Calculating Efficency for JVN Calculator

Hi. When working with the JVN calculator, for all mechanisms it gives the option of entering a drive base or gearbox efficiency. How do you determine that efficiency for different scenarios, such as using a gear ratio, sprockets, pulleys, or a versa planetary? Thanks.

See previous discussion here: JVN Gearbox Efficiency - VersaPlanetary Gear Box

Online references are your best bet, although generally the numbers are a bit optimistic as they assume excellent alignment, the right amount of lubrication, proper belt/chain tensioning, etc. Most FRC teams don’t achieve this, so always put some additional margin in to account for lower efficiency.

Spur gear efficiency is typically in the range of 94-98% per stage for reasonable ratios (e.g. up to 6:1). Less gear mesh is typically more efficient. Note that efficiency, particularly with high mesh, is going to improve over time as the gears “run in”. Always try to run in your gearboxes! Reference

Per Wikipedia, planetary gearboxes are usually around 97% per stage. However, I don’t think the VersaPlanetaries are quite that efficient, due to tight gear alignments, misalignments due to manual assembly, excessive grease, etc. I’ve had ones that are quite hot to the touch when operating for not very long. It wouldn’t surprise me if a poorly assembled VP was only 85% efficient per stage.

Timing belts and chain are around 98% efficiency and 91-98% efficiency respectively. However, tensioning matters a lot. Reference


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