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Author: Subject: Chain Tension / Idle Gear
woodsy144

posted on 27/11/19 at 10:04 PM Reply With Quote
Chain Tension / Idle Gear

Hello Guys,

Ive been looking at the diff mounting, chain tension arrangement etc.
One though was to fix the diff and use an idle gear / wheel.

I found these online.
http://www.tcbroschoppers.com/weld-on-chain-tensioner-530-sprocket.html

Thinking is, by using this I can increase the wrap around the engine gear while maintaining chain tension.
No need for diff movement.

Any experience with these?
Thoughts?

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Mr Whippy

posted on 28/11/19 at 12:06 PM Reply With Quote
Very common things, don't know where you are located but you can get them in the UK too, ebay sells loads of them. Usual use is to prevent the chain flapping about, you even get them for push bikes, my recumbent trike also has one.

Personally I'd only use them on the return side of the chain since that has the least tension but yeah should work perfectly, make sure the bearing is good quality an is easy to replace.

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nick205

posted on 28/11/19 at 03:09 PM Reply With Quote
No personal experience with chain driven diffs, but I can't see an issue with the part. Engines that run timing belts have tensioners and I'm sure many that run timing chains also have a tensioner as well.
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Mike S

posted on 28/11/19 at 04:20 PM Reply With Quote
Hi

Chain tensioners are fine when the load is in one direction only, such as in cam chain applications etc. where the tensioner is in the unloaded side of the arrangement at all times.

The problem with spring tensioners in transmission applications is that the the load direction changes (e.g. on overrun and engine braking) the tensioner is then on the load side, compressing the spring and the spring and idler then have little effect, and the chain goes slack.

I think the idler gear for adjustment is a sound one, but it IMHO, should be solidly mounted rather than sprung. It would still be possible to have a mounting arrangement that gave the adjustment so a solidly mounted idler could be used as the chain tensioner for a solidly mounted diff etc.

Cheers

Mike

[Edited on 28/11/19 by Mike S]

[Edited on 28/11/19 by Mike S]





There are more horses' asses in this world than there are horses

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jonny007

posted on 28/11/19 at 08:13 PM Reply With Quote
Other option could be to fix diff but pivot the engine around front mountings with turnbuckle adjustment at rear to adjust tension.

Like the idea of solid mount though as above and could also be used to supply reverse drive.

[Edited on 28/11/19 by jonny007]

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woodsy144

posted on 28/11/19 at 08:50 PM Reply With Quote
Some really good points.

With respect to the spring. It may raise issues as you mention. I was also thinking of running the reverse gear off the engine sprocket like the AB performance kit, using the spring tension-er may cause issues cause thats now the drive side.


Could you use a motor on the idle gear as the reverse? I had not thought of that to now.
My only concern is when the running normally which will be 99.9% of the time the motor will be spinning. Power will be generated but in wrong polarity to which it is wired.

Is there a motor with a one way bearing or slipper clutch to only work in one direction, maybe. But definitively worth considering.
Mount the motor arrangement on a cam arrangement and that is the chain tension-er.

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jonny007

posted on 28/11/19 at 09:10 PM Reply With Quote
I'm not sure Id have the motor permanently fixed to the idler, it would normally be free to rotate but you could easily then engage on cable or solenoid switch.

I'm looking at starting another BEC project so interested in others ideas. Maybe a motor in there as a hybrid is a further option assisting engine at low speed to boost torque...

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woodsy144

posted on 28/11/19 at 09:17 PM Reply With Quote
quote:
Originally posted by jonny007
I'm not sure Id have the motor permanently fixed to the idler, it would normally be free to rotate but you could easily then engage on cable or solenoid switch.

I'm looking at starting another BEC project so interested in others ideas. Maybe a motor in there as a hybrid is a further option assisting engine at low speed to boost torque...


Yeh free rotation would be idle, how to make that work is the head scratcher. Electric motor assist at low speed would be of assistance. Interesting thinking. once again, something to keep me up at night.

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Mr Whippy

posted on 29/11/19 at 07:59 AM Reply With Quote
quote:
Originally posted by woodsy144

Is there a motor with a one way bearing or slipper clutch to only work in one direction, maybe.


something like this on the motor? a bit like a push bike...

linky

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motorcycle_mayhem

posted on 29/11/19 at 09:36 AM Reply With Quote
The ADR 1000 had a chain tensioning jockey wheel, so searching that might help (or even speaking to ADR). Chap in the South West had one, failed at Castle Combe in the year that I saw it, probably underwent some sort of modification since it seemed to be generally problematical. Some of the off-road things use a tensioner jockey, in fact DRD probably have a suitable sprocket with a bearing in their shop somewhere.

A different thing - controlling chain slap on an extended swing arm, has seen a spring and jockey sprocket arrangement. Some folk have used skateboard wheels as an alternative. I wouldn't contemplate such a thing for tensioning, but if you're trying to tie up a long chain run it looks a good idea, certainly quiet. I've used a cam chain guide to do the same thing, with good results.

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