With more and more conveyor lifts in operation each year, there’s a growing need for proper maintenance. Conveyors are workhorse lifts, but no lift is maintenance-free. Both the structural components and the working parts should be part of an annual conveyor check-up.

Conveyor maintenance can mean working in tight spots, and that makes risk management a top priority. As much as possible, maintenance operations should be performed with the conveyor off and locked out. For the safety of all mechanics, a minimum of two qualified personnel must be present when performing maintenance while the conveyor is not locked out.

In particular, snow storage areas, a.k.a. snow pits, may or may not be suited for maintenance work. If you have a snow pit, it may be safe to be inside it while the lift is running. But some are not. Always use caution in enclosed spaces and follow safe practices. And that means, “If in doubt, stay out.”

OVERALL STRUCTURE

Inspect the fasteners that secure the lift components, together with the support attachments to the foundation.

Look up the conveyor. Is it still straight? Have snowcats pushed on one side or the other and affected alignment? For longer conveyors (300 feet or more), shoot along the conveyor using a transit or other surveying instrument to see if adjustments are needed to get it straight again. The better the alignment is, the smoother the conveyor will run with minimum wear.

Look along the profile of the conveyor as well. The pitch change from every 10 foot midsection to midsection should be uniform. Particularly pay attention to concave sections of the conveyor, where the midsections get steeper as you move up the conveyor. If the change in grade between sections is too abrupt, the belt can pull away from the running surface under maximum tension when the conveyor is fully loaded—not good!

1. Ensure that the structural integrity of the terminals and midsections hasn’t changed. Check integrity of the cribbing that supports the midsections and the snugness of all staging jacks.

2. With the conveyor stopped, walk down the center of the conveyor checking for excessive flexing, bending and/or instability of the frame. Check tightness of all walkways and their fasteners.

3. Frame/bearing bolts should be checked for tightness.

4. Check for broken edge and return guides, bearing noises, frozen rollers, belt splice condition, and belt condition. Broken or failing parts should be replaced.

5. Snags or protruding objects along the belt edge guides or walkways may damage the belt, and should be remedied.

BELTS

First, a few longevity items. At a minimum, areas should de-tension and cover the belt at the end of the operating season. Another option: remove the belt and store it in a cool, dark place, or in a covered spot, to minimize UV degradation. If removed, it is vital that the belts be reinstalled in the same direction as they were originally installed.

1. Once the belts are back in place, make sure the tension system is in good operational condition and that the belt is properly tensioned. Run the conveyor for several complete revolutions, checking for the following and correcting as required.

2. Look for tears, rips, cuts, delaminations, or punctures of the belt. Inspect for torn splices and missing splice plates. Make sure that no wires or metal pieces stick out from the splices.

3. There should be no excessive gaps or holes between the belt and walkways.

4. Keep oil and grease free from all rubber surfaces, including belt, drum liners, and belt edge guides.

5. The connection of the splice to the carpet (typically an “alligator” belt lacing) wears out over time, so even if the splice clips and rod look OK, the belt fibers themselves can be deteriorated. Consider cutting out the splice and replacing it every three years. For long carpets with higher loads, this may need to be performed annually.

6. All splice anomalies must be repaired, or the splice replaced. Visually inspect each splice for damage, and ensure that the splice meets the manufacturer’s recommendations for installation of the splice rods. Visually inspect the top and bottom of each splice for damaged or broken splice clips.

7. Belts bearing hard against the edge guides or framework may delaminate and/or tear out the splice. Check for unusual marks on the conveyor where the belt may have been rubbing. Gaps between the belt surface and the belt edge guide should not exceed the manufacturer’s specifications.

8. Check bolts on the V plow, if equipped, for tightness, and ensure that it interfaces correctly with the belt. Check for any sharp edges on the V plow, and grind any sharp edges off.

9. Long term, a belt can wear out by gradually getting narrower. If an older belt (5+ years) will not stay under the belt edge guides, it may be worn out.

