PREVENTATIVE MAINTENANCE:
HORIZONTAL CAROUSEL

Overview:

There are 2 basic types: Bottom Drive or Top Drive (similar to a dry cleaning conveyor). The bins (typically wire shelves, sides, and backs) rotate in a horizontal direction (left or right) along a tubular or solid track either suspended (top drive) or on the floor (bottom drive). Some Bottom drives are double or triple stacked. On either type, the bins are mechanically connected to each other, top and bottom via a linkage assembly.A large sprocket connected to a smaller driven sprocket via the motor, gear box, and motor chain drive, the bins along the tracks. Horizontal Carousels are electrically powered via a single 230 DC motor, or dual motors (wired in parallel 240 DC, or in series 480 DC via an AC to DC converter). There are other models that are powered via a 240 VAC or 480 VAC motors only via a drive inverter. The motor(s) are run with an electronic control system that handles the conversion of AC to DC power for smoothing of the AC voltage in an DC drive system. Furthermore the controls monitor the stopping position, safety circuits and over current draw from load deviation in the Carousel. Like any other mechanical device similar to an automobile, the carousels require 2-3 annually scheduled maintenances. Assuming the units have been installed properly, i.e. shimmed, leveled and plumbed the moving parts as well as the electronic parts require periodic attention.Linkage Assembly:

• The links, which connect the bins, have friction points that require lubrication.
• This interval of lubrication is determined on the amount of usage and weight on the carousel. On the bottom drive carousels the links are mounted over a plate and pin assembly, which also requires lubrication, as well as on top where the plastic guide wheels are connected to the links.
• The linkage assembly over time like any other conveyor chain due to usage, weight on the bins and other factors cause them to wear, causing too much slack.
• Bin link hardware also requires inspection.

Casters/Guide Wheels:

• On Bottom Drive carousels the casters are the main support and guidance of the bins on the guide tracks that require visual inspection. They have numerous grease fittings that require lubrication. There are upper guide wheels as well requiring attention.
  
• On the Top Drive systems the upper guide wheels (mounted on a yoke assembly) are actually sealed bearings. The rail they ride on requires lubrication. In addition there are lower guide wheels used to stabilize the bins as they turn.

Motors/Gear boxes:

• DC carousel motors wired in parallel must be checked for synchronization periodically.
• These motors have 2 brushes each, which wear down over time.
• The motors are connected via a #40 or #60 roller chain to the main drive guide sprocket which requires lubrication and can “stretch” over time.
• The motor is connected to the gear box via a belt which will stretch and/or wear over time.
• The motor and gear box also have pulleys on their output and input shafts respectively, which may come loose over time.
• Gear box mounting hardware can come loose and require inspection.
• Gear box oil levels require periodic inspection and possible replacement.
• The motor chain has a tensioner, which requires inspection. The spring can come off or hardware may come loose.
  

Motor Controller:

• The DC motor controllers have speed controls, which monitors the output for the best running efficiency of the carousel(s). Speed adjustment may be required to maintain optimum efficiency based on the AC input and wear/age of the motor(s). This is especially true for motors wired in parallel, and computer/software driven systems.
• The DC motor controller also has a current flow control, which also monitors the motors efficiency for the carousel(s).

Guide Sprockets:

• The guide sprockets grab the bushing that the plate and pin houses to pull or push the bins around. They also have a large driven sprocket connected to the gear box. There is usually a guide sprocket on the top (for bottom drive carousels) for additional guidance.
• On top drive carousels the motor, gear box and the guide sprockets are on the top only. The guide sprockets are held in with 2 pillow block bearings with set screws that need to be retightened periodically. Some guide sprockets also have a torque tubes connecting the top and bottom which also require inspection.

Safeties:

• Product protect safeties should always be inspected for alignment and functionality.

Peripherals:

• Light Trees, Sort Bars, 530 controllers, Foot Switches, PC connections, etc. all require inspection and testing.

When the linkage assemblies wear, all other components are affected, possibly causing derailment. Loose chains/belts affect carousel efficiency. Sluggish motors cause irregular drag on the carousels reducing performance. Poor voltage inputs and out puts can effect motor performance. Loose hardware may cause breakdowns, component damage etc.

• Worn neglected linkage assemblies cause poor rotational performance. They can also buckle enough to cause bin derailment.
• When links wear and bushings wear the casters see additional torque causing premature failure.
• A loose guide sprocket may cause it to either raise up or fall causing derailment and other component damage.
• Neglected chains and belts can cause premature motor failures.
• Motor speeds, brushes, low/high voltage discrepancies develop into poor carousel performance especially in computer/software controlled environments.
• Motor/gear box inefficiency will also reduce its life cycle and can fail shutting down the carousel.
• Misaligned or failed product protect safeties may cause jams possibly damaging bin/carousel parts as well as product stored on the carousel.
• Lack of lubrication allows steel on steel friction causing premature wear and future breakdowns.
  

Preventative/Corrective Maintenance:

1. Visually and audibly observe the carousels rotation in both directions
2. Observe the carousels rotation in both directions.
3. Inspect the link assemblies for slack, wear, and dryness. Lubricate and resize where necessary.
4. Check all casters, guide wheels etc. for wear and need for lubrication.
5. Inspect all bin and bin connecting hardware. Tighten/replace where required.
6. Check motor chain/belt tension and lubricate chain if necessary.
7. Inspect motor brushes.
8. With a tachometer check motor speeds.
9. Check oil level and hardware on gear boxes.
10. With a DVM test all voltage levels inside the motor controller as well as other peripheral devices.
11. Inspect all wiring for connectivity and security.
    
12. Test all product protect safeties and observe pinch points for effectiveness. Adjust/replace as required.
13. Check functionality of all peripheral devices.
14. Input computer commands to observe stopping accuracy. Make adjustments as necessary.
15. Always clean the floor area around the carousel as stray lubricants can cause a hazard. Leaving the site clean will also allow observation of any changes on the return trip during follow up maintenance.

Follow Up Maintenance:Efficiently running carousels will provide extended life and increased ROI (Return On Investment). Less down time and properly working carousels improve product picking and improved efficiency in other areas as well. Regularly scheduled maintenance permits scheduled down time for the maintenance. Always schedule follow up maintenance after completing a regularly scheduled maintenance. Always have failing or weak components replaced as soon as reported, especially product protect safeties. Regularly scheduled maintenance can be from 2-4 times a year depending on usage and weight of product on the carousels.

This document or any of its contents may not be copied or reproduced in any way without the written consent from:
Logic Level Technologies, Inc.