Cylindrical Roller Thrust Bearings

What is a cylindrical roller thrust bearing?

A cylindrical roller thrust bearing is a rolling bearing designed to carry heavy axial loads, which act along the line of the shaft. Instead of balls, it uses short cylindrical rollers arranged like the spokes of a wheel between two flat washers. The rollers make line contact with the raceways, which gives the bearing a very high load capacity and stiffness for its size.

A standard bearing has three main parts:

• A shaft washer, which fits onto the shaft and rotates with it
• A housing washer, which sits in the housing
• A cylindrical roller and cage thrust assembly, which runs between the two washers.

Because the rollers lie radially across the washers, the outer end of each roller travels further per turn than the inner end.

• This creates some sliding between the rollers and raceways, which is why these bearings run at lower speeds than ball thrust bearings.
• Larger sizes often have two or more short rollers in each cage pocket instead of one long roller, which reduces sliding and friction.

The bearing is separable, meaning the shaft washer, housing washer, and roller and cage assembly can be fitted separately. The components can also be bought individually, so the roller and cage assembly can run directly on a hardened shaft shoulder or housing face to save space. Washers and rollers are usually made from hardened chrome steel (grade 52100). Cages are most commonly glass fibre reinforced polyamide or machined brass, with light alloy and pressed steel also available.

Why are cylindrical roller thrust bearings essential?

They carry very heavy axial loads in a compact space and are insensitive to shock loads, which makes them the default choice where a shaft has to resist a large push in one direction. They carry axial loads in one direction only and cannot carry any radial load, so they are usually used with a separate radial bearing, such as a deep groove ball bearing or cylindrical roller bearing. Their high stiffness keeps axial movement to a minimum under load, which is particularly important in machine tools and gear drives. Their boundary dimensions are standardised internationally. So a bearing of a given reference has the same bore, outer diameter, and height, regardless of which reputable manufacturer makes it.

Typical applications include:

• Plastic and rubber extruder gearboxes
• Industrial gearboxes and worm gear drives
• Machine tools
• Crane hooks and swivels
• Oil drilling equipment
• Rotary tables
• Heavy-duty lifting equipment
• Marine and industrial thruster drives

The main types of cylindrical roller thrust bearings

• Single-direction cylindrical roller thrust bearings (811 and 812 series) - These are the standard design and by far the most common. The 811 series is the lighter section, while the 812 series has larger rollers and a higher load capacity for the same bore.
• Large cylindrical roller thrust bearings (893, 874 and 894 series) - These have larger sections and often multiple rollers per pocket. They are used for very heavy axial loads, such as in extruders and heavy industrial machinery.
• Roller and cage thrust assemblies (K) - These are the roller and cage assembly without washers. They are used where the shaft and housing faces are hardened and ground to act as raceways, which saves axial space and cost.
• Shaft washers (WS) - These have a ground bore to fit tightly on the shaft. They can be ordered separately as a replacement or to build up a bearing.
• Housing washers (GS) - These have a ground outside diameter to locate in the housing. They can also be ordered separately.
• Double-direction arrangements - These are created by fitting two single-direction bearings either side of a central washer or shaft shoulder, so axial loads can be taken in both directions.

Cage variants include:

• Polyamide cages - Light, quiet, and cost-effective, but typically limited to around 120°C in continuous use.
• Machined brass cages - Very robust, suited to higher temperatures, shock loads, and heavy-duty applications.
• Light alloy and pressed steel cages - used in some sizes and designs, depending on the manufacturer.

How to choose the right cylindrical roller thrust bearing?

• Size and dimensions - The bore must suit the shaft; the outer diameter and height must fit the housing. For the same bore, a heavier series has a larger outer diameter, larger rollers, and higher load capacity, but takes up more space.
• Load - Work out the axial load and whether it is steady or involves shocks. Compare it with the bearing’s basic dynamic load rating and basic static load rating, which are published in manufacturers’ catalogues. Cylindrical roller thrust bearings take no radial load, so a separate radial bearing is needed. If there is combined radial and axial load, a spherical roller thrust or tapered roller thrust bearing may be better suited.
• Minimum load - These bearings need a minimum axial load at all times to stop the rollers skidding, which damages the raceways. This is particularly important at higher speeds or where the load can drop away, and preloading springs are sometimes used.
• Speed - Because of the sliding along the rollers, limiting speeds are lower than for ball thrust bearings. For high speeds with light axial loads, an angular contact or ball thrust bearing may be a better choice.
• Alignment - They cannot tolerate misalignment. The shaft and housing faces must be square to the shaft axis, and the housing washer must be fully supported.
• Cage - Polyamide cages suit most general applications. Machined brass cages are better for high temperatures, shocks, and heavy duty.

Essential references and specialised ranges

How the numbering works:

The first digit, 8. Identifies a cylindrical roller thrust bearing.

The next digits indicate the series: 811 is the light series, 812 is a heavier series, and 893, 874 and 894 are larger, heavy-duty series.

The last two digits indicate the bore:

00 = 10mm, 01 = 12mm, 02 = 15mm, 03 = 17mm

From 04 upwards, multiply by five (for example, 81105 = 25mm and 81110 = 50mm)

Prefixes for individual components:

K = roller and cage thrust assembly (for example, K 81110)

WS = shaft washer (for example, WS 81110)

GS = housing washer (for example, GS 81110)

Suffixes:

TN, TV, TVPB = glass fibre reinforced polyamide cage

M, MB = machined brass cage

LPB = light alloy cage

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

FAQ - All you need to know about cylindrical roller thrust bearings

What is the difference between a cylindrical roller thrust bearing and a thrust ball bearing?

A cylindrical roller thrust bearing uses rollers with line contact, so it carries much higher axial loads and is stiffer and more resistant to shock. A thrust ball bearing uses balls with point contact, so it carries lower loads but can run at higher speeds with less friction.

Can they take radial loads?

No. They are designed for axial loads in one direction only. Any radial load must be carried by a separate radial bearing.

Can they tolerate misalignment?

No. Any misalignment concentrates the load on the ends of the rollers, causing heat, wear and early failure. If misalignment can’t be avoided, a spherical roller thrust bearing may be a better choice.

Do cylindrical roller thrust bearings need lubrication?

Yes, lubrication separates the rollers from the raceways, reduces friction, and protects against corrosion. Oil lubrication is generally preferred, particularly at higher speeds, as it also carries heat away from the bearing. Grease can be used at lower speeds.

Click here to learn how to maintain a bearing.

Can I replace a cylindrical roller thrust bearing myself?

In many cases, yes. Because the bearing is separable, each part can be fitted on its own. The shaft washer has the smaller bore and fits onto the shaft, and the housing washer has the larger bore and sits in the housing. Do not mix them up, and make sure the raceway sides face the rollers. Apply force only to the washer being fitted, and never strike the bearing directly with a hammer, as this can dent the raceways and greatly shorten its life.

How do I identify a bearing I need to replace?

The reference is usually marked on the side face of the washers. If the markings are worn away, measure the bore, outer diameter, and overall height with callipers and match them against a size chart. Also note the cage material, and whether the rollers run on washers or directly on the shaft or housing.

Click here to learn how to measure a bearing.

How can I tell if a bearing is worn or failing?

Warning signs include:

• Grinding, rumbling, or clicking noises
• Increased vibration
• Rough or uneven rotation
• Increased axial play in the shaft
• Overheating
• Marked, pitted or discoloured raceways on the washers

Click here to learn how to recognise a failing bearing and tips on how to extend the life of bearings.