PDA

View Full Version : Cam chain



darryl
07-08-2012, 03:52 PM
Maybe this is a 'duh' moment on my part, but I wondered today why cam-type chain isn't more widely used. It's quiet, and has more links connected to each pin, which should increase the strength of it. On the other hand, those pins are smaller in diameter than regular chain link pins, so maybe I've answered my own question. I like the idea that they have teeth with 'gear profiles' and mate with the matching gear without needing rollers.

Maybe they don't wrap as well around smaller diameter gears? Less forgiving of lack of lube?

aostling
07-08-2012, 04:55 PM
Camshaft drives often use inverted tooth chain, also known as silent chain. Since each link has so many plates in sliding contact I expect inverted tooth chain is less efficient than roller chain, which has very low friction.

darryl
07-08-2012, 05:54 PM
Hmm, I hadn't considered the friction between the links issue-

_Paul_
07-08-2012, 07:26 PM
AFAIK camchain type is normally of the HyVo variety and I would imagine they wont run too long without an oil bath or some such constant lubrication system.

Paul

kendall
07-09-2012, 12:28 AM
If I remember right, there were a few lathes made with silent chain drive like cam chains

BudB
07-09-2012, 12:35 AM
Many automatic screw machines including Davenports, Browne&Sharpe, and possible New Britan Gridley used "silent chain". It was the only thing that was silent on the whole machine.

Andrew_D
07-09-2012, 04:44 AM
Well, you can get roller chain that is more than one link wide....

http://www.jjengineersudaipur.com/images/Roller%20Chain.gif

http://www.qr-chain.com/upfiles/1261646044Short-pitch-transmission-precision-roller-chains-B-series1.gif

As a general rule, almost any chain will last longer if run in an oil bath. Having said that, there are many situations that I have seen on our farm equipment where an oil bath just isn't an option. Since roller chain is still used in those situations, I'm guessing that it must still be the best option out there....

Andrew

oldtiffie
07-09-2012, 07:24 AM
http://www.google.com.au/#hl=en&gs_nf=1&cp=8&gs_id=w&xhr=t&q=cam+chain&pf=p&output=search&sclient=psy-ab&rlz=1W1IRFC_enAU360&oq=cam+chai&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=d6a583b1f10ebbb2&biw=1920&bih=818

A.K. Boomer
07-09-2012, 10:02 AM
Yes the main reasons are both friction and wear as Multi-plate chains need to be inclosed in an oil bath environment, or at least kept very clean and well lubed.

Roller chains are just plain amazing --- I had a friend who used to race Mt. bikes with me and he very rarely if ever lubed his chain - it finally started to lose its rollers but the abuse it took was amazing...

Roller chains also adapt to any size sprockets with zero contact change - not so with Multi-plate,
Multi-plate chains fit only one cog size perfectly --- then if you go smaller or larger only half of the plates get involved in the contact process - this increases wear drastically.

All conventional crank to cam ratios are 1:2 generally what you would want to do is build the ML chain to fit perfectly for the smaller cog due to it not only being the drive cog but more importantly having the least amount of teeth in contact with the chain, then when the chain get's to the larger cam cog it has to lessen its arc, this causes only half the chains link faces to "get involved" BUT --- there is over double the teeth being in contact with the chain due to the cam not only having twice the amount but the increased "wrap" around the cam gear in comparison to the lesser wrap angle of the cranks, BUT,,,, this is not a "cure all" because chains stretch and this makes only a few of the cams teeth that are at the tension side of the chain have to carry the full load ----------- this happens with any chain that stretches - but at least rollers have rollers and they also have their full rated contact area instead of half --- this is were multi-links can snowball and accelerate wear patterns even more so than a roller...

Ideally - multi-plates should run on the same size cogs --- this would eliminate this one inherent design flaw...
But they have others - no system is perfect, still - many motorcycles have the multi-plate type and they do go a fair amount of miles if good oil is used along with changing it frequently....

Edit; does anybody have an old multi-plate with both the cam and crank cog laying around - lots of V/8's use them as well --------- I would like you to verify what I just wrote, im going strictly off of my minds eye and simple geometry but cannot verify...

Edit again; I built some crude cardboard mock-up's and found out something very cool about multi-plate chains (I think) - and Although I stick to the statement that "ideally" the cogs would benefit in being the same size (esp. in anything were the drive gear can become the driven as in transfer cases and although impossible ratio wise crank and cam due esp. at idle where the valve springs try to return power) there is an ingenious little fun fact about these units when being used on different sized cogs,

Im pretty sure that if these chains are installed correctly the drive side can have full contact of all the links - and due to the geometry and loading change so can a driven cog that's even twice the size,,,

If so it would explain a great mystery over the years and that's the fact that these type of chains on motorcycles and such (as far as I can remember) have one side with two chrome links - and you install these facing outwards and match them up to the crank and cam marks -------- this is not for convenience sake - it's to insure the chain's link geometry is lined up so the engagement faces the correct direction for loading all link faces on both the dive gear and the driven...