A90 Series Correspondence Lessons PART D Roller Bearings Lesson A9010 Cylindrical and Hyload Roller Bearings Lesson A9011 Self Aligning Spherical Roller Bearings Lesson A9012 Needle Rollers and CAM Followers
PART D Roller Bearings Series 90 Training
Correspondence Course LESSON A9010 Cylindrical and Hyload Roller Bearings PART D Roller Bearings Lessons A9010 to A9012 Table of Contents 1000 Series Bearings 5 E' Suffix 5 Metric Cylindrical Roller 4 200 Series Bearings 5 - imperial bearings 6 Metric Numbering 5 Systems - Metric Cyl Roller 5 - Metric bearings 5 MRJ, MRJA, NMRJ, NMRJA, 6 MMRJB, NMRJN - Hyload Type 8 HJ 4 N, NC, NJ 4 2200 Series Bearings 5 Hyload Interchange 12 NN 4 2300 Series Bearings 5 Hyload Numbering Chart 11 NNU, NU 4 300 Series Bearings 5 Hyload Roller Bearings 8 NUP 4 - Metric Cyl Roller 5 Imperial Cylindrical Roller 6 OR 8 - Hyload Type 8 Internal Clearance 3 RA 8 3000 Series (NN) Bearings 5 IR 8 Radial Clearance 3 400 Series Bearings 5 'K' Suffix 5 Roller Assemblies 13 4900 Series Bearings 5 Line Contact Rolling Motion 3 - Imperial 13 90000 Series Bearings 13 LRJ, LRJA, LLRJ, LLRJA 6 - Metric 9 Configurations 7 LLRJB, LLRJN 6 Taper Ratio 5 Crowned Rollers 3 MA - - - -... 10 WIR 8 Cylindrical Roller Bearings 3 MR - - - -... 10 WOR 8 DIR 8 MSN - - - - EX 10 WRA 8 DOR 8 MU - - - -... 10 XLRJ, XLRJA,XLLRJA 6 XLLRJKB, XLLRJN 6 Structured Training Plan This lesson is the tenth of a series of Correspondence lessons in the BSC Structured Training Plan. Objectives The objective of this lesson is to introduce students to cylindrical roller bearings including the standard range and the Hy-Load solid roller assemblies. An explanation of the numbering system will also be undertaken. Pre-requisites Completion of Lessons A9001 - A9009. Methods Achievement of the objectives is by presentation of lessons in an 'On-Line' or Correspondence Course format. The lessons in a Correspondence Course style are conducted for internal students in a lecture situation. Assessment A formal test is provided with this lesson. LESSON A9010 Series 90 Training
LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 2
Cylindrical Roller Bearings All bearings discussed so far have been Ball Bearings, that is, they have steel balls as their rolling elements. Cylindrical Roller bearings are similar to Ball bearings except that the rolling elements are steel rollers instead of steel balls. Remember, Roller bearings convert sliding friction into Line Contact Rolling Motion and are able to take larger radial loads than ball bearings. Some of them, if they have shoulders on both rings and the thrust is from the right direction, can take light thrust loads. Internal Clearance Cylindrical Roller bearings are made with an inbuilt NON- ADJUSTABLE INTERNAL RUNNING CLEARANCE. Crowned Rollers Most standard cylindrical roller bearings use a stamped steel cage to properly space the rollers around the bearing. Special precision made cages are used for applications involving extreme operating conditions, such as high loads or speeds, shock loads or vibrations. Some are precision machined from steel or bronze, others stamped from brass and still others are now being made from high impact plastics. The surface of a cylindrical roller is not perfectly straight, but slightly "crowned". This improves the distribution of stress due to loads and compensate for minor misalignment between rollers and raceways (see diagram to the right). Cylindrical Roller Bearings are manufactured to both metric and imperial dimensions. LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 3
Metric Cylindrical Roller Bearings There are several types of metric cylindrical roller bearings, most with a removable inner or outer ring. The illustration below shows the various types. NC TYPE ---Not very popular. Both rings nonremovable. NUP TYPE ---Outer ring has two lips. Inner ring has one integral lip & a loose (ring) lip. NU TYPE ---Outer ring has two lips. Inner ring lipless & removable. NJ & HJ TYPE - NJ type with an angle ring (hj). An angle ring can also be fitted to NU type. NJ TYPE ---Outer ring has two lips. Inner ring one lip, removable from one side. NN TYPE ---Double row N type. N TYPE ---Outer ring lipless & removable. Inner ring has two lips. NNU TYPE ---- Double row NU type. One further type needs mentioning and that is the RNU TYPE. This bearing is an NU type supplied without the inner ring. LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 4
NUMBERING SYSTEM - METRIC There are six series in single row cylindrical roller bearings (types NC, NU, NJ, N, NUP, and RNU) as below: EXTRA LIGHT SERIES 1000 LIGHT SERIES 200 LIGHT WIDE SERIES 2200 MEDIUM SERIES 300 MEDIUM WIDE SERIES 2300 HEAVY SERIES 400 The bore code is the same as for Deep Groove Ball Bearings eg. Part number NU203 is a Metric Cylindrical roller bearing of the light series with a 17mm Bore. The extra light series is not very popular and is normally only made in N or NU type only. Some of these bearings are being manufactured to take a higher Radial load than the equivalent standard bearing. The suffix "E" is used to distinguish these bearings. Note - the standard bearing, of the same size and series can not be used to replace an "E" type. NSK adds an additional letter to the E suffix to show the cage material: T: Polyamide Cage M: Machined Brass Cage W: Pressed metal Cage Double Row Metric cylindrical roller bearings have their own numbering systems. The NN type always has the series number 3000 whereas the NNU type always has the series number 4900. Again, the bore code is the same as Deep Groove Ball bearings. These bearing can be supplied with a Tapered Bore so that they can be mounted on a shaft with an adaptor or withdrawal sleeve (see lesson titles "Transmission"). When they have a Tapered Bore the suffix "K" is placed after the part number. The Taper ratio is 1:12. LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 5
Imperial Cylindrical Roller Bearings These are made in the same basic types as metric CR bearings but have different series numbering. An illustration of the various types is shown below. The code for the bore is simply the bore size in whole numbers and fractions. On older bearings at 4" and "E" was added to whole numbers to distinguish them from metric bearings EG.LRJ 1-1/4, MRJA 5E, this practice has now ceased. As with all bearings care must be taken to identify the bearing type as well as the part number as different manufacturers use similar part numbers for different bearings. NUMBERING SYSTEM - METRIC There are three series in Imperial CR bearings: EXTRA LIGHT SERIES -XLRJ, XLRJA, XLLRJA, XLLRJKB, XLLRJN LIGHT SERIES - LRJ, LRJA, LLRJ, LLRJA, LLRJB, LLRJN MEDIUM SERIES - MRJ, MRJA, NMRJ, NMRJA, MMRJB, NMRJN The code for the bore is simply the bore size in whole numbers and fractions. On older bearings at 4" and "E" was added to whole numbers to distinguish them from metric bearings EG.LRJ 1-1/4, MRJA 5E, this practice has now ceased. As with all bearings care must be taken to identify the bearing type as well as the part number as different manufacturers use similar part numbers for different bearings. LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 6
