#25 Chain

[JamesCH95]

We use, and love, Chain Saver as a chain and open-gear lubricant.

http://www.amazon.com/DuPont-Teflon-.../dp/B00KMMFE8Y

Can be found in may places, powered by the magical beast of Teflon. Spray it on, run things around a little by hand, then a few minutes later it's dried out and ready to go.

[Ether]

[quote=JamesCH95;1550502powered by the magical beast of Teflon[/QUOTE]

... and Moly B. Denum

[JamesCH95]

Originally Posted by Ether

... and Moly B. Denum

Of course! How could I forget dear Moly...

[Joe Johnson]

Back on the Chain vs. Live Axle. For a lot of teams, the majority I think, Live Axle is just not going to result in a more reliable drive train. Yes, there are some advantages, I just wouldn't want to be driving people to make a poor decision for their team based on something that might be right for another team but a disaster for them.

Dr. Joe J.

P.S. I love chain for drive systems. JJ

[Ether]

Originally Posted by Joe Johnson

Back on the Chain ...

When I saw the first four words of that sentence I had an immediate flashback to a time long long ago...

[evanperryg]

Originally Posted by Jeffrafa

We have used #25 chain successfully in drive and manipulator applications since our rookie year in 2004. I would definitely recommend #25H chain over #25 in all applications, the weight penalty is marginal for the added strength. I generally avoid #35 chain at all costs, due to weight, but if you are having failures with #25, I would say switching to 25H alone will likely be a marginal improvement - try to increase sprocket size as well. If you have the weight, consider #35 for the added reliability.

If you're worried about chain weight, a local team used #45 chain on their drivetrain in 2014... according to them, it weighed 20 pounds

[cbale2000]

Originally Posted by Joe Johnson

Back on the Chain vs. Live Axle. For a lot of teams, the majority I think, Live Axle is just not going to result in a more reliable drive train. Yes, there are some advantages, I just wouldn't want to be driving people to make a poor decision for their team based on something that might be right for another team but a disaster for them.

Dr. Joe J.

P.S. I love chain for drive systems. JJ

Can you give any examples of failures you get with a Live Axle system that you would not get by just using Chain on Dead Axles? In the 10 years I've been doing FRC I don't think I've ever seen a failure on a Live Axle, I have seen plenty of broken chains though.

What specifically do you see is the downside of a Live Axle system?

[Joe Johnson]

Originally Posted by cbale2000

Can you give any examples of failures you get with a Live Axle system that you would not get by just using Chain on Dead Axles? In the 10 years I've been doing FRC I don't think I've ever seen a failure on a Live Axle, I have seen plenty of broken chains though.

What specifically do you see is the downside of a Live Axle system?

Bent axles are one failure I've had from past years. But I suppose that is more of a problem with cantilevered live axles than live axles alone.

The gear train to get the torque from one axle to the next is another point of failure. Many multidrive live axle systems need a bunch of gears betwixt & between the live axles. More gears, more axles, more gear to gear interfaces, more center distances to get wrong (or have to manage at a minimum).

Typically gears have smaller working radii where the force is transferred from axle to axle than chain (not always but often). This in turn means higher forces for a given torque, which isn't unmanageable (obvs) but can be tricky.

Back to failure live axle failures, the most memorable one for me was when in the Soccer Game where we had to go over the bumps (well you didn't HAVE to but we did). The team I was with then had an 8 wheel beast with an AndyMark shifter direct driving one of the axles on each side and chain in between as some have suggested.

We were in a good place with a win in our first match of the Quarter Finals at the Long Island Regional. During that match we went over the bump a little more energetically than we had up to that point in the tournament (think Dukes of Breakaway). We won the match and thought everything was fine - in fact we were thinking we had some great footage for our highlight reel at the end of the season.

As it turned out, match 2 didn't go so well because we just couldn't get going in high gear. Between matches we checked everything out, couldn't find a problem. We put the robot back out there for our 3rd match only to get the same result: High Gear was useless. It wasn't until we got back to the school that we realized that we had it so hard we had skewed our frame a bit which skewed the gearbox a bit which was enough to make the current go up in high gear to the point that our breakers kept tripping on that side. Loosening some screws, giving the robot a kick or two, and tightening those screws again had us running like a champ again (of course if we were going to compete again we would have had to solve that problem but it was our last tourney that season).

So, was that a live axle problem? I kinda think so but others may disagree.

Dr. Joe J.

[cbale2000]

Originally Posted by Joe Johnson

Bent axles are one failure I've had from past years. But I suppose that is more of a problem with cantilevered live axles than live axles alone.

I will certainly grant you that as an issue with cantilevered live axles, or really any cantilevered axle for that matter. This is also why I think teams that build WCDs are crazy, but whatever works for you I guess.

Originally Posted by Joe Johnson

The gear train to get the torque from one axle to the next is another point of failure. Many multidrive live axle systems need a bunch of gears betwixt & between the live axles. More gears, more axles, more gear to gear interfaces, more center distances to get wrong (or have to manage at a minimum).

