Alb Mod Anti Friction A Flashcards
Anti-friction bearings commonly have their inner ring sitting on a shaft when mounted. This inner ring is made of:
Hardened high-grade steel
The surface the rolling members roll on is ground to a fine finish to reduce friction. It is called a:
Raceway
The outer ring is similar to the inner ring except that it sits in a _____ when mounted
Housing
The rolling members support the load and ideally should roll and not slide, skid or drag. This ensures two things: (2)
- Saves power
- Reduces wear
The cage that holds the rolling elements can be mounted in 3 ways: (3)
- Mounted to inner ring
- Mounted to outer ring
- Free of both rings
What are the three functions of a cage or separator? (3)
- Prevents elements from rubbing each other
- Pushes elements through unloaded zone
- Guide elements (with minimum friction)
What are three factors that affect a bearings ability to carry a load? (3)
- Area of contact
- Direction of load
- Loaded zone
Under a ball bearing, the area of contact is circular until a load applies to the ball, then it is:
Elliptical
Under a roller, the area of contact is a narrow rectangle. The size of these areas becomes larger as the size of the ____ increases
Rolling element
The larger the area of contact, the larger the _______.
Load capacity.
Note: this is because the load is distributed over a larger area
If the nominal contact angle is 0° and the load carries at 90° to the shaft axis, the bearing is a ____ load bearing
radial load bearing
If the nominal contact angle is 90° then the load is in line with the shaft axis and the load is _____
Axial or thrust
If the nominal contact angle is between 0° and 90° then the load acts at an angle to the shaft and is considered:
Combination radial and axial
The loaded zone is the:
Section of raceway where rolling elements are under load
Loading zone also depends upon the amount of:
Internal clearance or preload
A larger load zone means that more elements are supporting the load, thus:
Increasing load capacity
This bearing is the most common type of ball bearing. Mainly intended to support radial loads, it can also support combination loads as well as moderate axial loads in both directions. Has a contact angle the changes with the direction of loading, and tolerates very little misalignment.
Single row deep groove ball bearing (or Conrad bearing)
The name Conrad comes from:
The method that Conrad invented for loading the balls into the bearing
Note: allows you to easily remove the balls to inspect raceways on a failed bearing by clamping the bearing in a vice after cutting the cage
The deep groove ball bearing is available in a maximum capacity series. The bearing is similar to a regular deep groove ball bearing, except that it:
Is assembled with more balls
When compared to a regular deep groove ball bearing, the max capacity deep groove ball bearing has a higher radial load capacity, but a smaller:
Axial load capacity
Note: the max capacity version is also more sensitive to misalignment
This type of bearing provides a higher radial load capacity without increasing radial dimensions. However, because it has filling slots, it’s restricted to mainly radial loads
double row deep grove ball bearing
This type of bearing is used when alignment is impractical or impossible to maintain, often due to shaft deflection. Can support small thrust loads, and has speed ratings similar to a single row deep groove ball bearing. Also required for shafts that operate at high speeds with extreme accuracy
Internally self aligning ball bearing
Note: these bearings an never exert a bending influence on the shaft
This type of bearing has a spherically ground outer ring that mounts in a special housing. Allows for misalignment, but does not perform well with shaft wobble.
Externally self aligning ball bearing
Compared to externally self aligning bearings, internally self aligning bearings: (3)
- support smaller axial loads
- Same speed rating
- More suitable for shaft wobble
Single row angular contact bearings can accommodate what kinds of loads?
radial and thrust
The axial load capacity of a single row angular contact bearing increases with an increase in the:
Contact angle
Note: these are available in various contact angles
The low shoulder of a single row angular contact bearing allows you to install a greater number of balls, which:
Gives higher load ratings
With single row angular contact bearings, you can move the inner or outer rings axially, which adjusts:
Internal clearance or preload
Single row angular contact bearings are available in both ___ and ___ series
Standard and precision.
Because of the design of a single row angular contact bearing, if the bearing isn’t mounted as a pair, thrust must be:
In only one direction
With single row angular contact bearings, both the face to face and back to back arrangements can handle:
Reversing axial loads
The tandem arrangement of single row angular contact bearings can handle thrust in only one direction, but can handle more:
Radial loads (vs face to face or back to back)
In what arrangement of single row angular contact bearings do you hold the shaft more rigidly in angular alignment?
back to back
The double row angular contact bearing offers these three features: (3)
- Takes heavy radial and axial loading in both directions
- Speed rating is lower than Conrad or single row angular
- Cannot tolerate any misalignment
This type of bearing can only be used for combination or axial loads, can handle reversing thrust loads, is a separable bearing, can be made with more balls, and is made of uniquely shaped raceways that are made of circular arcs which resemble a gothic arch
Four-point angular contact bearing
The four point angular contact bearing has a narrow width, and occupies less space than a pair of:
Single row angular contact bearings
This bearing is designed for pure thrust load only. Can only accommodate half the speed limit as a radial load bearing, because at high speeds, centrifugal forces spin the balls out of the races.
