Cam Follower Roller Bearings

What is a cam follower roller bearing?

A cam follower roller bearing is a ready-to-fit roller bearing with a thick outer ring, designed to roll directly along a track, cam, or guide rail. Instead of sitting in a housing, the outer ring itself is the running surface, so it takes heavy loads and shocks from the surface it rolls on. Most cam followers have a threaded stud in place of an inner ring, so they can be bolted straight into a machine frame.

A standard stud type cam follower has five main parts:

• A thick-walled outer ring, which rolls on the track or cam
• A threaded stud, which acts as the inner ring and fixes the bearing to the machine
• Needle rollers or cylindrical rollers running between the stud and the outer ring
• Thrust washers or flanges that guide the outer ring axially
• Seals or shields on both sides to keep grease in and dirt out.

Most cam followers have an outer ring with a crowned profile.

• The running surface is slightly curved instead of flat, which spreads the load and reduces stress at the edges of the outer ring if the track is not perfectly aligned.
• Cylindrical (flat) outer rings are also available for tracks where alignment is accurate and the highest load capacity is needed.

The bearing is non-separable and supplied greased, ready to fit. Studs usually have a slot or hexagon socket in the end, so the stud can be held while the nut is tightened, and a lubrication hole so the bearing can be regreased. Outer rings, studs and rollers are made from hardened bearing steel, and stainless steel versions are also available.

Why are cam follower roller bearings essential?

They give machines a simple, compact, and very strong way to guide or follow a moving part. Because the outer ring is thick and hardened, it carries heavy radial loads and shock loads directly from the track without deforming. The integral stud means there is no separate shaft or housing to design, so a cam follower can be fitted in a single drilled hole with a nut.

They come in standardised sizes and are easy to replace. Many sizes are also available with an eccentric collar, which lets the roller position be adjusted after fitting to remove play or set the preload against the track.

Typical applications include:

• Cam mechanisms and indexing drives
• Conveyors and transfer systems
• Linear guides and slides
• Packaging and bottling machines
• Printing machines
• Forklift masts and lifting equipment
• Automated handling and robotics
• Machine tool changers
• Sliding doors and gates
• Textile and food processing machinery

The main types of cam follower roller bearings

• Stud type cam followers with a cage - These have needle rollers held in a cage. They run with low friction and are suited to higher speeds.
• Full complement stud type cam followers - These have no cage, so more rollers can be fitted, giving a higher load capacity. The trade-off is lower speed and more friction. They suit slow, heavily loaded or shock-loaded applications.
• Double-row cylindrical roller cam followers - These have two rows of cylindrical rollers and carry very high radial loads, with some ability to take axial loads.
• Eccentric cam followers - These have an eccentric collar on the stud. Turning the stud moves the roller sideways, so the position can be adjusted to remove play between the roller and the track.
• Yoke type track rollers - These have an inner ring instead of a stud and are mounted on a pin or shaft, supported on both sides by a yoke or fork. Because the shaft is supported at both ends, they carry higher loads than a stud type of the same size.
• Track rollers without axial guidance - These yoke type rollers have no flanges or thrust washers, so axial guidance must be provided by the surrounding parts.
• Inch and metric cam followers - Both are widely available. Metric types are usually sized by the outer diameter or stud diameter in mm, while inch types are sized by the outer diameter in inches.

Material and design variants include:

• Stainless steel cam followers - For wet, corrosive, or hygienic environments, such as food and packaging machinery.
• Sealed cam followers - With contact seals for better protection in dirty or wet conditions.
• Cam followers with a hexagon socket - Allow the stud to be held with an Allen key while tightening the nut, which is easier than using a slot.
• Cam followers with polymer tyres - With a plastic outer layer for quieter running and to protect soft tracks.

How to choose the right cam follower roller bearing?

