ROLLER BEARING TYPES

There are two broad categories of rolling bearings – ball and roller. we will discuss roller bearing types, including:

• Tapered Rollers

• Cylindrical Rollers

• Needle Rollers

There are two styles of roller bearings: those with “non-tapered” rollers (cylindrical and needle) and those with “tapered” rollers. The most apparent difference between the two types is the shape of the rollers and the curvature of the races. In a non-tapered roller bearing, the centers of each part run parallel to one another. In the tapered roller, if the imaginary lines were run through the outer race and inner race, they would taper off and eventually coincide at a point even on a line extended through the bearing’s center  Other differences between non-tapered and tapered rollers, such as operating conditions, load capacity and shaft direction, will be explained       

Tapered roller bearing

The tapered roller bearing resembles the wide edge of a cone rather than a circle. There are two major benefits to this design. First, true rolling motion is obtained. Secondly and more importantly, the bearing can handle all loads – radial, thrust or both – in any combination.

Benefits/advantages

The first benefit of the tapered roller bearing is its cone shaped design. Each roller in the bearing can align itself perfectly between the tapered faces of the cup and cone, without guidance by the cage. That is a major development in bearing design and operation. The large end of each roller has been ground so that it is square against the rib along the back of the inner race Without the “rib,” rollers would be forced from the cage  As each roller revolves about the cone, a wide area of contact is made between the large end of the roller and the rib. This wide area of contact compels each roller to maintain accurate alignment. With each roller perfectly aligned between the two races, the bearing works to maximum productivity. Each roller has an equal share in the total workload. The separator, also called the cage, is constructed with an open space over each roller. There are grooves cut in the sides of the roller pockets that correspond to the curvature of the roller when it is in the cage. This permits the rollers to turn evenly, unhampered by cage interference.

The second benefit – the bearing’s ability to support radial and thrust loads simultaneously – is a result of its internal design. A radial load on a tapered bearing produces both a radial and thrust reaction. The rib restrains the rollers and counteracts the load. That is why adequate lubrication and proper end play adjustment are necessary to prevent excess operating temperatures. When carrying simultaneous loads, the bearing should be adjusted toward another bearing capable of carrying thrust loads in the opposite direction. One construction feature makes tapered roller bearings unique from most other designs: the races are separable. When mounted, the inner race (cone) and rollers are assembled as one unit and the outer race (cup) as another. Industry standards in size and design permit cups and cones to be interchanged when necessary.

Applications

Tapered roller bearings are used in automobiles, trucks, tractors, and various farming vehicles, including:

• Transmissions

• Transfer cases

• Rear axle shafts

• Differentials

• Front wheels

• Trailer wheels

Cylindrical roller bearing

The cylindrical type consists of four basic roller bearing parts: inner race, outer race, cage and rollers. The cylinder shaped rollers are kept evenly spaced by the cage, which guides their turning movement on the flat surface of the two races. Some types have flanges or ribs, projecting from the edge of one or both of the races. This supports the rollers while permitting limited free axial movement of the shaft in relation to the housing.

Benefits/advantages

g High capacity under radial loads

g Accurate guiding of the rollers

g Limited free axial movement

(single flange design only)

Applications

• Transmissions

• Differentials

• Rear Axle Shafts

Needle roller bearing

The needle roller bearing is a variation of the cylindrical roller bearing. The main difference is in roller design capacity. The rollers are thinner in diameter, but there are more rollers per bearing. Full complement needle roller bearings do not have a cage. In this type of bearing one roller pushes against the other holding everything in place.

Benefits/advantages

 Good capacity under radial loads

Applications

• Transmissions

• Alternators

• Steering gears

• Universal joints