2DOF Joyrider + JRKs + Mobility Scooter Motors‏

Hello Everyone,

Firstly, thanks very much for having me on your great forum.

I am building my first 2DOF race sim. I have found this forum incredibly helpful in answering any qs, so thanks all!

I plan on a joyrider type platform driven by mobility scooter motors and jrks.

I don't have too much info on the motors apart from the following:

750w
20 amp under load
24v



I realize these motors are probably mass overkill, but they are free to me so I'm gonna try and make them work. I have taken them off their original gearboxes because they also had a diff and way too big. I have purchased a MCP2 gearbox (see pic), it matches up pretty well and is 25:1 (not knowing my motor's rpm, annoying . I need to sort out an output shaft for my motor that'll fit the gearbox (pics), any ideas where I might get this online?



I plan to run them at 12v as i really want to use the JRKs 12v12, I know the motors will get a bit hot, do you think there are any other problems in doing this? I could run them at 24v but then I find myself in trouble with power supplies? ( maybe just 2 car batteries in series, no mains power?)

This may all end up being too much work and I'll end up buying some more appropriate hardware, but I kind of like the journey. Does anyone else have any experience with these size motors?

My only other concern is the location of the pivot point. I understand it should be in line with the COG of the driver but I will have my triple monitors also mounted to the platform which will move the balance point forward ( only a problem without driver's weight? ). I would like the platform to balance with and without a driver ( I have a very light GRP seat but I weigh 95kgs). I have read of people using bungees or springs to do this, would this be a good solution?



Also, is there a better point to mount my push rods to increase level of movement(front/back) or is it the same, and more reliant on the height of platform and drive lever length? (don't want to do shoulder mounts I'm afraid).

Sorry for all the questions and general babbling, I've been building up to this for a month or two and it is a bit of a brain dump!

Cheers

The motors might be 20 amps under load, but sim motors run at stall current , which is usually about double the load current. This is because the motor uses power to stop and change direction.
The JRKS will run 30 amps continuous with a heat sink and fan cooling, but really, try not to stress them more.

And as for motor placement, it depends on the frame planned and the weight of the driver.
Motors just under the back of the frame will work well for a seat mover, but if you are planning a frame with wheel and pedals moving with you, move the motors as far as you can to the front for leverage.
I have run motors at 300mm forward and back from the pivot point, but for compact size, move them to the front as far as you can. Even 350mm will help. This saves you using shoulder mount motors, but be cautious of driver size. Like try to keep under 100kg for motors at 300-400mm. If you go further towards the front, you can use a fatter driver.
Have a dig through my projects for ideas.
2-dof-big-motor-foot-placement-sim-t3822.html this is the best leverage next to shoulder mounts, but will take a bit of engineering.
Otherwise, 2dof-redesigned-big-worm-gear-motor-sim-t3640.html , motors were 400mm forward. And it worked well.
Otherwise, you look to be on the right track.
Good luck with your project.

Thanks bsft. Your threads have been v helpful. I plan to end up with something similar to your first link.

I think I'm going to abandon these motors as sourcing a output shaft is proving impossible. I think I will go with the same motors as you, as I live just round the corner from Motion Control Products and they sell them. My only concern is the plastic gearboxes that they normally come with (mcp4), but hopefully they will mount to my mcp4s fine!

Thanks again and awesome sims mate, good work!

I meant my mcp2's!

Finally making some progress with the sim!

Acquired most of the parts a while back but fabrication has been slow due to other commitments. I sadly havent taken as many pictures as I would've liked but here we go:









I have now completed the platform/cockpit. Triple monitors and steering wheel mount are really sturdy but yet to be tested with motion so may need further modification. Driving position is excellent, not bad for sitting on the floor with a tape measure, lol.









Halfway through the fabrication of the base unit. I am now using two ZYT 90s with 50:1 gearboxes. Output is 100rpm so pretty happy with that.



Sorting out some kind of flange between my output shaft and drive lever has been my biggest headache to be honest. I finally found a taper bearing (see pic) that had the same keyway slot as the shaft. This has allowed me something to weld the drive lever to! I would be interested in other people's solutions to this area of their builds?!?



Using one turn 10k pots and model pulleys as linkage to the other side of the gearbox.



Wiring has been annoying due to the quite small inputs on the JRK pcb. I decided to double up on cabling and this proved to be a problem. This is my only criticism of the jrk as otherwise I think its a great bit of kit.



I have hacked up an old heatsink to create two nice little ones for each jrk, I also have a cool (excuse the pun) twin fan plate which will be the lid for the pcb enclosure (pics to follow).

Pretty much ready to test now so will hopefully have a video up soon of motion!

Thanks to the guys who I've PM'd for their help, especially bsft.