A needle bearing is a form of roller bearing. However, its length-to-diameter ratio is on the high side. They are used in a wide range of applications such as farm and construction equipment, alternators, automotive transmissions, gear pumps, gasoline engines, tool motors, and aircraft controls. They can be lubricated in different ways such as the use of grease, oil-mist, and oil. However, if it is to serve heavy-duty or high speed purposes, it is better to use oil or oil-mist as the lubricant. Bearings used for light-duty applications do not necessarily need to be lubricated.
The rollers of needle bearings are literally the smallest of all roller bearings for a particular bore size. Also, of all rolling element bearings, their load capacity is the greatest considering a specified radial space. However, they are not often used for bore diameters that exceed 10 inches.
Needle bearings are available in two design patterns. The first pattern is a full complement which means it does not have a retainer. The second has a retainer and it is called a caged needle. The role of the retainer is to ensure spacing and roller guidance. The load capacity of a caged bearing is less than that of a full-complement bearing. Also, its roller complement is way smaller. On the bright side, a caged bearing has a higher speed capacity than a full-complement bearing. Furthermore, the fact that cages bearings have retainers helps to ensure there is effective roller guidance. Also, their lubricant capacity is way superior.
A loose needle bearing is basically a full complement of needles that found in the middle of machine components. It forms the raceway of the bearing. They are easily be misaligned. Also, they make it possible for an inexpensive and sensitive bearing assembly that has moderate speed capability to be created.
The caged assembly acts as a raceway and it is often positioned between hardened machine components. It is a roller complement that has a retainer. They have greater speed capability than loose needle bearings. In fact, it is three times that of a speed bearing.
A drawn-cup full complement bearing is made up of a full complement of needles and a deep-drawn cup which is the outer race. The needle may either be retained by the cup lips or grease, depending on the design. This grease-retained bearing has a greater load capacity.
There are few-dimensional similarities between a drawn-cup caged bearing and a full-complement bearing. The only difference is in the use of a retainer. The retainer helps it to operate at a faster pace and reduced load capacity. However, the full complement bearing is not as tolerant as the caged bearing.
The outer ring of a heavy-duty bearing is slightly heavier. This ring is often made from materials that are hard and precise. They also have a high load capacity.
A cam follower can also be called a track follower. It is a needle bearing that can withstand heavy-duty application. It can have features such as eccentric-mounted studs, self-lubricating rings, heavy-duty studs, coatings, and platings.
Aircraft bearings are suitable for heavy-duty applications. They can operate under diverse conditions whether static, oscillating, or slow rotation. It can either be a single roller or a double roller. The single roller aircraft bearing does not compensate for misalignment while the double roller type does. Both types have oil holes and grooves that help keep the unit lubricated. A thrust bearing is a form of caged bearing. However, it has rollers and these rollers are properly assembled. A thrust bearing can operate under a fairly high speed condition.