Tapered Roller Bearing Cups

What is a tapered roller cup?

A tapered roller cup is the outer ring of a tapered roller bearing. It has a single tapered raceway on its inside surface, which the rollers of the matching cone assembly run against. The cup is fitted into the housing or wheel hub, and the cone assembly, which is the inner ring with the rollers and cage, is fitted onto the shaft. Together, the cup and cone make a complete tapered roller bearing.

A standard tapered roller bearing is made up of:

• The cup, which is the outer ring with the tapered outer raceway
• The cone, which is the inner ring with the tapered inner raceway
• The tapered rollers
• The cage, which holds the rollers in place on the cone.

Because the cup is a separate part, it can be bought and fitted on its own.

• The cone, rollers, and cage stay together as one unit, while the cup is a plain ring with no loose parts.
• This makes the cup easy to press into a housing first, before the shaft and cone assembly are fitted.

Cups are made from hardened chrome steel (grade 52100) or case-hardened steel, with the raceway precision ground to match the angle of the cone and rollers. On inch bearings, cups and cones are sold under their own part numbers, so a cup must always be matched to the correct cone.

Why are tapered roller cups essential?

The cup carries the full load from the rollers into the housing, so its condition is just as important as the cone’s. A worn, pitted, or dented cup will quickly damage a new cone assembly, which is why the cup and cone should always be replaced together. Buying the cup separately also means the correct part can be pressed into a housing or hub ahead of the cone, which is common in vehicle and equipment servicing.

Cups for standard bearings are made to internationally standardised dimensions. So a cup of a given part number has the same outer diameter, width, and raceway angle, regardless of which reputable manufacturer makes it, and will match a cone of the same series from another maker.

Typical applications include:

• Car, van, and trailer wheel hubs
• Truck and agricultural axles
• Gearboxes and differentials
• Industrial gear drives
• Pumps and compressors
• Construction and mining equipment
• Machine tool spindles
• Rail axleboxes

The main types of tapered roller cups

• Single cups - These are the standard design and by far the most common. They have one tapered raceway and match a single cone assembly.
• Flanged cups - These have a flange on the outside, which locates the cup axially in the housing without a shoulder. They simplify housing designs and are common in some wheel and gearbox applications.
• Double cups - These have two raceways in one ring and are used with two cone assemblies to make a double-row bearing. They carry axial loads in both directions and often have lubrication holes and a groove in the outside diameter.
• Inch cups - These are sold under their own part numbers, separate from the cone. They are the most common type bought on their own, especially for wheel and axle bearings.
• Metric cups - Most metric tapered roller bearings are sold as a complete bearing, but metric cups and cones made to ISO dimensions are also available separately in some ranges.

How to choose the right tapered roller cup?

• Matching cone - The cup must match the cone assembly it runs with. On inch bearings, check the cup and cone part numbers are a matched pair, as cups with the same outer diameter can have different raceway angles.
• Size and dimensions - The outer diameter must suit the housing bore, and the width must suit the housing depth. Measure the old cup, or check the housing drawing, before ordering.
• Load and application - Use a cup from the same series as the original, so the load capacity, contact angle, and fit stay the same. For heavier loads, a heavier series bearing may be needed, which means changing both the cup and the cone.
• Cup type - Choose a single cup, flanged cup, or double cup to match the housing design. A flanged cup cannot be swapped for a single cup without changing the housing.
• Quality - Choose a reputable brand. The precision of the raceway angle and finish has a direct effect on bearing life, noise, and how well the bearing can be adjusted.

Essential references and specialised ranges

How the numbering works:

Inch tapered roller bearings use separate part numbers for the cup and cone. The letters at the start show the load class, from light to heavy:

EL, LL, L = extra light to light

LM, M = light medium to medium

HM, H = heavy medium to heavy

HH, EH = extra heavy

On many standard inch bearings, cups usually end in 10 to 19, and cones end in 30 to 49. For example:

LM11949 = cone, LM11910 = matching cup

L44649 = cone, L44610 = matching cup

LM67048 = cone, LM67010 = matching cup

A cup and cone are often sold together as a set, using the cone and cup numbers together, such as LM11949/LM11910.

Metric versions made to ISO dimensions use a similar system with a J prefix, such as JLM104948 (cone) and JLM104910 (cup).

Suffixes:

B = flanged cup

D = double cup

CD = double cup with lubrication holes and groove

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

FAQ - All you need to know about tapered roller cups

What is the difference between a cup and a cone?

The cup is the outer ring, which sits in the housing or hub. The cone is the inner ring, which comes with the rollers and cage fitted as one assembly, and sits on the shaft. Both are needed to make a complete bearing.

Can I replace just the cone and keep the old cup?

It is not recommended. The rollers wear a running track into the cup, and a new cone in a worn cup will run rough, wear quickly, and fail early. Always replace the cup and cone together as a matched pair.

Are cups from different brands interchangeable?

Yes, a cup of a standard part number has the same dimensions and raceway angle from any reputable manufacturer, so it will match a cone of the same part series. It is still good practice to fit a cup and cone from the same brand.

How do I fit a tapered roller cup?

Cups are usually an interference fit in the housing, so they need to be pressed in. Use a cup driver or press that pushes evenly on the face of the cup, never on the raceway. Make sure the cup is fully seated against the housing shoulder, and check with a feeler gauge that there is no gap. Cooling the cup or warming the housing can make fitting easier.

How do I remove an old cup?

Most housings have notches behind the cup, so it can be driven out with a soft drift, working evenly around the cup. Blind housings may need a cup puller. Take care not to damage the housing bore, and check it for wear or marks that show the cup has been spinning.

How do I identify a cup I need to replace?

The part number is usually marked on the side face or outside diameter of the cup. If the markings are worn away, measure the outer diameter and width with callipers. It also helps to check the part number on the matching cone, as this identifies the correct cup.

How can I tell if a cup is worn or damaged?

Warning signs include:

• Pitting, flaking, or spalling on the raceway
• Dents in the raceway at regular intervals, matching the roller spacing
• Blue, brown, or straw-coloured marks from overheating
• Scoring or grooves on the raceway
• Polished or worn marks on the outside diameter, showing the cup has been turning in the housing
• Rust or corrosion on the raceway