Linear Bearings
Table of Contents
Linear Bearings |
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Non-recirculating Linear Bearings
Non-recirculating linear bearings have balls or rollers that directly support loads and are contained in a housing. The rolling elements inside of the bearing rotate about there own axis and do not move within the housing. Since the bearings don't are fixed and don't move within the housing they can only move a fixed distance. Also they have a high precision and travel accuracy because the bearings only rotate in place and don't circulate through the bearing. Due to their high precision and accuracy the bearings are used in machining tools and measurement devices.
Rolling Elements
Ball Bearing Slides
Ball Bearing Slides |
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Roller Bearing Slides
Roller Bearing Slides | |
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V-Type Roller Bearings
V-Type Roller Bearing |
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Crossed-Roller Bearings
Crossed-Roller Bearings |
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Recirculating Linear Bearings
This type of bearing can travel any distance because of how the ball bearings or roller bearings move throughout the bearing. In these kinds of bearings the rolling elements follow a circuit, a ball bearing will start at one point in the circuit and travel on the raceway up and around through the bearing and back onto the raceway. Since these bearing's rolling element recirculate this allows the bearing to roll in theory forever despite the small size of the bearing it's self. A problem with these bearings is there low accuracy cause by a pulsing force from the rolling elements. This pulsing occurs because the rolling elements go from a loaded state to a non-loaded state. A rolling element is considered loaded when it is in contact with the raceways and holding an applied load. it is considered to be non-loaded when it is not in contact with the raceways. Another draw back to using recirculating bearings is the maximum speed that can be achieved. As the rolling elements circulate they need to make a turn around the track, these turns are what cause forces that limit the max speed of the bearing. To increase the speeds ceramic rolling elements can used reducing mass of the rolling element and also reducing the force applied going around the turn. This however reduces the overall load capacity.
Recirculating Linear Bearings |
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Rolling Elements
Profiled Rail Linear Bearings with Recirculating Balls or Rollers
Rolling Element Circuit Track |
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Ball Screw
Ball Screw Cross Section | |
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