Gruber
HobbyMasters
M.L. Toys
KidsWheels
Gruber
HobbyMasters
M.L. Toys
KidsWheels
HobbyMasters M.L. Toys
Gruber
KidsWheels
Need new motors? Grind a gearbox? Adding teeth to a pinion?
User avatar
By Hackish
#147745
I decided to go with an ESC to control variable speed. In doing this, I decided to open a gearbox just to see what was inside, since these motors pull more than 10A. I really have no idea what sort of motor this is. The gears, although plastic do seem to be pretty beefy. I'm looking because I know AMAV is long gone, so there is no hope for replacement parts. Any ideas?
Attachments
2017-11-05 12.38.55-s.jpg
2017-11-05 12.51.47s.jpg
2017-11-05 12.51.56s.jpg
User avatar
By Hackish
#147746
Motor diameter is 37mm and the front holes are 25mm apart. An imprecise measurement shows a 3mm shaft. The body is 57mm. The pinion is 10.5mm tip diameter and the root is about 8mm. I'm not exactly sure how to measure the PA and all that just to match up a gear. I suspect these are standard off-the-shelf gears.
User avatar
By Hammer-fm
#147750
All of those dimensions line up with a standard "550" class motor. The 8 teeth combined with the pinion dimensions you measured would indicate it's likely mod-1 (1mm pitch spacing). No idea on the motor RPM or anything like that without either some measurements or more #s off the case (which may or may not help).
User avatar
By Hackish
#147752
I spent a bit of time with it this afternoon. I believe the original motor was made by Mabuchi. It doesn't seem that there are any good inrunner BLDC motors that would fit so I reluctantly decided to use some Titan 550's instead. They were slightly larger, but I made them fit. The shaft turned out to be 1/8" and I made the gear fit with a bit of grinding on the flat spot. With no load, the originals pulled about 600ma each and the Titan pulls about 1.6A.

I have 2 VESC 150A speed controllers. They can be run tandem with a CAN interface to equalize power draw and throttle inputs. Unfortunately, with no brushless motors, they can't do speed limiting or speed equalization, although I can cap the maximum current and peak voltage. The driver is only 3 1/2 so there is a difference between how fast she wants to go and how fast she should go! Another cool thing with with the VESC controller is that I can run a programmable ramp-up and ramp-down as well as regenerative braking. If I can figure out a decent pedal setup then I can run variable throttle and variable brakes.
Attachments
2017-11-05 23.27.59s.jpg
User avatar
By Hammer-fm
#147756
Sounds like a good setup. Limiting peak voltage should be close enough in terms of velocity limiters, although you'll still have the downhill effect. The current limiter and ramp-up control should help keep the gearboxes from, breaking pieces.

There are an large number of different variable-speed pedal options. I used a hall-effect scooter pedal and repurposed the stock gas pedal as a brake pedal. I swapped the gas/brake connections on the now-brake pedal and that allowed me to just keep the stock wiring there -- it's "on" the gas by default and hitting the brake pedal now switches it to the braking circuit (my homebrew PWM controller sits between the negative wire going to the battery and the battery negative terminal, rather than on the positive side of the motor or battery). The biggest problem I had was that the F150 tub doesn't really have space for a brake pedal -- I had to cut out part of the footwell; second problem is that now there's no brakes when it's just sitting, so on hills you have to park it against something. The next speed-controller I'm building now is aimed for a single-pedal solution with relay and re-engages the brakes ~0.5 seconds after the gas is released.
User avatar
By Hackish
#147771
You may want to consider the VESC (vedders) speed controller. It's open source, so if you want to do anything special, you can just add it to the firmware. In my case, I'm not running brushless, but if you were, you could implement a holding brake. The gear ratio of the AMAV and weight of my child (40lbs) is enough that it does not spontaneously roll down any hills. I could hold the brake on, but I think it would still need a little motor rotation to excite the windings enough for the braking.

At the moment, I do have a hall type foot pedal, but it is too stiff for the little kid and I haven't found a lighter spring that will fit. I've also ordered a few thermosters so I can limit current by motor temperature too.
User avatar
By Hackish
#147784
First test drive today with the kid driving. It goes about 25% faster and I think it sucks more current than the battery can supply. They are old tired batteries from a UPS. I'm running it on a chinese PWM speed controller at the moment since I didn't have time to finish the new gas pedal. Already, the kid stabbing the throttle has caused a weird sound to start on one of the gearboxes. Not good.

awesome, thanks, I think I pretty much got all the[…]

Looks good! Hopefully the new gears will last for […]

Hello all

Just getting really into Powerwheels. My son has a[…]

Would you guys share pictures of your set up with […]

HobbyMasters Udemy Course