Q&A Forum
good morning everyone, my name is Giacomo I'm a mechanic, in the last period I installed several reprogrammable ECUs, unfortunately many jobs I have to refuse because I don't have a bench and some cars it is impossible to map them on the road, I was looking for a test bench, but at the moment the my budget does not allow me, in doing a thousand searches on the internet, I happened on your site, and I read it in full, I must say that you gave me an exaggerated stimulus, I would like to start making a couple of dyno Hubs, unfortunately I really struggle to find a pair of magnetic brakes, and before making the wrong purchases I would like to ask you a series of questions, I apologize for my English, I use google translate to translate and I imagine that the translation is quite disgusting ....
1) I found a pair of Frenelsa F16-100 (1000nm) at a very interesting figure, I am afraid that 1000 nm are few to make dyno hubs, in your opinion?
2) always thinking about the type of brake to buy I made a series of calculations and asked you if they were right or wrong, a car that has relatively small tires (e.g. 175/55 r 14) at 220 per hour (i.e. fifth gear) the wheels would turn at 2000 rpm, so between the engine and the hub there is a reduction of about 3: 1, which halves the braking torque, if I mount two 1000 nm dyno hubs, I can brake
2000 nm but reduced 3: 1 would become 700 nm, so could I brake the maximum car with those powers? or is there something in my calculation of wrong?
3) must the two magnetic brakes be the same? or can the software work with two different brakes while still managing to synchronize the 2 Hubs?
4) someone advises me not to buy Focal models, i.e. those mounted on the gearbox as they do not have bearings to support the rotors is it true or did I not understand anything?
Thank you for your time
Yours sincerely
Vezzoli Giacomo
Hi Giakx14xe and Welcome to the forum ,
What speed is the Frenelsa F16-100 rated at ?
What gear do you plan to do the testing in ?
Here are a few xls spreadsheets you can play around with numbers which may answer some of you questions?
I don't know the Frenelsa F16-100 electric brake specification but I'm only basing it on the fact that its is smaller than a Frenelsa F16-120EL Maximum rpm = 6300 Maximum Nm = 1176 and larger than a Frenelsa F16-65EL Maximum rpm = 7000 Maximum Nm = 637 , so speed shouldn't be a issue.
Had to do two links
Thanks a lot for the answer. but
as I explained before I would
like to build dyno hubs, and from
what I have noticed the dyno hub
runs very slowly, because it is
connected directly to the car
without the reduction of a roller,
therefore it takes a lot of brake
nm ... attached I attach the
datasheet of the frenelsa in
question ... Thanks
Hi and welcome!
You need to use brakes with axels, in other words you cannot use the focal models without quite some mechanical work.
Your max braking capacity will be 2 x 1000Nm at the brakes, and divide the gear ratio to get the braking capacity at the engine (you did that correctly). However, note the torque vs RPM curve. It is only 1000Nm at a specific RPM, and tapers off both above and below that. Another point to remember is that when the brakes are hot they are quite a lot weaker. This is normally mostly a problem if you are running long steady state tests, not for a quick power sweep through the RPM range. But you anyway need margin! Go for double the capacity you need if you can. There will be some losses in the drive train, which is good in that respect, maybe 10% or so.
The brakes do not need to be the same, the software controls the two brakes completely independently. But of course you will be limited by the smallest brake.
Good luck!
Hello
For hub dyno, the two brakes must be the same.
Think about inertia. An inequal load can kill the differential when you release braking at full speed.
One of the best choice for hub dyno are Telma CC200. 200 daN of braking torque these brakes can run at 4000 RPM.
Old brakes but safe and reliable.
Best regards
Hello
Try truck breakers in Spain or France .
I found 2 very nice Telma cc200 at Martin Seb Casse Poids Lourds
In the South West France.
Seb is a very good Guy
Best regards
FOUND!!!
1 telma cc250
1 telma cc300
The rotor weight is identical, gap is perfect, only bearing the telma cc300 present light noise...
Next step disassembly entire brake, check bearings,
Is correct machining the surface of the flywheel??? Or do no touch the surface?? I think work the surface on the my lathe machine... is a bad idea??
Disassemble rotor(flightwheel)....
Clean rotor surface and check for runout first. Before any rotor machining ?
How much did you endup paying for them ?
Curious what horsepower vehicle you plan to mainly test on those two big boys ?
My dreams is testing car over 1000 bhp....
looks like the same as my brakes!! the Telma engineer from my local city, when i went to telma for buy grease when i bought these, he asked me for what truck, i told him i havent one! lol, it's for a Dyno for testing cars, i told him how i made everything and he told me, i have to visit you, i wanna see it..2 days later, he visited my shop, told me i was crazy, that brake is used for "mini" trucks with +25.000Kg lol. if i remember correctly my brakes are C8770 or something like that, i have noted in an email for sure because he sent me catalg for my brakes, by looking pictures looks really the same! to heavy and powerfull brakes for sure! check all coils for to be sure you will not have problems with any of these later.
FYI, ive been using my hub dyno for +2 years, and ive tested +680nm (so far) and brakes was around 30-33% only.
What Mach says, clean and check for runout, you shuold have not problem with that, just check coils too, i had to dissamble one time for fix one coil, problem with used brakes are the "cover" for the coils. (i dont know how it's say in english) but coils has some protection for currents.
Good luck!
@walter wooow you have build a dyno hub??did you succeed without big problems ?? as it is also my project and I am afraid to find too many problems, especially to make those powers stand up ... sorry for a question the weight of the car you put it on the dyno or keep it raised with a jack or a bridge