Low Profile Bearing

Low profile bearing are self-lubricating assemblies of rails and die-cast or plastic carriages. They are a cost-effective solution for linear applications that require limited installation space.

RBC manufactures custom bearings designed to optimize performance for specific applications. This can include changes to radial play, lubricants, materials and preloading.

It is essential to choose the right angular speed for your application. This will help ensure reliability and safety in operation.

Stiffness

The stiffness of a bearing is defined as how the force required to compress a spring through a certain distance (pressure/distance) changes with load. The higher the load, the lower the stiffness. This is why it is important to understand the load and speed requirements of your application so that you can choose a bearing with proper stiffness properties for maximum efficiency, accuracy, life, etc.

Several studies have developed an analytical expression for the time-varying stiffness of a bearing by separating the effect of centrifugal force and gyroscopic moment. However, these models do not consider the inertia force produced during high-speed operation which produces a non-linear time-varying stiffness matrix.

The periodical time-varying stiffness of a bearing can be minimized by selecting the proper shaft and housing fits. The recommended shaft and bore tolerances for thin section ball bearings are shown in the Tolerance Tables. This will ensure that the internal clearance of the bearing is kept to a minimum and will not change the operating characteristics of the bearing.

Load Capacity

For example, a duplex pair of C-Type bearings resists heavy combined thrust and radial loads. An X-type bearing could replace the duplex pair in less heavily loaded applications for weight, space and cost savings.

Load capacity requirements also vary with the motion characteristics of an application. For example, slow oscillatory motion of limited excursion can reduce bearing life unless special attention is given to distributing adequate lubrication to the areas of the raceway that experience the greatest wear. (The slewing rings that rotate tank turret azimuth bearings are an example of this type of application.)

Since many machines do not operate at a constant load or speed, selecting bearings for a specified number of hours rating life based on the worst expected operating condition may prove uneconomical. To avoid this, designers can calculate an L10 rating life for the anticipated duty cycle by determining the peak loads and speeds that will occur during the actual operation of a machine.

Reliability

Low speed bearings often operate under conditions with reciprocating motion and varying loads and speeds. This makes it impractical to select a rating life in revolutions because different load and speed peak values will be experienced over the course of the duty cycle.

Depending on the design, the bearing contact surface geometry, surface finish, lubricant, and retainer may need to be modified to minimize frictional torque variation. This is particularly true for oscillating bearings such as those used in tank turrets and aircraft guidance systems.

Hostile environments also affect reliability of low-speed bearings. For example, corrosion and moisture can eat away at the bearings’ internal clearance (radial play). Special lubricants are often specified to resist corrosive chemicals, fumes, dirt, and water. For equipment that will be in storage for extended periods, preservative lubricants can help extend service life. Similarly, bearings that will be in a hostile environment need to be designed to withstand shock loading.

Mounting

The lower profile of the URB-LP eliminates metal-to-metal contact and reduces vibration. It is lighter than the bronze bearing it replaces and can be mounted directly through a machine frame, making it easy to mount and install.

RBC Thin Section Ball Bearings can take radial and axial loads in a variety of mounting arrangements. For example, a duplex pair of angular contact bearings was designed to support an aircraft gun turret and perform at low temperature compatibility with a split inner ring and special balls that absorb moment and radial loading.

Special flanges, anti-rotation tabs and mounting holes can be incorporated in the inner and outer rings of super slim crossed roller bearings to make equipment easier to integrate into machinery frames. Mating parts can also be integrated into the bearing rings to simplify assembly and reduce cost. This allows a simple, cost-efficient solution with full rolling bearing performance. Contact a specialist for advice and to find out what options are available.