Rubbber bands on catapult

Do rubber bands add torque or tension to a robot?

Reason why people put rubber band on a robot is because it adds power to the catapult to shoot it in the goal

lets say you had a 2 motor choo choo mech and u wanted to change it to one motor, would u need to add more rubber bands??

One motor may not be able to pull more than 1 rubber band. You may need to increase the torque of the drivetrain to to the gears to make it pull more. It’s a balance.

No offence but can you answer my question? Me and my teammates are currently having a debate on the topic. To be clear, im not look for alternatives, but asking whether more rubber bands will be required when switching from a 2 motor to a one motor catapult

No. The motor needs to pull agnest the rubber bands when pulling back. With one motor, you will have less power to pull back, and will not be able to pull agnest all the rubber bands. To fix this, you can add a gear ratio on your choo choo, and then the mech will be slower, but more powerful


So u dont need more rubber bands?? Thats all i need to know btw

The rubber bands are your shooting power and are based on how many you need to make a ball in the goal with your geometry.

This is completely independent on how many motors you need to stretch them. That will be a function of your gear ratio that the motor is powering.

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The reason you’re getting such [seemingly] vague answers is because you are asking a question that doesn’t have one specific clear answer. We don’t have enough information on your specific situation to give you a quick “yes” or “no” answer.

It’s like coming to the forums and asking, “Is this apple red or green?” It could be yellow for all we know.

We don’t know how many rubber bands your catapult currently has, how accurate it is, how much it is struggling, etc.

When you gave us more information here, it was a start:

If you were wondering if you can make a catapult work with just one motor, the answer is yes.

But, you will have to change some things about your robot.

With two motors, you are able to brute force your way through some maybe not quite ideal (but close), geometry. With one motor, you have less motor power, so you need that perfect geometry to get the most out of your motor.

It’s no secret that one motor has less power than two. So you just have to utilize that power more efficiently.

If you gave us pictures and a complete run-down of your catapult and what you’ve tried so far, you might find our input more helpful.


I think your confusion is on the purpose of rubber bands and motors on a choo-choo mechanism. Adding more motor power, whether by a lower gear ratio or another motor, does not affect how far/high/fast your catapult will shoot. Adding more rubber bands makes your catapult shoot higher/farther, but also makes it harder for the motor to pull the catapult down. The motors’ only job is to pull the catapult down. The rubber bands’ only job is to pull the catapult up. If you have two motors, one motor, or ten motors running your catapult, it does not affect how far your catapult shoots. It only affects how easy it is for each of those motors to pull your catapult down, and therefore how fast your catapult will be able to go down. If you add more rubber bands to your catapult, they will collectively pull up harder on your catapult and it will be harder for your motor(s) to pull your catapult down. If you add another motor to your catapult, those motors will collectively have more power to counteract the upward force of the rubber bands, but since the motors do not supply any upward force to your catapult, adding and removing motor power will not affect the upward power of the catapult. However, it will affect your motors’ ability to pull your catapult down quickly.

Long story short, motors do not make your catapult shoot; rubber bands make your catapult shoot. If you remove a motor, your catapult will not have a harder time going up; it will have a harder time going down. Therefore, if you remove a motor, you will not have to add rubber bands to make it shoot as far. You will have to remove rubber bands to make able to pull down. Motors pull the catapult down, rubber bands make the catapult shoot (go up). More shooting force → add rubber bands. More pulling down power → add motor power (add a motor or gear down more).