Configurations Cylindrical Roller Bearings are divided into three distinct types, Separable inner ring, Separable outer ring and Non-Separable types. The Illustrations to the left show the first two combinations and from this you can see that the cage assembly may be attached to either the outer ring or the inner ring. This is sometimes referred to as an outer ring riding or inner ring riding cage. In order to save space, some applications may have an outer ring and cage assembly running directly on to the shaft in which case the shaft would have to be specially hardened to take the wear. An Inner ring and cage assembly could also be installed directly into a hardened housing. We stock our standard range Cylindrical Roller bearings as complete units, even if the components are separable. However, we also carry the Hyload range and these are stocked as separate parts wherever practicable. LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 7
Hyload Type Roller Bearings The Hyload range of bearings consists of a special series of bearings and bearing parts. These are manufactured to AFBMA standard and may be sourced on various suppliers. The following brands may be found in stock:- RBC, FMC, BOWER/BCA, DELCO-HYATT(NDH), ROLLWAY We will look at these products under the two separate headings of ROLLER ASSEMBLIES (RA) and SOLID ROLLER ASSEMBLIES. Roller Assemblies RA Roller assemblies are characterised by having rollers whose length is greater than the diameter (often many times greater). The rollers have Nibs at each end which seat into the cage assembly. The cage assembly comprises of end plates held in place by solid steel spacer bars. An illustration is shown below. Inner and outer races are completely removable and are supplied as separate items. These units can be used in the following ways:- Direct onto a shaft Direct in the housing bore On a solid inner race On a solid outer race In a split outer race The roller assembly numbering system is based on the following prefix letters:- RA - Roller Assembly WRA - Wide Roller Assembly IR - Inner Race WIR - Wide Inner Race DIR - Double Width series Inner Race OR - Outer Race WOR - Wide Outer Race DOR - Double Width series Outer Race The prefix is followed by a three digit number that indicates the series and bore size. There are two series: Light series 200 Medium series 300 LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 8
As these bearings are metric, the bore size code is the same as for Deep Groove Ball bearings, EG. Part number RA209 tells us it is a Roller Assembly, light series with a 45mm bore. SOLID ROLLER ASSEMBLIES These are metric roller bearings that are available in three different types:- Separable Inner Race Type Separable Outer Race Type Non-Separable type BSC stocks the separable types as separate parts: Inner Raceways Inner Raceways and Roller Units Outer Raceways Outer Raceways and Roller units An illustration of these three main types is given below along with the prefixes and suffixes for each type. We source these bearings from PTC Link Belt and the bearings are made by FMC. Thus we use FMC's numbering system. These bearings identified by a system of numbers and letters. The numbers indicate the bearing series and size, and the letters indicate the bearing configuration. The inner race is identified by a prefix and the code number (eg MA 1209), whilst the outer race is identified with 'M', the code number and a suffix. (eg M 1308 TV) The code number is made up of four numbers which indicate the series and size of the bearing. The first number indicates what width the bearing is:- 1 - Narrow width 5 - Wide width 7 - Intermediate width The second number indicates the series:- 0 - Extra light series 2 - Light series 3 - Medium series 9 - Extra Extra Light series LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 9
The third and fourth numbers indicate the bore size and the code is the same as used for Deep Groove Ball bearing (i.e. code x 5 = bore size). Segmented Steel Cage Separable Inner Type Formed Steel Cage Formed Steel Cage Separable outer ring type Segmented Steel cage Inner Ring No Rib Outer Ring No Ribs Inner Ring One Rib Outer Ring One Rib Inner Ring one Rib and End Plate Outer Ring One Rib and End Plate Non Separable Type Formed Steel Cage Non Separable Full Complement type Formed Steel cage Cageless Cageless A better explanation of the hyload bearing codes used is given in the Table below. LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 10
A9010 TABLE. Hyload Bearing Codes SYMBOL DESCRIPTION M A - 1 2 05 GEA X M A R SN U S (NONE) 6 1 5 7 0 2 3 9 05 G GG R RR C D E SN T U A H X M V B Metric series designation Plain cylindrical inner ring Single rib inner ring Short, single rib w/inner ring side plate Double rib inner ring Metric size bore of next smallest bearing Standard capacity High capacity series Narrow width Wide width Intermediate width Extra light series Light series Medium series Extra extra light series Bore size code (bore size divided by 5) Snap ring groove in outer ring O.D. Two snap ring grooves Snap ring groove in outer ring O.D. with snap ring Two snap ring grooves in outer ring O.D. with snap rings Plain cylindrical outer ring Single rib outer ring Double rib outer ring Short single rib with outer ring side plate Outer ring with two retaining rings in I.D. Single rib outer ring with one retaining ring in I.D. Oversize O.D. outer ring Blind dowel hole in outer ring O.D. Segmented cage Full compliment (no cage) Formed Steel Cage Polymeric cage LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 11
Hyload Interchange A quick reference comparison to other manufacturer s part numbering systems is given below. Caution needs to be taken when interchanging these bearings to ensure all factors, such as the internal clearance, type of cage and lubrication, are taken into account as well as dimensional interchangeability. FMC Separable outer ring type MU - - - - CX MU - - - - DX MU - - - - SNX HYATT BU - - - - Z BU - - - - L BU - - - - LNJ MU - - - - TV U - - - - TS Non Separable Types MU - - - - UV ROLLWAY U - - - - E U - - - - L U - - - - LP U - - - - B U - - - - J BOWER MU - - - - CL* or MU - - - - CV MU - - - - DL* or MU - - - - DV MU - - - - SNL* or MU - - - - SNV MU - - - - TV MU - - - - TM U - - - - YS U - - - - TM MU - - - - UV or MRY - - - - EL* UM - - - - B MU - - - - TM MU - - - - UM U - - - - YM UM - - - - J MU - - - - UM or MRY - - - - EM# FMC HYATT MA - - - - TV A - - - - TS MA - - - - UV A - - - - YS Separable inner ring type MA - - - - EX A - - - - WB MR - - - - TV R - - - - TS MR - - - - UV R - - - - YS MR - - - - EX R - - - - WB MSN - - - - EX JRN - - - - WB ROLLWAY E - - - - B E - - - - J E - - - - U L - - - - B L - - - - J L - - - - U LP - - - - U BOWER MA - - - - TV or MA - - - - EL* MA - - - - UV or MA - - - - EL* MA - - - - EL* MR - - - - TV MR - - - - UV or MR - - - - EL* MR - - - - EL* MSN - - - - EL* * Not a fully segmented cage # Rib and snap ring on inner ring, two ribs on outer A9010 Table - Symbol LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 12
90000 SERIES ROLLER ASSEMBLIES The 90000 series are inch dimension solid roller assemblies similar in appearance to the metric series shown on page 7. The numbering system is based on the following:- FIRST DIGIT Always 9 9 SECOND DIGIT THIRD DIGIT FOURTH DIGIT & FIFTH DIGIT Indicates roller diameter Indicates shaft size: Indicates the width of the bearing in 1/16" units. 2 = 5/32" diameter 3 = 3/16" diameter 4 = 1/4" diameter 5 = 5/16" diameter 6 = 3/8" diameter 9 = This is a special series 1 = 1/2" 2 = 5/8" 3 = 3/4" 4 = 7/8" 5 = 1" 6 = 1-1/8" 7 = 1-1/4" 8 = 1-3/8" 9 = 1-1/2" EG. 94512 = 3/4" width (12/16ths). LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 13
LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 14
A9010 Questionnaire Name: Employee No (from Payslip): Branch (eg QAA) Date: Cylindrical Roller Bearings Questions Q1. Cylindrical Roller Bearings have inbuilt internal running clearance. Answers A. Adjustable B. Non adjustable C. Standard Q2. A cylindrical Roller Bearing is said to be 'CROWNED'. This means that: A. Convex circumference B. Parallel circumference C. Concave circumference Q3. Which of the following types of cylindrical roller bearings has a removable inner ring? A. N B. NU C. NUP D. NC E. NN LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 15
A9010 Questionnaire (cont.) Name: Employee No (from Payslip): Branch (eg QAA) Date: Cylindrical Roller Bearings Q4. Explain the part number N 207 WE C3. A. N A. 2 lips on inner ring, none on outer B. 1 lip on inner ring, 2 on outer C. Non separable B. 2 A. Light series B. Medium series C. Heavy series C. 07 A. 7 mm bore B. 25 mm bore C. 35 mm bore D. W A. Wide series B. Steel cage C. Steel shields E. E A. Extra radial load capacity B. Extra wide series C. Polyamide cage F. C3 A. Less than standard clearance B. Standard clearance C. Greater than standard clearance LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 16
A9010 Questionnaire (cont.) Name: Employee No (from Payslip): Branch (eg QAA) Date: Cylindrical Roller Bearings Q5. Enter the prefix for each of the following LIGHT SERIES cylindrical roller bearing types in metric and imperial and also the same configuration in Hyload: A Metric Imperial Hyload For Hyload answers please use format like MU - - - - UV. B. C. Q6. Select the attributes which describe a a WRA 206: A. Angular contact bearing B. Wide roller assembly C. Light series D. Medium series E. 6mm bore F. 30mm bore LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 17
A9010 Questionnaire (cont.) Name: Employee No (from Payslip): Branch (eg QAA) Date: Cylindrical Roller Bearings Q7. Indicate the following as Inner Ring or Outer Ring only or as Ring and Roller Assembly, or as complete unit (Non-seperable). Tip - Refer to the diagram on page 8 and the chart on page 9. A. MU 1206 UV A. Non separable B. Inner ring Only C. Inner ring and roller assembly, separable. B. MA 1309 A. Non separable B. Inner ring only C. Inner ring and roller assembly C. MU 1308 TV A. Outer ring and roller assembly B. Inner ring only C. Inner ring and roller assembly D. MU 1313 X A. Outer ring and roller assembly B. Inner ring only C. Inner ring and roller assembly Q8. Describe a MU 5211 TV. A. Double ribbed inner ring B. Double ribbed outer ring C. Single ribbed inner ring Q9. What is the roller diameter of a 94526? A. 3/8 inch B. 1/4 Inch C. 5 mm Q10. What is the width of a 94532? A. 1 inch B. 2 inches C. 32 mm. LESSON A9010 Cylindrical and Hyload Roller Bearings Series 90 Training page 18
Correspondence Course LESSON A9011 Self Aligning Spherical Roller Bearings PART D Roller Bearings Lessons A9010 to A9012 Table of Contents Adaptor Sleeves 6 Numbering Systems: C type 3 - SASR Bearings 4 CAM type 3 - SR Thrust Bearings 7 CD type 3 - Vibrating Screen Bearings 8 EA Type 3 Press Fitting 5 Externally Self Aligning 3 Self Aligning Bearings 3 HPS series 3 Shrink Fitting 5 Internally self Aligning 3 Spherical Roller Bearings 3 K suffix 5 Spherical Roller Thrust 7 Lubricating Groove 4 Suffixes Used 5 M type 3 Vibrating Screen Bearings 8 Misalignment 3 Withdrawal Sleeves 6 Structured Training Plan This lesson is the eleventh of a series of Correspondence lessons in the BSC Structured Training Plan. Objectives The objective of this lesson is to acquaint students with self aligning spherical roller bearings. Pre-requisites Completion of Correspondence Lessons A9001 - A9010. Methods Achievement of the objectives is by presentation of lessons in an 'On-Line' or Correspondence Course format. The lessons in a Correspondence Course style are conducted for internal students in a lecture situation. Assessment A formal test is provided with this lesson LESSON A9011 Series 90 Training
LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 2
Self Aligning Bearings In lesson 9, we discussed ball bearings which are designed to cope with shaft misalignment which occurs when the housing and shaft are not exactly aligned along the same axis. Bearings may be either externally self-aligning or internally self aligning. Externally self aligning bearings rely on a spherical surface on the outer surface of the outer ring of the bearing which is either in contact with a matching second outer ring, or, more commonly, is mounted in a spherically ground housing. This is illustrated in the diagram below and is often used in the Wide Inner Ring type bearings which we will discuss in more detail in lesson 15. Internally self aligning bearings have a spherically ground inner surface on the outer ring and this matches the contours on the steel roller as shown in the diagram to the right. Spherical Roller Bearings These bearings feature two rows of barrel-shaped rollers which can align themselves freely in the spherical outer ring raceway. One feature is the ability to handle some misalignment of the shaft caused by mounting errors or shaft bending. They have a good radial load capacity and a capability to sustain thrust loads in either direction The current range supplied by NSK is their HPS (high performance spherical) type. NSK claim up to 2 times the life of previous designs and up to 20% higher limiting speed. For more information on this product see page 63 of The Manual 2007. There are basically three designs produced by NSK as shown below. CAM Type - Has outer shoulders on the inner ring and a floating guide ring to guide the rollers - the cage is one piece machined brass type. EA, C and CD Type - Has no shoulders but has a piloted roller guide in between the rollers - Cage is 2 piece pressed steel "pocket" type. M Type - has inner and outer shoulders on the inner ring and a 1 piece machined brass cage. The amount of misalignment which these bearings can handle varies from 1% to 2.5% depending upon the dimensional series and the loading. LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 3
A lubricating groove and hole can also be supplied if required and are standard on all bearings with a bore size of greater than 200 mm. Each of these three types is available with either a parallel (straight) bore, or with a tapered bore. We will discuss mounting methods later in the series but you will find a brief summary on page 4 of this lesson. S.A.S.R. NUMBERING SYSTEM The part number is made up of a five digit number (up to and including 480mm bore size followed by suffixes. There are nine different series that vary from each other in capacity and boundary dimensions. The series numbers are: 213-- 222-- 223-- 230-- 231-- 232-- 239-- 240-- 241-- The number always starts with a "2". The second number indicates the width series: 1 - Very Narrow Series 2 - Narrow Series 3 - Wide Series 4 - Extra Wide series. The third digit indicates the diameter series: 9 - Extremely Small Series 0 - Very Small Series 1 - Small Series 2 - Medium Series 3 - Large Series The last two digits are the bore code which is the same as used for deep groove ball bearings. At 500mm the part number changes to a six digit number. The first three digits are either 230, 231, 232, 239, 240 or 241 which is then followed by a '/' and then the actual bore size in millimetres, e.g. 239/630. LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 4