BELT ALIGNMENT

The drums or pulleys (manufacturers use these terms for the same items) are key parts of the alignment system. Conveyors need all pulleys aligned parallel to one another, level, and the frame must be straight and level side to side. Verify that the belt tracks consistently at both the drive and return drums. Side to side walking is common with belts, and as such their movement should be kept evenly centered on the drum.

1. Make sure that head and tail pulleys (a.k.a. drums) are square and level, with their axis at 90 degrees to the path of travel.

2. Square all snub pulleys (a.k.a. deflection rollers), bend pulleys and gravity take up pulley, making sure they are in line and in the same horizontal and vertical planes, and that all bearing and pulley bolts are secure.

3. Check that all frames are level.

4. Head pulleys can be adjusted in small increments if the belt runs to one side consistently. After each adjustment, the belt must go through several complete revolutions before any other adjustments are attempted.

5. If the belt runs crooked at the tail pulley, inspect the tail snub pulleys. Are they level and evenly adjusted in the frame? If not, with the take up pulley square in the frame, adjust the snub pulley feeding the tail pulley, steering that roller away from the side the belt is running off. Make very small adjustments, as these have a great effect on belt alignment. You may need to adjust the tail pulley bearings if the snub pulley will not get the belt moved into the desired position. This is a two-person job. If adjusting pulleys does not correct tracking problems, check that the terminal is not crooked to the line of the conveyor.

6. If side creep occurs in the vicinity of the belt splice, the splice may not be square to the belt. Resplice if necessary.

After any repairs or alignment changes are completed on the belt or the return and drive drums, turn the belt at least five complete revolutions to inspect the results.

PULLEYS, ROLLERS AND BEARINGS

Pulleys and bearings rarely fail, but can due to loose bushings, overloads, worn rubber lagging or belt covering, and misalignment.

The head, snub and tail pulleys located within the frame of the conveyor should be serviced per manufacturer’s specifications. This varies from conveyor to conveyor, even from the same manufacturer. Some are greased for life, some need annual attention, some require service every 200 hours. This service is a frequently overlooked item when conveyors are running. At the beginning of the season, before start-up, inspect the bearings for “weeping” and, if any is noted, determine if a seal has been damaged. If so, replace the damaged bearing.

1. Verify that pulley bushing bolts are tight per the specified torque table.

2. Check pulley welds at hubs for cracks; if any cracks are found, replace. Analyze why the pulley failed—was it due to an overload, loose bushings, or misalignment? Fix the problem that caused the crack(s).

3. Check pulleys for any movement. Readjust and tighten as necessary. Pulleys should be centered on all shafts and in the bearings. Check all bearing bolts for tightness.4. Check for regularly repeating noise in a pulley. Often, this is due to material between the pulley and belt, which causes no harm. During pulley manufacture, for example, a backing strip may have been used behind the weld, with some slag falling off during operation. But make sure the noise is not coming from a within a bearing or another mechanical part, such as the gear reducer/motor/backstop. Noise from adjacent power transmission components may seem to come from a specific component, which in reality is not faulty; careful analysis is required before breaking down the equipment.

5. A continuous growling sound may be due to inadequate tension. This growling may be belt slippage on the head drum due to a lack of belt tension. If so, adjust as necessary. In winter, ice can also cause a similar symptom; if ice is the cause, the drum will need to be cleaned, and possibly, a drum scraper will need to be either adjusted or installed.

6. Unusual noise or heat from a bearing indicates that bearing should be replaced.

7. Some pulleys or drums may have a coating, known as lagging. Worn lagging can be caused by normal use, misalignment of the belt, or by the belt freezing to the lagging and tearing out sections of it. If the lagging is worn, drums can be re-lagged, or the drum can be replaced.

8. Examine return rollers on each midsection for unusual conditions. With the lift running, this could include noise, such as bumping or squealing, etc. With the belt stopped and locked out, lift the belt up and see if the roller has any play. Note any area where structural steel shows signs of contact with the belt; adjust the belt if necessary.

