Master Links

Our team is having a dilemma over the strength/durability of master links. Please tell me about any good or bad experiences you have had using master links.

What are your alternatives?

Assemble the chain without a master link by using normal links. I have been working on other parts of the robot, but somehow we were able to push the pins through on normal chain links.

Some people on our team do not like master links for whatever reason and insist on not using them, but it seems impractical to not use them.

4 years of FIRST and I have never had a master link fail. Properly installed they are not any problem.

Seriously?! I have serious doubts that the strength of a chain that has been broken and reassembled with the same pin/links would be anywhere near as strong as a master link. As soon as you pop that pin through I imagine you are not going to ever get the same fit as the pin has when the chain is first manufactured/assembled. Maybe (maybe) if you had a technique to expand the ends of the pin to re-fix them to the outer plates of the chain, but even then I am skeptical.

I would be very curious to hear an explanation of how/why people are not using master links. I think it might be in your best interest to investigate how the chain is installed on your machine if no master links were used :slight_smile:

Better questions might be: “How much tension are you putting on the chain?” and “Is there any angular or offest misalignment between any sprockets?”

OOC, what size chain are you using, and for what purpose? You should be using #35 roller chain for most purposes on the bot. Anything smaller, and you risk chain failure somewhere. (…And any larger, and you’re probably wasting weight allowance).

Second: Master links typically come in at least two flavors:

  • C-clip locked
  • Cotter pin locked.

I’ve yet to see a cotter pin locked master link fail. I *have often *seen C-clip master links come apart, but mostly due to either faulty installation, or angular/displacement misalignment of sprockets relative to each other causing side forces to appear on the clip.

If any side-side forces are present, the normal chain links can handle them better than the C-clipped master link. Therefore, the master link is normally what fails, first via unclipping, and then full chain failure via unbending of the remaining unsupported “U” until the chain separates.

The solutions are to verify:
(a) there is no angular misalignment of the sprockets relative to each other,
(b) that the sprockets are kept in the same plane via proper colleting or other spacers, and
© that the sprocket shafts are not “sagging” due to either overloading, lack of a bearing block at both ends (cantilever), or excessive unsupported lengths.

This last one causes intermittent “sprocket misalignment”, which then typically manifests as a chain failure, often by the master link! This fools you into thinking it’s a chain or master link problem, when it’s really a sprocket “alignment maintenance” problem!

Does this make sense in your case?

  • Keith

I have never had any issues with using a master link with a clip. I would think that using a master link is the least of your issues to worry about and wouldnt be a failure point in your system. What would you use instead?

Thank you all for your replies so far. I guess I should further clarify the situation.

The chain will be #35 (and could be even larger, we definitely will have room for the weight!). It will be properly installed and will be the chain that drives our robot. We are using Andymark supershifters, but that still will not produce all that much extra tension at any time.

I believe the alternative is to use a chain tool to remove and reinsert the pin. Unfortunately, I also have not been watching the process too closely and am not exactly sure how this is being done.

My main question is this - Has your team had a properly installed drive chain break at the master link?

To my knowledge, neither team 330 nor team 1135 has had that problem.

I’ve had a few bad experiences with master links. Perhaps we don’t know how to properly apply them. They’ve dropped the retaining clip from time to time but we’ve never actually lost a chain due to a link. Anyway, I’ve gone to using a pin extractor re-insertion tool like on the bottom of this page
I had to file the pin straight ( it started to bend from uneven contact) but now it works like a charm and I don’t have to worry about finding a good master link or loosing the parts of the link when I’m in a hurry.
The trick here is that we’ve come up with a design to allow us to make a continuous loop chain that can be easily removed and tensioned. So we make the loops and never have to break the chain again. It took a little practice, but I’m satisfied the link is as strong as the original chain.

We’ve never lost a chain but had the retainer and the outer side drop off and I’d rather not deal with that. I think the trick is being able to snap that clip on with JUST enough force. Maybe needle nose pliers are not the right tool.

Chains main weakness is their master link. Installing the clip, so the open end of the clip is facing the direction of rotation, is a quick way to eject a master link clip as soon as it rubs against some part of the bot.

Improper installation of the clip leads to bending the clip and again increases the chance of loosing the clip.

Chain alignment is important

Chassis flex will also eject a chain.

A tight chain robs the motors of power and will require more power to spin the drive train.

If you use a chain, buy a pair of Snap-On “Duck-Bill” Pliers (basically a wide, flat version of a needle nose pliers) to install and remove your master clip. Replace your master clip often (if you are removing the clip often), Be sure your chain is aligned perfectly. Be sure there is about 3/8" to 5/8" of up & down play in the Chain (get in the habit of checking your chain after each use). Minimize frame flex. Make sure the chain can’t rub on any parts.

Always install the open end of the clip facing the opposite direction of rotation and safety wire the master clip to the chain.

1075 has had some experience wrecking chains using master links. We had chains custom made to the exact length we needed. I don’t recall if we did it in house, or had a sponsor take care of it. Our drives only have one very short chain in them that can’t translate itself very far anyway… the main reason we stopped using master links is there’s no room for them in the latest design. Everything is very close tolerance.

I’d like to see a picture of how to do this.

That depends on the situation and the size of the chain.
There are also different quality/materials used in making master links.

If the chain isn’t twisted at all, master links should hold up fine, but we all know in competition things can happen that aren’t supposed to be possible.

I know there are some chain breakers that push the pins back into the chain avoiding the use of a master link but a regular chain break and a master link usually holds up just fine.

Only once that I can recall in my 8 years on my team.

We had a protruding screw head in the path of the chain, and that got entangled with the master link clip and popped it off. :frowning:

This ONLY happened as a result of a quick replacement between matches of the screw with one with a non-countersunk head which was the only one available in the 5 seconds we had to put the screw back and get back in the game.

Lessons learned… :o

We have used them for 6 years and never had one fail.