Mt. Goat Cycletruck Gearing

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Jun 20, 2015
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407
If it is as simple as dividing the watts by rpms noted on the Luna cycles data, but is that motor rpms or planitary gear rpms?

About 331 rpm??? with 450lbs on 9% grade it will be a bit less? Especially with motorcycle tires? Or will that only affect the speed; the effect being rollng resistance.

Well only a reality check wil tell for sure. Could some one actually test it out?
 
That's a new one to me for testing motor speed.
Motors are rated in KV (rpm per volt applied)
The torque output is the current applied
Torque × rpm = power
Output power is measured in Hp
Current × voltage = input power measuered in watts

The watts being applied will rise as the torque demand is increased so half throttle at stall speed may equal the same or less watts with full throttle and a little momentum, so the watts applied can not give a clear indication of the speed your at.

Brushless motors are synchronous so they spin at the same speed as the magnetic field rotates with no slippage, The controller increase's it's frequency with hall feedback to detect rotor position and increase the rotor speed, The current applied is the amount of torque

Bldc motor's tend to produce all their torque at zero rpm, max power at midrange and max efficency at high rpm, There's graphs on Google to see the typical characteristics but typically you don't want to load the motor to much and try keep the rpm high like a drill making a hole keep the motor singing and it will reward you with low running costs.
 
If the motor spins 800rpm at 72v then ÷ the 800rpm by 72v to get the kv per volt and then × it by your rated voltage not the cells max volts and you get your expected rpm, It should be 533rpm.

The working current should not change whatever the motor is rated for use, There should be a max torque output for the motor if you apply the rated current you should still have max torque at zero rpm but it will fall away faster than using higher volts.

Last post I mentioned motor characteristics with points on a graph, that will alter depending on the voltage and current applied so the main thing is to make sure you always have plenty of start up torque in reserve so you can climb from a stand still and have decent efficency.

If your wheel spins at 80kph and your ride speed is 50kph when loaded then there's a high demand on torque and efficency will be crap you need to look at the graph to get geared decent and with a midrive it's easy with a dd hub it can be more tricky but they can still be torquey enough when in small rims.

This graph shows how the torque and efficency changes as the volts and amps are both increased, (a mildly overvolted motor)
Screenshot_2018-05-27-22-22-39-1.png

See how there's more torque available but the efficency zone has gone further up the scale and there's more overall power usage so with out careful gear selection it could lead to a motor that is using peak power constantly again a bad situation.

It's also possible to see from the graph that overvoltIng the motor and gearing it lightly so it can spin to max rpm easily can give an efficency of 75% at 250rpm and still be producing torque with the higher rpm over the stock motor that was all out of torque at that point.

The overall power will still be usable if the torque demand is low enough for the motor to have no issues in reaching the rpm even when climbing it's efficency will be higher than stock and the gearing back a bit and overvoltIng can actual give better climbing torque with simular speeds but much better range.

Running low volts is not a problem it can actual help as efficency drops down the chart a bit I find with my dd hub i run it at 10s so the rpm I need to reach for efficiency is lower at 20mph but nit as good as higher volts, on the plus side I get little wind resistance at 20mph so I've made this my sweet spot with gearing of the hub in the wheel and my self peddling along, I can get upto 30 miles off 350wh so lowering the volts to the hub lowered my efficency a bit but being a hub Its hard to gear down the only option was to use the smallest rim i could lower the volts to make efficency in the small wheel at lower speeds and then the lack of wind helped me gain overall with a steady 20mph easily achievable, where a geared down mid drive could take that 350wh past 50 miles at a slower pace and geared lighter but it needs gears and to put it's power down through the chain to do it, I'm well happy with my ride no gears just simplistic and robust all over.
 
ok it took a while but I understand it now
“If the motor spins 800rpm at 72v then ÷ the 800rpm by 72v to get the rpm per volt applyed (kv)

Kv (motor velocity constant, or the back EMF constant)
https://en.wikipedia.org/wiki/Counter-electromotive_force

800 ÷ 72 = 11.111111 x 48 = 533.3333 (at 48v) so then I have to figure out what the voltage will be at half throttle...but that will just have be a phisical test.
But I may as well just use the calculator to find a readuction ratio that will keep it under the speed limit.


