ISUTAMI BEARINGS
en
How do roller pillow blocks compare with traditional round shaft bearings?
ISUTAMI BEARINGS

How do roller pillow blocks compare with traditional round shaft bearings?

WRITTEN BY DANIELLE COLLINS

Round shaft guides are typically used with plain (composite, plastic, or bronze) or recirculating ball style linear bearings. But another type of round shaft bearing — referred to as a roller block or roller pillow block — offers better stiffness than plain bearings and higher speed capabilities than recirculating ball types.



Instead of balls, a roller pillow block uses three cam rollers to support and guide the load: one on the top (this is the primary load-bearing roller) and one on each side. One of the side rollers is an eccentric cam that can be adjusted to provide the desired amount of preload or clearance.


Two other styles — commonly referred to as double and twin pillow blocks — use six rollers: two on the top and two on each side. Double pillow blocks house all six rollers within the same dimensions as the standard, single pillow block, whereas twin pillow blocks are essentially two roller blocks machined into the same housing.



Roller pillow blocks are generally stiffer than plain bearings, and they can reach higher speeds than recirculating ball bushings. And the housings of roller pillow blocks are designed with the same mounting holes and distance from shaft centerline to mounting surface as traditional ball bushing pillow blocks, making them easy to interchange.


Load ratings for roller pillow blocks are typically much higher than for recirculating ball bushings of similar size. But with the top roller being the primary load-bearing element, roller pillow blocks can only support loads in one direction. Inverted mounting (with the mounting surface facing downward) is not possible, and vertical mounting or overhung loads are not generally permitted.

By using slots (instead of thru holes) for mounting, “floating” versions can compensate for misalignment of up to 0.125 in. between shafts. And the larger diameter of rollers — rather than balls — make roller pillow blocks more capable of withstanding the transition between sections of joined shafts, which are often required for travel lengths over 20 ft. Another unique feature of roller pillow blocks is their ability to traverse curved shafts.


The cam rollers used in roller pillow blocks can tolerate solid debris, such as dirt and chips, by“pushing” it out of the way as they travel along the shaft or by simply rolling over it. And like profiled rail bearings, side seals and scrapers can be added to help prevent contamination from entering the block. Although the rollers are lubricated and sealed, manufacturers often provide an optional lubrication port for the top roller, to help prevent accelerated wear when contamination, high speeds, or high temperatures are present.

The standard materials for roller pillow blocks include an aluminum housing (pillow block) and black oxide coated rollers. Liquid contamination and corrosives can be addressed with stainless steel or chrome plated rollers.

Roller pillow blocks are well-suited for applications such as woodworking, machining, and transport that require long lengths with joined shafts, high load capacity, and the ability to withstand contamination.
Related News
  • How to choose round shaft or profiled rail for linear motion?

    How to choose round shaft or profiled rail for linear motion?

    December 7, 2019BY DANIELLE COLLINS When designing a linear motion system, engineers have two primary choices in recirculating linear guides — round shaft or profiled rail. Choosing the wrong linear motion system ca...view
  • Installation of tapered roller bearings

    Installation of tapered roller bearings

    December 1, 2019Adjusting the axial clearanceFor the installation of tapered roller bearings, the axial clearance can be adjusted by adjusting nuts on the journal, adjusting washers and the threads in the bearing hou...view
  • The difference between linear bearing and sliding plain bearing

    The difference between linear bearing and sliding plain bearing

    November 9, 2019Sliding bearing, in short, is a bearing in which the journal and the bearing bush work under sliding friction. The sliding bearing works smoothly, reliably and without noise. The rolling bearing we ge...view
  • How to choose the right pillow block bearings

    How to choose the right pillow block bearings

    April 21, 2019A pillow block bearing, or a bearing housing or plummer block, is a pedestal that is used to prove support for a rotating shaft with compatible bearings. Pillow block bearings are actually housings th...view
  • Timing belt conveyors: benefits and uses

    Timing belt conveyors: benefits and uses

    January 4, 2020BY DANIELLE COLLINSIndustrial conveyors span a wide range of designs and configurations to suit specific purposes — from positioning delicate optical components for inspection to delivering automotiv...view
  • Two installation methods of pillow block bearing

    Two installation methods of pillow block bearing

    November 10, 20191. Press fit methodThe bearing can be press-fitted on the shaft with a press, and then the shaft and the bearing are installed together into the bearing housing hole. When pressing, pay attention to t...view
  • TEL:+86-574-6399-8066
  • FAX:+86-574-6399 8025
  • EMAIL: sales@isutami.com
  • ADDRESS:No.500, North 3rd Ring Road West, Cixi, Ningbo, 315300, China