Archive for the ‘cages’ Category

Rolling Bearings: Parts and Cage Types

Friday, February 27th, 2015

The main parts of the ball bearing are the races and the balls. There is an outer and an inner race. The outer race goes into a bore, and the inner races carries the shaft. In between these two parts is where the balls are placed to create the bearing’s rolling properties.

Likewise, roller bearings follow suit with this placement. In both roller and ball bearings, the rolling element lies between the outer race and inner race. Then, there is a separator between the inner race and the outer race, in which the rolling element actually sits. On the inside of the inner race is where the shaft sits.

Without these basic parts, there is no ball or roller bearing. The image here, from Encyclopedia Britannica Online, shows us how roller and ball bearings are set up within the races.

There are, however, other bearing parts to consider such as flange, shield, and bore. Here you will find a description of these types of parts explained in detail and with a map of terms, from

One additional part, for example, is the bearing cage, or retainer. All rolling bearings contain a cage. Depending on the number of ball or roller sets, the bearing may contain multiple cages. The purpose of the cage is to:

  • Reduce frictional heat in the bearing by separating rolling elements.
  • Evenly space the rolling elements to optimize load distribution.
  • Help avoid damaging sliding movements by guiding the rolling elements while in the unloaded zone.

Cages are stressed by friction, strain, and inertial forces, and can be degraded by high temperatures and certain chemicals. Thus, the design and material of a cage influence the suitability of a rolling bearing for an application. There are different types of cages for different bearing types and operating conditions. Below are three common types of cages.

Stamped Metal Cages: Typically made of sheet steel, stamped metal cages are lighter weight, and provide ample space inside the bearing to help maximize the effects of the lubricant.

Machined Metal Cages: Machined metal cages, typically made of brass or steel, generally permit higher operating speeds.

Polymer Cages: A third type of cage, the polymer cage, which is a fabric reinforced phenolic resin, has characteristics of both strength and elasticity. These cages are able to operate smoothly under poor lubrication conditions.

Koyo Needle Roller – Bearing types and cages

Thursday, June 30th, 2011

Needle Roller Bearings

Needle roller bearings are an economical alternative for applications requiring minimal space to carry a given load at a desired speed. Needle roller bearings can be an ideal choice because of their ability to handle a given level of speed and load capacity, yet have the smallest cross section of all roller bearing types.

We offer both inch and metric nominal bearings in popular designs such as: drawn cups, radial caged needle rollers, machined ring, track rollers, thrust bearings, combined bearings, and drawn cup roller clutches. Most of these bearing types can be operated directly on a machined shaft of suitable quality, or with a matching inner ring where this requirement cannot be conventionally satisfied.

Radial Needle Roller and Cage Assemblies

Radial needle roller and cage assemblies have a steel cage that provides both inward and outward retention for the needle rollers. The designs provide maximum cage strength consistent with the inherently high load ratings of needle roller bearings. Accurate guidance of the needle rollers by the cage bars allows for operation at high speeds. Also available are needle roller and cage assemblies using molded, one-piece glass-reinforced engineered polymer cages. Needle roller and cage assemblies are manufactured with either one or two rows of needle rollers.

Drawn Cup Bearings

The outer ring in the form of a cup is accurately drawn and no subsequent machining is performed to build the outer raceway. Drawn cup needle roller bearings are available in open ends or single, closed-end designs, They also are available with one or two integral seals. Other options include a single lubricating hole and matching inner ring.

Heavy-Duty (Machined) Needle Roller Bearings

These bearings are available in a wide range of inch and metric sizes plus an array of design features including: integral seals, side flanges (or separate end washers), inner rings, oil holes and single or double caged sets (or full complement) of rollers.

Track Rollers

Track rollers listed in this catalog are designed with outer rings of large radial cross section to withstand heavy rolling and shock loads on track-type or cam-controlled equipment. The outside diameters of the outer rings are either profiled or cylindrical, Profiled track rollers are designed to alleviate uneven bearing loading resulting from deflection, bending or misalignment in mounting. Stud-type track rollers are available with or without lip contact seals, or with shields. Yoke-type track rollers are designed for straddle mounting. Each yoke-type is available with either radial needle roller and cage assemblies, or with a single (or double) full complement row of cylindrical or needle rollers.

Thrust Bearings

Thrust needle roller and cage assemblies are available in a variety of inch or metric sizes. All types have very small cross sections. If the back up surfaces cannot be used as raceways, hardened washers are available. Thrust bearings are available with needle rollers or heavier cylindrical rollers for high load-carrying capacity.

