The early forms of ball bearings were full-ball types without ball cages. Friction between balls caused loud
noise, made high-speed rotation impossible and shortened the service life. Twenty years later, a Caged Ball
design was developed for ball bearings. The new design enabled high-speed rotation at a low noise level,
and extended the service life despite the reduced number of balls used. It marked a major development in
the history of ball bearings.
Similarly, the quality of needle bearings was significantly improved by the caged needle structure.
With cage-less, full-ball types of ball bearings, balls make metallic contact with one another and
produce loud noise. In addition, they rotate in opposite directions, causing the sliding contact between two
adjacent balls to occur at a speed twice the ball-spinning rate. It results in severe wear and shortens the
service life.
In addition, without a cage, balls make point contact to increase bearing stress, thus facilitating
breakage of the oil film. In contrast, each caged ball contacts the cage over a wide area. Therefore, the oil
film does not break, the noise level is low and balls can rotate at a high speed, resulting in a long
service life
Balls roll in four rows of raceways precision-ground on an LM rail and an LM block, and ball cages and
endplates incorporated in the LM block allow the balls to circulate.
Each row of balls is placed at a contact angle of 45°so that the rated loads applied to the LM block are
uniform in the four directions (radial, reverse-radial and lateral directions), enabling the LM Guide to be
used in all orientations. In addition, the LM block can receive a well-balanced preload, increasing the
rigidity in the four directions while maintaining a constant, low friction coefficient. With the low
sectional height and the high rigidity design of the LM block, SHS achieves highly accurate and stable
linear motion.
● 4-way equal load
Each row of balls is placed at a contact angle of 45°so that
the rated loads applied to the LM block are uniform in the
four directions (radial, reverse-radial and lateral directions),
enabling the LM Guide to be used in all orientations and in
extensive applications.
● Self-adjustment capability
The self-adjustment capability through Face-to-Face
configuration of THK’s unique circular-arc grooves (DF set)
enables a mounting error to be absorbed even under a
preload, thus achieving highly accurate, smooth linear
motion.
● Global standard size
SHS is designed to have dimensions almost the same as
that of model HSR, which THK as a pioneer of the linear
motion system has developed and is practically a global
standard model.
● Low center of gravity, high rigidity
As a result of downsizing the LM rail section, the center of gravity
is lowered and the rigidity is increased.