many teams use traditional spur gears to power their lifts, but worm gears seem to make more sense because they are anti-back driven( the driven gear can’t move the driver gear). This would allow lifts to hold their position when the motor is powered off. Some post claim that the worm gear’s gear ratio would have too much torque, but using a blue motor, worm gear, and a 36t gear would have a similar ratio as a red motor, 12t gear, and a 60t gear (16.6 vs 20 rpm). It seems like the better option, but I haven’t seen a team use it. Does anyone know why this is?
Part of it might be because of the strange mounting that would be needed for the motor, but most of it is probably because of the inefficiency.
Additionally, worm gears have a super powerful reduction, but it can be hard to build something that can actually handle the stress of whatever you need a worm gear for. most of the time in vex, your gears will skip before full torque is transmitted.
Additionally, worm gears are designed to work with the 24 tooth spur gears that have a slight helix to match the threads of the worm gear, and don’t do as will with other gear sizes.
But by all means feel free to prototype, this is just what I have noticed from my limited testing.
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Worm gears have much worse efficiency than regular gears due to the friction losses. You can easily lose 30% of the power even if when it’s well built and greased.
Worm gear based mechanisms only make sense when you need large gear ratio in small package, it’s rarely used, and passive safety is required. In other cases, and especially, when total available power is constrained, ratchets or active brakes make more sense.
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I actually prefer bevel gears, as they have superior traction and are much faster then your typical gear. I often use bevels any place I can, drive, intakes, and flywheels.
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I agree; thank you for the informative post Mr. Barton.
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