From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article announcing the development of the Fafnir New Mechanical Seal for bearings, with a related piece on its application in a furnace.
| Identifier | ExFiles\Box 115\2\ scan0556 | |
| Date | 1st November 1940 guessed | |
| The DRAGON Fafnir Develops New Mechanical Seal Absolute Protection Provided for Bearings Incorporating It THOSE ACQUAINTED with the problems of machine design know that ball bearing manufacturers have always recommended adequate closures or seals for ball bearing mountings. For efficient performance and satisfactory service, the mounting design must both keep the lubricant in and the dirt out, and also permit easy assembly and disassembly. Until very recently there were so many varied solutions offered to this requirement that often-times it was merely the personal preference of the machine designer that formed the sole basis for the selection of one of the numerous designs available. DEVELOPMENT OF SEAL AND SHIELD TYPES In an effort to effect a standardization of closures to relieve the machine builder of the necessity of designing his own sealing system, The Fafnir Bearing Company in years past has developed and marketed Grease-Shield and Felt-Seal Bearings which have proved entirely adequate for normal service conditions. In the most difficult service, however, where the highest seal efficiency is most desired, the problem heretofore has not been fully solved by any bearing maker. NEW SOLUTION FOR ABNORMAL SERVICE CONDITIONS After an extensive program of testing various types of seal combinations under the most severe operating conditions, The Fafnir Bearing Company has finally perfected an entirely new and super-efficient mechanical seal for use where the greatest efficiency is essential. This design provides positive protection against all floating dirt or moisture and at the same time retains the lubricant without increasing bearing friction or losing seal efficiency. Although this design is not effective against liquids under head or pressure, it does render a definite contribution to ball bearing mounting design in that it is no longer necessary to embody supplementary sealing pieces in the housing to attain maximum seal efficiency under all other conditions. The Fafnir Mechani-Seal design—leakproof and secure; external rotating slinger for dirt exclusion; inner trap seal for grease retention; and close clearances with no rubbing contact. DETAILS OF DESIGN The Mechani-Seal, by which term this design is defined as a mechanical seal The DRAGON draw furnace) has been perfected after a comprehensive experimental period, in which all requirements were carefully studied and each feature of the design painstakingly checked. The recirculating blower generates a continuous rapid circulation of the hot gases through the load. The blowers in the various units have ample capacity to develop very rapid circulation, which eliminates any excessive temperature drop in the gases as they pass through the work. This insures uniform temperature throughout the charge at all stages of heating. The “C” Cartridge is furnished complete with bearing, cap, wire and collar. This furnace incorporates many unique features. For instance, there is the ingenious cover arrangement which automatically shuts off the main burner as well as stops the blower the instant the unit is opened, thus affording the operator added protection from any blast of hot gases. In the fan construction which follows closely the design that Eclipse has been successfully manufacturing for the past twenty years, the fan shaft is a specially designed air-cooled unit. Small outside fans or rotors draw cool air through the hollow end of the shaft, thereby offsetting the conducted heat from the hot fan chamber and keeping the bearing points on the shaft cool. Considered vital for the continuous and satisfactory operation of the fan unit was a high-grade ball bearing mounting. Operating, as they must, under varying conditions of temperature, dirt, grit, and under long hours of continuous service (with perhaps little or no care) these bearings must necessarily possess such attributes as precision, sturdiness and dependability. Selection of the Fafnir Wide Inner Ring Type (employing the Self-Locking Collar which makes for a positive drive without the need for shaft shoulders) resulted in the obtaining of these various characteristics in full measure. Briefly, plain bearings could not be considered for the Eclipse application because of the disadvantages in lubrication, dust protection, etc. Nor was it found advisable to build a bracket on which could be mounted the conventional ball bearing pillow block or blower box. Thus, the use of the Fafnir Cylindrical Cartridge, incorporating the Self-Aligning B Type Wide Inner Ring Bearing, appears to have been an ideal solution. Applied and mounted as a unit, this “C” Cartridge is fitted in a straight-bored housing with a push fit, while lubrication is provided for by means of a grease plug. An assembly of a cap, wire and collar furnishes ample sealed protection for the bearing itself. 8 5 | ||