Suffixes used by NSK CAM - type as explained on previous pages. EA, C, CD - type as explained on previous pages. M - type as explained on previous pages. K - Tapered bore ratio 1:12 on diameter (this is the common standard) K30 - Tapered bore ratio 1:30 on diameter. E4 - Oil groove and oil hole present on outside diameter of outer ring. M - Machined brass cage. The spherical Roller range includes a surprisingly large size variance from the smallest to the biggest. Whilst the smaller S.A.S.R bearing may be only 25mm bore size, the largest carried in stock against specific contract requirements sometimes fill an entire pallet (one bearing per pallet). Fitting of Spherical Roller Bearings Here is a summary of the main ways in which a spherical roller bearing can be fitted to a shaft. Shrink Fitting All bearings need some method of fixing them on the shaft so that they remain in the installed position. When parallel bore bearings are used, the bearing is usually shrink fitted onto the shaft. This means that the bearing is heated up which causes it to expand. It is then slid on to the shaft and aligned to the required position, usually within a bearing housing. Once the bearing has cooled, it will be firmly located on the shaft. Press Fitting Parallel bore bearings may also be fitted using a tubular drift. This is a hollow tube, slightly larger on the inside diameter, than the shaft. For larger bearings, the bearing is assembled onto the shaft and the tubular drift is aligned to the bearing inner ring. This whole assembly is placed in a hydraulic press which is activated to press the bearing onto the shaft, to the required position. In this case it is important that the drift should only be in contact with the inner ring of the bearing, otherwise, the tapping action may be transmitted through the rolling elements, thus damaging the raceway at the contact point. Smaller bearings may be assembled in a similar manner but with the use of a hammer on the drift, to tap the bearing into position. In practice, both shrink fitting and press fitting would probably be combined. LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 5
Adaptor and Withdrawal Sleeves Tapered bore bearings allow fitting with either of two methods, known as Adaptor sleeve or Withdrawal sleeve. Adaptor sleeves are supplied with a nut and lock washer. During assembly, the sleeve is fitted on to the shaft, and the bearing positioned on to the sleeve with the tapered surfaces aligned so that they are in contact. The tabbed washer and nut are then added. the nut is tightened using a special tool and this forces the bearing further along the tapered surface of the sleeve. This has a tightening effect and so the bearing becomes firmly located on the shaft. The nut has indentations in it's outer surface and one of the tabs from the tab washer would be bent into the indentation to prevent the nut slackening off. Withdrawal sleeves are not very popular these days, but rely on a sleeve which is pressed into the gap between the inner ring of the bearing and the shaft. Unlike the Adaptor sleeve, a not is not normally supplies. the purpose of the nut is to assist removal of the sleeve and thus, it is only required during dis-assembly. This is only an Introduction to bearing fitting - a more detailed discussion will be included in lesson 16. LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 6
Spherical Roller Thrust Bearings Although not in very great demand, NSK and other suppliers do manufacture a thrust version of the spherical roller bearing. The Main advantages of these is that they are self aligning which allows them to self-adjust for mounting errors, and they have a very high thrust capacity. Although they can operate at very high speeds, they are best suited in slower speed applications under heavy load conditions, because of inherent lubrication difficulties. Up to 2% misalignment can be handled by Spherical Roller Thrust Bearings. NUMBERING SYSTEM The part number begins with "29"and there are 3 series" 292-- 293-- 294-- The number always starts with "29". The third digit indicates the diameter series: 2 - Light Series 3 - Medium Series 4 - Heavy Series The last two digits are the bore code which is the same as used for deep groove ball bearings. At 500mm the part number changes to a six digit number. The first three digits are either 230, 231, 232, 239, 240 or 241 which is then followed by a '/' and then the actual bore size in millimetres, e.g. 292/500 LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 7
Vibrating Screen Bearings A specially designed bearing is available for use in vibrating applications such as screens, compactors and feeders. These are often referred to as 'Shaker Screen Bearings' in the industry. These are modified versions of the standard bearing which have been designed to suit the rugged conditions of the application. These bearings are identified by two suffix character groups - 'U15' and 'VS' which indicate the following: U15 Reduced OD tolerance for improved housing fit. Reduced bore tolerance so that slippage is minimised. Precise internal clearance to control load distribution and heat generation. VS Vibrating Screen Bearing with special surface finish to ensure smooth operation and low running temperatures. Special heat treatment to increase shock loading capabilities. Vibrating Screen Bearings are supplied with machined brass cage, Type CAM-VS. The Heavy-duty two piece centrifugally machined brass cage permits each roller path to operate independently. Rollers are designed to operate in conjunction with the centre guide flange for improved guidance, reduced friction and cooler running. The rollers also are specially contoured on the OD and end to reduce heat and stress. Bearing Service has found this type of bearing to be preferable to the polyamide cage type since it is able to handle greater operating temperatures and is more suited to the rugged conditions. Numbering System There are only 23 Part numbers in this range, and the first 5 digits are in a similar format to standard type spherical rollers. Suffixes are as follows CA- CA Type M - Machined Brass Cage E4 - Oil groove in the outer raceway U15 - Reduced Tolerances - see section above VS - Vibrating Screen type - see above LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 8
A9011 - Questionnaire Name: Employee No (from Payslip): Branch (eg QAA) Date: Self Aligning Spherical Roller Bearings Questions Q1. There are two types of self aligning bearings. Please select these from the list. Answers A. Spherically self aligning B. Internally self aligning C. Externally self aligning D. Centrally self aligning E. Radially self aligning Q2. The rolling elements in a self-aligning spherical roller bearing are...? A. Tapered rollers B. Cylindrical rollers C. Barrel shaped rollers Q3. Currently, NSK is supplying Spherical Roller bearings in their HPS range. What does the initials HPS stand for? A. High performance spherical B. High phosphor steel C. High performance specials Q4. What is the taper ratio of a 22210K? A. 1:12 B. 1:40 Q5. Diagnose the part number 22220CDKE4C3 by typing the numbers and letters into the boxes provided. For Example, if you think that E4 is the clearance indicator, type E4 in box B. A. Oil hole and groove. B. Clearance indicator. C. No shoulders, piloted roller guide, 2 piece pressed metal cage. D. 1:12 ratio tapered bore. E. 100 mm bore size F. DRSR Bearing, narrow Width series, medium diameter series LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 9
