One of the most vital pieces of equipment for moving materials in a warehouse is the conveyor. And whether it's a belt or roller type, conveyors carry a range of items throughout the distribution center, operating nearly 24/7 at some locations.

But continuous operation and handling of heavy loads eventually takes its toll on a conveyor, sometimes bringing everything to an unexpected halt. It doesn't have to be that way if conveyor belts and rollers are maintained regularly, however.

Roller conveyors, which are gravity or motor powered, convey a variety of products and are ideal for carrying heavy loads. A roller conveyor consists of side rails, punched with hexagonal space holes along their length. Rollers, assembled from tubes with bearings in each end, generally ride on steel shafts that fit into these hexagonal holes.

One of the most common problems of any type of roller conveyor is frame and roller shaft damage. Each of a conveyor's rollers must rotate correctly in the frame's shaft openings to keep the entire conveyor system operating smoothly. However, as a roller's repetitive motion causes the shaft to twist back and forth in the side frame, the punched hexagonal holes eventually wear down to circular holes. At this point, the roller spins freely and the circular shaft hole grinds the shaft end until it breaks off completely, rendering the roller useless.

Replacement frame sections are available to solve frame and shaft problems. These small devices attach to the existing side frame, placing a new hexagonal hole over a damaged hole.

The elements driving motor-powered rollers, such as chains and line shafts, also wear out quickly if they are not maintained.

A line shaft-driven roller conveyor, for instance, has rubber bands called O-rings on the sides of the rollers, connecting the rollers to a long shaft below. If heavy loads rub against the O-rings or the conveyor simply is operated for long periods, the O-rings may break. Once these O-rings break, the roller stops altogether, creating a dead zone in the conveyor system. Spare O-rings should always be in stock to avoid unnecessary conveyor downtime.

With chain-driven roller conveyors, maintaining proper lubrication and tension is important. If a chain is not lubricated, parts such as the chain pins, sprockets and bearings will wear out quickly. Chains that are too tight or too loose will cause excessive wear and create noise. They will also force the system's gears and motor to generate extra power. Roller chains should be checked monthly for abnormal wear, excessive noise, broken sections and other noticeable problems. Lubricating the chains, bearings and other mechanical parts monthly or as recommended by the manufacturer will greatly minimize chain failure.

Another commonly used device for conveying products is a flat belt conveyor. This high-tension system consists of a drive roller on one end and idler on the other end acting together as pulleys. The belt can be made of a variety of materials and must withstand continuous pull without stretching significantly.

For proper operation, belt tension is critical. A belt that is too tight may produce heat from excessive friction and wear out prematurely. Alternatively, a belt that is too loose may slip off the drive roller and idler and result in overloading.

Belts must also be correctly aligned. If belt tracking is off-center, the belt will rub against the edges of the conveyor side frames and eventually tear. Misalignment can also shorten the life of the drive roller and idler, especially their bearings.

Fortunately, maintaining correct belt tension and alignment is not a science. Many belt conveyor manufacturers recommend inspecting the belt while it makes at least three full revolutions. If the belt looks off-track or makes unfamiliar, excessive noises as it revolves, the belt or even the drive roller and idler should be readjusted based on the conveyor installation manual.

When a belt tears or sags due to improper tension and alignment, the belt may need to be spliced rather than replaced. Splicing a belt reconnects two belt ends by means of a highly intensive heat or chemical process or with mechanical hooks. Either splicing technique involves precision and should be performed by knowledgeable maintenance personnel.

Don't let a small, reparable problem like a loose belt or broken O-ring lead to a serious conveyor breakdown. Monitor a conveyor's various parts on a regular basis to avoid costly repairs and downtime.

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