I do understand the concept of volting up and gearing down. But should I gear down the same percentage as I volted up?

This page tells even more:
http://www.ebikes.ca/learn/power-ratings.html

H3540at48V35ASimulator.jpg


This is from lunacycles for the cyclone3000w

Max speed 900RPM (unloaded at the output shaft)
Rated speed 800 RPM
Rated output 3000W (72V @ 40a)
Max output 4000W
Rated Torque 50Nm
Max Torque 100Nm
Rated Amp 40A




Ianhill said:
If the motor spins 800rpm at 72v then ÷ the 800rpm by 72v to get the kv per volt and then × it by your rated voltage not the cells max volts and you get your expected rpm, It should be 533rpm.
 
From those specs the motor likes 40amps continously for 50 nm or 80amp burst's to get the max torque of 100nm at 0 rpm.

Once you × it by 48v the first time your golden so the 533rpm, they state 900rpm max and 800rpm rated now I don't know if this is loaded vs unloaded expected rpm but it's 89% of max so if we adjust the 533rpm figure we get 485rpm which ideally at 48v you will be hitting peak efficency around these rpm.

If it's a middrive what are the gearing options you are considering it's going to be a gearing to the crank and then the rear so 2 ratios ? The motor to the chainset around 5-1 for a max 97 rpm cadence for you to match ? and then the chainring to cassete, And what size wheel etc ?

This motor got some good grunt at 100nm so it could run a single speed setup all day but you will sacrifice the middrive exceptional range, a good 10 speed rear cassete and the largest front sprocket is good for low speed torque and massive top end if needed and you can peddle along at low speed or top end what ever suits I'd be aiming for that and make a mountain goat with a lesser motor.

But you have to remember your dropping 100nm into the gears at 80 amp when your in low gears and climbing hard there could be some frame twisting going on with the gearing reduction so heavy the 100nm peak at start up could equal more than 400 nm for the motor to chainring to deal with and over 1000nm for the chain itself at the wheel, so if your in the lowest range gear and max demand from start up the chain could just say no thank you sir pop.

So I think it is a good reason for single speed as you can limit the torque for more than enough to start on steep hills and aim towards speed and have less stress on the frame and chain etc with a calculated max torque by using gearing and peak amps the ride would be sweet but theres alot to consider, it will sacrifice some range for reliability but it will be faster off the mark and overall without gears I can vouch for that you can just floor it and let the motor whine up while you peddle your heart out so you leave cars for dust.

I'm only doing single speed at 10s and 40amps with a hub and I can dust most cars and motorbikes off the light's but I tap out at 20mph it's my design limit and strictly it's got to be tuned to 350watt on the Bluetooth but ffs like that's just stupid I think 1500watt or 10s 40amps that's where ebikes become more than ebikes.

My 16s 60amp 3500ish watts stand up scooter would comfortably drive with cars at 50mph on flat and upto 45mph on hills drafting them, 15 mile range when flat out on 800wh but I'd travel 15 miles too in 20 minutes police got on top in the end spoil everything.
 
A single speed mountain goat tractor is exactly what I want to build out of my hand made cycle truck.

The only thing I don't know is whether or not I should make the top speed 19 mph or 23 mph.

If the 533.333 rpm is peak efeciency then maybe I should make the single gear more like 13 to 15mph. Right? no more like 20mph -ish

I do not care for speed, infact I would like to be able to tell the cops honestly that I cannot drive this truck over the 20mph speed limit even if I changed the controler settings.

As far as chain goes, I want to use 415 chain on double sprockets. The first chain maybe need to be two smaller single speed chains.

My drive wheel is 23” with compression. I swiched to a moped tire on a motorcycle rim a couple years ago. And the front tire is a motorcycle 16” on BMX rim. So much better than using wimpy bicycle tires.

I intend to set the controller to accellerat slowly so I will not brake spokes even though I used some good ones that are swaged from 14g to 13 or 12 at the $180 velocity hub.

I want to buy a 1300w output motor, but this is all I could find. So I really need to program the controller to cut off around 1600w battery power...

