Exposed gears/chain
 

Hi everyone,

I haven't been super active in the FIRST community since I graduated in '09, but in the 6 seasons since then (and especially at the PGH regional this past weekend) I've noticed more and more robots have exposed gears or sprockets/chains. I'm curious as to how this is legal; back when I was competing it was very important that these pinch points be covered, to some extent. And speaking from personal experience when I caught a finger between a moving sprocket and chain, why is this no longer a concern? On a very large number of robots I've seen, I could walk right up, and stick a finger or get caught in exposed gears, with zero protection around them. I understand it saves weight to not cover them, but at the expense of safety? Just seems a little odd to me.

Re: Exposed gears/chain
 

I remember when this used to be a rule that was strictly enforced. You are right that it has gone away in recent years.

From a safety perspective, I think FIRST is relying on teams to put their own safety measures in place as guards. I can't speak for all teams obviously, but we have a "hands off" policy when the robot is on to prevent these sort of issues. You could walk right up and stick your finger in a robot that was on but that would be a breach of safety protocol.

Technically, even in the years 2006 - 2009 there we always ways a person could hurt themselves by intentionally putting their hand in or on a active robot (with or without guards).

That being said, lots of safety conscious teams will still design these sort of guards to protect their students. But suffice it to say, if you don't have authorization/permission/training to touch a robot (whether it is on or off) don't touch it.

Re: Exposed gears/chain
 

OP's avatar checks out: Exposed gears.

Actual input: My team has exposed chain for the time being and we are working on a guard. I too am surprised they would be lax on this issue.

Re: Exposed gears/chain
 

I agree that it would be a good practice to always cover pinch points and exposed chains, but many times it's just not plausible with the design of the robot. However, fingers should never be anywhere near pinch points if the robot is running or parts are being moved by hand- that's common sense. Clear communication between team members working on the robot should be enforced to prevent someone from moving a mechanism or enabling the robot while someone else is working near a pinch point.

Re: Exposed gears/chain
 

We cover most exposed sprockets and chain where possible. This year we use a chain to run the lift so we couldn't cover the chain but we covered the sprockets. Normally if we don't we get dinged in inspection. It probably just depends on the inspector.

Re: Exposed gears/chain
 

Following Rule #1 of "Don't be an idiot" will generally protect you from open gears/chains.

If you're not following Rule #1...well a guard probably isn't going to protect you either.

Re: Exposed gears/chain
 

It's the 'generally' here that is a problem. Most people want their fingers to remain attached with a more reliable assurance than 'generally'. The idiot is the one that presses enable while the bot is in autonomous test mode, not you with your fingers in the gears.

As inspector I've told a couple of teams to protect their pinch points especially when they are highly exposed on the exterior faces of the bot.

Re: Exposed gears/chain
 

OP - Pics or ban!

Seriously, show an example of what you're worried about, it will make the discussion considerably more substantive. You say "exposed gears and chain" and have one mental picture for what that is, the rest of us have our own metal pictures that might be significantly different from yours. We must have some common ground for a productive thread. A great comparison would be something that had to be protected pre-2009 to pass inspection and something that is unprotected post-2009 and passed inspection.

See sig. for extrapolation of rule #1.

Re: Exposed gears/chain
 

They are definitely still checking for it in inspections, one of our first jobs on the safety inspection to-do list was to create a guard for the gears on our forklift and to create guard plates to cover our drive motor gearboxes.

Re: Exposed gears/chain
 

Our Inspector made us make chain guards at competition or he wasn't going to pass us..... Fun stuff....

Re: Exposed gears/chain
 

Did the inspector require you to add these guards to pass the inspection? Do you have pictures of your unprotected gears?