Combined (Radial and Thrust) Bearings

Combined bearings consist of a radial bearing (needle roller bearing) and a thrust bearing (ball or roller bearing). Some combined bearings are constructed similar to drawn cups, but with an added thrust bearing component. Like other needle roller bearings, these combined bearings can be matched with an optional inner ring or thrust washer as the opposing raceway.


Wednesday, June 15th, 2011


Composition cages combine light weight, precision and oil-absorbing features which are particularly desirable for use on high speed applications. This (CR) cage is a ring-piloted type and is available in Timken’s patented channeled construction for very high-speed applications. It is particularly associated with the outer-ring piloted, extra precision WO series bearings


For certain very high contact angle, light section aircraft bearings, molded nylon “snake” cages are employed, Cages are also made with high temperature materials in the various configurations described previously.


The SMBR and MSR cages are ring-piloted. The advantages of these cages are high strength even at elevated temperatures as well as high-speed capability due to the ring-piloted construction. In many cases these cages are silver plated for use in applications requiring high reliability.They are available in both ball and roller bearings.


Wednesday, June 8th, 2011


Bronze Cages are generally installed in bearings which are designed for use on heavily loaded applications, such as, deep well pumps, woodworking machinery, and heavy construction machinery. The following types of bronze cages are available:


This cage, a ball-piloted bronze retainer designated by the letters BR in the Fafnir/Timken line, utilizes two identical halves which are riveted together.


These cages are machines all over to provide ring riding surfaces and good static and dynamic balance. They are commonly incorporated as inner ring piloted designs in the 7000 angular contact series.

Because of their superior strength, these cages are generally used on heavily loaded applications such as deep well pumps, woodworking machines, and heavy construction machinery.

Stay tuned for Part 4 .. More cages


Thursday, June 2nd, 2011


Molded cages are either ball or land piloted and are available in the following types:


PRB (Nylon)

One-piece molded snap-in 6/6 nylon cages are specially processed to provide;

  • Toughness at moderately high and low temperatures
  • Resistance to abrasion
  • Resistance to organic solvents, oils, and greases
  • Natural lubricity
  • Long term service at temperatures up to +250 degrees Fahrenheit (+121 degrees Celsius)
  • Dimensional stability

These cages offer superior performance in applications involving misalignment due to their greater flexibility.

PRB molded nylon cages provide uniformity of ball pocket clearances for consistent operation. They are suitable for temperatures up to +250o F (+121o C) continuous operation and can tolerate +300o F (+149o C) for short periods.

These cages are available in both Conrad (K) and maximum (W) complement bearings and are standard for the more popular wide inner ring bearing series.

PRC (Reinforced Nylon)

Molded 6/6 nylon reinforced with 30% (by weight) long glass fibers and 5% (by weight) M0S2. This material is used primarily for one piece ring piloted cages used in precision grades of angular contact bearings.

PRC cages offer outstanding strength and long term temperature resistance. Molded to very close tolerances and uniformity, combined with light weight design, they permit higher speeds and reduced noise.

PRC cages are most commonly, the one piece outer piloted “L” type design but are also available in two piece riveted inner piloted or one piece ball controlled designs.


For very high speeds o very high temperature applications special materials can be used. Nylon with a PTFE additive is available for molded cages required for very high speed applications for applications involving extra high operating temperatures (up to +450o F, +232o C) molded cages made of fiber reinforced polyphenylene sulphide can be made.

Stay tuned for Part 3 .. Bronze Cages


Tuesday, May 31st, 2011

Cages (sometimes referred to as rolling element separators or retainers) perform an important function in the proper operation of rolling bearings. They serve to maintain uniform rolling element spacing in the races of the inner and outer rings of the bearings as the rolling elements pass in and out of load zones. Cage types in several materials and configurations have been developed to meet various service requirements.

Some of the materials from which cages are made include pressed-steel, pressed-bronze, cast bronze, machined bronze, machined steel and compositions of various synthetic materials.


Steel cages are generally ball-piloted and are available in the following types:


Light in weight and made from strong, cold rolled steel, the pressed-steel cage because of its compactness is the optimum design for use in shielded and sealed bearings which must conform to the ABEC boundary dimensions. This is a general purpose design and is frequently used for ABEC-1 radial ball bearing sizes.


The welded steel cage provides greater strength, increased rigidity, and better pocket alignment than the finger type. The projection welding of the cage halves eliminates weakening notches or holes and fingers or rivets. It assures better mating of cage halves circumferentially and radially.

This construction also provides more uniformity of ball to pocket clearance. Improved pocket geometry permits higher speeds, reduces cage wear, provides cooler operation, and improves and extends lubricant life. This cage is standard in most radial non-filling slot bearings of the open, shielded, and sealed types.

Stay tuned for part 2 … Molded Cages