Help — I’ve fallen and can’t get up. 

Now that I’ve used the allotment of cliches where do I go from here.  Even the best of us run into brain blocks, and I’m no exception.  I have been doing research, and working hard learning the background information for the new website, www.bearingsinc.net that is soon to be launched.  I know “you’ve heard this all before”, but be assured that it is close to launch date, and it will change consistently once it is launched.  We want to make it better and easier for you to use. 

Right now, I have uploaded “most” of our Timken line; which is our biggest line.  This consists of both ball and roller bearings.  Ball bearings consisting of Angular contact, Wide inner ring, and Housed units. Roller bearings consisting of the Tapered Roller Bearings Cups, cones, and sets that Timken has always been famous for. 

I have also uploaded our Koyo Ball bearing line, which could offer some of the same parts as Timken.  We also have SKF-Chicago Rawhide currently uploaded which offers seals, and speedi sleeves.

In my plans, and my next uploading attempts consist of Koyo NEEDLE bearing line, and MBL (Mitsuboshi) belts.  These will cover quite a bit of items we can currently offer, but you need to watch the sight because once it’s launched, I will be configuring other databases to upload.  This way it will keep the sight changing, and interesting. 

New items = new choices = more options

While I’m not making any promises of a launch date; keep in touch and help us celebrate our launch when all of our hard work has finally come to an end.

Shock Loads – Reversing Loads – Intermittent and Variable Loads

All bearings listed herein are capable of carrying for short intervals overloads and shock or reversing loads of an intermittent or variable nature, in excess of the ratings assigned.  Where these loads occur due to abnormal, seldom-repeated conditions, it is not necessary to provide additional capacity, but avoidable, suitable additional capacity is desirable.  Bearings are capable of carrying for short periods, loads 100% in excess of their capacity.  It should be remembered, however, that shock loads, even of short duration, can have the effect of much higher steady loads than is usually appreciated, and liberal allowances should be made under conditions of this sort.

Overloads

Aside from the abnormal shock load consideration, bearings may be regularly subjected to loads beyond their normal rating if for short periods of operation only, as in low gear speeds of automobiles and trucks.  Experience has shown that in cases of this nature bearings may operate satisfactorily for many years even though regularly exposed to low gear loads of from two to three times their rating.  Loads due to heavy starting torques and stalling torques may also be carried satisfactorily.  While these overloads can be handled by the reserve capacity of the bearing, it is always well to consider their nature and duration and make any allowance possible for them.  In other words, the mere fact that bearings have reserve capacityshould not suggest complete disregard for shock and overloads.  In some cases special retainers may be needed to meet severe conditions and consultation with the bearing makers engineering department is then most desirable.

High Speeds

Ball bearings operatevery satisfactorily at speeds beyond the range of satisfactory experience with plain bearings, and are today operating up to 50,000 revolutions per minute.  Speeds as high as 10,000 and 15,000 RPM are common.  With high speeds extra precision is generally desirable, and the Non-Filling Slot Type, having a completely symmetrical inner ring, offers more as regards perfect balance than the Maximum Type.  It is best with very high speed conditions to design the simplest bearing assembly possible using the Single Row Types; and the more complicated types, such as Double Row, Grease-Shield, and Felt-Seal Bearings, should not be used except when no other solution of the problem is possible.  Furthermore, since the Extra-Precision Bearings meet high speed requirements better than the standard tolerance bearings, they should be used at the higher speeds.

Misalignment

Housings and shafts should be processed in such a way s to make bearingseats as concentric as possible.  All shoulders, faces, etc., involved in the location of bearings should be square and true with the shaft axis.  However, in some cases it is not always possible to bring these factors into accurate relationship, and resort must then be had to self-aligning bearings of various designs.  The single row deep-groove bearing may be also supplied with slightly increased internal looseness to compensate for minor degrees of inaccuracy.  Where bearings are mounted in loose blocks or where parts cannot be accurately machined at succeeding operations, these points should be studied and compensated for by the proper selection in bearing type or by suitable changes in an otherwise standard assembly.

