Conveyor vrs pneumatic plunger

Which common intake design seems more beneficial (regardless of motor usage and spacing) a 3 cube conveyor belt or a 2 cube pneumatic plunger, both on a rd4b.

I don’t think there is one better than the other. I just got done watching Day 1 of the New Zealand Championship online and it was a good example of this. There are both styles, but depending on how well each team optimized the intake and how much practice the driver had they could be equally as good.

If you want a plunger style, I think you have to be on par with team 2915.

Team 2915 reveal video

Yeah that video is what actually struck up this question, they are really good with only 2 cubes but at what point does a conveyor belt capable of 3 cubes beat that or at what point does a 2 cube plunger beat a 3 cube conveyor belt.

I notice that conveyor type intakes are much more likely to stash a cube crooked, which consumes extremely valuable time straightening the cube so more can be stashed.

Of course, I’m sure a conveyor can be optimized to work quite well…but the ones I have seen always seem to have a higher probability of mistakes than the plunger style.

I think speed will play a factor in what choice of manipulator to choose as well. From what I’ve seen, the pneumatic plunger is faster than the conveyor, because you dont have to wait for the cycle of the conveyor. With the plunger you can drop and go, and if there are 2 cubes, you can get 2 cubes at once. Some teams may prefer the speed over capacity, but its a important difference when deciding what type of intake you want to do.

It does not matter what intake system you use as long as you can use it well. Skyrise is an efficiency game, meaning it does not matter if you hold 1 cube or 5 because in reality the most important thing is the ratio of time spent picking up cubes to scoring them. So you could have a 1 cube intake system that can score incredibly fast which would be better than a 5 cube intake system. Belts and Needle intakes are very popular as they as are both not too hard to implement and are quick. The important thing when deciding is that you remember you autonomous because if you lose that then you being driver control playing a game of catch up which never works out well even if you score very quickly because it takes a lot to over come that 10 point crutch. I personally prefer needles over belts because although a belt can work just as well it takes more work to do efficiently as your auton setup becomes hard because you have to have the hooking mechanism line up perfectly with the cube to pick up whereas for a needle it becomes an easy up and down motion. Also once the cube is stuck on a post, if you spend time to try to fix it you will lose out on scoring time but for a needle you can easily drop it straight down. Time is too precious in this game to waste.

Our team is switching from a 2 cube plunger to a 3 cube conveyor. Like everyone else has said, skyrise is a game of efficiency. We have seen good cube robots that are both plungers and conveyors. The thing that plays the biggest role is how much practice the driver gets. The conveyors are a little harder to line up well enough to score, but if enough practice is in, it is obviously worth the switch from 2 to 3 cube capacity.

From what I’ve seen, a pair of 1 cube (New Zealand & U.S.), 2 cube (Canada), and 3 cube intakes (latin america), are capable of scoring an entire field of cubes. Because of this, capacity is almost irrelevant.

However, stepping away from a strategic perspective to a mechanical perspective, siphoning the motors from a conveyor intake towards the lift system or drive system could be more beneficial for fighting over goals or reaching that last skyrise in autonomous.

the way I see it is a give and take with a conveyor you lose a motor, but with a needle you lose a pneumatic tank that could go towards other things. so really it is a matter of what you want to do and using what you have.

Speed is definitely a major factor his year, as well as autonomous scores. What must be decided is what is the most reliable, efficient way for your robot to score. One of our teams did a 2- hook belt where one hook could do skyrise sections. That robot did pretty well, but could be outscored by some of the bigger robots at state. Another team built what is likely the highest capacity robot in our state- but its drive train was too slow.

I’d say conveyor belt, but only if you are also building the skyrise also. The best cube-only robot I saw was from a video on youtube, channel is UHS Robotics, takes in 4 cubes and hold it on a ramp-like thing made out of metal, it folds at the beginning of the match, and it uses a piston to dump all 4 cubes in 1.5 seconds. Really quick, but I’d say their previous model that could hold 3 cubes was better and faster. They scored 90 points with their alliance in one match, where their alliance member solely built the skyrise. They had only one unscored cube remaining at the end. Lots of amazing robots like them are going to worlds. Sorry for going off topic also. This year’s skyrise challenge was the best challenge ever (my thoughts), I’m gonna miss it. Can’t wait for the new challenge.

Thank you for all the responses, in the end we decided to go with a two cube plunger because of multiple reasons.

Reason number 1: The plunger can quickly release the 2 cubes by dropping them. While a conveyor takes time to release and line up. The plunger is more efficient even though only being able to hold 2.

Reason number 2: The plunger is more compact compared to our conveyor belt, it doesn’t take a lot of space to implement.

Reason number 3: We found out that with a conveyor belt you have to have the cubes perfectly centered or else they will tilt our entire lift beyond 90 degrees. With the plunger it holds the cubes perfectly straight and virtually eliminates lift tilt (unless on a low battery). This is critical for us because we do not have any lift straightening programs so we rely on the motors and the 3 cross bars we have.

Reason number 4: We save two motors with will be used as a strafe wheel and a skyrise arm. The way we designed our plunger allows us to drop the cubes 60+ times before losing air pressure.

Reason number 5: The plunger allows us to easily “stash” and maneuver cubes. We also reduce the chances of the cubes getting hung up but if they do its not a problem. We also securely hold the cubes making it extremely hard to drop any and it is a quick pick up compared to a conveyor.


  1. The cubes must be perfectly lined up to pick them up
  2. All the weight is in the front of the robot which is not a problem but when we drive forward fast we loose back wheel traction.
  3. With its height we can only score one cube on the 50 inch goal and can only score both cubes on 5 skyrises, but we can score one cube on 6 skyrises. Vrs our conveyor which could score 3 cubes on any goal including the 7th skyrise.

I would say the pneumatic plunger is better because it is faster at loading and off loading, and the faster you can score, the more points you can achieve in a match, or in skills.