A9011 Questionnaire (cont.) Name: Employee No (from Payslip): Branch (eg QAA) Date: Self Aligning Spherical Roller Bearings Q6. Why are some bearings supplied with a tapered bore? A. To allow them to be fitted using an adaptor or withdrawal sleeve. Q7. What is the bore size of a 23956 selfaligning spherical roller bearing? A. 560 mm B. To make it easier to machine out to the correct shaft size. C. To reduce the contact area. B. 180 mm C. 280 mm Q8. What is the bore size of a 239/560 self-aligning spherical roller bearing? A. 560 mm B. 180 mm C. 280 mm Q9. What misalignment can be handled by a spherical roller thrust bearing? A. up to 1 % B. up to 2% C. up to 3% Q10. What does the letters 'VS' indicate when used in the part number 223320CAME4C3U15-VS? A. Vibrating screen bearing B. Very small bearing C. Thrust type bearing LESSON A9011 Self Aligning Spherical Roller Bearings Series 90 Training page 10
Correspondence Course LESSON A9012 Needle Rollers and CAM Followers PART D Roller Bearings Lessons A9010 to A9012 Table of Contents Cage 4 Open Type 3 Cam Followers 13 Outer Ring (OR) 3 Cam Followers Part Numbers 15 Part Numbering System Charts 5 Close Type 3 Precision Ground Type 3 Drawn Cup Type 3 Re-circulating Linear Ball Bearings 20 Full Complement NRB 3 Roller Followers 13 Inner Rings 5,11 Roller Followers Part Numbers 18 Linear Motion Bearings 20 Sealing Rings 5 - Metric 22 Shell Type 3 - Imperial 23 Stud 13 Needle Roller and Cage Assembly 3 Stud Type Cam Follower 13 Needle Roller Bearings (NRB) 3 Wiper Seals 20 Needle Rollers 4 Yoke Type Cam Follower 13 Structured Training Plan This lesson is the twelfth of a series of Correspondence lessons in the BSC Structured Training Plan. Objectives The objective of this lesson is to teach students how to identify INA Needle Roller bearings and CAM Followers in relation to their part numbers. Students should also have a good knowledge of the INA history and general information. Pre-requisites Completion of Correspondence Lessons A9001 - A9011. Methods Achievement of the objectives is by presentation of lessons in an 'On-Line' or Correspondence Course format. The lessons in a Correspondence Course style are conducted for internal students in a lecture situation. Assessment A formal test is provided with this lesson. LESSON A9012 Series 90 Training
LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 2
Needle Roller Bearings Needle roller bearings are used in confined spaces to take radial loads. As their name implies, the rollers are similar to needles in shape, but generally have a larger diameter. Please note that there is also a series of needle roller bearings designed to handle thrust loads. We will not be covering these in this lesson as they are included in lesson A9014 which is specifically on thrust bearings. The most common used type is the SHELL or DRAWN CUP needle roller bearing. In the SHELL type there are two basic configurations, Open type and Closed type. In both of these the bearings can be either a caged type or full complement type. The full compliment type can take higher radial loads but there is the danger that the rollers can slew sideways and thereby reduce the service life of the bearing. It should be noted that in certain cases, one of the parts (outer ring, needle rollers, cage) may not be included in the bearing construction. For example, where the bearing has no outer ring, this is called a Needle Roller and Cage Assembly. This type of bearing is intended to be used where both shaft and housing can be produced to sufficient quality standards to run needle rollers directly on. Also, where the bearing has no cage, this is called a Full Complement Needle Roller Bearing. This type of bearing is intended to be used under high loads at low turning speeds (for valid technical reasons), and the description "full complement" refers to the bearing being "full" of needles (ie no space taken up by a cage). The bearings can either run directly on a properly finished shaft or on an inner ring. Let us begin by examining the 3 basic parts: 1. Outer ring Basically, there are two different types of outer rings produced for needle roller bearings. a) Drawn Cup, or Shell Type Outer Ring This type of outer ring is produced by a manufacturing process known as 'drawing'. In this process thin sheet steel is pressed into a "die' or mould, which is of the shape required. Following this process, the resulting "drawn cup' or 'shell' is hardened to the required hardness of a bearing ring. The outer ring is then ready to have the rest of the bearing parts assembled into it. The thickness of the drawn cup ring is approximately 1 mm in the finished state, allowing the finished bearing to be a very compact design. b) Precision Ground Outer Ring Unlike the drawn cup outer ring, this type of outer ring is precision machined from bearing steel tube, and is much thicker, giving the finished bearing higher load carving capacity. Following machining, the outer ring is hardened to the required hardness of a bearing ring, and then is ready to have the rest of the bearing parts assembled to it. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 3
2. Needle Rollers These are the "rolling elements" of a needle roller bearing, which give the bearing its anti-friction properties. Needle rollers are basically a special form of cylindrical roller. The distinguishing feature which separated needle rollers from cylindrical rollers is that the length of the roller is at least 1.7 times its diameter. The needle rollers are produced by machining and grinding, and are of a very high accuracy. 3. The Cage The main task of the cage in a needle roller bearing is to provide highly accurate guidance of the needle rollers. By this, we mean that the needle rollers are retained in the 'pockets' of the cage, and are held so that they always stay in their correct position relative to the shaft and bearing outer ring (which is parallel to the shaft axis). The cage eliminates the possibility of skewing' of the rollers, a condition where the rollers stray from their appointed position in the bearing, resulting in reduction of the bearing service life or even bearing failure. The cage also has the secondary function of providing a lubricant reservoir in the needle roller bearing. This is obtained as the empty space provided in the bearing by the cage can be filled with lubricant, therefore extending the bearing's re-lubrication interval. Advantages of Needle Roller Bearings In general, bearing load carrying capacities are dependent on the following: 1. Diameter of rolling elements (ie needle rollers, balls, etc). 2. Area of contact between rolling elements and bearing rings (or 'raceways ). This can have different values due to such factors as type of rolling element, material of raceways, etc. 3. To a lesser extent, thickness of the bearing rings. The major advantage of needle roller bearings over ball bearings arises from point (2) above. As explained in Lesson A9005, the contact between the bearing raceway and a ball bearing is a point (eg. like a ball resting on a flat surface). In contrast to this in a needle roller bearing, the contact between the bearing raceway and needle roller is a line (eg. like a round bar resting on a flat surface). From this, it can be seen that a needle roller bearing of similar shaft size to a ball bearing has a greater area of contact between rolling elements and bearing raceway, and therefore much higher load carrying capacity. In addition, the needle roller bearing, because of the geometry or shape of the rolling elements, offer a much more compact design that the ball bearing. One drawback, however, is that needle roller bearings can not carry axial or thrust load. Only mere ball bearings can. In comparison to plain bearing, or bushes, needle roller bearing offer the advantage of lower friction, as rolling friction is a much lower value than sliding friction. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 4
