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I just had a question...has anyone here been able to successfully build a
limited slip differential (LSD) or automatic locking differential out of the
Technic elements? I've been toying around with the various types of
differential designs used in real life and been trying to implement them
into Lego models and was able to make a "simulated" manual lockable
differential which basically allows for switching between the differential
or a pair of standard gears...but I can't seem to think of a way to do the
other kinds. Any ideas?
-Gaurav Thakur, raving madman
Can be reached at cp5670@supermail.com
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I have managed to make a LSD using the white clutch gear (clutch-pack
type of LSD). Sorry, no pics yet!
My original plan was to make a torsen type LSD, but after learning how
one works, I have concluded that it's impossible to do with lego parts.
Torsens require helical gears of the proper angle, plus they have to be
made of materials with the correct coefficients of friction... Lego has
a limitation afterall!
//Henry Chea
hchea@kungstorget.nu
*S* Göteborg, jaja, jag behöver inget mer! *S*
http://www.kungstorget.nu
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In lugnet.technic, Henry Chea writes:
> I have managed to make a LSD using the white clutch gear (clutch-pack
> type of LSD). Sorry, no pics yet!
Cool...I think I have a vague idea of how one can be made using that slip
gear; let me know if you ever happen to get some photographs of the design...
> My original plan was to make a torsen type LSD, but after learning how
> one works, I have concluded that it's impossible to do with lego parts.
> Torsens require helical gears of the proper angle, plus they have to be
> made of materials with the correct coefficients of friction... Lego has
> a limitation afterall!
Yeah I noticed that too...since all the Lego pieces (or almost all) are made
using the same plastic mold, it probably won't be that simple...
The MLD isn't too hard to build either, although I haven't had any luck with
an ALD yet. Although many sources seem to say that the MLD is probably the
best overall for both off-road and paved terrain...only reason it isn't used
much in real life is the cost. I'll probably just stick to this thing in my
creations...
-Gaurav Thakur, raving madman
Can be reached at cp5670@supermail.com
http://cp5670.50megs.com/TC/
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Gaurav Thakur wrote:
> The MLD isn't too hard to build either, although I haven't had any luck with
> an ALD yet.
Curious, what do MLD and ALD mean?
BTW I took some quick pics of my clutch-pack LSD (installed in my
McLaren F1).
Two views of the engine bay are here (I removed the spoiler and opened
the hatch):
http://www.kungstorget.nu/designs/images/lmclaren/lsd1.jpg
http://www.kungstorget.nu/designs/images/lmclaren/lsd2.jpg
The LSD is near the bottom of the pictures, below the engine bay.
A closeup of the LSD is here:
http://www.kungstorget.nu/designs/images/lmclaren/lsd1closeup.jpg
The halfshaft on the right side is connected to the LSD housing ONLY.
It is not connected to any gears! The blue piece on the housing is part
2711 (Technic Rotor 2 Blade with 2 Studs), and this is what the right
halfshaft connects to.
The left halfshaft spins freely in the housing (the black parts of the
housing are part 32017 "Technic Liftarm 1 x 5"). The left halfshaft
goes all the way through the white clutch gear and the 16 tooth gear in
the middle.
This is not a complete differential because it has no method of
connecting the drivetrain to it. My McLaren actually has two
differentials for the rear, the second one used to connect to the drivetrain.
//Henry Chea
hchea@kungstorget.nu
*S* Göteborg, jaja, jag behöver inget mer! *S*
http://www.kungstorget.nu
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In lugnet.technic, Henry Chea writes:
> Curious, what do MLD and ALD mean?
Manual Locking differential and Automatic locking differential I presume.
> BTW I took some quick pics of my clutch-pack LSD (installed in my
> McLaren F1).
Does it work?
Steve
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Steven Lane wrote:
> > BTW I took some quick pics of my clutch-pack LSD (installed in my
> > McLaren F1).
>
> Does it work?
It works extremely well actually. It is easy to push the car when it is
going straight, but as you turn the steering wheel, you can feel the
gradual tug of the LSD working as the car goes into a tighter turn. On
grippy surfaces like linolium or concrete, if the car is turning in its
tightest circle, you can see the inner wheel clawing for traction--the
inner wheel slips a little on the ground, but is still able to have a
different speed of rotation than the outer wheel.
From personal experience, if this LSD were in a real car, the car would
be undriveable at higher speeds in turns--there would be more oversteer
than one could control.
