Chain drive vs. cogged belt drive(timing belts)
 

Has anyone tried cogged belts (timing belts) instead of chain?
Any ideas?
Any comments about the idea?

:confused: :confused: :confused: :confused:

Re: Chain drive vs. togged belt drive
 

Do you mean cogged belts?

If so then according to Goodyear "Because of their higher coefficient of friction, cogged belts tend to be more sensitive to alignment. While envelope belts can tolerate some misalignment, cogged belts are more likely to turn over under the same conditions. Cogged belts should not be used in clutching drives, drives with severe shock loads, and drives that have changing center distances, such as shaker screens. In these applications, the aggressive nature and flexibility of cogged belts can cause vibration, belt turnover, and belt breakage. Cogged belts should also be avoided in drives that require slippage during frequent stops and starts."

Re: Chain drive vs. togged belt drive
 

I've never used timing belts (cog belts) on a first machine before, but use em a lot around work. They work very well for high transmission energy, minimal backlash, high accuracy situations. Have a linear positioning table using a large timing belt drive (4 leadscrews driven by 1 step motor), whole system is accurate to +/-0.0005" with up to 600lbs on it :ahh:

cog belts work awesome for high precision/high torque applications, just make sure you do your math right and line everything up, and keep at least a few teeth engaged in each pulley to prevent skipping teeth.

if any ?'s hit me up.

-Q

Re: Chain drive vs. cogged belt drive(timing belts)
 

1293 used timing belt on their elevator lift in 2005. The lift was smooth as anything--it was beautiful stuff.

Re: Chain drive vs. cogged belt drive(timing belts)
 

We don't use timing belts for the drive because of slippage that might occur. Plus there's the fact that there is no way to alter the length of a belt and they are a hassle to put on.

Re: Chain drive vs. cogged belt drive(timing belts)
 

We hope to use them next year, At least from the motor to the first drive wheel. They have been more reliable for us than chain, and I still love taper-lock :) But we'll really just have to wait and take a look at next years game to see ...

Re: Chain drive vs. cogged belt drive(timing belts)
 

we used 2 for our ball collector this year... it seemed like a good idea at the time.

What it really amounted to was frustration everytime we took the darn thing apart, and now in the offseason, (probably because we 'over-tweaked' the robot) when we go to give demonstrations, and we pick up balls, the collector actually stops once the ball gets in it :confused:, then the ball slowly crawls up and in. (not saying it will happen to you, but be wary)

Re: Chain drive vs. cogged belt drive(timing belts)
 

well we used the timing belts for our ball collector and it worked fine but the chain for our drive train would break all of the time and we thought that we might want to use the cogged belts next year.

Re: Chain drive vs. cogged belt drive(timing belts)
 

This year probably saw more teams using timing belts for the synchronous belt pulley on the large CIM. They are a whole lot quieter, but for adjustability in length I'll use chains.

Re: Chain drive vs. cogged belt drive(timing belts)
 

Both of them have their pros and cons
Cogged belts can beat chain in lighter weight, and chain can beat it in high torque transfer such as in a really torquey drivetrain. A timing belt is pretty reliable for transferring lots of torque, but there is the chance you could rip it in a worst case scenario, which could be avoided by a good design. Though like Gabe said, you have to get your design down first before ordering belts, because you can't change its length quickly like you can with chain by just popping out a link or two.

If you design it well, it will perform well.

Also, both chain and belts will stretch, so you need someway to tension it. If you just keep it static, then as it stretches, problems will arise of the belt or chain popping off and it failing.

Good luck with your designs though.

Also Lord Britten, what pitch of chain did you use? #25 or #35?

Re: Chain drive vs. cogged belt drive(timing belts)
 

for our shooter we hooked up the large sime via a small cogged belt. it worked beautifully and we had only one problem. the belt semi wore out through the course of 1.5 competitions and needed to be replaced. we expected this so we were able to easily disassemble and replace the belt no prob.

Re: Chain drive vs. cogged belt drive(timing belts)
 

When half of your robot gets bashed in during a match, you'll be happy you used #35 chain. :)

Re: Chain drive vs. cogged belt drive(timing belts)
 

Okay, with the 2003 robot, "The Raging Squid," Team Fusion used belt drive. The advantages to belt drives are weight and responsiveness (lack of slack like with chains). However... the belt drive slips so much that there is no way that it could compete with our 2005 or 2006 robot in a pushing contest. As with chain, you usually don't have to worry about slippage or it snapping like with belts, but of course with chain, you must use metal sprockets and the metal chain weight quite a bit. We use #25 chain for our robots to cut the weight and we have not had any of our chains break in the past 2 year.

Re: Chain drive vs. cogged belt drive(timing belts)
 

#25

Re: Chain drive vs. cogged belt drive(timing belts)
 

Mt team used #25 chain last year and our chains would break all of the time. that is why lost in the semi-finals at the Portland regional we did not have time to fix the chain.

Re: Chain drive vs. cogged belt drive(timing belts)
 

Were you a high traction pushing robot? If so then you might want to go with #35 chain.

Our team has used #25 chain every year except 2004 and haven't had problems breaking them that I've ever known of (I know we haven't the past 2 years; don't know about before). We've never been a robot with high traction wheels that does a bunch of pushing either though, so I doubt we put as much stress on them as other teams do.

