Importance of Total Lost Motion
Many engineers look at backlash as the most important element when sizing for an application that requires precision. However, backlash is just one piece of the puzzle. This article will explain areas you should consider when sizing applications.
What is lost motion?
Total lost motion is crucial when sizing applications requiring dynamic and precise movement. Lost motion, as defined by Webster, is: “The motion of a machine or mechanism during which no useful work is performed.” It encompasses backlash, play between mechanical components, strength of the transmission, and material deformities. Lost motion truly does have an impact on repeatability. Here are two areas to examine when sizing for precise applications.
- 1. Backlash
Backlash is a component of lost motion that can simply be defined as the play between the gears. Gear teeth have gaps between them, which is necessary for the gears to rotate and provides a space for the oil to lubricate the teeth. The more backlash a gearhead has, the less precise the gearbox will be in the application because the load shaft can be moved from its desired state.
- 2. Torsional stiffness
When sizing an application, torsional stiffness must be considered. Every mechanical element has torsional windup. This tells us how much springiness is in the input and output shaft diameters and gearing. It is a function of the torque applied in a particular application. The higher the torsional stiffness, the easier it is to have a repeatable movement. Evaluating the torsional stiffness of a gearbox indicates how it will handle cyclic applications.
How does STOBER handle total lost motion?
Backlash is easily managed with the new Generation 3 Planetary series. These gear units feature wider gear teeth, so there is more surface area contact. These units also have the ring gear integral to the housing, which results in up to a 50% increase in stiffness! And the process for making our gears is extensive. STOBER’s smoothness of motion and minimal velocity ripple are possible through our optimized gear hardening process.
STOBER takes the extra steps to grind and deburr the gears, removing the peaks and valleys and flattening the tooth flank. All of this adds up to a gearbox that does not have its backlash increase over time. There is also an option for reduced backlash to have the most precise unit on the market. STOBER knows how to calculate for total lost motion, ensuring your application is precise and repeatable.
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