//Henry Chea
hchea@kungstorget.nu
*S* Göteborg, jaja, jag behöver inget mer! *S*
http://www.kungstorget.nu
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In lugnet.technic, Henry Chea writes:
> From personal experience, if this LSD were in a real car, the car would
> be undriveable at higher speeds in turns--there would be more oversteer
> than one could control.
Shouldn't that be understeer? If the inner wheel is provideing a force,
surely that would cause the nose of the car to veer outwards rather than
inwards.
Steve
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Hello,
I have built both LSD and manual locking diff.
Both were simple AND worked very well, BUT they are not realistic; I mean
that they do not work the way the real LSD and locking diff. work. I'm still
working on that...
One of my creations is a HEMTT truck, which incorpotates tandem axles; one
is LSD and the other is locking diff.
See http://olivierg.50megs.com/hemtt/hemtt.htm for the project.
See http://olivierg.50megs.com/hemtt/pic2.htm for a close-up pic of the
layout.
Thanks,
Olivier
http://olivierg.50megs.com
-->
Gaurav Thakur <cp5670@supermail.com> wrote in message
news:GBsqA8.En1@lugnet.com...
> I just had a question...has anyone here been able to successfully build a
> limited slip differential (LSD) or automatic locking differential out of • the
> Technic elements? I've been toying around with the various types of
> differential designs used in real life and been trying to implement them
> into Lego models and was able to make a "simulated" manual lockable
> differential which basically allows for switching between the differential
> or a pair of standard gears...but I can't seem to think of a way to do the
> other kinds. Any ideas?
>
> -Gaurav Thakur, raving madman
> Can be reached at cp5670@supermail.com
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olivier wrote:
> One of my creations is a HEMTT truck, which incorpotates tandem axles; one
> is LSD and the other is locking diff.
> See http://olivierg.50megs.com/hemtt/hemtt.htm for the project.
> See http://olivierg.50megs.com/hemtt/pic2.htm for a close-up pic of the
> layout.
Olivier--
Very nice, simple designs! I wish I knew how to have the differential
automatically engage the lock, but I can only think of ways that involve hydraulics...
//Henry Chea
hchea@kungstorget.nu
*S* Göteborg, jaja, jag behöver inget mer! *S*
http://www.kungstorget.nu
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Steven Lane wrote:
> Shouldn't that be understeer? If the inner wheel is provideing a force,
> surely that would cause the nose of the car to veer outwards rather than
> inwards.
In the case of a RWD car with a *stiff* LSD in the rear, the inner wheel
is always slipping a little bit whether on the throttle or brakes or
nothing.. Considering that the highest amount of grip is typically at a
15% slip angle, it is not good for the tyres to already be slipping
under non-agressive loads.. Basically a stiff LSD in the rear makes it
easier for the car to break traction on both rear tyres at the same
time, whether on the throttle or the brakes.. Not good while in a turn!
The ideal rear LSD would be strong enough to limit inner tyre spin, but
not so much that the inner wheel causes the outer wheel to break
traction as well. I don't know if I'm making any sense..
//Henry Chea
hchea@kungstorget.nu
*S* Göteborg, jaja, jag behöver inget mer! *S*
http://www.kungstorget.nu
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In lugnet.technic, Henry Chea writes:
> The ideal rear LSD would be strong enough to limit inner tyre spin, but
> not so much that the inner wheel causes the outer wheel to break
> traction as well.
> I don't know if I'm making any sense..
I don't know if your making any sense either :-)
Steve
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> > Curious, what do MLD and ALD mean?
> Manual Locking differential and Automatic locking differential I presume.
Hehe..yeah, that's what those meant (they were mentioned in the first post).
I wrote up that post at around 4:30 in the morning and was too tired to
write out the full names so I just abbreviated them. :-)
> BTW I took some quick pics of my clutch-pack LSD (installed in my
> McLaren F1).
> Two views of the engine bay are here (I removed the spoiler and opened
> the hatch):
> http://www.kungstorget.nu/designs/images/lmclaren/lsd1.jpg
> http://www.kungstorget.nu/designs/images/lmclaren/lsd2.jpg
> I have built both LSD and manual locking diff.
> Both were simple AND worked very well, BUT they are not realistic; I mean
> that they do not work the way the real LSD and locking diff. work. I'm still
> working on that...
Great designs there! I suppose the slip gear design could be used when more
friction is required (for dedicated off-road vehicles) while the rubber
belt-based one would be preferred for light off-road machines. I need to try
building those sometime...
My manual locking differential looks very similar to yours and this type
seem to work well for Lego models. One setting ues the differential while
the other uses two standard gears and skips the differential altogether.
