264 Harken Materials & Properties Aluminum 6061-T6: an aluminum alloy that has excellent corrosion resistance to air and salt water. It is an easily welded, tough alloy that responds well to anodizing. 7075-T6: the strongest aluminum alloy with strength comparable to many steels. Harken uses 7075-T6 in its Grand Prix cylinders which are built to handle extremely high loads at minimal weight. A vigorous maintenance schedule is required when using this alloy, because corrosion resistance is lower than 6061-T6. Available in hardcoat or clear- anodized finishes. Bearings Bearing properties are functions of contact area, material type, bearing cages, and whether the bearing rolls or slides. Types Ball bearings: very low-friction; low/medium-load capacity. Roller bearings: low-friction; high-load capacity. Sleeve bearings: medium/high-friction; extremely high-load capacity. Materials Stainless steel is stronger than Torlon® thermoplastic and Torlon is stronger than Delrin® acetal resin. Because stainless is heavier and usually higher maintenance, Torlon is used in most high-load applications. Contact Area More contact between the bearing and the race increases friction, but also increases load capacity. Balls are loaded on small points, cylindrical rollers are loaded along their length, and sleeve bearings are curved around the shaft so a large portion is in contact. Unlike balls and cylinders, sleeves are not prone to being flattened by extreme or static loads because they already conform to the curvature of the shaft. Motion (rolling, caged rolling, or sliding) Sliding bearings (known as sleeve, plain, full-contact, bushing, or journal bearings) are very high strength, but have nothing to reduce friction between contact areas. At most, they have a low-friction sleeve between the surfaces. Rollers and balls avoid almost all of this friction because they do not slide against the race, though they can come in contact with each other. Caged roller bearings are separated from each other to avoid this. Caged Bearings Caged bearings are roller bearings held in a cage that keeps them separated from each other and parallel to reduce friction. Caged bearings are used in winches and Black Magic blocks. Captive Bearings Captive bearings are ball bearings that are contained so they won't spill during product maintenance. Black Magic blocks have ball bearings held captive by the lip of the sheave. CB traveler cars feature ball bearings held captive by a wire guide. Carbo Carbo Air blocks feature lightweight, fiber-reinforced, nylon-resin sideplates with a 60% higher MWL than stainless-reinforced Classic blocks. Lightweight fiber-reinforced Carbo-Cams are ideal for racing where weight is critical. The Carbo name comes from an additive that gives blocks their color and UV-resistance. Carbon Black Carbon black is a color additive used in black Delrin ball bearings, block sheaves, and sideplates to protect against UV exposure. Delrin balls Torlon balls Stainless balls Caged rollers Uncaged rollers Sleeve bearing Roller bearing contact area Ball bearing contact area Caged rollers Uncaged rollers Delrin is a registered trademark of E. I. du Pont de Nemours and Company or its affiliates. Torlon is a registered trademark of Solvay Advanced Polymers, L.L.C. CB traveler Black Magic sheave Carbo Air block Carbo-Cam cleat Bearing efficiency (low-friction) Bearing load capacity For complete listing, see www.harken.com/glossary
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