9. Clean and grease the mechanical tensioning system’s all-thread rods, carriage rails, etc., per manufacturer’s recommendations.

TRANSITION AND STOP DEVICES

Check the transition stop device (a.k.a. relief plate, stop plate) and associated mechanical and electrical components for proper function and adjustment per the manufacturer’s instructions. This device is one of the most important components on the conveyor.

With the conveyor running, test the function of each stop and safety function of the conveyor. Check the stopping distances for normal and emergency stops. Adjust transition stop gate settings as per manufacturer’s requirements.

Stopping distances vary with belt speed/length/width, friction in the system, and temperature. Stopping distances should be tested with an empty belt to minimize friction.

Set the transition stop device with minimal clearance from belt to the edge of the stop device. Pay attention to minimizing the distance between the TSD and the belt surface. Check for the proper operation of any manual or electric reset devices. Ensure that, when tripped, restart cannot occur until the reset command has been given.

GEARMOTOR

Gearbox oil should be changed per the manufacturer’s specifications. (Note: some units are lifetime greased and require no oil change.) Use only the indicated oil, as the specifications are suited to cold-weather use. Do not mix different types of oils, as they may congeal in the gearmotor, causing hard starting and lubricating deficiencies that promote wear. Synthetic oils are generally not compatible with mineral oils, and with other, different synthetic blends. Consult with the conveyor or gearmotor manufacturer before changing the oil or grease type.

When servicing the gearmotor, always lock out the equipment power switch. Always use safety glasses, protective clothing, gloves, and shoes. Only authorized/trained personnel should service the gearmotor.

1. Check gearbox for any movement; tighten bolts as necessary. Check seals around shafts for any signs of leakage.

2. Bolts securing the torque arm should be checked for tightness.

3. If a high speed backstop or rollback drop dog is present, confirm their function. Follow manufacturer’s instructions for testing these. The rollback device should engage in a matter of inches; ideally, it will be two inches or less.

TENSIONING SYSTEM

Clean and grease the mechanical tensioning system’s all-thread rods, carriage rails, etc., per manufacturer’s recommendations.

If applicable, every 5,000 operating hours or five years (whichever comes first) change the hydraulic tensioning pump’s oil.

ELECTRICAL CONTROLS

Only qualified personnel should work on the electrical system, and must use appropriate lockout/tagout procedures. No off-season maintenance should be done with the lift running or without proper lockout/tagout procedures. Dangerous conditions exist under the lift, and these can cause serious injury or death.

Some conveyors are designed to allow the control box to be removed and stored inside during the off-season. This can help protect against exposure to lightning and physical damage. If the box is removed, reinstall it early enough in the fall to check functionality and avoid surprises.

Do not bypass any part of the electrical system. Electrical bypass is not allowed; nor are temporary jumpers.

1. Check electrical connections for tightness, burned wires and terminal screws. Visually inspect all plugs and external wire connections. Check the wiring between the drive and return stations for damage from weather exposure, animals, and/or abrasion from the machinery. Look inside all junction boxes and switch enclosures for wet conditions or damage from animals.

2. Check the functionality of all operator-controlled push buttons, switches, and signaling devices.

3. Check any other protection circuits, such as belt slip detection, overspeed detection, drive safeties, etc., following manufacturer’s specs.

4. Brush on/off switch: Verify that brush bristles run against the belt, not in the same direction as belt travel.

5. Verify the grounding electrode (point of common ground) is secure and all wires terminated to this electrode are tight. Check for less than 50 ohms resistance between the grounding electrode and the conveyor machinery.

SIGNAGE

Signage must be appropriate for the lift. Such signs may be required for customer guidance and safety, confined spaces, lockout/tagout procedures, “no admittance” areas, and other situations. Annex D in the B77-2011 code describes the required signage and any sign, stating, “PERSONNEL WORKING ON CONVEYOR—DO NOT START” must be available before any maintenance on a conveyor is performed.

Risk managers must determine if additional signage is required as part of operational, customer, or maintenance plan procedures.