Double Row Ball Bearings.

What are Double Row Bearings?

Double row bearings carry their load across two parallel rows of balls held in a single set of rings, rather than the one row of a standard bearing. That second row roughly doubles the load capacity for a given bore and, depending on the internal geometry, changes what kind of load the bearing can take. 

Double row ball bearings come in deep groove and angular contact forms. Accu's range is the double row angular contact ball bearing, where the two rows sit at opposing contact angles. This arrangement lets a single unit carry radial load, together with axial thrust, in both directions whilst resisting the tilting movements that would unseat a lesser bearing. 

In effect, a double row angular contact bearing does the job of two single row bearings mounted back to back, but in one compact component that is quicker to fit and easier to keep in line.

How Double Row Bearings Work

A double row bearing works by sharing the load between its two rows of balls, which run in raceways ground into a common inner and outer ring. In the angular contact design, each row makes contact along a line set at an angle to the bearing axis. Because the two rows angle in opposite directions, the bearing takes thrust whichever way it is pushed. Those opposed contact lines also sit a set distance apart, which is what gives the bearing its stiffness against tilting. As the shaft turns, both rows carry the radial load together, so the bearing runs cooler and lasts longer under a load that would overwork a single row.

Take the output shaft of a compact helical gearbox. A helical gear generates axial thrust as it transmits torque. That thrust reverses when the drive reverses, so the shaft sees radial gear load in one plane and axial load pushing both ways along its length. A single double row angular contact ball bearing fitted at that position handles the lot. It reacts the radial load, holds the shaft against thrust in either direction and keeps the gear meshing squarely under a tilting moment, all without the alignment fuss of setting two separate bearings against each other. The engineer saves space and part count while getting a stiffer, better-located shaft.

Materials Double Row Bearings Are Made From

The double row range comes in two metals, balancing load capacity with corrosion resistance where the environment demands it.

• Steel - (AISI 52100): The standard chrome bearing steel, hardened for the highest load ratings in the range under clean, dry conditions.
• Stainless Steel - (420): A high-carbon martensitic stainless that hardens close to bearing-steel levels while shrugging off corrosion, holding good load capacity in damp or washdown settings.
• Rubber - Buna (sealed variants): Nitrile rubber seals close the 2RS variant on both faces, sealing grease in and keeping grit out of the raceways.

Sizes and Types of Double Row Bearings Available

Accu's double row ball bearings span the 4200 and 4300 series, covering a spread of bores and load ratings for combined-load positions in small and mid-scale machinery.

• Inside diameters: from 10 mm to 30 mm
• Outside diameters: from 30 mm to 62 mm
• Thickness: from 14 mm to 24 mm
• Dynamic load ratings: from 4,480 N to 34,500 N

Every bearing is supplied in its natural finish, with no additional coating or plating. Each carries a specified radial internal clearance, from 0.002 to 0.013 mm on the smallest bore up to 0.008 to 0.028 mm on the larger 4300-series parts. Grease and oil speed ratings are published for each size, reaching 18,000 RPM on grease and 22,000 RPM on oil at the smallest bore.

Two closure options cover the range of working conditions.

• Open: open on both sides for maximum speed and the highest dynamic load rating, suited to clean, higher-duty positions.
• Double Seal (2RS): nitrile rubber seals on both sides retain grease and keep contamination out, ideal for dusty or exposed assemblies.

Each option is offered in Steel - (AISI 52100) as standard and, where an S prefix appears on the part number, in Stainless Steel - (420) for corrosion resistance. The 4200 series is the standard-width range, while the 4300 series runs a wider, heavier cross-section that lifts the load ratings for the same bore.

FAQs

Q: What are double row bearings?

A: Double row bearings carry their load across two parallel rows of rolling elements held in a single unit, rather than the one row of a standard bearing. Doubling the rows raises load capacity and, in the angular contact design Accu supplies, adds real stiffness against tilting moments. A double row ball bearing effectively does the work of two single row bearings mounted side by side, but in one compact component with a single pair of rings, which saves space and simplifies assembly.

Q: What is a double row roller bearing used for?

A: A double row roller bearing uses two rows of cylindrical or tapered rollers to carry very high radial loads in a compact width, which is why double row cylindrical roller bearings turn up in machine tool spindles, rolling mills and heavy gearboxes. The rollers present a larger contact area than balls, so they suit heavier, slower duty. Accu's double row range is the ball type rather than the roller type, namely the double row angular contact ball bearing, which trades some outright radial capacity for higher running speed and the ability to take axial load in both directions.

Q: What is the difference between single row and double row bearings?

A: A single row bearing has one row of balls and is the general-purpose choice for radial load with limited axial capacity. A double row bearing adds a second row, which roughly doubles the radial load capacity for a given bore and, in an angular contact layout, lets the bearing carry thrust in both directions and resist tilting far better than a single row can. 

The trade is a wider bearing. Where a single row deep groove ball bearing would need pairing up to handle a bidirectional thrust or a tilting moment, a double row bearing manages it in one position.

Q: What is the difference between 2RS and ZZ bearings?

A: 2RS and ZZ describe how a bearing is closed, not how it runs. 2RS means two rubber contact seals, one each side, that grip the inner ring to retain grease and keep out dust and moisture, at the cost of a little more friction. ZZ, sometimes written 2Z, means two metal shields that sit close to the inner ring without touching it, keeping larger debris out while allowing higher speeds and lower drag. 

Accu's double row ball bearings are offered Open for maximum speed and load or as 2RS sealed units for dirty or exposed conditions.

Bespoke Double Row Ball Bearings Manufacture.

High precision, bespoke manufacture of Double Row Ball Bearings to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.