• Size and dimensions - Choose the outer diameter to suit the track and space available, and check the stud diameter, thread, and length suit the mounting hole and frame thickness.
• Load - Work out the radial load and any shocks. Compare it with the bearing’s basic dynamic load rating and basic static load rating, and also with the permissible load on the outer ring and stud, which are published in manufacturers’ catalogues. Full complement and yoke types carry higher loads than caged stud types.
• Track - The track or cam must be hard enough and smooth enough for the load. A soft track will wear or dent quickly, even if the bearing itself is strong enough.
• Outer ring profile - Use a crowned outer ring where alignment between the roller and track cannot be guaranteed. Use a cylindrical outer ring where alignment is accurate and maximum load capacity is needed.
• Caged or full complement - Caged rollers suit higher speeds. Full complement rollers suit higher loads and lower speeds.
• Adjustment - Choose an eccentric type if the roller position needs to be adjusted after fitting.
• Environment - Use sealed types for dirt and moisture, and stainless steel for wet, corrosive, or hygienic conditions.

Essential references and specialised ranges

How the numbering works:

Cam follower numbering varies between manufacturers, so the number does not always mean the same dimension:

Metric stud types such as KR - the number is the outer diameter in mm, so a KR 35 has a 35mm outer diameter.

Metric stud types such as CF - the number is the stud diameter in mm, so a CF 10 has a 10mm stud.

Inch stud types such as CF - the number is the outer diameter in inches, so a CF 1-1/2 has a 1.5 inch outer diameter.

The letters at the start identify the design:

KR = single-row stud type track roller

KRE = stud type with eccentric collar

KRV = full complement stud type

NUKR = double-row full complement cylindrical roller stud type

NATR = yoke type track roller with axial guidance

NATV = full complement yoke type track roller

NUTR = double-row full complement cylindrical roller yoke type

Always check the outer diameter, stud diameter, and thread before ordering a replacement.

Suffixes:

PP = sealed on both sides

X = cylindrical (flat) outer ring instead of crowned

SK = hexagon socket in the stud end

UU = sealed type

R = crowned outer ring

V = full complement rollers

B = hexagon socket in the stud head

F = stainless steel

Suffix codes vary between manufacturers, so check the supplier’s catalogue for the exact meaning.

FAQ - All you need to know about cam follower roller bearings

What is the difference between a cam follower and a track roller?

The terms are often used for the same thing. Cam follower usually means a stud type, which bolts directly into a frame. Track roller is often used for both stud types and yoke types, which mount on a pin or shaft supported on both sides.

Why do most cam followers have a crowned outer ring?

A crowned outer ring has a slightly curved running surface. If the roller is tilted against the track, the load stays near the centre of the outer ring instead of digging in at the edges. This reduces wear on both the roller and the track.

What is an eccentric cam follower used for?

An eccentric cam follower has an offset collar on the stud. Rotating the stud before tightening the nut moves the roller slightly towards or away from the track. This lets several rollers be adjusted to share the load evenly, or removes play in a guide.

Do cam follower roller bearings need lubrication?

Yes. They are supplied greased, but many applications need regular regreasing, especially with heavy loads, shocks, or dirt. Grease is fed through the stud, usually via a grease nipple in the stud end or a radial lubrication hole. The lubrication hole should sit in the unloaded side of the bearing, away from the track.

Can I replace a cam follower roller bearing myself?

In most cases, yes. Remove the nut while holding the stud with a screwdriver, Allen key, or spanner on the flats, then fit the new cam follower into the same hole. The stud should be a close fit in the hole and the flange should sit flat against the frame. Tighten the nut to the torque given in the manufacturer’s catalogue. Over-tightening can damage the stud. Never hammer on the outer ring.

How do I identify a cam follower I need to replace?

The reference is usually marked on the stud head or the side of the outer ring. If the markings are worn away, measure the outer diameter, outer ring width, stud diameter, thread size, and stud length with callipers. Also note whether the outer ring is crowned or flat, whether the bearing is sealed, and whether the stud has a slot or hexagon socket.

How can I tell if a cam follower is worn or failing?

Warning signs include:

• Flat spots or pitting on the outer ring
• The outer ring sliding instead of rolling along the track
• Rough or uneven rotation when turned by hand
• Play between the outer ring and the stud
• Noise or vibration as the roller passes along the track
• Grease leaking from the seals
• Wear marks or grooves forming on the track