Re: Exposed gears/chain
 

Guys,
R8 dominates in this discussion. Inspectors will look at your robot as a potential issue for volunteers on the field and students who are working on or near your robot. Sprockets that are buried inside your robot frame or near the floor or very high may pose less of a threat than items near handholds, or the outside of your main frame. If the inspector thinks it poses a safety issue, they will ask you to come up with a method to protect all around your robot. For those of you who have never pinched a finger in your bike chain, it is nearly the same as a soldering iron burn without the smell. The difference can be that a soldering iron won't break your finger while a sprocket may.

Re: Exposed gears/chain
 

Yes, and no, but I will take some at our next regional.

The forklift motor is mounted at the top of a lift frame and the gears were mounted on the outside of the frame so it was definitely a pinching hazard. We felt the drive gearboxes were one of those "well, if you really want to stick your fingers in there, you're asking for it" things, but better safe than sorry.

Re: Exposed gears/chain
 

Sorry, I'll try to make this more clear. Several pictures that teams have posted, or in reveal videos, show things that seem like they could be dangerous to me.

I want to make it very clear that the following pictures are just examples, and I am in no way saying anything bad about these teams or their robots, this is a concern of the rules in general.

2015 robots: http://imgur.com/a/hIHRC

I don't have many pictures of robots 5+ years ago, but this website has a decent listing of some of them: http://frcdesigns.com/designs-robot/ There are a few with the exposed gears/pinch points, but it seems that more of the robot is covered. This might be due to the game/robot size limits, but it just seems like this used to matter more.

These are from '08 and '09, the first two pictures are from my own design/team. There's always a human factor in these robots, and it was fully my own fault I ended up needing stitches one year. http://imgur.com/a/vOKDk

Re: Exposed gears/chain
 

While I generally agree with this sentiment, it won't work in the real world if you're being audited by OSHA.

Re: Exposed gears/chain
 

Thank you, this is good to know so we can have a plan in place in case we fall into the same situation.

Re: Exposed gears/chain
 

There is no requirement to comply with OSHA standards as a FRC team.

I'm all for safety but adding guards is often not actually more safe than teaching students real safety (like never working on the robot without it being disabled, or even better, off entirely).

The fact that volunteers will often invent or incorrectly interpret rules requiring changes to the robot (in this case adding guards) is a source of continual frustration. Nowhere in the manual does it say all pinch points must be protected from insertion of a finger. Obviously anything egregiously unsafe should be addressed, but that's not what is generally being discussed here.

People will reply with "But safety!!!", but there is only so much you can do to protect people from themselves and at a certain point the safety theater becomes a burden for everyone.

Re: Exposed gears/chain
 

At week 0 one of the inspectors (who is also the lead at one of the regionals) told us we will need guards for our robot to pass inspection.

We are just making a bunch of plastic disks that will slide on the axles on either side of the sprockets. They are large enough to extend past the chain and stiff even though they are fairly thin. They are held in place by the sprocket and either the frame or a collar. This way they spin loose on the axle in case you bump up against it.

Maybe I'll post pictures later.

Re: Exposed gears/chain
 

I will agree with Al on this one.

Re: Exposed gears/chain
 

Agreed. I would much rather have students protected by sound decision making skills than by chain guards you learn you have to add only once you're at the regional. Sheids etc do have their place, but chain guards are only really in a position to be helpful if you're sticking your hand inside an enabled robot. If you're doing that, you're asking to be hurt whether or not there are chain guards.

To draw a parallel to surfing: you can make everyone wear a life jacket before they can even look at water, but at the end of the day it's best to give people a healthy understanding, respect and fear of the ocean.

Re: Exposed gears/chain
 

I can't recall ever getting to work on equipment in industry before going through a certification class. If it were as easy as educating people to not do unsafe things, why are there OSHA standards? :)

I think it's safe to assume that the vast majority of people that work on or around our robots are not idiots and know that sticking their finger into a chain will have bad consequences. Accidents happen when people aren't paying attention and inadvertently put their hand where it shouldn't go.

