Hitachi

Engineering Class Chains Conveyor Chain Selection Conveyor Chain Useful Information Basic Conveyor Layout Take-up Loading Area Chain Travel Discharge End Support Rail Tail Sprocket Return Rail Head Sprocket Arrangement Power should be supplied to the head sprocket (discharge end) whenever possible to avoid high loading on both the carrying and return side. This will reduce the rate of chain elongation. Matched Chain Strands Multiple strand conveyors often require matched and tagged chains. In this case each strand will be measured and matched so that adjacent strands are all within 0.031" of each other in length. Sprockets We recommend using the largest sprocket diameter that space will permit to minimize speed variations and pulsation caused by chordal action. Speed variations on sprockets with few teeth result from the difference in the chains radial position from the shaft center-line when a tooth or a tooth pocket is top dead center. Since the shaft turns at a constant speed a larger radial distance will speed up the chain and a lesser radial distance will slow down the chain. The fewer the number of teeth the greater the speed variation. This effect becomes negligible at approximately 18 teeth. Right and Left Hand Strands On dual strand chain conveyors when the attachments are not symmetrical it is often necessary to order right and left hand chains. In many applications the cotter pins must face inside to avoid interference with rails on angle tracks. This can create asymmetric situation even though the attachments are symmetrical. For large pitch conveyors a compensating Drive Chain arrangement can be designed to vary the head shafts rotational speed to compensate for the effect of chordal action. Hardened Teeth for sprockets are recommended particularly if there are fewer than 15 teeth. Match Sprockets When a double strand chain conveyor has slats, flights, apron pans, or other parts that connect the two chains rigidly together, both head shaft sprockets should be matched. This can be done by specifying that the sprockets be keyed on the center-line of the tooth. We also recommend that on the tail shaft one sprocket be keyed and one sprocket be allowed to turn freely between set collars for automatic repositioning of the teeth if uneven chain wear occurs. Conveyor Length Unusually long conveyor lengths can result in pulsation due to the chain's elastic properties. If this occurs, it may be necessary to use two conveyors with a transfer point or additional drives Take Up Tension The correct amount of take up tension that should be applied is the minimum amount that allows for smooth action over the tail sprocket. As a guide this usually amounts to approximately .5% - 2% of the chain's Average Ultimate Strength. 30 Chain Supports Conveyors over 15 feet in length need to be supported on the return side to avoid pulsations, chain whip, or elongation causing excessive sag to strike adjacent conveyor components. A return rail or idler sprocket is used for this purpose. Lubrication Effective lubrication is the single most important maintenance practice that can be done to extend chain life, reduce power consumption, and assist in smooth running trouble-free service life. High quality non-detergent oils should be used. In some cases chain can be lubricated with grease through a fitting mounted on the chain pin (diameter should be at least 0.750" in this case) or less frequently through a bushing lubrication hole (Rollerless Steel Bushed or Welded Steel Chains). For Roller Conveyor Chains carrying large loads it may be best to fit the roller with a sealed roller or ball bearing to minimize friction and extend chain life. Hitachi engineering personnel are available to assist with lubrication guidance for specific applications. Calculating Horsepower HP = (T x S) / 33,000 T = Maximum Chain Tension (lbs) S = Linear Chain Speed HP = (Torque x rpm) / 63,000 Torque is in inch-pounds

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