components.

10. Links

• DSTU 2315-93 (ISO 5048-89): Belt conveyors. General design requirements.
• DSTU EN 1037:2018: Machine safety. Prevention of unexpected start.
• DSTU EN 166:2017: Means of individual eye protection. Requirements
• DSTU EN ISO 20345:2016: Personal protective equipment. Protective shoes.
• EN ISO 12100:2010: Safety of machines. General design principles.
• ISO 4347: Transmissions are chain. Roller chains with straight side plates.
• Equipment manufacturer's documentation (OEM Documentation).