Ball thrust bearing
With a ball thrust bearing, the non-self aligning ball thrust bearing cannot tolerate:
angular misalignment between the shaft and housing
Cylindrical roller bearings are separable in both directions. Since the bearings separate axially, they can support only a pure:
Radial load
An angle ring with a cylindrical roller bearing can prevent:
axial movement in one direction
The cylindrical roller shape has a larger area of contact than a ball bearing of the same diameter, giving it a higher:
load capacity
Note: can also be increased further by increasing the number of rollers
Cylindrical roller bearings are available in a ______ for very heavy thrust loads
thrust configuration
Needle bearings are available in a variety of types. the three most common types are bearings with: (3)
- No cage/inner ring
- a drawn steel cup and no inner ring
- machined inner and outer rings
The cageless design of needle bearings are limited to: (2)
- Slow speeds
- oscillating motions
Note: this is because the rollers rub into each other
The drawn steel cup design of needle bearings can be operated at high speeds, and must be fitted to a:
Smooth, accurately machined housing.
Note: depends on the bore for support
The machined inner and outer ring design of needle bearings saves the shaft from wearing against the _______. It can be operated at high speeds.
rolling elements
Note: also takes up more radial space than the other two common styles
These types of bearings are assembled to support radial loads only. They are similar to cylindrical rollers, except that they are 2.5 to 10 times as long as their diameter. Can be used where space is limited, and offer a high load capacity.
Needle bearings
The two parts of the single row tapered roller bearing are the: (2)
- Inner ring, aka cone
- Outer ring, aka Cup
The cage, cone, and rollers of a tapered roller bearing are all on the same assembly, and installed into:
-Cup, or outer ring
The tapered raceways of a tapered roller bearing allow it to:
Carry heavy combined radial and thrust loads in one direction
Note: can tolerate little misalignment
You can use a pair of tapered roller bearings to: (2)
- Accommodate Reversing loads
- Prevent separation
With a tapered roller bearing, this type of cage allows for closer roller spacing and therefor provides a higher maximum load:
pin-type cage
These tapered roller bearings are matched pre-set assemblies, so the components are not interchangeable. Used for heavy applications, can be double cone or double cup.
Double row tapered roller bearings
Note: can be made with a tapered bore
This version of the double row tapered roller requires a cone spacer, and can be used as a floating assembly in a housing
double cup assembly
This bearing has barrel shaped rollers which provide a wide load contact area, provides combined thrust (both directions) and radial load capacity, is internally self aligning without reducing bearing capacity. Most commonly made in a double row configuration, it’s also available in a single row design with high radial load capacity but very little thrust capacity
spherical roller bearing
This type of bearing was designed to solve bearing failure problems in paper mills. It’s used in applications requiring better floating bearings. It is radially compact, but with some misalignment capability. Can allow axial displacement more than any other bearing, and for that reason is not recommended for thrust loads.
CARB or Compact Aligning Roller Bearings
CARB bearings or compact aligning roller bearings have more axial displacement than any other bearing, up to ____ % of its width.
20% of its width
The speed of a bearing depends on how smoothly it rolls. The things that affect the smoothness are: (5)
- Type and size of rolling element
- Precision of bearing
- Type of cage
- Type and method of lubrication
- Type of seal
The dynamic load rating of a bearing depends on the load distribution. the load distribution depends on: (3)
- size of rolling element
- Type of bearing
- Loaded zone
The loaded zone can be increased by: (2)
- Reducing internal clearance
- increasing contact angle
Dirty environments can lessen the life of a bearing. You can counter this with integral seals. What are the two types of integral seals? (2)
Non-rubbing seals (shields)
Rubbing seals
For a bearing that will withstand moisture, you should pick one with: (2)
- Stainless parts
- Brass or polyamide cage
For a quieter running bearing, you want a bearing that is:
Made to closer tolerances
High speed machine tools require minimum deflection, which is achieved by using bearings that are:
Made to closer tolerances
Most standard bearings are stable up to _____°
120°C or 250°F
How tightly or loosely a bearing fits in its mount directly affects its: (2)
- Performance
- Length of life
The correct fir ensures that the bearings: (4)
- Rings do not spin on their seats
- rolling elements don’t skid or bind
- Inner ring not so tight it cracks from hoop stress
- Preload is present
The tolerance for any dimension is the :
total permissible variation on size
Fit is the term for the:
Range of permissible tightness or looseness of mating parts
You use ____ or ____ to ensure you have the proper fit between the shaft and inner ring, and the bearing house and the outer ring.
Tolerance codes or fit codes
The letter in the tolerance code has 3 pieces of information: (3)
- Upper case letter indicates tolerance for a hole
- Lower case letter indicates tolerance for a shaft
- The letter also tells us the tolerance position
When interpreting the fit tables, you require the: (3)
- Operating conditions
- Bearing type and size
- type of ring loading
The types of ring loading that are available are: (3)
- Rotating
- stationary
- Intermediate
When determining fits, you should use a micrometer that reads up to ____” in detail
0.0001”