I still don't know what size battery pack to buy. I am hoping that the 1750wh pack will do. And charge it to only 80% to make it last longer.



cyclone%2Bmax%2Bthrottle%2Bcalc.JPG


my-rig-40-percent.jpg
 
Sorry for no reply Hugh, I got to have 8 teeth out and I've been waiting for over 2 years, the nerve pain can get so bad I just can't think straight

I'd possibly set the rpm to 485 so I can get to efficency more easy but Ill be honest I'm useless at the moment I'll have to look at it next few days sorry fella.

Edit.
See I think I was full of shit by there that would increase top speed and torque demand off the line my brains a fog stick with the 535.
Sorry I'm useless at the moment just can't wait for my op and get this fuking pain in the arse wisdom teeth out the twats are impacted and wrapped round my lip nerve so when they gone I'll have no feeling in my lip but while they are there its hell I've lost my job through being unreliable never thought adult teeth could bring so much troubles ruined my later life.
 
oh man, that hurts just thinking about it. I had all my remaining teeth pulled out years ago so I would nto have to got through the pain any more. I hope you have some Hydracodone, excellent pain killers.

Last night I brain-stormed the right answer to the problem and then forgot how I got there. It would be bit different at a higher voltage but this is a workable solution: reduction ratio of 1.89:1.

Now my math maybe wrong because I am vertualy math illiterate. And my word proccesor has stoped corecting my spelling as well. How can I function without a fully functional computer!!

1300w is 67.7 % of 1920w (533.333's wattage?) and 361rpm is 67.7% of 533.3333rpm

But is that the aplied voltage?
only problem now is finding a 24t sprocket for the cassette. I may have to scavange two off old cassettes.

So I was correct about using the 533.3333rpm at about 20mph because 12-13mph at 1300w should be almost exactly what I need for the 9% grade with 450lbs. (An estimate only)

However this will leave the motor straining a bit if I want to haul more bricks up the same hill. But there is plenty power left over. Maybe I should run the darn thing on a 52v battery just to be sure. But I am not going to strain my brain with more math.

This gear should work good for the rightside drive:

13mph%2Bgear%2Bcyclone%2B3000.JPG
 
My infection is calming now I feel a bit human again, player fuk with hospital pushed my op forward to next Tuesday I've only been waiting for 2 and half years lol.

So your gonna have a maximum weight of about 1/4 a ton and an incline of 10% say to get it up ?

I'd possibly gear for 15mph to be sure I can chuck a bit more weight on if I need to, your doing right going with the 428 chain that should do the job torque demand wise, you will have to take it easy on them spokes mind.

I like the effort it's a proper haulage bike fair play.

One thing to remember about that graph is where efficency is of you can't reach it you lay in the area of max power demand and then it will get hot so it will be a suck it and see really but you have geared low enough I would have thought and the motor is very low kv so as long as you get that rpm up you will be fine take a little run up to the climb first.
 
Hugh-Jassman said:
15mph at 533 rpms will be esyer to find sprocket for....This machine will be so strong that I may just pop my spokes...hope I can accellerate slow enough not to.

Fat chance of that. Remember that you're dividing the torque among 36 spokes. No single one of them has to work very hard.
 
I'm not sure what chalo's means by there I think when you divide the torque up among the 36 spokes or what ever you have the load they carry will be low which is fairly correct.

Hit a big bump on the way up mind and it could deform the rim theres more chance of that really through overloading than ripping the threads of the nipples and deleacing the wheel on the spot.

If your using a middrive have you considered a cast alloy drive wheel from a motorbike ? Be more robust for your heavy duty work there is a lot of weight on the rim, too much side loading and the wheel will fold no matter the spokes strength the alloy out is thin.

Think of it like this too the contact area of the rim will have heck of a lot of pressure on it even with a flat tyre that about 1.5 inch squared and 1/4 of a ton pressing down go off tarmac and it will be a nightmare dig in like a stuburn dog, you need more rolling surface area to distribute the load weight.
 
That is good not to have to worrie about the spokes. But I don't think I am going to find sprockets for the 428 chain unless it will work on the 415 chain sprockets.

ok this is going to kill my free hub body. I will have to start over and drive the left side. Then I will need larger sprockets....and motor oneway bearing for the oposite direction and I do not know if the motor can be run in reverse...probablty will. this is what I wanted to do in the first place.

