A bearing unit is a bearing unit that combines a rolling bearing with a bearing seat. For supporting rotating shafts and couplings in power transmission systems. It consists of a housing (mounting block) and an insert bearing which is usually self-aligning.
The rolling bearing and the machined bearing housing are installed together to form a bearing unit with various structures, good versatility and interchangeability. The housings are perpendicular to the shaft and have bolt holes that allow the user to secure the pillow block bearings in place. In addition, this type of mounted bearing is sealed and shielded for a clean, enclosed environment.
The bearing with seat is composed of two parts: a deep groove ball shaft vertical or angular contact bearing or thrust ball bearing and a bearing seat.
The inner structure of the bearing with seat is similar to the deep groove ball bearing, but the inner ring of this bearing is wider than the outer ring. The outer ring has a truncated spherical surface, which is equivalent to the concave spherical surface of the bearing housing and can be self-aligning.
Usually, there is a gap between the inner hole of this kind of bearing and the shaft, and the inner ring of the bearing is fixed on the shaft with the top screw, eccentric sleeve or adapter sleeve, and rolls with the shaft.
Mounted bearings are versatile and are used in a variety of applications including rolling mills, ventilation systems, paper machines, conveyor belt pulleys, and long shafts connecting motors and industrial gearboxes. The main way is to support the rotating body of the mechanical structure, and it is often used to fix the shaft and ensure its rotation. Suitable for heavy and light industries, commonly used in transmission equipment, conveying equipment, reduction devices, cages, etc.
It is important to note that pillow block bearings are similar to Plummer block housings but not the same. They are applied differently. Plummer housings are suitable for applications requiring high-power transmission and heavy load handling. On the other hand, mounted bearings are generally used in light duty applications.
Pillow housing bearings with a set screw locking system use screws to secure the inner ring to the shaft. This type of shaft-locking mechanism is easy to use and requires no collar. Also, they are suitable for reverse applications.
What is a seated outer spherical bearing
With a bearing seat, the outer spherical bearing is the bearing core embedded in the bearing seat. The two are perfectly matched, the outer ring of the bearing and the inner wall of the housing have the same characteristics, and both are arc. Generally, the code name of this bearing is printed on the plane of the inner sleeve, while the code name of the bearing seat is engraved on the outer plane of the base.
Outer spherical bearing series with seat
- UC… series (extended inner sleeve, cylindrical bore, with stop screw).
- UK… series (a tapered hole, with fasteners, to be equipped later).
- NC… series (cylindrical bore, with NU concentric set wheel).
- NA… series (cylindrical bore, with eccentric retaining ring).
- SB….series (short inner sleeve, cylindrical bore, with set screw).
- ER….series (cylindrical bore, flat outer ring, with snap ring).
- RB…. series (cylindrical bore, outer ring flat, with set screw).
- SC…. series (cylindrical bore, deep groove ball bearing with curved outer ring).
Some main types of mounted bearings
Mounted bearings perfectly solve the disadvantages of deep groove ball bearings which are hard to fix and have low torque. This design allows the bearing and the housing to withstand 3 degrees of misalignment to cope with misalignment caused by shaft deflection.
The UCP series bearing unit is the most representative bearing assembly situation. UC-type bearing core + P-type bearing seat, also called pillow block bearing. Has the following features:
- The root of the mounting part of the bearing seat is equipped with a rib, which is a high-strength structure for loads in all directions.
- Mount the bearing housing to the main body of the machine, using two screws for mounting.
- For tapered holes (UKP), add the nominal model H of the applicable fastener to the nominal model of the component.
Diamond bearing housing
The diamond-shaped bearing housing is a bearing assembly composed of a bearing core and a bearing housing with a diamond-shaped seat. Also known as 2-hole flange bearings. Has the following features:
- It is suitable for installation on vertical surfaces such as the side of the machine.
- Compared to square modules, the installation space is reduced and the module weight is also reduced.
- When installing the bearing housing to the main body of the machine, fix it with two bolts.
- The center distance between the two mounting bolt holes of the diamond-shaped seat is the same as the center distance between the center distances of the two diagonally positioned bolt holes of the square seat.
