Ball splines (Ball Spline
bearings) are a special type of
linear motion bearing
A linear-motion bearing or linear slide is a bearing designed to provide free motion in one direction. There are many different types of linear motion bearings.
Motorized linear slides such as machine slides, X-Y tables, roller tables and some ...
that are used to provide nearly frictionless linear motion while allowing the member to transmit torque simultaneously. There are
grooves ground along the length of the shaft (thus forming
splines) for the ball bearings to run inside. The outer shell that houses the balls is called a nut rather than a
bushing, but is not a nut in the traditional sense—it is not free to rotate about the shaft, but is free to travel up and down the shaft. For a shaft travel of any significant length the nut will have channels that recirculate the balls, operating in the same way as a
ball screw
A ball screw (or ballscrew) is a mechanical linear actuator that translates rotational motion to linear motion with little friction. A threaded shaft provides a helical raceway for ball bearings which act as a precision screw. As well as bein ...
.
By increasing the contact area of the
ball bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...
s on the shaft to approximately 45 degrees, the side load and direct load carrying capabilities are greatly increased. Each nut can be individually
preloaded at the factory to decrease the available radial play to ensure rigidity. This process not only increases the contact area, increasing direct loading capabilities, but it also restricts any radial movement, increasing the overhung moment capabilities. This creates a sturdier structure that can handle a very strenuous working environment.
See also
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References
Bearings (mechanical)
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