Hi
I have researched a lot about gear ratios, but all the websites contradict with each other. Some say that gear ratio is output / input and some say that it is input / output. I have also saw other VEX forum topics about the subject, but they were kind of confusing. If I have an input of a 60-teeth wheel and an output of 84-teeth wheel, then is my gear ratio 5:7 or 7:5? Thanks!
I believe that output:input is technically correct, but I generally will say something like 1:5 speed ratio or 5:1 torque ratio so that people don’t get confused.
I’ve have always listed 5:7 because 5/7 would represent the amount of the output RPM compared to the input RPM. But this thread seems to explain (it as how many turns of the input:how many turns of the output). Just for clarity include whether it is a speed ratio or torque ratio and people will figure it out. Gear Ratio's - How to properly show them?
@aix This may be a bit confusing, but…
There are 2 ways to do ratios (as you said): output:input and input:output.
In simple terms, output:input calculates torque, while input:output calculates speed.
In VEX, gear ratios are almost always listed as input:output (since we mostly judge drivetrains by speed, such as 61 in/sec or 73 in/sec). So, when talking about robotics to other forumers or builders, list your gear ratio as input:output (which would be 5:7 in your case)
In the industry, however, they are usually listed as output:input.
To avoid confusion on the forums and discord, people also usually list the final wheel rpm after the ratio (such as saying “60:84 428rpm” {assuming a 600rpm motor is driving the input} instead of just “60:84”)
(Thx to Milan 6121A and Milo 948J for your help with this)