electric horse-drawn tow !!!

Cars, buses, bicycles, electric airplanes: all electric transportation that exist. Conversion, engines and electric drives for transport ...
BobFuck
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by BobFuck » 29/01/13, 23:30

Grelinette wrote:
Forhorse wrote:Frankly, how much did the strain gauge cost?
What is its share in the overall cost of the project?


Probably less than 1 €, but the implementation is complicated: it is an electronic element of a few mm2, which sticks to a metal part which deforms under stress. The strain gauge measures the deformation of the support on which it is glued. To measure a force, you therefore need a mechanical assembly with a part which will deform precisely under stress. That explains the price: the gauge costs nothing, but the part on which it is glued is part of a mechanical assembly machined with precision, and therefore expensive. When you pay dearly for a force transducer, what you buy is mechanical engineering, in fact.

> It already exists on your electric bikes which only work
> while pedaling, the motor gives more force if you pedal harder!

On advanced models (Panasonic and Bosch engines for example), yes. In fact in the crankset there is a deformable element, with a strain gauge which measures the deformation and therefore the force. On rotten models, there is just a magnet sensor: you pedal, the engine starts fully. I tested both and the force sensor is really nicer. The other is really binary.

By the way, how much does the car ride? Do the wheel motors have a reduction gear or not?
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by Macro » 30/01/13, 08:33

Grelinette wrote:In action ...
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(at the controls, the coachman, alias Grelinette, next to it, Alexandre the student engineer), and in front, Nénuphar, the main engine. With 2 wheel motors the results are already very good: the horse attacks this good climb in a good trot and without effort.
This week we are fixing the other 2 wheel motors: it will be a 4x4 carriage! : Cheesy:


A rolling assembly has 8 motor points in all ... formidable in All terrain ...

But tell us..Water lily wouldn't he be doing a bit of fat ??? By pretending to pull his cart ... : Mrgreen:

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by Grelinette » 30/01/13, 21:23

Macro wrote:...
A rolling assembly has 8 motor points in all ... formidable in All terrain ...
But tell us..Water lily wouldn't he be doing a bit of fat ??? By pretending to pull his cart ... : Mrgreen:

Meuuh no, it does not make fat the water lily, it's just that it has its winter coat! : Cheesy:
On the other hand, it is true that I found that it looked very light during the tests of the carriage, even on the climb! ....
We will check the parameters of the motorized assistance. Every time we crashed and we put more than 100% assistance: it is the carriage that pushes the horse. You surprise me that he looked comfortable. Sacred Water Lily, he said nothing to me!

For the 8 motor skills points, it's even more because the trailers intended to be hung behind the carriage (benches, bucket, tank, etc.) will also be equipped with motorized assistance according to the same principle: all together is triggered upon traction.
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by Grelinette » 30/01/13, 22:01

BobFuck wrote:By the way, how much does the car ride? Do the wheel motors have a reduction gear or not?

For speed, the answer is simple: as it is an assistance motorization, it is the horse which determines the speed, the carriage follows (roughly 20 km / h max). It should be tested on a bench to know its maximum theoretical speed.

The wheel motors do not have a reduction gear.
Advantage: no resistive torque when the motorization is inactive
Disadvantage: less starting torque. With the 4 wheel motors, starts should be easier.
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by Grelinette » 31/01/13, 18:46

Not yet fortune, but already a little glory !!!! : Cheesy:
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by Grelinette » 22/02/13, 11:12

2 pupils of 1st S asked me if they could make a technical file on the horse-drawn car. Here is their TPE, with some formulas for amateurs: http://aveniratoutcrin.free.fr/doc/TPE-mathieu-m.pdf

I have to provide a small presentation of the project for a fair.
What do you think this succinct presentation? : http://aveniratoutcrin.free.fr/doc/Hippomobile-hybride.pdf
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by Grelinette » 20/11/13, 11:53

Hello everybody

Help ... I come back to you once again to help me complete a table of calculation of force necessary for a traction.
(The horse-drawn carriage project continues: this summer, the hybrid horse-drawn carriage was presented with great fanfare at the Haras National du Pin in Normandy. http://aveniratoutcrin.fr. I will give more news later).

To come back to my request, I try to make a synthetic table which gives an approximate value of the necessary traction force calculated with some obvious parameters: slope, towed mass, type of wheels / pads, type of soil, etc ...

I started to make an Excel table but I am not competent enough in the matter to finalize it.

Can you help me ? Excel table here: https://www.econologie.info/share/partag ... f2ws8b.xls

If you have ideas and improvements to suggest to me ...

NB: The results of this table should be applicable to all sets of types "tractor module / towed or pushed module", whether it is a horse / cart, bicycle / trailer, mother / stroller, worker / wheelbarrow, Santa Claus / sleigh ... : Mrgreen: it is soon topical!
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by Grelinette » 22/11/13, 15:18

Well, I have advanced a bit on the question and I found a very interesting table giving most of the coefficients of friction between 2 classic classic materials (there are even horses' hooves): http://www.engineeringtoolbox.com/friction-coefficients-d_778.html#.Uo9iMycxjMo

I also have a formula for calculating the theoretical horsepower based on its weight and height at the withers. I have compiled all these data in this pdf:
https://www.econologie.com/fichiers/partager3/1385127799iLUiPt.pdf

As I modify it regularly, I downloaded the excel table here:
http://aveniratoutcrin.free.fr/doc/Tableau_calcul_force_traction.xls

By the way, the weather forecast for this weekend is cold, rain and snow ...Image
I suggest you stay warm with good tea or good steaming coffee and help me finish this picture.
: Cheesy:
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by dirk pitt » 22/11/13, 15:58

the coefficients of friction of the materials are not useful to you in this case. it is not friction but rolling.
the rolling resistance coefficient of a given wheel on a given ground is very difficult to define theoretically. the best way is to determine it experimentally by the method of natural deceleration.
the principle is to launch the vehicle at a low speed (even just by pushing it by hand in your case) and then measure the distance it takes to stop. by doing this in one direction and in the other to eliminate a possible slight slope, we obtain a fairly precise measurement of the rolling resistance coefficient which takes into account the overall implementation: wheels on the ground but also friction of the hubs, etc.
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by Grelinette » 23/11/13, 10:48

dirk pitt wrote:the coefficients of friction of the materials are not useful to you in this case. it is not friction but rolling.
the rolling resistance coefficient of a given wheel on a given ground is very difficult to define theoretically. ...


Effectively defining the “real” Coefficient of Bearing / Friction is not simple, but initially, the idea is to define a “relative coefficient” allowing to have relatively reliable computational results. Secondly, a measurement with a dynamometer will allow me to re-evaluate the coefficients against each other.

If I pull a cart equipped with large large inflatable wheels, then the same with thin metal wheels, the force I would have to provide will be different for the same floor.

In fact, it is more the formula taking into account this coefficient that is important.
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