Posts Tagged ‘wide inner ring’

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

Specific Characteristics of Ball Bearings

Tuesday, January 4th, 2011

In the modern  ball bearings the machine designer has available, also, many widely varying specific characteristics, according as different types are considered, over and above the general advantages commonly listed as attributes of anti-friction bearings as a whole.

In this way they are particularly adaptable to a great many specialized fields, slight variations here and there enabling them to meet satisfactorily those factors of operation or service requiring special consideration.

LOADS

Ball bearings in various types and sizes are designed to carry either radial loads or thrust loads in nearly any practical magnitude.  In general, they afford maximum load capacity in the smallest possible space.  Most of them will have the ability, furthermore, to carry both radial and thrust loads at the same time,in various proportions and totals.

SHAFT LOCATION

Requirements may demand that shafts be located positively under light thrust loads or it may be necessary to provide very positive location even under considerable thrust.  Specific types of ball bearings offer these possibilities.  For example, the standard Single Row Type is satisfactory for locating shafts end-wise in assemblies, where slight end-wise or axial deflection under load is not serious.  On the other hand, if under load practically no movement of the shaft is permissible, and great rigidity must be assured, the Double Row Angular-Contact Bearing may be employed or perhaps a Duplex Unit.  These qualities of definite axial location are procured with certain types of bearings without sacrificing their capacity for radial an d thrust loads as well.

TWO-DIRECTION THRUST

Thrust in both directions — as experienced with reversing worm drives — can be carried by more than one type of  bearing, but other designs are not suitable at all, and some discrimination must be exercised.

SPEED

Where the speed factor is involved still other characteristics may be required, and these too can be obtained by proper selection, some bearings carry greater loads at higher speeds than others, due to their internal design.

RIGIDITY

Radial rigidity of shaft — as well as the end-wise rigidity mentioned — is offered by various types of assemblies, including preloaded bearing combinations, for the extreme rigidity of machine tool spindles, etc.  Shafts must be adjusted end wise on initial assembly to compensate for certain demands which may be made in service.

ADJUSTMENT

Adjustable bearings are available to meet particular requirements, but on the whole, adjustment of bearings is a negative feature, since the principle of ball bearing design permits of virtually non-wearing operation.  The majority of bearing types are non-adjustable, requiring no adjustment either in mounting or in service, even though their useful life may be extended over many years.

PRECISION

The extreme degree of precision which may be obtained with ball bearings is well known, and in many applications is the determining factor in their use.

COMPACTNESS

The small amount of space along the shaft which ball bearings occupy in comparison to other bearing types is very often a deciding point in their favor, and appeals particularly to machine designers.

The foregoing constitutes a rough outline of the specific characteristics which to one degree or another are a feature of each ball bearing type and design, all of which must be considered in selecting the proper bearing in view of the service demands to be made upon it.

Wide Inner Ring Bearings

Thursday, October 14th, 2010
continued from October 7, Wide Inner Ring Bearings with Concentric Collars

Collar Assembly

Eccentric Self-Locking Collar

To install the self locking collar, perform the following 4 steps:

1) Observe cam design of the wide inner ring and self-locking collar
2) Mate the cam of the collar with the cam of the inner ring.
3) Press the locking collar against the wide inner ring and turn in the direction of the shaft rotation until tightly engaged. For applications involving vibration and / or heavy loads, it is recommended that the collar be locked using the drift pin inserted in the drift pin hole.
4) Tighten the set screw in the locking collar.

 

Clamp-Type Concentric Collar

To install the clamp-type concentric collar, perform the following two steps:

  1. Place the collar of the extended split inner ring with the set screw above the depression in the ring surface.
  2. Tighten the set screw to anchor the extended split inner ring to the shaft.

Wide Inner Ring Bearings with Concentric Collars

Thursday, October 7th, 2010
Continued from September 30th; Wide Inner Ring Bearings with Locking Collars – Part 2

The following series are available with the Concentric Locking Collar.

GC-KRRB Series

  The GC-KRB wide inner ring bearings are relubricatable with spherical outside diameters and shroud seals. The metal shroud maintains tight seal contact against the inner ring and shields the rubber seals from damage due to dirt or fibre wrap. The concentric collar is locked to the shaft by two set screws, located 120 degrees apart. which are mated with threaded holes in the collar and drilled holes in the bearing inner ring.

GC-KRRBG-2 Series

This series offers a large variety of sizes of relubricatable, extended inner ring bearings for through-bored housings. All bearings in this series are equipped with snap rings which eliminate the need for machining housing shoulders. The R-Seal with shroud cap provides the most effective contact seal available in a standard bearing to retain lubricant and prevent contamination.  

Clamp-Type Wide Inner Ring Bearing

  Clamp-type wide inner ball bearings are designed with a split extending inner ring and a collar with a set screw. Tightening the set screw on the split inner ring exerts a squeezing action which firmly secures the inner ring to the shaft without the set screw contacting the shaft. Easily installed and removed, these bearings resist loosening due to vibration, sudden stops and starts, or shaft reversal.  The clamp-type bearings are available in the following variations: two shields (DD type), two Plya-Seal (PP or NPP type), and two Mechani-seals with snapring (LLG type).

 

Watch for October 14th Collar assembly….