Associated Products All discussion to date has assumed that the needle roller bearing is running directly on the shaft. However, where the shaft is not of sufficient quality or hardness to be used as a raceway, 'inner rings' are available from INA to overcome this problem. As the name suggests, inner rings are simply a ring which fits over the shaft, and whose outside surface is of sufficient quality and hardness to run the needle roller bearing on. Also, if the bearing is being used in a dirty environment or lubricant is required in the bearing, and seals are not already present in the bearing, "sealing rings" can be obtained from INA for these purposes. INA needle roller bearings are available in metric and imperial roller bearings. PART NUMBERING SYSTEMS Metric- Drawn Cup or Shell Type This series of needle roller bearings consist of a thin walled drawn cup outer ring and a needle roller and cage assembly, which together, form the bearing unit. Drawn cup needle roller bearings are available with open ends (HK) or closed ends (BK). They are also available sealed one side (HK and BK) or sealed both sides (HK only). These bearings must be fully supported to ensure proper load carrying capacity and the bearings running surface must be hardened and ground, otherwise, a suitable inner ring must be used. HK - - Drawn Cup Open end Caged type also available with seals one side or both sides (RS, 2RS) BK - - Drawn Cup closed end Caged type also available in a sealed version (RS). Note - Numbers following prefix in part number represent dimensions in mm Examples HK1210 = 12mm id 10mm width, BK2020 = 20mm id 20 mm width LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 5
Imperial SCE - -, SCH - - Drawn Cup Open end Caged type SCE - Normal Duty SCH - Heavy Duty BCE - -, BCH - - Drawn Cup Closed end Caged type BCE - Normal Duty BCH - Heavy Duty SCE - - P, SCH - - P Drawn Cup Open end Caged type SCE - Normal Duty SCH - Heavy Duty Sealed one side BCE - - RS, BCH - - RS Drawn Cup Closed end Caged type BCE - Normal Duty BCH - Heavy Duty Sealed one side SCE - - PP, SCH - - PP Drawn Cup Open end Caged type SCE - Normal Duty SCH - Heavy Duty Sealed both sides S - -, SH - - Drawn Cup Open end Full Complement (Cageless) S - Normal Duty SH - Heavy Duty CS - -, CSH - - Drawn Cup Closed end Full Complement (Cageless) S - Normal Duty SH - Heavy Duty S - - G Drawn Cup Open end Full Complement (Cageless) Extra precision Note - numbers following prefix give sizes in 16th of an inch. Example SCE44 = 0.25" ID x 0.25" width LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 6
PART NUMBERING SYSTEMS Metric- - Ribbed series Precision Ground Type The needle rollers in this series have a high load capacity and a small sectional height. The hardened outer ring has ribs and together with the needle roller and cage assembly, the complete bearing unit is formed. The series is available with or without inner rings. NK - / -, NKS - / - NK ID 10mm or less NKS ID 12mm or less Precision ground outer ring Caged type NK - / -, NKS - / - NK ID 12mm or more NKS ID 14mm or more Precision ground outer ring Caged type Oil hole and groove RNA49 - / - ID 35mm or more Precision ground outer ring Caged type also available with seals one side or both sides (RS, 2RS) Oil hole and groove RNA69 - / - ID 40mm or more Precision ground outer ring Caged type Double row rollers Oil hole and groove NKI - / - With inner ring ID 7mm or less Precision ground outer ring Caged type NKI - / -, NKIS - / - With inner ring NKI ID 9mm or more NKIS ID 8mm or more Precision ground outer ring Caged type Oil hole and groove LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 7
NA49 - -, NA 69 - - With inner ring ID 30mm or more Precision ground outer ring Caged type Oil hole and groove NA - - With inner ring ID 32mm or more Precision ground outer ring Caged type Oil hole and groove Note NK, NKS - Numbers following prefix in part number represent dimensions in mm Examples NK12/12 = 12mm ID 12mm Width, NKS14 = 14mm ID, NA, RNA49 and RNA 69 part numbers are not dimensionally connected. Metric Rib less series RNAO - - No inner ring Precision ground outer ring Caged type Single Roller RNAO- - With inner ring ID 16 mm or more Precision ground outer ring Caged type Double roller Oil hole and groove NAO - - With inner ring Precision ground outer ring Caged type Single Roller NAO- - With inner ring ID 25 mm or more Precision ground outer ring Caged type Double roller Oil hole and groove Note Numbers following prefix in part number represent dimensions in mm Examples RNAO 12X22X12 = 12mm ID 22mm OD 12mm Width, NAO20X35X17 = 20mm ID 35mm OD 17 mm Width, LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 8
Imperial NCS - - Precision ground outer ring Caged type Single row Note - numbers following prefix give sizes in 16th of an inch. Example NCS1012 = 0.625" ID x 0.75" Width For a full list of available sizes consult The Manual. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 9
PART NUMBERING SYSTEMS Metric Needle Roller and Cage Assemblies These bearings provide high accuracy and load carrying capacity with good rigidity and low radial height. The running surfaces for the needle roller and cage assembly must be a suitably ground and hardened surface, otherwise, an inner ring must be used. The cages of this series are manufactures from steel, plastic (TN series) for smaller sizes, or brass for larger diameters. The assemblies are also available in double row (ZW) or split design (D). K -x - x- High Accuracy High Load Smaller sizes have plastic cage indicated by TN suffix K -x - x -ZW High Accuracy High Load Smaller sizes have plastic cage indicated by TN suffix Note - Numbers following prefix in part number represent dimensions in mm Examples - K12x16x13TN = 12mm ID 16 mm OD 13mm Width with plastic cage, Imperial C - - - High Accuracy High Load Steel cage only Note - numbers following prefix give sizes in 16th of an inch. Example C101212 = 0.625" ID 0.75" OD x 0.75" Width For a full list of available sizes consult The Manual. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 10
PART NUMBERING SYSTEMS Inner Rings Metric Inner Rings and Sealing Rings Hardened and ground inner rings are used to provide a suitable running surface for needle roller bearings when the existing running surface is unsuitable. Inner rings are available in series IR and LR. IR inner rings are hardened and precision machined. They have lead chamfers on the edges and are available in special executions. These executions include increased accuracy, grinding tolerances and lubrication holes. LR inner rings are hardened and fine machined. The side faces are not ground and the corners are only broken. The LR series is not available in special executions. IR x x Precision machined Chamfered edges Available with lubrication holes LR x x Fine machined Side faces not ground Note Numbers following prefix in part number represent dimensions in mm Examples IR12x16x18 = 12mm ID 16 mm OD 18mm Width, Inner Rings Imperial PI - - - Precision machined Chamfered edges Available with lubrication holes y Note numbers following prefix give sizes in 16 th of an inch. Example PI101212 = 0.625 ID 0.75 OD x 0.75 Width LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 11