Although you're right; this design does not exactly match the type used in
real vehicles. But it works all the same, so who cares... :-)
One way to incorporate a realistic clutch plate based LSD into a technic
creation might be to line up several rubber pieces (such as small wheels) on
the sides of the differential itself, which would make it more realistic but
probably less effective. (this is where the fact that most Lego elements are
made of the same material becomes a limitation)
I can't really think of a way to do an automatic locking differential
though. Even if it is possible, the mechanism will probably take up a
significant amoutn of space due to its complex nature.
> One of my creations is a HEMTT truck, which incorpotates tandem axles; one
> is LSD and the other is locking diff.
> See http://olivierg.50megs.com/hemtt/hemtt.htm for the project.
> See http://olivierg.50megs.com/hemtt/pic2.htm for a close-up pic of the
> layout.
This model looks amazing...I just saw it for the first time...
-Gaurav Thakur, raving madman
Can be reached at cp5670@supermail.com
http://cp5670.50megs.com/TC
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In lugnet.technic, Steve Lane writes:
> In lugnet.technic, Henry Chea writes:
>
> > Curious, what do MLD and ALD mean?
>
> Manual Locking differential and Automatic locking differential I presume.
Here are some pictures of a manual locking differential. It uses the newest
Lego differential and some parts from the gear box found in the Super street
sensation car.
I've been thinking about measuring the speed of each wheel using two
Mindstorm angle sensors and locking the differential (using a micro motor
and maybe some pneumatic) when the difference of speed between the two
wheels is greater than it would be when the car makes a turn at its smallest
radius.
http://wegmuller.org/lego/hi_lock_differential1.jpg
http://wegmuller.org/lego/hi_lock_differential2.jpg
http://wegmuller.org/lego/hi_lock_differential2.jpg
Greetings,
David
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David Wegmuller wrote:
> I've been thinking about measuring the speed of each wheel using two
> Mindstorm angle sensors and locking the differential (using a micro motor
> and maybe some pneumatic) when the difference of speed between the two
> wheels is greater than it would be when the car makes a turn at its smallest
> radius.
Nice design for the manual locking lsd. If you throw an
adder-subtractor in there, then you would only need one rotation sensor.
The drawback would be added friction in the drivetrain and space.
//Henry Chea
hchea@kungstorget.nu
*S* Göteborg, jaja, jag behöver inget mer! *S*
http://www.kungstorget.nu
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In lugnet.technic, Henry Chea writes:
> If you throw an
> adder-subtractor in there, then you would only need one rotation sensor.
> The drawback would be added friction in the drivetrain and space.
Why didn't I think of this before? I have only one rotation sensor, but I do
have five differentials...
Thanks for the tip!
Greetings,
David
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Here is a design that I used a while ago.
It works good when one of the wheeles gets off the ground, but takes a
second to get engaged.
http://www.geocities.com/BourbonStreet/Quarter/3073/test.htm
In lugnet.technic, Steve Lane writes:
> In lugnet.technic, Henry Chea writes:
>
> > The ideal rear LSD would be strong enough to limit inner tyre spin, but
> > not so much that the inner wheel causes the outer wheel to break
> > traction as well.
>
> > I don't know if I'm making any sense..
>
> I don't know if your making any sense either :-)
>
> Steve
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In lugnet.technic, Dave Forrest writes:
> Here is a design that I used a while ago.
> It works good when one of the wheeles gets off the ground, but takes a
> second to get engaged.
>
> http://www.geocities.com/BourbonStreet/Quarter/3073/test.htm
Looks nice! That design looks much more realistic...the medium pulleys act
exactly like the clutch plates do in a real LSD to provide the necessary
friction...
-Gaurav Thakur, raving madman
Can be reached at cp5670@supermail.com
http://cp5670.50megs.com/TC/
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Thanks.
I did that design over two years ago.
It drives like a tank! Its geared low and can haul around a 5 lb. bag of sugar.
In lugnet.technic, Gaurav Thakur writes:
> In lugnet.technic, Dave Forrest writes:
> > Here is a design that I used a while ago.
> > It works good when one of the wheeles gets off the ground, but takes a
> > second to get engaged.
> >
> > http://www.geocities.com/BourbonStreet/Quarter/3073/test.htm
>
> Looks nice! That design looks much more realistic...the medium pulleys act
> exactly like the clutch plates do in a real LSD to provide the necessary
> friction...
>
> -Gaurav Thakur, raving madman
> Can be reached at cp5670@supermail.com
> http://cp5670.50megs.com/TC/
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