Outer Ring Rotation

In most applications the inner ring of the bearing rotates with the shaft and the outer ring is stationary in the housing. In loose pulleys and other similar applications, the shaft is stationary and the outer ring rotates around the stationary inner ring.  This calls for a type of mounting wherein the outer ring is tightly pressed into the bore of the housing and the inner ring is a slip fit on the shaft,thus insuring the driven element of the ball bearing (in this case the outer ring) rotating positively with the housing.  Since the rotationof the outer ring produces a greater ball speed than if the inner ring were rotated at the same RPM, it is necessary to compensate for this condition by applying a correction factor.  The actual RPM of the outer ring is multiplied by this factor, and the load rating determined from the tables for this speed. This then is the capacity of the bearing when the outer ring rotates.

These factors are:

• Light Series ——- 1.5
• Medium Series — 1.7
• Heavy Series —–1.9

Space Restrictions

Loads which can be carried in one way by a number of bearings or by a specific size of bearing may sometimes be more satisfactorily carried by another type when it is desired to reduce the space occupied by the bearing diameter because of definite limitation imposed for distances between shafts or other interfering parts of the mechanism.  A good example of this is in the use of the smaller Double Road Baring to replace a Singe Row Bearing of larger diameter in cases where the housing diameter must be kept as small as possible.  The Narrow Width Bearings may also be advantageously used where restrictions make a reduction in assembly length imperative.  Where provision cannot be made for suitable protection featurs in the housing members themselves, the Grease-Shield Bearing and the Felt-Seal Bearing lend themselves admirably to a most efficient application from the standpoint of space occupied.  In general it is desirable to select, wherever possible, the more common types of bearings for a given application, principally the variations of the Single Row Type, but the other types are available where conditions demand other designs, and are widely used for meeting space and weight problems.

Temperature Conditions

Rise in temperature has the effect of increasing diameters and lengths of shafts, rings, housing, etc., due to expansion of metals.  Consequently, when temperatures are such as to cause an expansion of any parts after the apparatus has been set up, due allowance must be made to take care of this.  A typical instance is illustrated in the case of an induced draft fan handling hot gases.  The shafts expand on being subjected to this heat, and one or more of the bearings supporting the shaft must therefore move laterally to avoid assuming a heavy thrust load from this expansion.  Normally, all conventional single row applications are mounted with one bearing fixed axially, the other floating, and in many cases the temperature variation may only be such that this arrangement is sufficient.  Where the temperature rise is rather extreme, however, special design provisions should be made to permit compensating adequately for the maximum expansion.

Temperature may affect bearing rings in another way.  It may be that the inner ring is exposed to heat transmitted through the shaft, whereas the outer ring is kept relatively cool due to passage of air or radiation from the housing.  This is well illustrated by motors of certain types, wherein the temperature rise of shafts exceeds that of the outer ring, which is more or less cooled by the passage of air through the ventilating opening.  For this type of temperature condition it is necessary to resort to greater radial clearance in the bearing, as provided by an increased clearance between balls and rings. When temperatures in excess of 125 degrees Fahrenheit are involved, it is best to consult the supplier engineering department, since not only may special features relating to the bearing be necessary, but some consultation on lubricants and lubrication is also advisable.

Acids, Gases, Moisture

Problems involving acids, such as acetic and sulphuric, fumes of a decidedly corrosive nature, or applications submerged in water, demand special treatment from the standpoint of bearings and housing, and should not be undertaken without consulting experienced bearing engineers.  Housings may be made of special alloys and the bearings themselves may be of stainless steels.  In cases of moderate exposure, synthetic lacquers may be used to retard corrosive action.  When housings incorporate sealing felts the felts must be specially treated to add resistance to deterioration. Unprotected anti-friction bearings will not operate satisfactorily submerged in water or other liquids, since a definite amount of lubricant is required, and if absent rapid abrading of the ball retainers and other parts will result.

Service Conditions Affecting Selection of Type — Part 3

• Shock loads–Reversing Loads–Intermittent and Variable Loads
• Overloads
• High Speeds
• Misalignment
• Outer Ring Rotation

Radial Type of Load

Bearings of the Single Row Radial Type(both Non-filling slot and maximum constructions) Extra Small Series, Narrow Width, Radial-Thrust, Open Type, Double Row Angular Contact, Grease-Shield, Felt-seal, Self-Aligning, Adapter — and the Wider Inner Ring Bearing with its assembly variations — are all suitable for carrying radial loads.  From among these styles the proper type and size of bearing can be selected to carry the specific loads imposed - as determined by a simple calculation and by reference to the recommended factors of safety in connection with the load capacities tabulated herein. 

