Deep Groove Radial Ball Bearings: Also known as the Conrad style, are among the most widely used of all bearing designs. They are found in everything from skateboards to aircraft. Their popularity is due to their ability to handle moderate to high speeds with moderate radial and axial loading. Though its load carrying capacity is not as high as its roller bearing counterparts, it makes up for this by compensating for misalignment. An all-around performer, their high production numbers keep the pricing low.
The Conrad style ball bearing is named after its inventor, Robert Conrad, who was awarded British patent 12,206 in 1903 and U.S. patent 822,723 in 1906. A Conrad bearing is assembled by placing the inner race into an eccentric position relative to the outer race, with the two races in contact at one point, resulting in a large gap opposite the point of contact. The balls are inserted via this gap and then evenly distributed around the bearing assembly, causing the races to become concentric. Assembly is completed by fitting a cage to the balls to maintain their positions relative to each other. Absent the cage, the balls would eventually drift out of position during operation, causing the bearing to fail. The cage carries no load and serves only to maintain ball position.
Though Conrad's design was the first modern radial ball bearing, it was by no means the first. Roller bearings had been developed since ancient times and the first recorded patent on ball bearings was awarded to Mr. Jules Suriray, a Parisian bicycle mechanic, on 3 August 1869. The bearings were then fitted to the winning bicycle ridden by James Moore in the world's first bicycle road race, Paris to Rouen, in November 1869.
were first produced in Europe, so they were
standardized to metric dimensions. The standard has
been and remains metric for this and most bearing
designs worldwide. We offer several variations which
include inch dimensioned bores for adaptability to
This design is available with shields or seals. Shields are typically non-contact designs which are usually of metal. These are used to exclude larger debris. Shielded bearings are sometimes preferred because of their excellent high speed capability.
Sealed bearings are better than shields when excluding smaller debris. They are best utilized in dusty and/or abrasive environments, where such contaminants would shorten the bearing's potential/theoretical life.