Typically gears have smaller working radii where the force is transferred from axle to axle than chain (not always but often). This in turn means higher forces for a given torque, which isn't unmanageable (obvs) but can be tricky.

I would agree that using live axles in combination with gears does add more points of failure depending on the drive configuration (our team has learned ways to mitigate this over the years to the point it's largely a non-issue). That said, it's also certainly possible to use chains along with live center axles to put some redundancy into the system without changing much in the way the chains are run.

I would personally say that using live axle gear-drives is NOT the best thing for most teams to do without careful research, planning, design, and precision machining. Using live axles on chain drives, however, is a very easy thing for just about any team to do (in fact the KoP chassis ships in this configuration, but with belts instead of chain) and, in my opinion improves the overall durability of the drive system.

Originally Posted by Joe Johnson

Back to failure live axle failures, the most memorable one for me was when in the Soccer Game where we had to go over the bumps (well you didn't HAVE to but we did). The team I was with then had an 8 wheel beast with an AndyMark shifter direct driving one of the axles on each side and chain in between as some have suggested.

We were in a good place with a win in our first match of the Quarter Finals at the Long Island Regional. During that match we went over the bump a little more energetically than we had up to that point in the tournament (think Dukes of Breakaway). We won the match and thought everything was fine - in fact we were thinking we had some great footage for our highlight reel at the end of the season.

As it turned out, match 2 didn't go so well because we just couldn't get going in high gear. Between matches we checked everything out, couldn't find a problem. We put the robot back out there for our 3rd match only to get the same result: High Gear was useless. It wasn't until we got back to the school that we realized that we had it so hard we had skewed our frame a bit which skewed the gearbox a bit which was enough to make the current go up in high gear to the point that our breakers kept tripping on that side. Loosening some screws, giving the robot a kick or two, and tightening those screws again had us running like a champ again (of course if we were going to compete again we would have had to solve that problem but it was our last tourney that season).

So, was that a live axle problem? I kinda think so but others may disagree.

2010 was a brutal year for drive systems. Going over the bumps between zones created problems even for us. We had to replace a number of the 3/8" steel shafts on the dead axles wheels in our drive system that year because they kept bending. Never had any problems with the two live axles though, so could have been an issue with your specific drive configuration or just bad luck. No drive system is completely without it's issues or immune from bad luck unfortunately.

[Munchskull]

So suppose that a team did use #25 and suppose they HAD TO have half links, what are the strongest half links on the market?

Also can you replace #25 chain with #25H chain with out changing sprockets?

[Chak]

Originally Posted by Munchskull

So suppose that a team did use #25 and suppose they HAD TO have half links, what are the strongest half links on the market?

I don't know what the real answer is, but my team ran into this exact situation with our practice bot and we used half links from mcmasters as well as some half links from amazon. I would definitely recommend the mcmasters ones. No pesky cotter pins to deal with, and besides we broke the amazon half links the moment we began ramming into our wooden practice defenses. Meanwhile, the mcmasters half link held while another full-link failed elsewhere on the chain.

[Joe Johnson]

Originally Posted by Chak

I don't know what the real answer is, but my team ran into this exact situation with our practice bot and we used half links from mcmasters as well as some half links from amazon. I would definitely recommend the mcmasters ones. No pesky cotter pins to deal with, and besides we broke the amazon half links the moment we began ramming into our wooden practice defenses. Meanwhile, the mcmasters half link held while another full-link failed elsewhere on the chain.

THIS TYPE of Half Link:



ARE MUCH BETTER THAN THIS TYPE:



Just don't even think about using the cotter pin type. Please.

Dr. Joe J.

[Billfred]

Originally Posted by Joe Johnson

THIS TYPE of Half Link:



ARE MUCH BETTER THAN THIS TYPE:



Just don't even think about using the cotter pin type. Please.

Dr. Joe J.

Cosigned. Not even once.

Sincerely,

Lessons Learned In Week 0.5, inclusive of pre-bag time.

[Ether]

Originally Posted by Joe Johnson

Just don't even think about using the cotter pin type. Please.

Originally Posted by Billfred

Cosigned. Not even once.

Hey Guys,

Can you please expound on "why". Where is the failure point with the cotter pin type.

[Billfred]

Originally Posted by Ether

Hey Guys,

Can you please expound on "why". Where is the failure point with the cotter pin type.

I'll expound: the cotter pin fails, and then the whole thing flies apart spectacularly.

Okay, maybe not spectacularly--it just kinda dumps out the end of the tube. But at least on double-sprocket applications (like the 221 sprockets we're using), the cotter pins are more likely to hit something and fail. It's worse if you don't think about it and don't put the pins facing out each way, but the other style just avoids this problem entirely and makes things that much more idiot-resistant.

(I didn't say idiot-proof, because you know what happens then--just idiot-resistant.)