Needle Roller Cages
837 products
Loading filters…
Needle Roller Cages
What is a needle roller cage?
A needle roller cage, also called a needle roller and cage assembly, is a set of needle rollers held in a cage, with no inner or outer ring. The needles run directly on the shaft and in the housing bore, which act as the raceways. This makes it the most compact type of rolling bearing, with a cross section only as deep as the needles themselves.
A standard needle roller cage has two main parts:
- A cage, usually made of steel or glass fibre reinforced polyamide
- A set of needle rollers held in the cage pockets.
Because there are no rings, the shaft and housing do the work of the inner and outer rings.
- The shaft and housing bore must be hardened and ground so they can act as raceways.
- The needles in each cage are made to a very tight diameter tolerance, so they share the load evenly.
The cage guides the needles accurately and keeps them parallel to the shaft, which prevents skewing and allows higher speeds than loose needles. Needles are made from hardened chrome steel (grade 52100).
Why are needle roller cages essential?
They give the highest load capacity for the smallest possible space, with nothing between the shaft and housing except the needles. This makes them ideal for gears, connecting rods, and other parts where space and weight are critical. They are stiff, run smoothly, and handle high speeds and oscillating movement well.
They are also simple and low in cost, as there are no rings to make or fit. Their dimensions are standardised, so a cage of a given reference has the same shaft diameter, outer diameter, and width, regardless of which reputable manufacturer makes it.
Typical applications include:
- Gearbox idler and planetary gears
- Engine connecting rods, at the crank pin and piston pin
- Two-stroke engines, such as in motorcycles and garden equipment
- Compressors
- Pumps
- Rocker arms and cam mechanisms
- Gear pumps and hydraulic motors
- Power tools
The main types of needle roller cages
- Single-row needle roller cages (K) - These are the standard design and by far the most common. They have one row of needles in a steel or polyamide cage.
- Double-row needle roller cages (ZW) - These have two rows of needles in one wider cage. They are used where a longer bearing is needed, as two shorter rows guide better than one very long row.
- Connecting rod cages - These are specially designed for the big end (crank pin) and small end (piston pin) of engine connecting rods. They are made to cope with the high speeds, accelerations, and loads in engines, and are usually guided on the connecting rod or the piston.
- Split needle roller cages - These are divided so they can be opened and fitted around a shaft where they cannot be slid on from the end, such as on a crankshaft.
- Axial (thrust) needle roller cages (AXK) - These are flat cages with the needles arranged like the spokes of a wheel. They carry axial loads in a very small space and run against thrust washers or hardened faces.
Cage variants include:
- Steel cages - Strong and suited to high temperatures, and the standard choice in many sizes.
- Polyamide cages - Light and quiet, with good running properties, but typically limited to around 120°C in continuous use.
How to choose the right needle roller cage?
- Size and dimensions - Check the shaft diameter, housing bore, and width available. The shaft diameter and housing bore together decide the size of needles the cage must hold.
- Shaft and housing - The shaft and housing bore must be hardened, typically to at least 58 HRC, and ground to a smooth finish, as they act as the raceways. If they cannot be hardened, use a needle roller bearing with rings instead.
- Load - Work out the radial load and whether it is steady, oscillating, or involves shocks. Compare it with the cage’s basic dynamic load rating and basic static load rating, which are published in manufacturers’ catalogues. Needle roller cages carry no axial load, so add an axial needle roller cage or thrust bearing if axial loads are present.
- Single or double row - Use a double-row cage for longer bearing widths, as it guides the needles better than a single very long row.
- Cage material - Steel cages suit high temperatures and heavy duty. Polyamide cages are lighter and quieter.
- Fitting - Use a split cage where it cannot be slid on from the end of the shaft.
Essential references and specialised ranges
How the numbering works:
The letters at the start identify the type:
K = single-row radial needle roller cage
AXK = axial needle roller cage
Radial cages are sized by three dimensions, in mm:
Shaft diameter x outer diameter x width, so a K 20x24x10 fits a 20mm shaft, runs in a 24mm housing bore, and is 10mm wide.
Axial cages are sized by the bore and outer diameter, so an AXK 1226 has a 12mm bore and 26mm outer diameter.
Always check the shaft diameter, housing bore, and width before ordering a replacement.
Suffixes:
ZW = double row
TV = glass fibre reinforced polyamide cage
TN = polyamide cage
Suffix codes vary between manufacturers, so check the supplier’s catalogue for the exact meaning.
FAQ - All you need to know about needle roller cages
What is the difference between a needle roller cage and a needle roller bearing?
A needle roller bearing has at least an outer ring, and often an inner ring, which provide the raceways. A needle roller cage has no rings at all, so the needles run directly on the shaft and in the housing bore. This saves space but means the shaft and housing must be hardened and ground.
Why do the shaft and housing need to be hardened?
The needles put a very high pressure on the surfaces they run against. If the shaft or housing is too soft, the needles will dent and wear grooves into it, causing noise, play, and early failure.
Can needle roller cages take axial loads?
No. Radial needle roller cages are designed for radial loads only. Axial loads must be carried by an axial needle roller cage with thrust washers, or by a separate thrust bearing.
Do needle roller cages need lubrication?
Yes, lubrication separates the needles from the shaft and housing, reduces friction, and protects against corrosion. Needle roller cages are usually lubricated by the surrounding oil, such as in a gearbox or engine, so make sure oil can reach the needles.
Click here to learn how to maintain a bearing.
Can I replace a needle roller cage myself?
In many cases, yes. The cage is simply slid onto the shaft or into the gear or housing bore. Always inspect the shaft and housing raceways before fitting a new cage. If they are worn, pitted, or grooved, they must be repaired or replaced too, or the new cage will fail quickly. Never mix needles between cages.
How do I identify a needle roller cage I need to replace?
The reference is not usually marked on the cage itself, so it is best identified by its dimensions. Measure the shaft diameter, housing bore, and width of the cage with callipers. Also note whether it has one or two rows of needles, and whether the cage is steel or polyamide.
Click here to learn how to measure a bearing.
How can I tell if a needle roller cage is worn or failing?
Warning signs include:
- Grinding, clicking, or rattling noises
- Play in the gear or shaft
- Missing, loose, or damaged needles
- A cracked, worn, or distorted cage
- Wear marks, pitting, or grooves on the shaft or housing bore
- Discoloured needles or raceways from overheating
