Our team is currently in the process of building a double reverse 4 bar, but we encountered an issue, which we assume is with the gear ratio of the lift, the gear ratio is 1:5. For some reason when we tested it, the lift does not extend all the way, it just seems to go half way. Has anyone else encountered this problem. We also do have rubber bands on the lift, and we also tested without them.
Thanks for your help!

Are there any hard stops that you might be missing? Also are your motors hooked up yet or is it just the structure with no power or sensors?

were testing it with power going to the motors

Also, what exactly do you mean by hard spots, as we press the button on the controller, running the motor at full speed, it extends to approximately halfway and then stops. Is that what you mean?

Try replacing the motors. We had a similar issue and it turned out to be a hard stop that we missed but might as well be safe and make sure it isn’t the motors

we have already tried that

we are thinking of changing the ratio to 1:7

Look to make sure none of the bars are hitting anything like screws. Extend your lift, and see if you can slide a piece of paper between the two 4 bars. Hope this helps!

If you can extend it all the way manually, but the motors cannot lift it, then here are some things to look for:
Lift is not made out of steel or 5 wide c channels.
All motors are plugged in and spinning (if not, could be motor, motor controller, or program problem).
Rubber bands are tight enough to hold the lift at any position without motor power.
No sections of code that would stop or slow down the motors.

I’d be surprised if 1:5 could not lift a dr4b, even with only two motors, with enough rubber bands.

Also make sure the backs of your c channels that are attached to the gears aren’t hitting any of the gears on the middle towers :slight_smile: