yantra yatra
100 W
could you please explain about the pulling in different directions? Do you need to set them up differently for this?
Leaf / leafmotor / leafbike high efficiency 1500w motor
- Thread starter neptronix
- Start date
Chalo
100 TW
When the motor is propelling forward, the axle is trying to rotate backwards. If you only have forward propulsion, it bumps into the the limit of the torque arm flats and stays there. But when you use regen braking, the axle tries to rotate forward. Alternating drive and regen rocks the axle back and forth, which tends to unscrew the axle nuts until a catastrophic failure occurs.
The remedy being suggested is to slew one torque arm forward to brace against the axle turning backward, and the other torque arm backward to brace against the axle turning forward, before screwing them down firmly. In this way you can minimize (but not completely eliminate) the range of motion through which reversing torque backs off the axle nuts.
lnanek
10 kW
You could buy a motor with an integrated torque arm if you really want to do regen. Grin has one.
The Toecutter
100 kW
- Joined
- Feb 8, 2015
- Messages
- 1,489
The more the range of motion increases, the faster the rate of change in the rate of motion increases. Quality torquearms and correct installation are everything.
Given the mileage I have ridden and the lack of unwanted drama on this subject for my use case since the first and only failure, I suspect that tightening down torquearms and axle nuts will be so seldom on my builds that it will only need to happen as a result of a tire/tube change or wheel/motor service as has been my experience thus far. I can literally go 10,000+ miles without issue on this, with regen being the vast majority of my braking. When I remove the axle nuts to periodically check, everything appears flush and solid without any noticeable gap or movement.
That is the result of using high-quality, precision-machined torquearms and/or clamping torqueplates on both sides and checking to assure everything is seated correctly during installation, coupled with programming low max regen current/torque into the controller setting. Anything less robust than this, and I wouldn't trust regen at ALL for my use case thanks to my first and only failure where I lost an axle nut. I was about to kill off any idea of using regen at all after that. I'm glad I tried it again, because I love it.
Last edited:
ZeroEm
1 MW
The problem is most torque arms have some play. Some people have tried to shim the slack out. The issues arise from how much power you have or use. If you use low enough power you don't need torque arms. Same with regen if lightly used the axel does not twist the opposite way. As Chalo pointed out it does not always work. I'm at my limits if I used more power would need to go to clamping dropouts.
Note that no matter how good a torque arm is, motor axle flats aren’t always machined to spec, so a poor axle can contribute to looseness. As mentioned, shimming may be an option. I used a piece of a razor blade to jam between the axle flat and torque arm for a super tight fit. It’s a hassle to remove, but better than the problems any movement would create.
Whenever I have a loose TA, I fire-up the MIG and add a few brief tacks to the axle flat(s), then hand-file it to achieve a tight TA fit. When I specify 'brief',... that's exactly what I mean. If you're concerned about excessive heat disrupting the axle temper or perhaps a motor seal, then you have no clue what a 'tack' is.
ti is worth noting that in this case as in others, it's not the fall that kills you, it's the sudden stop at the end.
So because of the accelerated motion, and the amount of motion, the impact at the end of motion is greater, and the resulting surface and structure modifications
of the meeting materials is greater.Given the popularity of those leaf motors, how comes there is still no decent inbuilt torque arm option ? Flattened axles should really be obsolete by now, and I have a couple of cheapo chinese DD motors that actually came with useable torque arm mounts so I don't think it's a cost problem.
ITs' cheap, and it "works" (in that people still buy them anyway).
Engineering a correct and easy to install "universal" solution isn't easy; it took Grin quite a while to come up with what they use now for GMAC and GAA. Even if the many other motor companies out there just copied Grin's (or heinzmann's) it'd take a while to get them to start making *working* versions of them (meaning, correct copies, not just wrong general-idea-copies like usually happens). They have to get both materials *and* design correct, on the motor and the arm and the mounting bits for the frame end.
Ebike.ca has high standards and the added difficulty of adapting existing models. If you're a manufacturer, you can easily change your molds / machining setup for simpler torque arm implementation.
For an instance, the first DD hub I had was an early go swissdrive. The TA was a simple 50-60mm long piece of Steel cut with a square hole matching an equally cut slot on the axle. Still worked way better than all flattened axles I've seen, even in Regen mode. Arguably go swissdrive was a super expensive motor, but their TA implementation was cheap and simple.
So I guess you're right when stating that "people still buy them anyway".
