Linear Ball Bearings
Rolling-element bearings that use balls to provide low-friction travel along a shaft or rail. Recirculating designs allow long or continuous travel.
BEAR / LINE — LINEAR MOTION REFERENCE
Linear Bearings.
Linear bearings guide machine components along a controlled straight path while reducing friction and supporting applied loads. Depending on the design, motion may occur through recirculating balls, rollers, sliding surfaces, bushings, profile rails, round shafts, or precision slide assemblies. Selection depends on load direction, travel, speed, stiffness, accuracy, mounting, lubrication, contamination, alignment, and expected operating life.
OPERATING PRINCIPLE
Linear bearings separate guidance from actuation.
The primary purpose of a linear bearing is to constrain a moving component so that it follows a defined straight path while supporting forces acting on the carriage, bushing, rail, or shaft.
The bearing itself does not necessarily create movement. Motion may be supplied by a linear actuator, ball screw, lead screw, pneumatic cylinder, hydraulic cylinder, belt drive, rack-and-pinion system, or manual force.
This separation is important because the guide system must carry loads and maintain alignment independently of the device that generates travel.
LINEAR BEARING IDENTIFICATION
Guide
Round shaft, profile rail, flat way, slide, or other guide geometry.
Carriage
Moving bearing block, bushing, truck, or slide member.
Travel
Required linear stroke or usable guide length.
Load
Forces and moments supported during operation.
Accuracy
Positional and geometric control required from the guide.
Preload
Internal loading used in some systems to reduce play and increase stiffness.
SECTION / 01
Common Linear Bearing Types
Linear bearing systems differ in rolling-element type, guide geometry, contact method, stiffness, accuracy, contamination tolerance, load capacity, and mounting method.
Linear Roller Bearings
Systems using cylindrical, needle, or specialized rollers to increase contact area, stiffness, or load capacity compared with many ball-based arrangements.
Plain Linear Bearings
Sliding bearings using low-friction material interfaces rather than rolling elements. They can offer simple construction and good contamination tolerance.
Profile Rail Guides
Precision rail-and-carriage systems commonly used where stiffness, repeatability, moment-load capacity, and controlled machine motion are important.
Round-Shaft Bearings
Linear bushings or bearing blocks operating on cylindrical shafts. They are widely used in automation, positioning, packaging, and general machinery.
Crossed Roller Bearings
Precision guides using rollers arranged in alternating orientations to provide rigidity and support loads from multiple directions.
Linear Slides
Integrated guided-motion assemblies combining moving and stationary structures into a controlled linear stage or machine slide.
Dovetail Slides
Sliding systems using mating angled surfaces to provide guidance, stiffness, and resistance to side movement.
Precision Linear Guides
High-accuracy systems engineered for controlled straightness, low play, repeatability, smooth travel, and predictable stiffness in demanding machinery.
SYSTEM / ARCHITECTURE
Linear motion is an assembled system.
The bearing cannot be evaluated independently from its guide, mounting structure, lubrication, seals, alignment, and actuator. Each part influences motion quality and life.
LINEAR MOTION SYSTEM COMPONENTS
Rail / Shaft
Provides the geometric path followed by the bearing
carriage or bushing.
Carriage
Moving component containing rolling or sliding
interfaces and attachment features for the machine load.
Rolling Elements
Balls or rollers positioned between the carriage and
guide surfaces in rolling-element designs.
Wipers / Seals
Help prevent chips, dust, moisture, and other
contaminants from entering the bearing contact region.
Lubrication
Reduces friction and wear while protecting loaded
contact surfaces in designs that require lubrication.
Mounting Base
Machine structure that supports the guide and affects
straightness, stiffness, alignment, and load distribution.
Actuator
Generates motion using a screw, belt, cylinder,
motor-driven mechanism, or another linear drive.
SECTION / 02
Load, Accuracy & Motion
Linear guides are selected by how they control movement while carrying forces through the carriage and guide structure.
Load Capacity
The bearing must support vertical, lateral, reverse, and other forces without excessive deformation, wear, or loss of guidance.
Moment Loads
Loads applied away from the carriage center can create pitch, yaw, or roll moments that must be resisted by the guide arrangement.
Accuracy & Stiffness
Machine-tool, inspection, automation, and positioning applications may require controlled straightness, repeatability, rigidity, and minimal play.
