Belt Conveyors

VOL. 21 NO. 11

Belt conveyors are an important segment of this company's product line. Including conveyors in the product line enables Gem to furnish complete processing systems. When times are tough, conveyors are much more apt to be purchased, than the large fryers, blanchers and batter systems that are the backbone of this company's product line. One conveyor is a relatively small order. A customer, who would be very nervous about trusting a new supplier with a large order, is willing to take a chance when purchasing a conveyor. This does not mean that belt conveyors are foolproof. Belt conveyors can be the source of major problems.

Last summer, Gem manufactured a polymerized fabric belt conveyor that dealt out hard lessons to everyone involved. The application and configuration, specified by a consultant engineer, are part of a dewatering, elevating system located at the discharge end of a large raw product conveying flume. Whole potatoes are received from the flume, elevated and discharged onto another conveyor. The discharge end of the flume fans out to spread the potatoes over the width of the conveyor. The fan shaped end of the flume has bar grid sides for primary dewatering. The conveyor belting is perforated to provide additional dewatering. The infeed end of the conveyor is underwater. Plastic bearings, the type normally used on flood washer discharge conveyors, support the tail pulley. Neither the processor nor Gem had experience with this type of conveyor for this specific application. Because this system is used in other french fry potato plants, the consultant engineer was comfortable with the basic design.

Unfortunately, operating conditions in this customer's plant were different than those in the plant the consultant had observed. In addition, Gem added to the problem by selecting belting too light for the application and operating conditions were harsher than the underwater plastic bearings and UHMW wear strips could handle. During initial operation, potato vines plugged the dewatering grid on the discharge end of the flume, overloading the dewatering capability of the conveyor. The excess water caused operational problems and grit in the water resulted in failure of the underwater bearings and the UHMW wear strips on the infeed end of the conveyor. Plant personnel are dealing with the excess water until heavier belting with a higher percentage of open area can be installed. The plastic bearings have been replaced with bearings composed of stellite bearings contacting stellite sleeves fastened to the tail pulley shaft. Wear resistant stainless steel will replace the UHMW wear strips on the infeed end of the conveyor.

The problems experienced with this conveyor prove that it is unwise to assume that because a system operates well in one plant, it will work equally well in another. As often is the case, operating conditions were different and this difference was not determined prior to manufacturing the equipment. Should the consultant have caught this before it became a problem? Probably. Should Gem have furnished a more satisfactory conveyor? Definitely. Gem's responsibility is to furnish equipment that operates to the customer's satisfaction, regardless of the accuracy of information received from third parties.