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Retainers keep the balls evenly spaced around the raceway preventing ball to ball contact and allowing higher speeds. They also help to retain grease around the balls and raceways. For greater accuracy and to prevent additional friction, it is important that the retainer is not allowed too much radial movement. To achieve this, the retainer is guided by either the balls or one of the rings. See below for information on how each cage type is guided.

These standard retainers are manufactured from carbon steel for chrome bearings and AISI304 or AISI420 grade stainless steel for stainless bearings. These were often made from brass which also offered a high temperature capability but this is much less common due to higher cost of brass and advances in steel technology.

For higher temperatures, stainless steel is usually recommended. The crown cage and ribbon cage perform the same function but the crown cage is used primarily on smaller miniature bearings and thin-section bearings where space is more limited. Steel cages are preferred for arduous operating conditions and where high levels of vibration are experienced.

This moulded fibreglass-reinforced synthetic retainer has better sliding characteristics than the steel cage and produces fewer fluctuations in running torque. It can increase maximum speeds by up to 60 percent so is generally used in high speed applications and has good low noise properties. This retainer is not suitable for low temperature applications as it loses elasticity below about 30°C. In vacuum applications, it may become brittle.

This low speed retainer is used in 316 stainless steel bearings. It has very good corrosion resistance so can be used in the presence of seawater and many chemicals.

A full complement (or full ball) bearing contains extra balls and has no retainer. It is used for its greater radial load capacity although axial load capacity is very small due to the risk of the balls fouling the filling slot during rotation. These bearings can only be used at low speeds and bearing torque is increased due to ball to ball friction. An exception is a hybrid full complement bearing (ceramic balls)  which can be used for higher speeds due to the lower friction coefficient of the ball material. Improved steel and hardening techniques have increased the load capacities of bearings with cages and the full complement bearing is much less common now.

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Metal Crown / Ribbon

• Good for low to medium speeds
• Can withstand higher temperatures according to the type of steel (see "Bearing Material" section)
• Crown type - inner ring guided
• Ribbon type - mainly ball guided

Reinforced Nylon Crown (TW)

• High speed and low noise
• Temperature range approx -30 to +120°C
• Ball guided

Polyethylene Crown (PE)

• Very corrosion resistant

• Temperature range -50 to +110°C
• Inner ring guided

Full Complement (F/B)

• Higher radial load capacity
• Low speed only (except with ceramic balls)
• Low axial load
• Increased bearing torque

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Ball bearing nylon retainer Ball bearing phenolic retainer Full complement bearing
Crown type
Ball bearing crown retainer
Ribbon type
Ball bearing ribbon retainer

Ball Bearing Retainers

PEEK cages are often used in ceramic bearings, 316 stainless steel bearings and PEEK bearings. They are highly corrosion resistant, have a wide temperature range and are suitable for vacuum use.

PEEK Crown (PK)

• Very corrosion resistant

• Low outgassing so suitable for vacuum use

• Temperature range -70 to +250°C
• Inner ring guided

Ball bearing phenolic retainer

This retainer is used in ceramic bearings, 316 stainless steel bearings and PTFE bearings. It is highly corrosion resistant and has a very wide temperature range.

PTFE Crown (PE)

• Very corrosion resistant

• Temperature range -190 to +250°C
• Inner ring guided

Ball bearing phenolic retainer

This is mainly used in our acetal plastic bearings. Unlike the TW cage, this is not a reinforced cage so not suitable for high speeds. It is corrosion resistant but may swell after a few months if constantly used in water or a continuously damp environment.

Nylon Crown (PE)

• Corrosion resistant

• Temperature range -40 to +180°C
• Inner ring guided

Ball bearing phenolic retainer