Quadriple Reverse 8 Bar lift(QR8B)

This weekend, I had access to a whiteboard. At the same time, I was thinking about a lift, something which would go beyond the tallest tower, to very smoothly and easily knock cubes out. While at the same time be stable, and easy to create, as a solid foundation for competition. The principle will be largely identical to the DR4B, however, it will essentially be two DR4Bs stacked on top of each other. My previous idea of a scissor lift was cancelled after I realized that it wouldn’t be very stable since it would be relying on a sliding system. Hopefully someone can provide information as to whether or not it would be practical.

ur crazy.
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is there something wrong with the system, which you want to point out, or is that just a joke?

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so. 2 dr4bs stacked on top of each other. It would require at least 4 motors if you want to compete against regular ones at all in lifting speed. also there’s the problem of spacing. how are you going to fit 2 dr4bs even in a max 18 inch robot? even if you managed to overcome all the problems stated above your robot would be crazy heavy and when your lift is at max height you wouldn’t be able to move the chassis w/o the robot toppling forward. might as well build a dr6b or scissors lift and end up with an actually practical robot.


as with sliding systems, I personally haven’t used them but I’m pretty sure you can tighten the clearance between the rail and the sliding block and put oil in between to reduce friction and slop.

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I think using a 36:6:1 ratio should be able to lift the arm. Speed really isn’t that much of an issue. Because the time the robot takes to move between the cubes should be spent moving the arm to the desired height.

The issue is would a DR6B go straight up and down?

of course it would as long as the 2 DR6/4Bs’ main bar are the same length.

Anytime it is a double reverse anything, it will go straight up and down. This is assuming that your bars are all the same length. This occurs because as one lift is raising and making an arc, the second stage is also lifting and making an equal arc. The two arcs cancel out, and you end up with no sideways movement.

As for a quad reverse four bar, I strongly suggest you write the idea in your engineering notebook and describe the pitfalls. Other than that, you most likely do not want to use it. As @doge already stated, there are many problems. In my opinion, they missed the most important one. Why would you ever need a lift that is 11 feet tall?!

A standard double reverse four bar fully optimized for height could reach 60-65 inches tall. Two would be between ten and eleven feet tall. The tallest tower is somewhere in the forties for inches (might be wrong, don’t know off the top of my head). I’ve seen single double reverse four bars reach it.

I would go for a Dr4b or a Dr6b if I were you.

I hope this helps, and good luck🙂


The idea of a quadruple reverse 8 bar is preposterous. I thought this would be a joke thread when I opened it. It would be way too tall, require way too much power, be way to hard to compact, and it would likely flop over when fully extended from its own weight. just no. a dr4b should be fine height wise, but if you need a little more height, you could go dr4/6b (first stage 4 bar, second stage 6 bar), or dr6b (both stages six bars.)


Actually with taller lifts stacking speed should be similar if the same amount of motors are geared down, since more arms are moving up at the same speed as another lift it will actually move faster assuming all motors are geared the same as a smaller lift

Edit: this is assuming the force/resistance against the motors is the same when the weight of the lift passes through the gearing, and the. If the bottom of say a DR4B and a QR4B are rotating at 10°/sec the Top of the QR4B will be reaching a higher height faster. And yes I am ok


Are you feeling alright?


I mean, competition wise, no. Even if you somehow made it work, the lift would be over the top excessive, and would not be worth the time or resources to develop.

But if you every need recruiting material for your club/team, you know what to do!


To stack many cubes on top of each other.

But it means less space for more height.

The reason I think of the QR8B is because it would be a space saver. If a DR4B wanted to reach, say 1.2 meters and a QR8B was designed to do the same, it would take up half of the space will reaching the same height. From what I have seen, the cubes aren’t very heavy so stability wouldn’t really be an issue. It definitly would be comprised but not enough to prevent it from working. I would just gear the motors down by a lot to allow it to lift smoothy, likely with some sort of counterweight or elastic band system.

What do you mean by less space? What two lifts are you comparing?

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I would like to point out for the sake of conversation that your terminology is just a hair off. If all 4 lifts are 4 bars then wouldn’t it be a quadruple reverse 4 bar (QR4B) rather than (QR8B)?

an 8 bar is pretty much as high as a dr4b. think about qr8b:scream:

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But then in that case a DR4B would be a DR2B. With 2 bars, rather than 4.