Sealing Rings - Metric Sealing rings are contact seals and provide protection against contaminates whilst also acting as a grease retaining device. They are small enough to match the low radial section of needle roller bearings. They are easy to fit as they are simply pressed into the housing bore. Type GR are single lip type made from synthetic nitrile rubber. Type SD are double lip and incorporate one contact lip and one non contact lip. The seal lips are made from thermoplastic PU elastomer. These sealing rings are separate unit and should not be confused with sealed bearings in which the seals are incorporated in the actual bearing it 'self. G - x - x - For shaft sizes 8 mm to 70 mm Single contact lip Operating temperature - 30 to +110 degrees C GR - x - x - For shaft sizes 4mm to 7mm Single Contact Lip Operating temperature - 30 to +110 degrees C SD - x - x - For shaft diameters 8mm to 50 mm One contact and one non contact lip Operating temperature - 30 to +100 degrees C Note - Numbers following prefix in part number represent dimensions in mm Examples - IR12x16x18 = 12mm ID 16 mm OD 18mm Width, For a full list of available sizes consult The Manual. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 12
Cam and Roller Followers The basic parts which make up a cam and roller follower are the following: Thick Section Outer Ring Needle or Cylindrical Rollers inner Ring or Stud (in some cases) The basic difference between cam and roller followers is that the cam follower rolling elements run on a hardened "stud' (very much like a short piece of shaft), which is an integral and non-separate part of the bearing, whereas roller follower rolling elements run either directly on a plain, hardened shaft or on an inner ring. These units are also differentiated and named by the terms "stud type cam follower" (cam follower) and 'Yoke type cam follower' (roller follower). These units are not intended to be pressed into a housing. A normal needle or cylindrical roller bearing (and normal ball bearing) are intended to be pressed into a housing and stay in a fixed position while the shaft (and inner ring) rotates within the bearing. In contrast, cam and roller followers are intended to be used on a stationary shaft (in cam followers, stud in stationary) while the outer ring rotates. This means that the cam or roller follower outer ring may remain stationary and rotate while the surface it is running on moves, or the running surface remains stationary with outer ring rotating, therefore moving the bearing unit along the running surface (very much like a car wheel on a road). We will now examine in slightly more detail the basic parts which make up a cam or roller follower. 1. Thick Section Outer Ring In contrast to needle roller and cylindrical roller bearing, the outer ring of a cam or roller follower is much thicker (thick section). This is required due to the additional 'stresses' built up in the outer ring when it is rotating on a surface. The outer ring is normally supplied ground, ie. With a slightly convex surface. This ensures that when the roller is run under pressure the load is spread evenly over the whole width on the roller. Cam follower can also be supplied with a cylindrical outer surface and this is indicated by the suffix X after the part number. 2. Needle or Cylindrical Rollers Standard needle or cylindrical rollers discussed previously. 3. lnner Ring or Stud As discussed previously, stud-type cam followers (cam followers) have an integral, or non-separate, stud on which the rolling elements run. This stud acts as the shaft and is therefore hardened and finished to the required quality standard. In the case of yoke-type cam followers (roller followers), these can be run directly on the shaft (where the shaft is of sufficient hardness and quality), or an inner ring. In a number of cases, the inner ring. is special and is an integral and non-separable part of the yoke-type cam followers unit. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 13
Advantages of Cam and Roller Followers The advantages of cam and roller followers result directly from their intended application of thick-section outer ring rotating against a surface. If a standard bearing were used in an application requiring a cam or roller follower, it is highly probable that the stresses built up in the outer ring would result in the cracking of the outer ring. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 14
PART NUMBERING SYSTEMS Cam Followers - Metric Cam and Roller Followers Stud type cam followers consist of a thick walled outer ring, a high tensile strength solid threaded stud and cage guided or full complement rolling elements. Stud type cam followers are supplied as standard with a crowned outside diameter to prevent edge loading. They are also available with a cylindrical outside diameter which is indicated by the suffix X. These cam followers are easily secured in their application by the threaded stud. Nuts, grease nipples, and dust caps are also available for use with stud type cam followers and should be requested when ordering if required. KR - -, KR - - PP Axial guidance by rib carrier KR..PP has lip seals on both sides KR has gaps on both sides OD from 16 mm to 90 mm KRV - -, KRV - - PP Stud with eccentric collar Cage guided needle rollers Axial guidance by rib and washer Lip seals on both sides OD from 16 to 62 mm KRE - -, KRE - - PP Full complement needle roller set Axial guidance by rib and washer Lip seals on both sides OD from 16 mm to 90 mm NUKR - -, NUKRE - - Optimized INA outer ring profile Full complement cylindrical roller set Axial guidance by rolling elements labyrinth seals on both sides NUKRE has eccentric locking collar OD from 35 mm to 90 mm LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 15
PWKR - -, PWKR - - 2RS Optimized INA outer ring profile Full complement cylindrical roller set Axial guidance by rolling elements and rib lip seals on both sides large grease reservoir OD from 35 mm to 90 mm PWKRE - -2RS Optimized INA outer ring profile Full compleme nt cylindrical roller set Axial guidance by rolling elements and rib Lip seals on both sides large grease reservoir Stud with eccentric collar Note - Numbers following prefix in part number represent dimensions in mm Example - KRV16PP = 16 mm OD with 2 lip seals LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 16
Cam Followers - Imperial CF - -, CF - - PP, CF - - SK Full Complement needle roller set CF has gaps on both sides CF..PP has contact seals on both sides CF.. SK has hex socket in centre of stud OD from 1/2 inch to 4 inch CFE - -, CFE - - SK Stud with eccentric collar Full Compleme nt needle roller set Axial guidance by rib and washer CF.. SK has hex socket in centre of stud OD from 1/2 inch to 4 inch CFCE - -, CFCE - - SK Stud with eccentric collar Cage guided needle rollers Axial guidance by rib and washer CF..PP has contact seals on both sides CFC.. SK has hex socket in centre of stud OD from 1/2 inch to 4 inch Note - numbers following prefix give sizes in 16th of an inch. Example CFCE12 = OID 0.75" LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 17
Roller Followers - Metric Yoke type roller followers consist of an outer ring, a needle roller and cage assembly or a full complement needle or cylindrical roller set with or without an inner ring. They are mounted on a shaft, have a thick-walled outer ring with a crowned outside surface and can support high radial loads. Yoke type track rollers without inner ring require a hardened and ground shaft as a raceway. Series NUTR and PWTR...2RS have a new, optimized profile for the outside surface of the outer ring. Other series of yoke type track rollers are supplied as standard with a curvature radius of R = 500mm. STO - -, RSTO - - Without axial guidance for the outer ring RSTO without inner ring Parts can be moulted separately OD 16 mm to 90 mm NA 22 -- 2RS, RNA22 - - RS Without axial guidance for the outer ring Lip seals both sides RNA22..RS without inner ring OD from 19 to 90 mm NATR - -, NATV - -, NATR - - PP, NATV - - PP Axial guidance for outer ring for washers Gap seals on both sides NATV has full complement needle roller set For shaft sizes 16 mm to 60 mm PP type has lip seal both sides NUTR Optimized INA outer ring profile Full complement cylindrical roller set Axial guidance by rolling elements Labyrinth Seals on both sides For shaft sizes 35 mm to 110 mm LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 18
PWTR - - 2RS Optimized INA outer ring profile Full complement cylindrical roller set Axial guidance by rolling elements Lip Seals on both sides For shaft sizes 35 mm to 110 mm Note - Smaller sizes supplied with plastic cage have suffix TN. Note - Numbers following prefix in part number represent dimensions in mm Examples - NATR12 = 12mm ID, For a full list of available sizes consult The Manual LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 19
Re-circulating Linear Ball Bearings The basic parts which make up a recirculating linear ball bearing are as follows: Outer Ring Cage. Rolling Elements (Balls) Integral Wiper Seals (where specified) In contrast to normal bearings which are axially stationary and run on a rotating shaft, re-circulating linear ball bearings are intended to facilitate linear guidance'. This means that the bearings guide a piece of equipment to which they are attached in linear travel by running up and down a stationary shaft. The bearings are termed "re-circulating" due to the fact that the balls in the bearing which contact the shaft re--circulate through the bearing as it moves along the shaft, giving the bearing unlimited travel length. Because of the bearing's construction, this linear guidance can be performed very efficiently, with very low friction and high accuracy. We will now examine in more detail, the basic parts which make up a re-circulating linear ball bearing. 1) Outer Ring The outer ring is either one of two types: Drawn Cup or Shell Type and Precision Ground Type, and are similar in construction and manufacture to the equivalent outer ring types in needle roller bearings as discussed previously. However, in the case of re-circulating linear ball bearings, the outer ring actually houses the ball guiding cage, therefore making the bearing non-separable units. 2) The Cage The cage in re-circulating linear ball bearings serve the purpose of guiding the rolling elements (balls) in and out of the 'load zone', that is, onto the shaft, recirculating through the bearing and back on to the shaft. Therefore, it is the cage design which allows the bearing to have unlimited travel length. The cages are manufactured in rigid moulded plastic. 3) Rolling Elements (Balls) The balls in re-circulating linear ball bearings are manufactured from high quality bearing steel. They are produced by machining and grinding, and are of a very high accuracy. 4) Integral Wiper Seals Where required, re-circulating linear ball bearings can be supplied with integral wiper seals made from rigid, moulded plastic. The wiper seals, as the name suggests, serve the- purpose of Wiping' the shaft free of contaminants (eg. dirt) before the bearing travels over that section of shaft, and therefore do not allow contaminants to enter the bearing itself. They can also serve the purpose of retarding flow of lubricant out of the bearing. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 20
Linear motion bearings are supplied in two versions. The type shown in the photo near the top of the last page is referred to as the closed type as it consists of a closed full circle unit. The second type is the open type and is illustrated in the picture to the right. This bearing is shown mounted in a housing which illustrates a common use of the open linear bearing. The complete unit (along with three others) would be bolted to the underside of a table in a machine tool application and run on a rail, thus providing extremely accurate movement of the table. Advantages of Re-circulating Linear Ball Bearings The major advantage of re-circulating linear ball bearings is discussed previously, to facilitate high accuracy and low friction linear guidance of attached equipment. A further advantage of these bearings is they are extremely compact (small section) and take up a little more space than plain bearing, yet exhibit much lower friction. An important point to note is that re-circulating linear ball bearings are manufactured only to facilitate linear guidance only (ie. travel linearly on a stationary shaft). They are not intended for rotary motion (ie to be used on a rotating shaft). LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 21
PART NUMBERING SYSTEMS Linear Motion Bearings Metric - light series Other names for this type of bearing are Ball Bushings Available as a closed, adjustable or open bearing. Closed KH - -, KH - - PP Drawn Cup outer ring Balls circulates in plastic retainer Available with one or 2 seals as suffix P or PP OD from 6 mm to 50 mm KGHK - - Drawn Cup Outer Ring Balls circulates in plastic retainer Cast steel housing OD from 6 to 50 mm Metric - Standard series KB - -, KB - - PP Rigid outer ring Available with one or 2 seals as suffix P or PP OD from 12 mm to 50 mm Available in Closed (KB), Split (KBS) or Open (KBO) versions Split version has adjustable clearance Closed Bearing Split Bearing Open Bearing Note - A re-greasable version is available - suffix AS Note - Numbers following prefix in part number represent dimensions in mm Example - KB4080 PP AS = 40mm ID mm 80 mm OD with 2 lip seals, re-greasable LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 22
Imperial LMB - -, LMB - - PP Full Complement ball bearing set LMB..PP has contact seals on both sides OD from 1/4 inch to 4 inch LMB - -AJ Full Complement ball bearing set OD from 1/5 inch to 4 inch LMB - - OP Full Complement ball bearing set OD from 1/2 inch to 4 inch Note - numbers following prefix give sizes in 16th of an inch. Example LMB122026 = ID 0.75" OD 1.25" Width 1.625" This page only includes a summary of the most common linear motion bearings. The range includes rigid and self aligning housings, shafting, shaft support blocks, rails, ball screws and nuts. For a more detailed listing consult The Manual. LESSON A9012 Needle Rollers and CAM Followers Series 90 Training page 23