400 COMMONWEALTH DRIVE WARRENDALE, PA 15096 810757 Automotive Hub Bearing Units—European Experience Sven A. Benktander SKF Passenger Car Meeting Dearborn, Michigan June 8-12, 1981 Downloaded from SAE International by University of British Columbia, Sunday, August 19, 2018The appearance of the code at the bottom of the first page of this paper indicates SAE's consent that copies of the paper may be made for personal or internal use, or for the personal or internal use of specific clients. This consent is given on the con­ dition, however, that the copier pay the stated per article copy fee through the Copyright Clearance Center, Inc., Operations Center, P.O. Box 765, Schenectady, N.Y. 12301, for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for genera! distribution, for advertising or promotional purposes, for creating new collective works, or for resale. Papers published prior to 1978 may also be copied at a per paper fee of $2.50 under the above stated conditions. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Order Department. To obtain quantity reprint rates, permission to reprint a technical paper or per­ mission to use copyrighted SAE publications in other works, contact the SAE Publications Division. ISSN 0148-7191 Copyright © 1981 Society of Automotive Engineers, Inc. Downloaded from SAE International by University of British Columbia, Sunday, August 19, 2018810757 Automotive Hub Bearing Units—European Experience Sven A. Benktander SKF Traditionally, the front wheel hub bearing arrangement for driven as well as non-driven wheels, has comprised two bearings, usually of the separable type, so that four bearing components have been involved. Interest in a pre-adjusted assembly for driven wheel hubs was early shown by the automotive industry. This would eliminate the need for adjustment or for the close tolerances on many components required for random assembly methods. Today double row ball bearing units are commonly used in the hubs in European motor car production; some of these incorporate the hub function. BACKGROUND The first application dates back to 1936 when the forerunner of present hub bearing units was developed by Citroen and SKF for the driven front wheels of the Citroen Berline 15 CV; fig. 1. In most post-war driven front wheels bearings still had to be adjusted. In the sixties the trend turned towards the use of random assembly methods. A typical assembly which still uses two separate bearings is shown in fig. 2. It includes two inner rings with intermediate spacer, two outer rings and two oil seals. The outer rings abut shoulders in the forged hub carrier. Thus, if random assembly is to give correct axial clearance, six components have to be made to stringent tolerances. FIRST GENERATION OF PRE-ADJUSTED UNITS The break-through for the pre-adjusted double row angular contact ball bearing with two-part inner ring and seize-resistant moulded cages came 15 years ago. This subsequently became a sealed and greased-for-life unit. One of the first applications was the NSU Ro BO, the first production car with a Wankel engine. The same arrangement was adopted by Volkswagen for their first front wheel drive car, fig. 3a. A steel sleeve was cast into the light alloy carrier to provide a seating for the bearing. The light alloy design has since been dropped. Fig. 3b shows a typical front wheel arrange­ ment of today; the carrier is a steel forging. Another design incorporates a pressed and welded hub carrier fig. 3c. Again a double row angular contact ball bearing unit with two-part inner ring and moulded cages is used. The bearing is sealed, the lips of the flat rubber seals riding on the inner ring. Adjacent components provide extra protection against water and dirt