Help me understand, explain, and fix or solve torque twist

[opek]

There are all sorts of rigs with TT from the MRC ,to the creeper, to all those awesome shaft driven supers! Help me understand and explain TT.

http://www.rccrawler.com/forum/axial...-new-post.html

[CREEPERBOB]

Maybe this will help;
Torque is the same as Force, only Force is a push or pull and Torque is a twist. If we want to calculate Acceleration we fall onto the simple equation:
F = MA or Force = Mass * Acceleration
Rearranged for A:
A = F / M or Acceleration = Force / Mass

A simple observation here is that more Force or less Mass will allow you to Accelerate faster. But we all know that one. :-)

Torque gets converted into Force ( twist gets converted into push ) when Torque applied to your axel turns your tires and the tires act on the ground. The ground is stationary, so the car must move forward. Converting engine Torque to Force allows me to point out that Torque accelerates your car, not Power. Power is the amount of work per unit of time.

[opek]

How does that translate into the way link triangulation affects TT?

[ClassicGMJunkie]

Lecture 18

[donhd04]

Mirror your tranny and switch to a 4 link suspension preferably with a sorta wide mount points on the axles for your upper links. Helped me tremendously.

[Charlie-III]

A simple way to look at it is, with a ring & pinion axle (like all the rigs you listed, but NO MOA's!!) the drive-shaft & pinion are trying to climb the ring gear in the diff. Since you're also trying to accelerate the axle & wheels (which are likely weighted) you have 2 forces fighting each other.
-One force is the twist down the length of the rig caused by the rotating drive-shaft.
-One force is across the rig caused by the axle.

When you accelerate the rig, the drive-shaft is trying to accelerate the axle but there is some resistance (object at rest tends to stay at rest......) so some extra power is wasted by rocking the rig over (torque twist).

Triangulation spreads the loads wider giving more leverage of the chassis against the axle, thus helping reduce the signs of torque twist.

Dropping wheel weight would help as well since there would be less resistance to acceleration (or deceleration).

Does that help any?

[JeremyH]

Originally Posted by Charlie-III

but NO MOA's!!

Or worm gear axles....

[jdm06]

i like torque twist ;)

[Duuuuuuuude]

Originally Posted by JeremyH

Or worm gear axles....

Its still there, just in a much smaller amount because of the gear reduction. The greater the ratio, the less twist you will have. If you had a worm gear axle with the same amount of reduction as a garden variety ring and pinion, the twist would be the same.

I've never considered the "gears are trying to climb" idea as a very good explanation of TT. Realizing that you have rotational force originating from a base that is not solidly anchored (chassis) and applying it to something that is more stationary (axle) and its pretty easy to understand that something has to move. The easier it is for that rotational force to transfer power (gear reduction) the less effect the twisting motion will be evident.

A properly tuned 4 suspension will mechanically and preemptively counteract or redirect that force but not eliminate it. When enough force is applied, TT will always show up eventually.

[ROCKEDUP RICKY]

What he said.

[opek]

Originally Posted by Charlie-III

A simple way to look at it is, with a ring & pinion axle (like all the rigs you listed, but NO MOA's!!) the drive-shaft & pinion are trying to climb the ring gear in the diff. Since you're also trying to accelerate the axle & wheels (which are likely weighted) you have 2 forces fighting each other.
-One force is the twist down the length of the rig caused by the rotating drive-shaft.
-One force is across the rig caused by the axle.

When you accelerate the rig, the drive-shaft is trying to accelerate the axle but there is some resistance (object at rest tends to stay at rest......) so some extra power is wasted by rocking the rig over (torque twist).

Triangulation spreads the loads wider giving more leverage of the chassis against the axle, thus helping reduce the signs of torque twist.

Dropping wheel weight would help as well since there would be less resistance to acceleration (or deceleration).

Does that help any?

I don't understand the leverage of the chassis against the axle. Supposing you have well aligned heims and spin the axle or chassis along the roll axis wouldn't twisting of the axle and chassis be nearly independent of each other?

[opek]

Originally Posted by ClassicGMJunkie

Lecture 18

So a coil spring operates by twisting as it compresses? That is too cool.

So what I'm getting from this is there are two torques in play. The first "Troll" is going to be where the roll axis intersects the plane perpendicular to the output shaft on the transmission. The other "Tout" is going to be in the center of the output shaft itself. Varying the distance between these two points will change how much mechanical advantage Tout will have when it is applied to Troll.

Would raising the roll axis make the lever arm coming from the trans output longer? Would that reduce the appearance of TT?

[JeremyH]

Originally Posted by Duuuuuuuude

Its still there, just in a much smaller amount because of the gear reduction.

That, and because of the location and direction of contact on the gears. The pinion gear is on top of the spool pulling it forward as opposed to pushing the drive gear up or down...

Originally Posted by Duuuuuuuude

I've never considered the "gears are trying to climb" idea as a very good explanation of TT. Realizing that you have rotational force originating from a base that is not solidly anchored (chassis) and applying it to something that is more stationary (axle) and its pretty easy to understand that something has to move. The easier it is for that rotational force to transfer power (gear reduction) the less effect the twisting motion will be evident.

A properly tuned 4 suspension will mechanically and preemptively counteract or redirect that force but not eliminate it. When enough force is applied, TT will always show up eventually.

Newton's third.

[Duuuuuuuude]

Originally Posted by JeremyH

That, and because of the location and direction of contact on the gears. The pinion gear is on top of the spool pulling it forward as opposed to pushing the drive gear up or down...

I would still consider that to have much less effect than the twisting motion of the driveshaft...

Ask anyone who's ever ran a floor buffer...the greater the resistance between the pad and the floor, the greater the chance of you getting tossed on your ass. Not because of how the pad is driven, but because of how much the floor resists the rotational force of the pad. Because the floor is anchored to the earth, and the buffer is anchored (loosely) to you, the floor isn't likely to move.

[JeremyH]

Originally Posted by Duuuuuuuude

I would still consider that to have much less effect than the twisting motion of the driveshaft...

That whole mechanism is causing a major portion of the torque twist. If you were to compare a stock LCC and a stock AX10, which one has more torque twist? They both have driveshafts...

[Duuuuuuuude]

Originally Posted by JeremyH

If you were to compare a stock LCC and a stock AX10, which one has more torque twist? They both have driveshafts...

The LCC has greater reduction at the axle, making it easier for the driveshaft to transfer force.

Like I said earlier, build a worm gear axle with the same reduction as an average ring and pinion setup and the TT will be nearly the same.

[ROCKEDUP RICKY]

Harumph.

[JeremyH]

Originally Posted by Duuuuuuuude

Ask anyone who's ever ran a floor buffer...the greater the resistance between the pad and the floor, the greater the chance of you getting tossed on your ass. Not because of how the pad is driven, but because of how much the floor resists the rotational force of the pad. Because the floor is anchored to the earth, and the buffer is anchored (loosely) to you, the floor isn't likely to move.

Now consider a roto-tiller......any fear of the operator getting tossed to the side? Nope. They might fall on their face and get drug around, but they wont be tossed off to the side like in your example.

[JeremyH]

Originally Posted by Duuuuuuuude

Like I said earlier, build a worm gear axle with the same reduction as an average ring and pinion setup and the TT will be nearly the same.

Ok, I will wait patiently for you to finish this project.

[Duuuuuuuude]

Originally Posted by JeremyH

Now consider a roto-tiller......any fear of the operator getting tossed to the side? Nope. They might fall on their face and get drug around, but they wont be tossed off to the side like in your example.

A roto-tiller doesn't apply force to the ground in the same manner. Lay it on its side and it does.