Absolutely pure radial load exists infrequently for even in applications where only  radial load is theoretically possible, there are slight inaccuracies in alignment (due to locating forces) which may place some degree of thrust load on the bearings.  Thrust loads of this variety may be neglected, however, in the presence of the predominantly radial loads.

Thrust Type of Load

Where the weight of parts or actual thrust loads caused by hears or other driving methods must be considered in the design, variations of the radial type, or perhaps pure thrust bearings, may be necessary. Al of the conventional types of bearings mentioned above have thrust load carrying ability to varying degrees, in addition to their radial ability.

Bearings of the Thrust Type will carry pure thrust loads where no radial load is involved, or where the radial load is carried by another radial support.  For the lower range of speeds the Thrust Type Bearing is very satisfactory, and it is merely necessary to make a selection as to size, based on the load requirements.

In a great many cases, however, and nearly always where pitch line speeds are high, the once popular ball thrust bearing is being replaced with a variation of the radial bearing, since the latter type is more versatile in operation. In some cases the Non-Filling Slot Type of Radial bearing lends itself admirably to the carrying of rather appreciable thrust loads.  And still greater thrust carrying ability is available with the Radial-Thrust or Angular-Contact Type, and the Duplex Units (particularly the tandem arrangement of bearings).

Combination Type Of Load

There are many cases in mechanisms where radial loads and thrust loads are combined, and there are many bearings with ability to carry these combinations very satisfactorily.  Bearings of the single row radial type, the extra small series, the narrow width series, the radial-thrust type, the open type, the double row angular-contact, the grease shield, felt-seal, and self aligning bearings, as well as the wide inner ring units and assemblies are suitable for carrying combined loads within their respective capacities.

Service conditions Affecting Selection of Type —– continued

• Space Restrictions
• Temperature Conditions
• Acids, Gases, Moisture

A fisherman, in his first kitchen encounter with a sausage, exclaimed: “There ain’t much left of it after you clean it.”  The same is true of a shocking amount of our communication.  This may be because our sausage was a skimpy one to start with.  More often, it is because we find it easier to express our thoughts in our language, instead of that of our listeners.

An astonishing number of people — possibly you — speak in terms that are completely clear only to others off the same bolt.  The lawyer, the doctor, the scientist, the theologian, the professor, the plumber, the advertising man, and yes — even in Bearings Sales, have no trouble in getting through to persons who speak their private jargon.  But, though the may not suspect it, half of what they say to others rolls off their consciousness without leaving even a damp spot.

A college president, recognized as an authority on many subjects, laments the fact that he can no longer speak simply, that people always seem less impressed by what he says than by the educated way he says it.  William Penn, in his The Fruits of Solitude, advised us to “Speak properly, and in as few words as you can, but always plainly; the end of the speech is not ostentation but to be understood.”

We at Bearings Incorporated take pride in breaking that language barrier.  We are not afraid to explain something to those that don’t know, or are out of that “circle”.  Dealing with Bearings Incorporated may just expand your knowledge a little further.

NTN Catalogue – Part 2 of 2

Continued from Part 1 of August 12, 2010

DOUBLE ROW SELF-ALIGNING BALL BEARINGS utilize an inner ring with two rows of balls, in two deep raceways; and an outer ring with a single spherical raceway.  In this way, the inner and outer rings can be misaligned relative to each other.  The resulting affect is a comparatively large angle imposing moment loads upon the balls. 

The boundary dimensions of the 1200 and 1300 series are the same as the 6200 and 6300 single row deep groove bearings.

CYLNDRICAL ROLLER BEARINGS have rollers which are essentially cylindrical in shape.  This provides a modified line contact with the cylindrical inner and outer ring raceways, while the rollers are guided by ground ribs on either the inner or outer ring.  The cylindrical shape allows the inner ring to have axial movement relative to the outer ring (except the NH type).  This is especially important when accommodating thermal expansion when both rings must be press fitted. 

In this series, the NJ, NF, and NH types can carry light or intermittent thrust loads.  The bearings utilizing machined bronze cages are suitable for high speed operation.

The NN3000 and NN3000K series are available in high precision tolerances and are well suited for use in machine tool spindles.

TAPERED ROLLER BEARINGS utilize conical rollers and raceways arranged so that the rollers and raceways meet at a common apex.    The rollers are guided by contact between the large end of the roller and a rib on the inner ring.  This provides high capacity for radial and single thrust loads.