During testing this year, I was a few inches away from getting a finger caught in a floating idler, since I forgot it had been added to the robot, and didn't check that the robot was disabled. I can assure you that I wouldn't have been close to that spot if I knew that, but miscommunication, accidents... etc.

Re: Exposed gears/chain
 

Because OSHA exists to force the employer to create a safe environment for employees when they would otherwise cut corners to save cost.

Re: Exposed gears/chain
 

I think there's an XKCD on this topic...

And this is exactly right. I also agree with Cory's "safety theater" comment: I was reprimanded earlier this year for not yelling "robot" in front of a virtually empty pit row. Is it technically safer to yell robot at all times? Probably. What are the chances that it will ever stop someone from being hurt? Near zero.

Here's a really interesting look at why school buses don't have seat-belts in them (generally): http://www.nbcnews.com/id/40820669/n.../#.VQCkwvnF_8o

This is safety design done intelligently and effectively.

Re: Exposed gears/chain
 

Robot shields can present a false sense of security. You should NOT be working on a power up and enabled robot if you are concerned about safety.

I've had to deal with OSHA regulations this year, and let me tell you, the people who write these things have never used this sort of equipment in their lives. In some cases, OSHA regulations make equipment more dangerous - such as 'safety' shields that get parts stuck against grinding wheels, saw blades...

Re: Exposed gears/chain
 

The primary "OSHA like" regulation I'd use (as someone who deals with it daily) is lock-out / tag-out, which is sufficient for purposes of working on a robot.

I'm not actually saying to apply a locking device on the computer, but in general... but either by direct control (throwing breaker) or procedure, make it well known that robots are not to be enabled when anyone is working on them.

The bigger concern I typically see is just people getting too close to robots moving (whether it be a pinch point or just something moving quickly with lots of mass). It's particularly an issue on practice fields at events, with 6 teams + drivers + pit all standing around trying to troubleshoot an issue, with moving robots less than 5 feet away from them.

Re: Exposed gears/chain
 

My personal rule of thumb is that if a system failure could cause serious injury even while the robot is properly disabled and/or unpowered (perfect example is a stored energy catapault from 2014) you should definitely implement some sort of safety device for that system.

For example, if any part of our shooter latch system would have failed last year (pneumatic system, latch control, set point check, latch pin, etc.) it would have made for a very bad day for anyone with a body part anywhere near it even with the robot properly disabled. Thus, we made sure to diligently utilize a safety strap anytime work was required around the robot when energy was stored in the catapault and the robot disabled and/or unpowered.

On the flip side, we have exposed sprockets and chains on the intake of our robot this year, but we don't utilize a specific guard or shield. The reason is because anytime the robot is properly disabled, those gears/sprockets aren't at risk of moving and causing an injury. See the difference between the two situations? If you follow general safe procedures regarding robot/person interaction and making sure the robot is always disabled and/or unpowered, you shouldn't have a safety concern regarding open sprockets and chains. Does that make sense?

Re: Exposed gears/chain
 

There's a false dichotomy being presented by many posters here. Having inaccessible pinch points and following proper safety procedures are not mutually exclusive. It's possible to both "not be an idiot" and have safety guards to mitigate the risk of accidental injury. There's enough risk of injury from accidental and unpredictable scenarios to warrant taking steps to avoid the potential for harm. I know for a fact that at least one of the teams arguing against safety shield in this thread has had a student require medical attention at an event because of an exposed hazard on an elevator of theirs in the past (albeit not a pinch point).

Re: Exposed gears/chain
 

Since you're talking about us, it's worth noting no amount of shielding would have prevented the injury.

Re: Exposed gears/chain
 

I wasn't meaning to imply that shielding would have prevented that particular injury. Simply pointing out that mistakes can and do happen, even to the teams that have established an effective safety culture.

