Belt driven actuators are the workhorses of the electromechanical world, offering longer stroke lengths and faster speed capabilities than screw driven designs, with less inertia and better resistance to contamination than rack and pinion drives. And although linear motors boast better positioning accuracy than belts, the price-performance ratio of a belt driven actuator is difficult […]
FAQs + basics
How to size a spline shaft: Shaft strength in bending and torsion
Choosing a shaft for a traditional linear ball bushing is relatively easy — choose the appropriate diameter, material, and hardness, check the dimensional accuracies and tolerances, and if the shaft is unsupported, perform a beam deflection calculation. But because spline shafts can withstand both radial and torque loads, it’s important to ensure the shaft strength […]
How to calculate bearing life for a ball spline
A ball spline is much like a linear ball bushing and shaft, but with axial grooves along the outer diameter of the shaft and the inner diameter of the nut. These grooves prevent rotation of the bearing (referred to as a spline nut) and allow the ball spline to transmit torque. Because a ball […]
What is stepper motor resonance and how can it be avoided?
The discrete, step-by-step movements that give a stepper motor its accurate positioning capability can also lead to some undesirable performance characteristics — namely, vibration and audible noise due to resonance. Stepper motors naturally exhibit small vibrations with each step, due to the inertia of the moving rotor, which causes the motor to slightly overshoot (or, […]
What are the differences between incremental and sine-cosine encoders?
Encoders that provide incremental position measurements (whether rotary or linear) output two signals, or channels, typically termed “A” and “B,” to provide position and direction information. These output signals can be in the form of analog sine and cosine waves or in the form of digital square waves. Those that produce digital output signals are typically […]
How to calculate linear ball bushing life (and how it differs from other life calculations)
The standard life calculation for linear ball bearings is widely known as: L = bearing life (m) C = rated dynamic load (N) F = applied dynamic load (N) But linear ball bushings often experience operating conditions that aren’t accounted for in the general bearing life equation. To account for these adverse conditions, the life calculation […]
How does shaft hardness affect the life of a linear ball bushing?
A linear ball bushing riding on a round shaft is often compared to a radial ball bearing, with the bushing acting as the outer race of the bearing and the shaft acting as the inner race. But in linear bushing assemblies, the surfaces of both the ball and the shaft are spherical, so contact between […]
What are stroke ball splines and how do they differ from standard ball splines?
Standard ball splines use balls that recirculate within a nut, or housing, similar to that of a recirculating ball linear bushing. But the mechanisms and geometry required for ball recirculation result in a spline nut that is relatively large in diameter compared to the diameter of the spline shaft. For a more compact assembly, several […]
What’s the difference between a ball screw spline and a traditional ball screw?
A ball screw spline is a combination of two components — a ball screw and a rotary ball spline. By combining a driving element (the ball screw) and a guiding element (the rotary ball spline), a ball screw spline can provide both linear and rotary motion, as well as spiral motion, in a highly rigid, […]
How to make sure you get the right linear bushing interchange
Linear ball bushings are one of the few interchangeable product types in linear motion, with industry-standard sizes and styles, so that a product from one manufacturer can often be substituted with a product from another manufacturer that has very similar dimensions and technical specifications. And most linear bushing manufacturers offer several product lines that are […]