Well at least it will be easyer to get sprockets for a motor bike drive train. With 2.25:1 ratio I would be moving at about 16mph or so, (probably flat land)
I may need to stick with the 415 chain....

I think I better take it easy on the accelleration and every thing else, other wise I may have to just build a whole new Mt Goat.

I hope the motorcycle rim will hold up, I would hate to have to buy another...


Chalo said:
Hugh-Jassman said:
15mph at 533 rpms will be esyer to find sprocket for....This machine will be so strong that I may just pop my spokes...hope I can accellerate slow enough not to.

Fat chance of that. Remember that you're dividing the torque among 36 spokes. No single one of them has to work very hard.
 
It's true the freehub body is probably the weak link when you turn up torque to super-superhuman levels. The only remedy against that is using a small diameter wheel.
 
I wish I could put a 19" rim on this bike, but I would have to use a large diameter tire to bring up the rear so the steering would be the same. and nothing more than a 2.25" wide tire will fit. I ended up with a 2ply moped tire on the rear 19"rim 2.25"wide. with the wide rim it was a bit wider than the tire says. but teh rear frame was made for a 24 mt bike tire, so the end diameter was about 23" with compression. the front has a 2.25 motorcycle tire 4 ply. maybe I should rethink that a 16" rim with a 3" tire would be 22" od aproxamatly. I will have to measure my frame. I know a 2.75" tire may fit easyer but still may afect the steering....maybe moving at a slow speed it does not matter much...???

Sprockets are keeping me down on this project.
The sprocket on the motor is 2.25mm thick,and it looks like it is an integral part of the bearing sleve so I will not be able to use two together which would be about 4.5mm [0.177”] wide...so now I need to scrap that unit and find a oneway bearing that can hold some kind of 18-20t sprocket, hopefully one for a #41 chain. The only way to do it is with a single-speed free-wheel holder that fits onto a 3/4” motor shaft with 1/4” keyway.
But that is probably how they built one on the motor. And I don't think I am going to find a single speed freewheel that has wide sprockets or two sprockets together. I may have to pay a machine shop way too much money to build what I need. Got any ideas where I could find such a thing?

I may have found it, I will have to read the specs later....but will a #41 or 415 chain work with it?

http://www.staton-inc.com/store/index.php?p=product&id=985

0040.jpg


The 415 sprockets are only: [0.170in or 4.34mm]....so is it possible to use a 420 chain? Or will I need to stick with a 415 (or #41 being stronger)

Will a 1/4” width bushing chain (420) wobble possibly causing chain suck?



Chalo said:
It's true the freehub body is probably the weak link when you turn up torque to super-superhuman levels. The only remedy against that is using a small diameter wheel.
 
You settled on the 3kW Cyclone gear motor, right? That motor has a 20mm shaft with a 6mm keyway. The Staton part you linked has a 3/4" bore (19.05mm) with a 3/16" keyway (4.76mm). You would have to get a highly qualified machine shop to modify it for you.

Fortunately, Staton offers one that fits without modification:
http://www.staton-inc.com/store/index.php?p=product&id=2234

In either case, the smallest commonly available freewheel for that thread size is 16t. There are out-of-production 15t units out there, but you may not be able to find one. All the usual 13-14-15t single freewheels mount on a special M30x1.0 thread, as opposed to the 1-3/8"-24 thread most freewheels use.

#41 chain runs fine on narrower sprockets. The teeth don't have to fill the chain in from side to side. It's analogous to the common bicycle practice of using 1/8" chain on 3/32" sprockets. #41 is grossly overspeced for a 1500W application, though. There's no practical reason to use chain that can withstand much higher forces than every other component in your drivetrain, anyway. I'd get a half dozen regular cheap 1/8" chains and a chain checker, and replace them as they reach 0.5% longer than new.
 
thanks, my brain is gettting old....but I think I had better stick with the 415 or 41 chains. And I have decided that there must be an adapter for motorcycle sprockets. I need at least 20t for the 415 chain and up to 30t on hte motor. that will let me use a 60t sprocket on the rear adapter. the larger the better.

