Spherical plain bearings are designed to fit within a small envelop while managing radial and axial loads. They are ideal for moderate misalignment in static and oscillatory applications, such as articulation joints on construction equipment.
The important factors to consider when choosing a spherical plain bearing including:
- Structure
- Style
- Type
Spherical Plain Bearings Structure
Spherical plain bearings are made with through-hardened bearing steel and are available with different sliding contact surfaces. When a bearing is steel-on-steel (or metal-on-metal), it is an economical solution for many applications, however, it requires maintenance. The ground inner ring is housed with a mated outer ring without rolling elements, such as rollers or balls.
Maintenance-free spherical plain bearings have different materials on the inner and outer rings. For example, the inner ring may use PTFE, nylon or a self-lubricating bushing. This type of bearing eliminates the need for periodic maintenance.
Operating Temperature: Spherical plain bearings can operate in temperatures ranging from -30 degrees C to 130 degrees C. It is important to know that the load carrying capacity is reduced at higher temperatures. Work with a bearing expert when selecting a spherical plain bearing.
Open and Sealed: This type of bearing can be manufactured with a seal on either side or without a seal. The seal prevents ingress of containments and is used in environments where operating conditions may involve debris.
Types of Spherical Plain Bearings
- Angular Contact SPB/Thrust Spherical Plain Bearing
Sliding contact surfaces are special in shape and offset at an angle to the bearing axis. This type of bearing accommodates radial and axial loads, but the axial load can only be in one direction. They are used in low speed, high thrust and radial load application like steering axles and suspensions. - Self-lubricating Angular Contact (Thrust) Spherical Plain Bearings
Used in low speed, very high thrust and radial load applications, and where self-lubricating is required or re-lubrication can’t be carried out. High strength PTFE fabric with low coef. of friction is bonded to spherical surface of outer ring.
Typically found in low speed, and high radial load applications like steering axles, hydraulic cylinders and steering linkages, this spherical plain bearing can support high radial loads and high impact loads.
This spherical plain bearing operates quietly while being used in low speed, and heavy radial load applications and where self-lubricating is required or re-lubrication can’t be performed.
Used in low speed, high frequency vibration and high radial load applications like shocks and absorbers. The outer ring is formed around inner ring and machined precisely.
The sliding surface is metal-to-PTFE and found in low speed, high frequency vibration, and very high radial load application and where self-lubricating is required
Spherical Plain Bearing FAQs
What does the “2RS” after a bearing name mean?
It simply means that there are two seals.
What coatings can help ease the bearing’s running-in phase?
Phosphate coating and molybdenum disulfide coating can help in running-in phase and avoid galling and seizure.
Can a spherical plain bearing replace a taper roller bearing?
Yes. In some cases, an angular contact spherical roller bearing can supplant a taper roller bearing. Work with a bearing expert to choose the correct solution for your application.
Is there a way to cross reference spherical plain bearings among manufacturers?
Yes. Many manufacturers have reference charts on their websites in both inch and metric sizes.