Re: Exposed gears/chain
 

yeah this robot worries me in general... keep in mind it's a reveal video and they may have to make changes before competition
the one thing I will say about this robot is that those chains don't appear to actually move much, and there seems to be no way to cover them without damaging the functionality of the arm
(full video of them here https://www.youtube.com/watch?v=kokq6fgOOP4 if you hadn't watched it yet)

Re: Exposed gears/chain
 

I can tell my co-workers all day long to not be an idiot, but that won't prevent them from being tired, or sleepy, or hurried, or stressed, or distracted, or uncoordinated... in general, careless and prone to mistakes.

I can however engineer out risks whenever I'm able to; otherwise I'll put barriers and guarding in between the identified risks and my coworkers; when I find that isn't enough I will require specific safety equipment and procedures in order to keep them safe.

Re: Exposed gears/chain
 

QFT.

Re: Exposed gears/chain
 

I panicked for a few moments trying to think of how we could quickly fashion a guard - we didn't bring enough spare aluminum, and I was starting to figure out how I was going to quickly cut and bend a U-shaped bracket out of Lexan... then we found an extra piece of coroplast we were using to mount our team number, folded that into the appropriate shape, added some self-tapping screws and voila! Problem solved.

For the drive gearbox cover plates we did cut some Lexan so we could still see what was going on down there.

Re: Exposed gears/chain
 

I do not understand why there are more restrictive requirements at some regionals. Not able to compete because an inspector requires a chain guard?? How can this happen? I can understand a guard being required if a failure could cause parts of the robot to fly off the field but not a chain. No one should be touching the robot while it is running on the field.

Re: Exposed gears/chain
 

Is the chain anywhere near an area your hand might be while carrying your robot off the field? Is that chain attached to a mechanism with a lot of leverage, and can it move while the robot is disabled?

Re: Exposed gears/chain
 

Andy,
I have to trust my inspection staff at events. If they ask that you cover a pinch point, it is likely that they are evaluating that individual robot based on past experience. I have seen things that would turn your hair grey and fall out. (Have you seen my picture?) As for some of the others, how many of you using chains can operate the mechanism without power? Can gravity cause it to move even if it hasn't ever done that? Can another person bump into your robot in the queue or on the floor and cause that mechanism to move? If you answered yes to any of these, someone is going to have a hand near or in your robot at some point.

Re: Exposed gears/chain
 

All it takes is one mistake... You don't regrow fingers. Perhaps it's too far in the past for many to remember, but there was a widely talked about incident in 2008. I can't find the thread dedicated to it (I'm pretty sure there was one), But it's discussed here: http://www.chiefdelphi.com/forums/sh...&postcount=125

The end result was that someone (I believe it was a college aged mentor) lost part of his finger when it got caught between a chain and sprocket.

You can't just evaluate safety based on likelihood of someone being an idiot. It's a combination of likelihood, random mistakes, and severity of the result. Losing part of your finger is a very severe result, and we try to treat it as such when asking people to put guards on their robot.

Re: Exposed gears/chain
 

I'm all for guards, build them all the time. But proper hand saftey must still be taught and enforced at all times.

Probably 80% of belt and chain injuries I've seen in industry have been during service or troubleshooting with the guards removed.

Safety is a three part process, proper personal training, physical safeties/PPE and proper leadership.

Re: Exposed gears/chain
 

I remember being a student on an FRC team and guards were always on our mind during the design process, after going to several regionals in past years and having to add them on.

Now I do agree that guards for chain and gears are not being mandated like when I was on the team. But now that I am a mentor for 5+ years I have found that this should be the mentors job not the RI. There is a way to design things safely and keeping that as a goal is important for design intent. The kids don't know how to design things safely yet, they are still learning, that is where mentors step in to teach and show them how to do it, and then let the kids spend time in CAD making it safe. There are many ways to make a safety guard advantageous in your systems. If you are using belts or chain you can use a guard to help increase your tooth wrap or to auto tension your system.

In the end if the bot is unsafe and someone gets hurt it is on the mentors.