Chain and CVT guarding |
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jtrnw
Double Secret Probation Joined: Mar/17/2017 Location: Illinois Status: Offline Points: 7 |
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Posted: Mar/17/2017 at 9:49pm |
I've been a lurker on the forum for a while, and I finally decided to jump in. This is my first year on Baja (and sadly my last, senoir)
Regardless I've finally stumped the search function. I'm working on the guarding of the CVT and chains on my team's car, and I'm looking for ideas. Rule B15.2 says "Rotating parts must also be guarded all around, in addition to the guard around the periphery. All around guarding
(finger guards) must prevent small, searching fingers from getting caught in any rotating part. Non rigid, fabric
coverings such as "Frogskin", Ceconite, and neoprene are unacceptable for use as finger guards.
A complete cover around the engine and drivetrain is an acceptable shield." My teams driveline package is very tight, what I'm wondering is if I can use the engine as "part" of my guard. If there is nowhere for a chain to escape if it cuts loose would that be accepted? Or does the guard have to guard the engine as well? I can always create a box for the entire driveline, it'll just be huge and heavy, and there must be a better solution. Maybe there is another solution I haven't thought of. I've included a cad picture of the driveline layout and one area of concern below. What do you guys think? http://i.imgur.com/w5bVqKrl.png The Orange circles are large sprockets. What I'm concerned about is between the last sprocket and the second to last. As can be seen below the small sprocket wound up a little closer to the muffler than intended. http://i.imgur.com/2XbNMoBl.jpg
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SIyer
Bolt Sorter Joined: Feb/15/2016 Location: Vancouver, BC Status: Offline Points: 15 |
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I think that's a question for the SAE tech inspectors. My 2 cents is that it will not suffice for a couple reasons:
1: There's enough room to get a finger in there (you'd have to be stupid, but it can be done) * Take note of the term "searching" A team member is fiddling with the engine while it's running and suddenly you exceed CVT idle speed, is their potential for their fingers to get caught in a chain (or breaking chain?) 2: Do you really want your chain flying into your exhaust? 3: You need to cover that spinning shaft as well which looks more exposed anyways That said, if I recall correctly, they allow you to mount things to your exhaust cage (so long as you dont modify the cage itself and it's rigid) so that might be worth investigating for weight. As a side note, have you left any room for adjusting chain tension? Your bearing block mounting looks really neat and clean, and the rear end looks very compact, nice work! |
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jtrnw
Double Secret Probation Joined: Mar/17/2017 Location: Illinois Status: Offline Points: 7 |
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Thank you for your reply! I thought about asking a rules question, but I didn't know how to word it concisely, and I figured a discussion might be more useful anyways.
1. The searching finger thing seemed kinda strange to me since the only opportunity for it is when the car is parked, but I see what you mean. 2. The thought did cross my mind, but the exhaust seemed pretty tough, and based on the torques we should see I don't think we're at too much risk of a chain breaking. But then again I don't have a lot of experience with chains. 3. For some reason covering the shafts never occurred to me. That could have very easily been one of those duh moments down the road. Thank you! We have two pit bike spring type chain tensioners, one per chain that should mount up on the bottom of those chains. Whether or not they work well enough is still to be determined. |
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RLM
Baja Godfather Joined: Nov/15/2012 Location: Hamilton, ON Status: Offline Points: 1258 |
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as said above, make sure that shaft is covered. we got busted for that about 6 years ago and had to rig something up at comp out of sheet metal. much easier to do in a nice warm shop.
One of the main reasons behind the "wandering finger" rule is for the recovery crew. most often, the recovery team at comp is comprised of local volunteers from the host school who have never even really heard of baja, let alone, know the risk areas. when you have 2 cars stuck together and 2 drivers yelling at you to get them back on the track (drivers are rude in the heat of racing) you just grab whatever you can to pull on to get them going again. often, the drivers are also trying to get themselves unstuck at the same time by flooring the throttle. last thing you want is someone to slip and their finger to go into a speeding chain. This mindless grabbing is also the reason for the sharp edges rule. as for weight, remember that the 1/16" steel or 1/8" aluminum is only required around the periphery of the chain/sprocket. everything else can be lightweight plastic / gfrp / carbon.
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McMaster Baja Racing (09-Dec 2015)
Team Captain 2012-2015 Suspension Lead 2015-2016 All spoonfeed PM requests will be billed at $10 USD per reply, payable via paypal. |
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