the cylindrical roller cam follower a superior product for a new century of industrial applications werner guilford director of engineering rbc bearings www.rbcbearings.com 800.390.3300
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switching to cylindrical rollers delivers other benefits as well dynamic capacity is primarily a function of the roller diameter thus dynamic capacity increases and is therefore greater per unit of o.d size figure 1 this means better fatigue endurance to make room for the larger roller diameter the wall thickness of the outer ring has been reduced to comply with standard boundary dimensions of the series 150000 rbc roller cam followers needle roller cam followers 120000 90000 rbc roller® cylindrical roller bearing cam follower u.s patent number 5531137 lbf 60000 rbc roller ® in response to strong market demand for a more durable cam follower capable of higher operating speeds and reliable maintenance-free operation rbc developed and patented the cylindrical roller bearing cam follower the rbc roller long lifetm cam follower this technical paper presents an itemization of the engineering design features that afford this superior level of performance and compares these characteristics
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relative rotation of rollers outer ring roller guidance center thrust ring roller guidance in full complement bearings adjacent rollers rub against each other in opposing directions as a result the grease film on the roller surface experiences a shearing action which tends to deteriorate the quality of the grease through oxidation the amount of shear is directly related to the number of rolling elements which determines at how many places shear occurs the relative velocity of adjacent rollers is also a determining factor in the generation of shear forces with fewer rolling elements of larger diameter the cylindrical roller cam follower has fewer locations of shear and the relative velocity between rollers is lower than in a needle roller cam follower figure 4 that means the grease charge in cylindrical roller cam followers does not oxidize as quickly which makes a lubricated for life cam follower feasible figure 3 cylindrical roller cam follower rotation outer ring vr2 r1 vri rolle
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in a cylindrical roller cam follower these voids between rollers and raceways become larger although there will be fewer of them but additional space for lubricant is provided in the area between the two rows of rollers and between rollers and seals this results in up to four times more grease in like-sized cylindrical roller cam followers than needle roller cam followers figure 6 in 95 of all applications more grease supply means longer service life origin of thrust forces this section will briefly examine the origin of thrust forces with which a cam follower must contend it can be assumed that the cam follower outer ring is not axially constrained e.g by running in a channel a condition that would introduce unpredictable thrust forces in a typical application the cam follower runs on a track parallel to its axis and its surface can only support perpendicular forces under these constraints thrust forces will be generated by misalignment either because the cam follower axis is not p
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unavoidable and shortens the life of needle bearing cam followers and compromises the sealing capability the cylindrical roller cam follower was developed to remedy this problem by providing more positive roller end support this improves the cam follower s ability to sustain and manage thrust loads resulting from type 1 misalignment figure 11 shows the type ii misalignment with the cam follower axis not perpendicular to the direction of motion in this case the outer ring wants to roll from point a to b but is forced to point c by the equipment the cam follower gets to c by a simultaneous rolling and sliding action consisting of rolling from a to b and sliding from b to c the thrust force generated by the sliding motion is the radial load times the coefficient of friction between outer ring and track note that the angle of misalignment does not enter into this equation therefore the magnitude of the thrust force is independent of the angle however the work done on the system and the amo
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speed limits and operating temperature the speed limit of a rolling bearing depends largely but not exclusively on roller guidance and lubrication oil lubricated bearings can usually be operated at a speed 50 higher than grease lubricated bearings however roller guidance has a much more profound effect on the maximum permissible speed typically the speed limit for full complement needle bearings ranges from 50,000 to 80,000 dn where dn is the bearing inside diameter in millimeters times the rotational speed in rpm the speed limit for unsealed cylindrical roller bearings ranges from 200,000 to 400,000 dn however in the case of a sealed cylindrical roller cam follower like the rbc roller the speed is limited by the maximum permissible surface speed of the seal usually around 1,000 to 1,200 ft/min figure 14 14 12 10 8 million 6 revolutions 4 2 0 cylindrical roller needle roller 10000 9000 8000 7000 rbc roller cam followers needle roller cam followers figure 15 cylindrical roller cam foll
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summary the rbc roller represents a superior alternative to the classic needle bearing cam follower design circa 1950 this product has been developed to achieve higher reliability in the demanding operating environments of modern machinery and is produced from the finest bearing quality steels the table below summarizes those important design features that achieve this superior performance level comparison of rbc roller cylindrical roller cam followers and needle roller cam followers dynamic capacity cylindrical roller cam followers are rated 30 to 70 higher than like-sized needle roller cam followers increased dynamic load capacity directly influences a design operating life that can be over five times that of needle roller cam followers superior guidance of short cylindrical rollers in the rbc roller cam follower permits operating speeds that are nearly twice those of needle roller cam followers the contacting lip seals of the rbc roller cylindrical roller cam follower provides more
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rbc bearings designs and produces precision bearings in 12 facilities in north america and europe founded in 1919 the corporate headquarters is in fairfield connecticut usa products produced by rbc include quadlube® and impacttuff® spherical plain bearings pitchlign® heavy-duty needle roller bearings tyson® tapered roller bearings heim® rod ends precision ground ball screws thin section radial bearings nice® ball bearings fiberglide® self-lubricating plain bearings needles and rollers and a wide variety of cam followers since rbc first produced cam followers in 1939 numerous design enhancements have been implemented by the company the patented rbc roller cylindrical roller cam follower described in this report is a major improvement over traditional needle roller cam followers in numerous performance areas © copyright 2002 roller bearing company of america no part of this publication may be reproduced in any form without the prior written permission of roller bearing company of america
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