- So they are interchangeable.
UCF series bearings
UCF type is a bearing assembly composed of a bearing and a bearing seat with a square seat. Also known as a 4-hole flanged bearing with a seat.
It is suitable for installation on the vertical surface such as the side of the machine, similar to the FL type.
When installing the housing to the main body of the machine, use four bolts for fixed installation.
T type bearing
T-shaped bearing housing, also known as take-up bearing housing.
- A bearing assembly consisting of a bearing and a bearing seat with a track groove.
- By moving the bearing housing radially along the rail groove, the support position of the shaft center can be adjusted.
- Mainly used for belt conveyors, where the shaft center position needs to be adjusted, etc.
- Effectively reduce the friction coefficient of the mechanical load of the mechanical equipment during the transmission process
- High versatility, stable installation, convenient loading, and unloading
- Large load capacity, low noise
- Long life
- Excellent sealing performance
Key points for selecting outer spherical bearings with housings The correct selection of outer spherical bearings with housings is an important link for exerting the performance of the bearings and achieving the normal operation of the host.
From a variety of bearings and bearing housings, the following factors should be considered when selecting a suitable type of outer spherical bearing with seat that meets the requirements of the host machine:
- The structure of the machine itself requires the support:
- Requirements for the size of the bearing seat in the space of the installation part;
- The size, direction, and nature of the load borne by the bearing seat;
- The service life and reliability requirements of the bearing seat;
- The working speed of the bearing seat
- The positioning requirements of the bearing seat;
- The dustproof requirements of the bearing seat;
- The temperature requirements of the bearing seat use environment (high-temperature resistance, low temperature);
- The surrounding medium, dustproof, moisture-proof, waterproof, and other requirements of the bearing seat;
- The strength requirements of the bearing seat;
- The bearing Seat economy requirements.
So how do we choose a correct seated bearing? Your best bet is to have all the writing on the bearing assembly copied. Matching the model of the bearing core with the model of the bearing housing is a complete set of perfect components. I also recommend that you buy it back and write down the model number of the outer package, or take a photo for preservation.
- The installation of the bearing with the seat of the machined parts should be fixed to the installation plate before installing the shaft. In principle, the bearing unit can be installed anywhere, but in order to ensure the service life of the bearing, the mounting surface must be flat and firm.
- Bearing units with blackened surfaces should be avoided being used in humid environments as much as possible. During installation, sweaty hands should be avoided, and wet hands should not directly touch the product. Antirust oil should be sprayed regularly for antirust treatment after installation and during use.
- Pay attention to the use of the shaft ring for back-to-back combined bearings.
- Pay attention to the concentricity of the installation when using the bearings with seats in pairs.
Maintenance and maintenance
- The original upper deep groove ball-bearing cover plate is sealed with grease and does not require additional lubrication.
- Needle roller thrust ball bearings and back-to-back combined bearings with housings are not sealed with grease, and regular lubrication and maintenance should be performed during use.
FAQ and analysis
- The unevenness of the mounting surface will cause the difference in the center height of the bearings used in pairs to cause locking, increased friction, increased heat generation, and reduced service life.
- The bearing with the seat of the deep groove ball bearing can withstand large radial force, but the axial force is limited, and axial force should be avoided as far as possible. To bear axial force and radial force, you can choose the back Combination or Needle Roller Thrust Ball Units
- The bearing is a precision mechanical part, and it should avoid impact as much as possible during use, so as not to cause damage to the track surface or balls, which will increase the heat generation and shorten the service life of the bearing due to the increase of friction control.
- There are different types of dust-proof covers for bearings with seats. ZZ is the metal dust-proof cover that is correctly selected according to the needs during use. It has small friction, high-speed performance, good sealing performance, and good dust-proof performance, but poor waterproof. VV is a Non-contact rubber sealing ring, with small friction, good high-speed performance, sealing, and dust-proof performance is better than the metal dust cover, but poor waterproof DD is a contact rubber sealing ring, high friction, poor high-speed performance, best sealing, dustproof, good waterproof, can be used in splash environment.