Avoneer
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| posted on 29/9/04 at 09:48 PM |
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LSD and Straight Cut Gearbox
Sorry, not being from a mechanical or motorsport background, could someone explain how an LSD works and how is it better than a normal diff and what
is a straight cut gearbox - in english.
Cheers,
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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Peteff
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| posted on 29/9/04 at 10:07 PM |
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Try google.
Lsd transmits power to both rear wheels to increase drive. Staight cut gears are noisy.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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JoelP
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| posted on 29/9/04 at 10:11 PM |
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helical gears are used in road cars due to quieter turning, but they have greater transmisison losses. Straight cut (also dog tooth?) are noisy as
hell but have less drag.
Limited slip diffs would rather that both wheels turn the same amount. they slip enough to go round corners, but they wont let the unloaded wheel spin
freer, as will happen in open diffs.
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liam.mccaffrey
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| posted on 29/9/04 at 10:15 PM |
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was gonna post earlier but was afraid i didn't know anything
normal diff diverts power to the wheel with lest resistance(i.e. a spinning wheel)
lsd diverts power more equally to both wheel regardless of grip or speed
i hope thats right??
i think straight cut gears are stronger
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Tblue
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| posted on 29/9/04 at 10:18 PM |
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What sort of slipper? Plate, viscous or ATB?
Have a look at the Quaife site, it might help.
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andylancaster3000
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| posted on 29/9/04 at 10:21 PM |
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This is one reason why it is advisable not to use straight cut gears in a road car...
http://www.kimini.com/Video/index.html
(then click on super car challenge BMW)
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Avoneer
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| posted on 29/9/04 at 10:22 PM |
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Right, got the LSD bit - I think. It limits the slip on the wheel that wants to slip (spin) and if it was a normal diff, the slipping (spinning) wheel
would just slip (spin) more...
As for the straight cut - it is just the patern of the teeth, so rather than sliding in gradually, they have to be forced in hard and then off you
go???
Pat....
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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liam.mccaffrey
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| posted on 29/9/04 at 10:33 PM |
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that is ear splitting good vid though
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andylancaster3000
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| posted on 29/9/04 at 10:34 PM |
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The selection (i think) is the same on a 'dog-box' as it is in a gearbox with helical gears. It is merely how the gears are cut which is
the difference. As mentioned above, they are more efficient then helical gears with a lower power loss.
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Tblue
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| posted on 29/9/04 at 11:08 PM |
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Some video that, but those pesky kit cars took some catching!
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Northy
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| posted on 29/9/04 at 11:09 PM |
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An LSD is better cause I've just sorted one out for mine!
Your not keeping up with the Jones'! Remember the advert!?!? 
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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OX
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| posted on 30/9/04 at 12:05 AM |
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lol good vid and what a noise it makes ,i thought only dogs could hear such a high pitch
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Kissy
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| posted on 30/9/04 at 07:08 AM |
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What a dog
The word dog seems to have several meanings here.
Regarding gearboxes, you can have a 'dog-leg' pattern box which refers to the gear lever positions, usually 1st is on its own, bottom
left, 2nd is forward centre (hence the dog-leg kink), 3rd is behind 2nd, 4th is top right. this, I think also applies to Hewlands on s/seaters. The
other use of dog, refers to the engagement of driven gears. Where two gears, on a common axis need to engage/dis-engage, they are typically meshed
together by a matching set of castellations, known colloquially as dog teeth.
Straight cut boxes are more efficient at power transfer, as they do not have the frictional losses of the 'sliding' helical gears. Down
side is they are bu**ers to mesh once moving. Motorcycle gearboxes (sequential) use both straight cut teeth, and dog teeth.
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Kissy
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| posted on 30/9/04 at 07:10 AM |
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dog
To clarify, dog teeth, are on the side of the gear, to 'join' the two gears on the same shaft. Straight cut and helical are on the
periphery to transfer power from one shaft to another. I'll shut up now!
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ned
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| posted on 30/9/04 at 10:25 AM |
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as kissy says, a dog box is to do with the meshing of the gears, a dog ring (looks like a castle battlement) meshes with another on the relevant gear
shaft to engage the gear. they are faster and transmit power quicker/easier and are i believe stronger.
straight cut gears are stronger, but clatter and whine like the sound a car makes in reverse which uses an idler gear
a dog leg box is where first is bottom left and 2,3,4,5 are like 1,2,3,4 in a 4 speed box, so on track you rarely use 1st, so the other gears are
easier to shoft between. obviously sequential is better still.
Ned.
[Edited on 30/9/04 by ned]
beware, I've got yellow skin
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James
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| posted on 30/9/04 at 10:33 AM |
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quote:
Originally posted by andylancaster3000
This is one reason why it is advisable not to use straight cut gears in a road car...
<snip>
Cool vid.
Not all straight cut gearboxes sound that loud/high pitched though.
I've stood 2 feet from a Formula 1 gearbox running at around 19,000RPM (on a test rig so no engine noise) and it was nowhere near that noisy.
James
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stephen_gusterson
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| posted on 30/9/04 at 10:47 AM |
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helical (not straight cut) gears
 
Rescued attachment image010.jpg
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JohanP
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| posted on 30/9/04 at 02:19 PM |
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If you need to know how just about anything works, you should visit:
http://www.howstuffworks.com
Endless reading!
/Johan
I have fun Seven days a week!
Finished: http://www.locostbuilders.co.uk/viewthread.php?tid=52344
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