122N-m torque (84.3 lbs of trust) tested today !!!!

[Doctorbass]

I finally validated the ebikes.ca simulator data today!

When i select these parameter: (see image below)

I have to say that the simulator is acurate at more than 95% for my ebike setup!! :wink:

[youtube]JQmddJT1e6c[/youtube]

8 4 . 3 lbs !!! t r u s t

I really love these kind of tests!!!!

Doc

 

[swade]

Cool! Just be careful that thing doesn't wack the back of your head if it pulls loose!

 

[Ben]

Good to see the simulator is accurate.

Now, what about a 24" 96V test?

 

[steveo]

i don't think torque will change much on a test like that .. wheel size i would think helps you once you are movin .. not on a stand still like doc has done ....

5304 & 5305 are very close torque wise.

-steveo

 

[fechter]

That's a lot of thrust!

Now do the math and figure out what the forces are on the axle bolt and torque arms. They need to design better torque arms into the motor.

 

[Doctorbass]

That's a lot of thrust!

Now do the math and figure out what the forces are on the axle bolt and torque arms. They need to design better torque arms into the motor.

That's done.. and it's 4600lbs

taking account that my wheel is 26", the axel and the flat on it have a diameter of 14mm - 2mm for the flat = 12mm = 6mm from the center to the flat edge. and that i have 80lbs trust on the tire circunference


2 tons!!!! THAT'S the BEST REASON WHY WE NEED TORQUE ARM

 

[lazarus2405]

Yup, it's crazy.

With a 5303 at 112v and 100a (which I plan to run soon), that's 200N-M. Remember, though, that you have two sides of those dropouts locked in a dropout (without torque arms). I used 10mm as the lever arm when I ran the numbers. 12 might be more accurate, assuming that both flats are locked. That worked out to 4500lbs of force on each flat!

So, I instead mentally pulled out a 6" long wrench. With that lever acting as a torque arm, it's "only" 300lbs!

So, take out a wrench, put it on the axle, and stand on it. That's a fair estimate of how much torque an overvolted overamped x5 will produce (depending on your weight and the wrench). Crazy.

 

[Link]

 

[fechter]

That's a lot of thrust!
Now do the math and figure out what the forces are on the axle bolt and torque arms. They need to design better torque arms into the motor.

That's done.. and it's 4600lbs
taking account that my wheel is 26", the axel and the flat on it have a diameter of 14mm - 2mm for the flat = 12mm = 6mm from the center to the flat edge. and that i have 80lbs trust on the tire circunference

2 tons!!!! THAT'S the BEST REASON WHY WE NEED TORQUE ARM

Thanks Doctor, and in pounds no less.

The amount of force on the axle flats is insane if none of the torque is transmitted to the dropout by the friction of being clamped. Open end spanner wrenches don't stand a chance at those levels.

 

[Mark_A_W]

I did the sums on the back on an envelope and got ~100Nm from 84lbs of thrust (I wish you would have stuck to metric units instead of mixing them...was that 84 pounds or 84 foot pounds or 84 pounds force????)

84/2.2 =38kg

38*9.81=373N

373*0.3m=111Nm (a guess of 0.3m being wheel radius....I didn't check)

My car only has 220Nm

You have 373N of thrust. If mass is around 100kg

a=f/m

a=373/100

a=3.73ms-2...for an instant, then it will drop. But still, that's 1/3 of gravity

 

[Doctorbass]

I did the sums on the back on an envelope and got ~100Nm from 84lbs of thrust (I wish you would have stuck to metric units instead of mixing them...was that 84 pounds or 84 foot pounds or 84 pounds force????)

84/2.2 =38kg

38*9.81=373N

373*0.3m=111Nm (a guess of 0.3m being wheel radius....I didn't check)

My car only has 220Nm

You have 373N of thrust. If mass is around 100kg

a=f/m

a=373/100

a=3.73ms-2...for an instant, then it will drop. But still, that's 1/3 of gravity

Your calculations are right.. it's just the data of the diameter that are incorrect :wink:

26" wheel it's not 0.3m but 0.3302m.. that give 123N-m

Doc

 

[Mark_A_W]

Depends how fat your tyres are

Despite the colloquial usage, smaller wheels do not give more torque (torque is always at 1m), they give more THRUST

 

[lazarus2405]

Depends how fat your tyres are

Despite the colloquial usage, smaller wheels do not give more torque (torque is always at 1m), they give more THRUST

Yes, but since he was converting from thrust to torque he needed to know the wheel radius.

24" wheels make the job easier for those dealing in anglo-american units. Your quantities of thrust and torque will be exactly the same, since your lever arm is one foot.

 

[Microbatman]

Yup, it's crazy.

With a 5303 at 112v and 100a (which I plan to run soon), that's 200N-M. Remember, though, that you have two sides of those dropouts locked in a dropout (without torque arms). I used 10mm as the lever arm when I ran the numbers. 12 might be more accurate, assuming that both flats are locked. That worked out to 4500lbs of force on each flat!

So, I instead mentally pulled out a 6" long wrench. With that lever acting as a torque arm, it's "only" 300lbs!

So, take out a wrench, put it on the axle, and stand on it. That's a fair estimate of how much torque an overvolted overamped x5 will produce (depending on your weight and the wrench). Crazy.

I could not agree more that the dropouts on for these motors are not strong enought for the force they put ou.
Call me a geek
But I am wondeing what the math is to come out at 4500?
Nice work figuring this out.
I am curious as to what the formula/math is at ariving at 4500?

 

[lazarus2405]

200 Newton-meters of torque is 200N of force at a 1m lever arm.
If the axle is 10mm across the flats, the lever arm (radius) is 5mm. Since this torque is split between two sides of the axle, it is in effect a (5mm*2) 10mm lever arm.
200Nm/.010m= 20,000 Newtons force.
20,000N= 4,496 pounds force.

That of course is shared between the two sides of the axle.

 

[dirty_d]

89 lb/ft of torque on the axle, thats about as much torque as you're supposed to put on a cars lug nuts. when i was in the army as a tanker we had to torque bolts on the tracks to 400lb/ft!, we used about a 4 foot long torque wrench, and there were hundreds of the bolts, i don't miss doing that