Dictionary The contents of this dictionary is mainly based on words and expressions used in technical contexts at all levels within the SKF Group. For obvious reasons most of the terms relate to rolling bearings which have been the core business of the company for nearly a century. As the world leader in the business, SKF stands for many epoch-making technological breakthroughs, such as the invention of the self-aligning ball bearing in 1907, by its founder Sven Wingqvist. Many such terms coined within SKF have for these reasons become generic in the business. A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A ABEC See Bearing Precision Classes   ABS Anti-Lock Braking System   ABS Sensor The SKF ABS sensor, used in anti-lock braking systems, acts passively according to the induction principle. An impulse ring with 29 teeth rotates past a permanent magnet which is positioned in a coil. As the wheel moves, an electric signal is induced in the coil; the frequency and amplitude of the signal depend on the rotational speed. In contrast to conventional sensors used today, the SKF arrangement has a stronger signal by which the lower speed limit can be reduced, thus further enhancing vehicle safety. See also Anti-Lock Braking System The ABS sensor integrated in the wheel bearing unit HUB 3 Accessories See Bearing Accessories   Actuator See Linear Actuators and Rotary Actuators respectively.   Adapter sleeve Adapter sleeves are the most commonly used components for locating bearings that have a tapered bore, onto cylindrical shaft seatings as they can be employed both on smooth shafts and stepped shafts. They are easy to mount and require no additional fixation on the shaft. Using adapter sleeves on smooth shafts, the bearing can be located at any position on the shaft. SKF adapter sleeves are supplied complete with lock nut and locking device. The sleeves are slotted and have an external taper of 1:12. Additives To obtain a lubricant with special properties, one or more additives are included. Below are some of the most common used for grease: - Rust-inhibiting additive to improve the protection +against corrosion - Anti-oxidants to delay the degeneration of the lubricant - EP (extreme pressure) additives to increase the load carrying capacity of the oil film. For oils the most common additives are: - Anti oxidants - Anti wear - Anti-foaming - EP - Rust-inhibiting Additives in a grease Adjusted rating life The bearing life Lnna calculated with SKF Life Method, where not only the load is considered but also several other factors e.g. lubrication, cleanliness etc. Aerospace The aerospace industry requires very special bearings produced according to detailed specifications for safety reasons. SKF supplies aero engine bearings as well as flight control systems and electromechanical equipment for fly-by-wire, airframe bearings and rods. Aerospace application products A common name for aero engine and helicopter bearings. Plain and rolling bearings as well as mechanical and electro-mechanical equipment for airframe and flight control applications. See also Solutions / Aerospace Aftermarket Customers using machines and equipment who need bearingseals and other products for replacement. The bearing aftermarket is mainly served by distributors. Paper mills and steelworks are examples of industries in the aftermarket. Alignment In order to achieve reliable functioning of a bearing arrangement, the shafts connected to each other must be carefully aligned. Today this is often achieved by laser assisted equipment. ABMA See American Bearing Manufacturers Association   American Bearing Manufacturers Association The American Bearing Manufacturers Association (ABMA) is a non-profit association consisting of American manufacturers of anti-friction bearings, spherical plain bearings or major components thereof. The purpose is to define national and international standards for bearing products. Ampep PLC An SKF company and manufacturer and designer of lubrication-free plain PTFE bearings for aerospace, automotive and industrial applications. See www.ampep.co.uk   Angular contact ball bearings Single row ball bearings in which the raceways of the inner and outer ring are displaced with respect to each other in the direction of the bearing axis. By this the load lines form an angle to the radial plane. This means the bearings are particularly suitable for accommodating simultaneously acting radial load and axial load in one direction. Usually mounted in pairs to give a stiff bearing arrangement. Double row angular contact ball bearings have two rows of balls arranged back-to-back. Thus the lines of action of the load at the contact between balls and raceways (load lines) diverge at the bearing axis and form an angle of 30° to the radial plane. This means the bearings are particularly suitable for accommodating simultaneously acting radial load and axial load in both directions. They are also available with seals or shields. See also Contact angle and four-point angular contact ball bearings as well as www.lec.skf.com Single row ball bearing Double row angular contact ball bearing Angular contact spherical plain bearings Plain bearings with spheroidal sliding surfaces on the inner and in the outer ring which are arranged at an angle to the bearing axis. They are therefore particularly suitable for carrying combined (radial and axial) loads. A single angular contact spherical plain bearing can only accept axial loads acting in one direction. Thus the bearings are usually mounted in pairs, adjusted against each other. The sliding contact surface combination is steel/PTFE composite. They are primarily intended for loads of constant direction and are maintenance free. Angular contact thrust ball bearings Designed to carry thrust loads but can also accommodate radial loads in addition to axial loads. Single direction bearings (1) are able to support axial loads acting in one direction only. In double direction bearings (2) the upper row of large balls has high load carrying capacity in one direction and the lower row of small balls locates the shaft in the opposite direction.Double direction bearings of design (3) are high precision bearings intended for machine tools and can only carry thrust loads. See also www.iec.skf.com Anti-Lock Braking System Modern cars use an anti-lock braking system (ABS) for more controlled braking on wet, slippery roads. In these braking systems an electronic sensor at each wheel detects wheel lockup, a condition where severe brake action prevents one or more wheels from turning although the vehicle is still moving. A central computer then modulates brake line hydraulic pressure in bursts to that wheel, allowing it to turn briefly under lower braking force. Braking efficiency is greatly improved and the car's steering ability is maintained. SKF wheel bearing unit HBU 3 equipped with ABS Sensor @ptitude™ An online web-enabled source for asset management knowledge that provides access to the global expertise of SKF and its alliance partners. Subscribers gain instant access to a knowledge bank of documents including articles, technical handbooks, best practices and benchmarking information, as well as web-based interactive decision-support services. See also www.aptitudexchange.com   Automotive SKF supplies a wide variety of standard and special bearings, including sensorised bearings as well as ready-to-mount bearing units, to the automotive industry for different car and truck applications. The range includes: - hub bearings for cars and trucks - Hub Units for cars and trucks - belt tensioner units- water pump spindles - clutch release bearings - propeller shaft intermediate and support bearings - propeller shaft centring bearings - suspension bearings - free wheel clutches. AquaMax See SKF AquaMax   Auto-Balancing unit See DynaSpin™   Axial load Load on a bearing acting in the direction along the shaft axis. This type of load is also called a thrust load. For heavy axial loads, a thrust bearing should be used.   Axlebox Bearing housing for railway applications incorporating cylindrical, spherical or taper roller bearings. The picture shows a taper roller bearing cartridge unit. Top of page