SPHERICAL ROLLER BEARINGS have two rows of rollers in separate raceways which allows the bearing to compensate for angular errors.  They have large radial and thrust load capacity for heavy shock and impact loads, suitable for heavy industrial equipment.

DUPLEX BEARINGS use a set of two on a common shaft with the inner and outer rings clamped solidly together.  They are used to gain axial shaft control, rigity and extra capacity.

There are three fundamental combinations n duplex bearings: face to face (DF); back to back (DB); and tandem (DT).

The back to back mounting (DB) has the load lines through the balls converging toward the outside of the bearing.  This arrangement is preferred when the pair of bearings is to resist moment loading.

The face to face mounting (DF) has the load lines through the balls converging  towards the axis of the bearing.  This arrangement is less sensitive to slight angular errors in mounting of the bearings.

The tandem mounting (DT) is arranged so that the load lines through the balls are parallel to each other.  This mounting is used when it is desired to divide a heavy thrust load between the two bearings.  Since this mounting carries thrust load in one direction only, a third bearing should be provided to take thrust load in the reverse direction.

SINGLE DIRECTION THRUST BALL BEARINGS consist of two washers having ball grooves ground into their adjacent faces with balls and cages mounted between these grooves.  They are normally equipped with either pressed or machined cages and are suitable for carrying thrust loads at moderate speeds.

DOUBLE DIRECTION ANGULAR CONTACT THRUST BALL BEARINGS are back to back duplex bearings with a larger contact angle than that of normal angular contact ball bearings. 

These bearings have been recently developed, and are primarily designed as thrust bearings for machine tools.  They utilize machined brass cages. 

SPHERICAL ROLLER THRUST BEARINGS are similar to double row spherical roller bearings, but have a greater contact angle.  They are guided by ground flanges on the inner ring and operate against the spherical raceway in the outer ring.  The contact angle is approximately 45⁰.  Machined cages are normally used and oil lubrication is recommended.

NTN Catalogue – Part 1 of 2

SINGLE ROW DEEP GROOVE RADIAL BALL BEARINGS  are the most widely used bearings and utilize an uninterrupted raceway, which makes these bearings suitable for radial loads, or a combination of radial and thrust loads.  This design permits precision tolerances even sat high speed operation. 

The cage in this bearing is pressed steel.  For high speed bearings, machined brass cages are available.  Bearings with locating snap rings are also available.

PRELUBRICATED BEARINGS have integral seal, or shields, which are packed with long-life grease.  In many applications, these bearings may be used without supplementary seals, closures, or protective devices.  This design offers the lowest possible manufacturing cost to the consumer. 

The boundary dimension of this type is the same as the corresponding bearings without the seals or shields.

SHIELDED BALL BEARINGS incorporate securely fastened, steel reinforced, rubber seals, fastened to a groove on the outer ring.  Contact with the inner ring is by sealing lip (Contact suffix LLU). Or, non-contact with the inner ring is by labyrinth seal (non-contact suffix LLB) to provide positive sealing at all times.

SINGLE ROW ANGULAR CONTACT BALL BEARINGS  feature raceways with high and low shoulders.  These opposing raceways are designed to carry thrust load in one direction. 

These bearings may be preloaded at the factory so that the correct preload will develop within the bearing.

The bearings in this series are assembled with a specific internal clearance so that they will have a specified contact angle under stress load.  The standard contact load used by NTN is 30⁰; bearings made to 40⁰contact angle carry the suffix B.

For high speed grinding spindles the 7000C, 7200C and the 7300C series are available.  They are high accuracy bearings with a 15⁰ contact angle, and phenolic resin cages for high speed operations.

DOUBLE ROW ANGULAR CONTACT BALL BEARINGS have an inner and outer ring with a double raceway.  The two rows are so related that the contact angle is similar to a pair of back-to-back single row bearings.  The 5200 and 5300 series offer continuous races, and can carry thrust loads in either direction.  Since the 3200 and 3300 series have filling slots, it is necessary to mount them with the thrust load acting against the un-notched face of the rings.

To be continued August 17, with Double row self-aligning ball bearings, Cylindrical roller bearings, Tapered roller bearings, Duplex bearing, Single direction thrust ball bearing, and double direction angular contact bearings.

See Part 2