Speed & Acceleration
High travel speeds and rapid acceleration increase demands on rolling elements, cages, recirculation paths, lubrication, seals, and mounting rigidity.
SECTION / 03
Linear Bearing Specifications
Replacement systems should be evaluated using both dimensional compatibility and operating requirements.
Specification
What to Verify
Why It Matters
Guide Size
Shaft diameter or rail cross-section and mounting geometry.
Determines whether the bearing fits the existing guide system.
Carriage Size
Width, height, length, mounting holes, and attachment surfaces.
Controls machine-envelope compatibility and load mounting.
Load Rating
Static and dynamic capacities in applicable load directions.
Determines allowable force and expected operating life.
Moment Rating
Pitch, yaw, roll, or equivalent moment-load capability.
Important when forces act away from the carriage centerline.
Preload
Internal preload or clearance condition.
Influences stiffness, friction, smoothness, and system life.
Accuracy
Straightness, height variation, parallelism, and precision class.
Determines whether the guide can meet positioning requirements.
Speed
Maximum travel speed, acceleration, and duty cycle.
Affects rolling-element behavior, lubricant demand, and heat generation.
Lubrication
Lubricant type, interval, delivery method, and compatibility.
Directly influences friction, wear, corrosion, and service life.
Environment
Dust, chips, coolant, moisture, chemicals, vacuum, or clean conditions.
Determines sealing, materials, lubrication, and maintenance strategy.
SECTION / 04
Linear Bearing Selection
Start by defining the required motion path and loading, then evaluate guide geometry, stiffness, accuracy, environment, installation, and maintenance.
01
Define the Travel
Establish stroke length, travel direction, speed,
acceleration, cycle rate, duty cycle, and required
stopping or positioning behavior.
02
Calculate Loads
Identify forces acting vertically, laterally, upward,
or at offsets that create pitch, yaw, and roll moments.
03
Set Accuracy
Define acceptable straightness, play, deflection,
repeatability, rigidity, and positional accuracy.
04
Choose Guide Type
Compare round shafts, profile rails, ball guides,
roller guides, plain bearings, and slide arrangements
against the application's performance requirements.
05
Evaluate Environment
Account for chips, dust, water, coolant, chemicals,
washdown, cleanroom conditions, temperature, and
corrosion exposure.
06
Verify Integration
Confirm mounting surfaces, fastener locations,
lubrication access, seals, actuator alignment,
parallelism, carriage spacing, and maintenance access.
Compatibility / Note 05
Similar rail size does not mean interchangeable.
Linear bearing systems can differ in carriage height, rail width, mounting-hole spacing, internal raceway geometry, preload, accuracy class, load capacity, lubrication, seals, and reference dimensions even when their nominal size appears similar. In many systems, rails and carriages are intended to function as matched component families. Check the Bearing & Bushing Selection Guide and Component Compatibility Guide before approving a replacement.
SECTION / 05
Linear Motion Resources
Additional resources covering linear bearing assemblies, ball-based linear motion, slide bearings, machine slides, and guided positioning systems.
Linear Bearings
Industry resource covering linear bearings, guide systems, applications, component configurations, and supplier research.
Research Linear BearingsLinear Ball Bearings
Focused resource covering linear rolling-element systems that use balls to support smooth travel along shafts or guides.
Research Linear Ball BearingsSlide Bearings
Supporting information covering sliding bearing arrangements, materials, motion characteristics, applications, and component selection.
Research Slide BearingsLinear Slides
Industrial resource covering slide assemblies for positioning, machine motion, automation, and controlled travel.
Research Linear SlidesMachine Slides
Additional information for guided machine-slide systems used to support controlled movement and positioning in industrial equipment.
Research Machine SlidesXY Tables
Related resource covering multi-axis positioning tables used where two perpendicular linear motions are combined into a controlled stage.
Research XY Tables
Reference note:
External resources are provided for additional research and do
not establish compatibility, interchangeability, certification,
approval, or endorsement. Verify rail and carriage dimensions,
mounting geometry, load ratings, preload, accuracy, lubrication,
seals, and operating conditions before specifying or substituting
a linear bearing system.
RELATED / BEARINGS
Continue the Bearing Reference
Compare linear bearing systems with rotary ball bearings, industrial bushings, and the broader bearing-selection process.