Re: Chain drive vs. cogged belt drive(timing belts)
 

we have used them for the past 3 years
2004 the arm that hooked the bar- worked well
2005 the arm for picking up tetras- we use timing belts on the secant pivot but when we put it together and tryed to move it with no load and it riped the cogs off so we change 35# chain
2006 the upper Harv that moved balls to the shooter we used double sided timing belt

but after seeing 1503's robot i like chain

Re: Chain drive vs. cogged belt drive(timing belts)
 

We've used #35 chain for 5 years. We have never had a drivetrain malfunction and only need to adjust chain tension once during a regional. That is probably because we don't get much practice time in ahead of time and things are just getting seated :)

One thing I like about chain is that it's easy to add or remove links to get the right length. When we can do it, we position the gearbox between the front and rear drive wheels (4 wheel drive). This keeps the chains short, which helps with weight and reduces the effect of chain wear. Chain tensioning is done by placing shims (washers) under the gearbox where it mounts to the frame. Very simple, very sturdy.

Re: Chain drive vs. cogged belt drive(timing belts)
 

We used cogged belts on mech wheels last year and we broken normal timing belts and stripped Kevlar ones.

We ended up using gears for reliable operation. We also tried chain but couldn't find a robust 8 tooth sprocket the fit the dewalts.

Re: Chain drive vs. cogged belt drive(timing belts)
 

If you design the drive train correctly, you should never have any problems. (use large sprockets, dont have any slack, have chain guides)

We have been a high traction robot for two years with our 6WD system. The secret is the larger sprockets, it allows for more chain to go over a single sprocket than a smaller sprocket, which would give you more torque. Think of it as a bicycle, if you put your bike on the highest speed, it causes you to push harder (which also puts more tension on the chain), if you put it on a low speed, there isn't as much tension on the chain. The same applies with using 2 large sprockets or 2 small sprockets. The weight cost to go to larger sprockets is minimal, and will save you at competition.

Re: Chain drive vs. cogged belt drive(timing belts)
 

Our team (93) used cog belts and cogs for our drive train last year and found that the drawbacks outweigh the benefits - at least for our application. We had a four-wheel tank-style drive using one CIM on each side and our modified variation of Andy Baker's two-speed transmission. We ran into three major issues with the belts.

First, the belts needed to be aligned precisely and captured enough that they don't wander side to side at all. Any wander will result in the belts walking off and the loss of one or both sides of the drive. Wander is also an issue with chain (although much more forgiving) but seemed amplified with the belt.

Second, the belts had to be extremely tight or they would skip over the teeth in the cog and not transfer any motion to the wheels. To remedy this meant to tighten the belts with a tensioner which led to our third problem.

Finally, the belts had to be tightened so much to prevent slippage that we created a ton of friction in the system which definitely translated to loss from the CIMs to the floor.

This year we are returning to chain and sprockets. It has worked well in the past and we know it will work well in the future. We've used #35 in the past but are going to test out #25 to save weight. Based on what many on these forums have to say, the smaller chain should be sufficient.

Our adventure into belt drive was definitely a learning experience and we would return to them if we could overcome some of the problems we encountered. At this point it is easier to return to the familiar and focus on improving that. If anyone has ideas on how to overcome these "opportunities", please share your insights!

Good luck!

Sean

Vee belt polyurethane belting?
 

Chaning the thread a bit,

How many teams have used vee belt for their drive-train. Percieved advantages from someone considering using it this year; less weight than rollerchain, make your length as with chain via hot-knife butt welding kit, alignment less of an issue than with timing belt as vee groved pulley helps center, some slippage not an issue, no need to tension as it stretches to fit.

I am ordering Eagle brand orange 85 and clear 95 vee belt for the drive-train and the same durometers in one size of round belt for .... ;)

I've been told that teams from Michigan have been using this stuff for years :cool:

APS

Re: Vee belt polyurethane belting?
 

although we did not use a v belt for drive it was again on our shooter. the v belt performed better than we thought and showed no signs of slippage and no damage short of normal ware and tare. the v belt and its pully's were the only component on our robot that did not need to be fixed at all.

from my experience, a v belt is easier to align/tention/is more forgiving than a cog belt.

Re: Chain drive vs. cogged belt drive(timing belts)
 

In 2003 we used 4L v belts for the drive. They worked OK but since then we have gone back to #35 chain. V belts will slip when torque goes above a certain threshold. This can be a good thing. Locking up a drive is bad. Something has to give or the motors are going to fail. We used timing belts for our arm in 2004 and 2005. If we have to use an arm again we will probably try something different. Timing belts probably would have been good as a drive for the shooter wheel this year. We used direct drive for the shooter and chose the wheel to match our velocity requirements. Less points of failure and eliminates some friction losses. The timing belt pulleys of the size needed for 6 wheel drive are expensive compared to IFI's aluminum sprockets.

Re: Chain drive vs. cogged belt drive(timing belts)
 

Chain!!! #35. We have used it with no diffuculties whatsoever. It ran our drivetrain last year. We ran an extremely high ammount of torque through them and they never failed. We ran at 2.5 feet per second with 4 2" wide 8" diameter IFI drive wheels with the wedgetop tread material. We never met anyone we couldn't push, at regionals or at Nationals. We bent our frame, which pinched the chian between the wheel and the frame causing it to rub and misalign. Never fell off and never broke. Can a belt do that?!