Posts Tagged ‘angular contact bearing’

Bearings In The News – January 2017

Friday, January 13th, 2017

This month we are featuring two articles: “Sikorksy S-92 Tail Rotor Failure Blamed On Bearing” and “Replacing Damaged Rubber Bearings Of Concrete Bridge”.

(more…)

Angular Contact Bearings

Friday, April 3rd, 2015

DEFINITION:

Angular Contact Bearings are constructional bearings which use the rolling element of the ‘ball’. This is another common type of bearing using the ball as the rolling element. This type of bearing is composed of many steel balls, kept together by a cage, set between two races.

The internal design of an angular contact bearing is meant to take on radial load, as well as moderate axial load from one side only. The contact angle is defined as the angle between the line joining the points of contact of the ball and the raceways in the radial plane, along which the load is transmitted from one raceway to another, and a line perpendicular to the bearing axis. This contact angle varies from about 25° to 40

Angular contact bearings can support fairly heavy axial loads in one direction in addition to radial loads. The axial load carrying capacity of angular contact ball bearings increases with increasing contact angle.

SINGLE ROW ANGULAR CONTACT

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.

DOUBLE ROW ANGULAR CONTACT

Double Row Angular Contact ball bearings have two rows of balls arranged back-to-back. In essence, they work similarly to having a matched pair of Single Row Angular Contact ball bearings. The difference is that Double Row Angular Contact ball bearings can take a bi-directional axial load in one bearing where it takes a matched pair otherwise.

APPLICATIONS:

Angular contact ball bearings are suitable for applications which require high accuracy and good high-speed performance.

Most bicycles use angular-contact bearings in the headsets because the forces on these bearings are in both the radial and axial direction.

Higher speed applications include turbines, jet engines, and dentistry equipment.

MOUNTING:

They can be mounted (flush) in sets of two or more, with regards to the application. To ensure that these bearings operate properly, they must be assembled with a thrust load. This loading, or preloading, creates a contact angle between the inner race, the ball, and the outer race. The preload can be built into the bearing or created when the bearing is inserted into an assembly.

CONSTRUCTION:

Angular contact bearings may be constructed of materials such as stainless steel, plastic, and ceramic hybrid. They may also be plated – common plating materials are cadmium and chrome.

LUBRICATION:

Angular contact bearings have a variety of lubrication options. They can be re-lubricated, pre-lubricated, or have solid lubrication.

SEALS:

Single row and double row angular contact bearings can be supplied with or without shields or seals, depending on the customer’s request and the requirements of the application.

Oh oh .. Have run into a road block …..

Thursday, January 20th, 2011

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.

Service Conditions Affecting Selection of Type — Part 3

Tuesday, January 18th, 2011

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

Service Conditions Affecting Selection of Type — Part 2

Thursday, January 13th, 2011

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.

Coming up on Tuesday, January18, 2011 ….

Service Conditions Affecting Selection of Type — Part 3

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

Service Conditions Affecting Selection of Type

Tuesday, January 11th, 2011

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.

Upcoming on Thursday … January 13 ….

Service conditions Affecting Selection of Type —– continued

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

On Speaking

Thursday, December 9th, 2010

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.