I am not going to worry about using a oneway bearing on the motor, I can't push the pedals any how.

yes I did settled on the 3kW Cyclone gear motor, and bought it before I put enough thought into the engineering part. Although it does seem to be the only motor I could use, just because of teh planitary gears and 6:1 reduction. so the total reduction is going to be around 13:1.... what a mt. goat!


Chalo said:
You settled on the 3kW Cyclone gear motor, right? That motor has a 20mm shaft with a 6mm keyway. The Staton part you linked has a 3/4" bore (19.05mm) with a 3/16" keyway (4.76mm). You would have to get a highly qualified machine shop to modify it for you.

Fortunately, Staton offers one that fits without modification:
http://www.staton-inc.com/store/index.php?p=product&id=2234

In either case, the smallest commonly available freewheel for that thread size is 16t. There are out-of-production 15t units out there, but you may not be able to find one. All the usual 13-14-15t single freewheels mount on a special M30x1.0 thread, as opposed to the 1-3/8"-24 thread most freewheels use.

#41 chain runs fine on narrower sprockets. The teeth don't have to fill the chain in from side to side. It's analogous to the common bicycle practice of using 1/8" chain on 3/32" sprockets. #41 is grossly overspeced for a 1500W application, though. There's no practical reason to use chain that can withstand much higher forces than every other component in your drivetrain, anyway. I'd get a half dozen regular cheap 1/8" chains and a chain checker, and replace them as they reach 0.5% longer than new.
 
Hugh-Jassman said:
I am not going to worry about using a oneway bearing on the motor, I can't push the pedals any how.

It would be nice to coast without dragging the motor along, though-- and without putting reversing torque loads through every part of the drivetrain. For that, you have to have an overrunning clutch, which in your case could be a freewheel on the motor shaft.

If you let a direct drive motor overspeed on downhill runs, you can cause unregulated recharging of the battery. That's not good if it happens before the battery has discharged enough to make room for the new charge, or if the charge rate exceeds what the battery is rated for.

Last I checked, you could still get 16t freewheels for fat 3/16" BMX chain. That would be a pretty swell match for your fat industrial chain.
 
Freewheel and all that weight sounds like a disaster, I've got them freewheels in my scooters and I dumped them in the end and went direct drive they where to fragile for my torque needs and your ride is a lot more heavier I find my scooter rolled just as well but there are instances with a strong motor thats low kv that can have lots of drag and uneaten slowing down.
I'm not familiar with middrives so chalos will be more informative I can help with gearing and cadence etc but I can't see how this is going to pan out with a freewheel pawl system involved it's going to need to be ibeyond the norm and industrial to cope.

I'm not trying to be defeatist, I would say keep it simple and strong it's possible but don't worry about freewheeling drag when you got half a ton hanging of the back of you its a good opertunity for some banging regen it's not ideal but it will be stronger and more reliable.
 
I would definatly like to not need the free wheel, they are all out of stock for the left hand thread and flange mount.

Mybe I should be looking for some kind of industrial one way bearing. unfortunatly when it comes to industrial parts it is even harder to find what I want.

maybe I should go to a machine shop and ask...
4pcs-lot-LMF20UU-20mm-Flange-Linear-Bearing-Router-Shaft-Bearing-CNC.jpg


https://endless-sphere.com/forums/viewtopic.php?t=17309


Planetary gear lubrication?

I have not found any info about how often I need to lube the palnetary gear on the cyclone... how often I should lube these panetary gears. I hope I don't have to lube the planetary gears more than once a winter. Has anyone tryed filling the cyclone's gear housing with STP? Or would it just leak out?

https://endless-sphere.com/forums/viewtopic.php?f=3&t=6348&start=100&hilit=Mystik

And I have not seen anything about how to reverse the motor. If it is as simple as reversing the polarity, I can make it happen....But if I have to reprogram the controller, I will have to buy a “smart phone”.
 
Hugh-Jassman said:
I would definatly like to not need the free wheel, they are all out of stock for the left hand thread and flange mount

When you use a shaft mounted freewheel adapter, you can reverse its one-way action by flipping it around on the shaft. You don't need a left hand threaded freewheel.
 
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