Author Topic: Just asking, where does the torque go?  (Read 1835 times)

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Online works4me

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Re: Just asking, where does the torque go?
« Reply #25 on: December 30, 2018, 03:44:22 am »
Most modern gearboxes are used to increase torque while reducing the speed of the engine output shaft (e.g. a motor crankshaft). This means that the output shaft of a gearbox rotates at a slower rate than the input shaft, and this reduction in speed produces a mechanical advantage, increasing torque.
It’s the reduction ration, not the number of gear sets, that matters.
Who was it that said “Give me a gear big enough and I shall move the world.”?

Offline RWulf

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Re: Just asking, where does the torque go?
« Reply #26 on: December 30, 2018, 03:41:54 pm »
I was a lever, not a gear.

Offline connie_rider

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Re: Just asking, where does the torque go?
« Reply #27 on: December 30, 2018, 03:46:12 pm »
You are reversing your ratio's.

Changing to a lower gear will increase torque at the rear wheel and will lower wheel speed.
Changing to a higher gear will decrease torque at the rear wheel and will increase wheel speed.
ie; 1st gear produces more rear wheel torque and lower wheel speed.
     2nd thru 6th gear produces less rear wheel torque and higher wheel speed.

But neither will increase the torque that is driving the gears.
Using gear's will allow you to get more work out of the same amount of torque, but you have the same initial amount of torque.

NOTE:
Changing the gear ratio's does not alter the torque produced at the motor.
The torque number that the dyno is producing, does not change when you change gears.
    The speed at the rear wheel does change.

  A basic Dyno, records the engine speed, wheel speed, and the time it takes to accelerate a roller up to speed; to do the calculation.
  Others have load cells (or other) that measure the actual torque and calculates the HP using the data. 

Ride safe, Ted
« Last Edit: December 30, 2018, 08:38:59 pm by connie_rider »
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Re: Just asking, where does the torque go?
« Reply #28 on: December 30, 2018, 03:51:22 pm »
oh boy, now you're really gonna confuse him!!

Online works4me

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Re: Just asking, where does the torque go?
« Reply #29 on: December 30, 2018, 06:01:32 pm »
So, what you’re saying, is any vehicle will accelerate equally quickly,
regardless of gear chosen, because torque at the rear wheel is a
constant.

Offline connie_rider

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Re: Just asking, where does the torque go?
« Reply #30 on: December 30, 2018, 08:49:56 pm »
No... all kinds of things effect acceleration.

The rear wheel torque changes.  The engine torque does not. The numbers you see from a dyno are showing engine torque.
  A dyno measures at the rear wheel, adjusts the calculation for the gear {etc} differences, and tells you how much torque was produced by the engine..

I admit, I'm over my head. I need help from the Engineers.
How can I explain this better?

Ride safe, Ted
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Offline WillyP

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Re: Just asking, where does the torque go?
« Reply #31 on: December 30, 2018, 09:02:51 pm »
Engine dynos show engine torque, not wheel dynos. Wheel dynos show torque measured at the (in this case, rear) wheel. Wheel dynos do not compensate for losses in the drive-train. Therefore, wheel dynos are more accurate for predicting the performance of the whole vehicle, though it is possible to make a calculated guess based on engine dyno performance. Wheel dynos do not tell you how much torque the engine is producing, they tell you how much is delivered at the driven wheel.

For example, if you had a small scooter engine driving a huge dump truck drivetrain, you might see very little or no power transmitted to the rear wheel due to the high friction losses encountered in the massive gears of the dump truck. The dyno doesn't account for that, it simply reports little or no power.
« Last Edit: December 30, 2018, 09:08:44 pm by WillyP »
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Online works4me

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Re: Just asking, where does the torque go?
« Reply #32 on: December 30, 2018, 11:44:54 pm »
No Ted, you explained it just fine.
I would like everyone to read the following over
and over again until you have an “Ah-ha” moment:

“The rear wheel torque changes.  The engine torque does not. The numbers you see from a dyno are showing engine torque.
  A dyno measures at the rear wheel, adjusts the calculation for the gear {etc} differences, and tells you how much torque was produced by the engine..”

Then go back and read post #19.

Offline Tour1

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Re: Just asking, where does the torque go?
« Reply #33 on: December 31, 2018, 07:08:20 am »
A gear is really a lever where the axle is the fulcrum.  2 gears of different sizes are like a single lever turned inside out, but it simplifies:  2 teeth on different gears push against each other with the exact same force and they move at the same speed.  The tooth on the bigger gear makes more torque but it doesn't move its shaft as quickly as the tooth on the smaller gear.  The tooth on the smaller gear makes less torque on its shaft but the shaft turns faster because the tooth is on a smaller circle.

So jumping ahead you can just imagine all the gears combine into a single big lever, for example, one side of the lever has the lit piston pushing it at piston speed and the other end of the lever has the bike being pushed at bike speed.  The long end of the lever goes a long way to move the short end a short way.  In theory there's no limit to the force that can be applied.

I posted this question because I forgot what the rear drive & linkage looked like, I suppose.
I'm also thinking about what might be done with ATV parts & such that could bolt to the C10 w/o mods.
ATV pinion gears might not take C10 power but if the housing bolts on with the same studs etc that won't be the failure point.
It also became a reminder of how important some of the nuts & bolts are because they oppose engine power as well as weight and bumps.
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Offline connie_rider

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Re: Just asking, where does the torque go?
« Reply #34 on: December 31, 2018, 03:33:22 pm »
Thanks Tour 1.
I understand your question more now.
  This is going back to your thoughts of installing a ATV differential on a Connie to make a 3 wheeler.
A large ATV differential might well stand up to a Connie as it is built tough, to turn 2 wide tires in rough terrain.
NOTE: Bob was correct in his statement {Post #X} the bolts are in shear or tension. They are not being twisted by torque.
Also, there are multiple bolts resisting, not just 1. So you would have to go from torque to shear load in your calculation's.

WillyP, you and I are saying about the same thing, only differently. But, I disagree with you about what is being measured.
  you; they tell you how much is delivered at the driven wheel.
  me; adjusts the calculation for the gear {etc} differences, and tells you how much torque was produced by the engine.                 

An engine  dyno {measures how much engine power is being produced} but has few losses because there aren't many variables.
A Chassis dyno does the same, it just measure's available "engine" power at the rear wheel. {After more losses}
ie; I agree, it does have more losses, but is more real world.

NOTE: In both cases, the engine is producing the Power.
          Both dyno's measure/plot how much power is being produced {after losses}.

Proof is; Steve's Charts with stock and Torque cams installed.  {1 produced 60 lb-ft and the other 65 lb-ft}
Both are a measurement of available engine power.

When I had my dyno, {Dynajett 150}  I ran a test on my bike, using 3 different gears. {I was trying to determine which gear was best to use for future tests}.
The Torque/HP numbers were almost the same because the dyno was measuring engine RPM and how much time it took for the engine to reach 9000 RPM while spinning-up a 500 lb wheel/load.
Different gears changed the time it took to spin that load up, and there were more losses, but the engine torque/HP results plotted out about the same.

Works4me; Thank you as well. I don't think I worded the explanation's right. Hoping an Engineer can correct my errors.

Ride safe, Ted
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