what teams have used belt drive on thier robots? im thinking of using it for this and this. i once again look forward to your posts!
thanks,
pb
If by belt drive, you mean treads. MOE 365 used treads in 2001 on Lil’ MOE
We used timing belts to drive our robot last year (4 wheel drive, 2 motors per side). We had 4 sets of belts on each side between the motors and the wheels, and we discovered that in some places belts work well, while in other places it would be better to use chain.
For example, the belt connecting to the front wheel was the longest and had the most torque being transferred through it, and it tended to either snap or strip itself to uselessness when push came to shove in a match, no matter how much we tensioned them. We ended up switching to #35 chain for just that section. On the other hand, we never had problems with the relatively short belt connecting the two motors together.
To sum up, here are what we found to be the pros and cons of belt drive:
Pros:
- belts are lightweight compared to chains; also, you can get by with aluminum pulleys which tend to be lighter than steel sprockets
- they come in fixed lengths, so no fiddling around with links and half-links
Cons: - belts tend to strip or snap in high-torque situations
- replacing belts during competitions is time consuming since you can’t just join the ends together like with chain (we got around this by looping several spare belts around the shafts and zip-tying them out of the way)
- they have to be really well tensioned so as not to slip/strip (chains are much more forgiving)
- belts tend to slip off their pulleys if not well aligned, unlike chains
I hope this helps you out.
We used two XL series 3/8" wide timing belts to lift our arm for the light weight. We kept them tensioned very well but often times they still slipped. We broke a belt twice. We were able to uncap the small goal with this arm, but that is about the limit before they started slipping. We probably would have been better off going with something like #35 plastic roller chain.
Are you referring to Belts as opposed to wheels in a Drive system or belts and chain as part of the drive system
Team 522 also has used belt drive in 3 out of the 4 years of their exsistance and found it to be quite dominating if you use the right belt for the right game for the right surface the robot was running on:
2001 - Their robot used belt drive
Pros: it was superior for pushing a disabled robot to the end zone for pts.
Cons: it appeared they had some issues but not major ones when the robot was run in reverse.
2003 - Their robot used belt drive
Pros: it was superior for traction & as well as being immovable when it came time to be king or in the robots case “QUEEN” of the hill.
Cons: Non really noticeable A job well done by that time.
2004 - Their robot used belt drive
Pros: same as above & it was superior for climbing capability
Cons: same as above
C:\ START RANT HERE
Some teams have their different opinions about belts: belts are good for one thing but have their defects. I would choose belt over chain any day
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belts won’t damage the playing surface but will pop the balls due to friction unlike chains which can either scratch / tear the playing surface and possible pop the balls.
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Traction - Different belts give you different traction capability unlike chain
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I personally think that belts are quicker to change then chain
3a) if the robot is designed a certain way the chain may not fit the same way when you first put it on - almost as if it changed its size magically - this statement is just off of speculation and not an actual fact
3b) you have to fiddle with getting the half / master link on
3c) there’s the slight off set that you could lose a part critical to keeping the chain in one piece
3d) for belt drive if the robot is designed a certain way the pulley / sprocket systems can be un - bolted and removed so that you just drop the belt ride in place and bolt everything up.
3e) as said before the belt is in one piece already
3f) a part lost on the floor for a belt system can easily be spotted / replaced
Attached at the bottom are some pics i found on delphi of team 522’s robots.
Don’t build something because you want to; build it because you need to!
meaning don’t build a belt / chain / wheeled system because you want to, build it because thats gonna be the main key in helping you win the game aside from the scoring capabilites you want your robot to have.
Aces high, team 176, used them in 2004. I don’t remember how well it worked for them, but i remember at UTC, they had a few problems such as some of them snapping. BUT, they worked good for them at BAE since they ended up winning. You can look a little bit more into their 2004 bot if you want more info, or just talk to someone from their team on the forum.
(if they were not timing belts, then I am sorry for this post, but i am 99% that they were)
I may be wrong, but I think he’s asking how many people used belts to drive their wheels, instead of chain, not belts instead of wheels 
thank you very much cory, sorry if i wasn’t clear enough.
(here ya go, Alex)
We (team 45) have used treads to propel the robot, but not belts to drive the wheels. I like the direction you are going, and I have wondered how well a FIRST robot would work by using “v-belts” or powered timing belts to drive the wheels. Heck, motorcycles do it (Harley Davidson, at least).
Just like a tank, treaded drive, you have to watch belt alignment and tension. These are the two important factors with any belt design issue. I assume that the advantage of chain (especially 35 series) is that it can handle misaligned sprockets better than belts can handle misaligned pulleys. Also, chain does not need as much tension to work adequately.
In industry, belts are used all over the place to power SCARA robots, linear actuators, and conveyor equipment.
I believe that it CAN be done on a FIRST robot. A think that a belt-drive drive base can be made lighter than a chain & sprocket drive base, as long
as it is done correctly.
Andy B.
i’m pretty sure that in 2003, team 1083 (emoticons) used belt drives. you might wanna try PMing George1083 about it.
Timing belts and pulleys are typically advertised as a replacement to chains and sprockets. Chains have a couple major problems: a low lifetime (which FIRST teams generally don’t need to worry about), and a tendency to stretch. Companies like Mectrol and Gates make belts that they claim do not stretch, and have an extremely long life.
The downside is that they are a pain in the neck. Unlike chain, you can’t simply remove or add a link. So you’ve got to design your system right the first time. You cannot allow any distance change in between your two (or more) pulleys. If one pulley moves towards the other, for example, your belt is going to strip teeth or skip teeth. Finally, you have to pretension your belt to a known pretension that you can calculated based on the belt geometry. If your pretension is to small, it will cause excessive belt wear or the teeth will skip. If too high, your belt may snap under high loads. It’s very hard to come up with a simple way to pretension the belts. There are two ways I’ve considered when designing a belt transmission. First, you can place spring-loaded idlers in the system, which add the tension you want. It sounds simple, but it makes design complicated. Further, for power transmission applications like FIRST, you need to move in both directions. So you’ve got to have an idler on both sides of the belt (slack side and powered side). The other option is what I prefer, but still is not simple. You need to set up your system so that when you install the belt, you have a means of increasing the center distance between the two pulleys until the belt is properly tensioned. Then, you need a way to lock the system in that location so that it never moves.
The bottom line is that belts are great for some industrial applications because they can have little to no maintenance. On the other hand, FIRST robots have a very short lifetime and you don’t have much time to spend on design… So chains make a lot of sense to me.
Patrick