# Can I Move a wheelchair with two outrunner motors? [closed]

I am trying to turn a wheelchair electric and want to use a VESC to do so. However, I was wondering if an outrunner brushless motor with a belt to a larger gear would be effective and could move the wheelchair with a person if I had two of them. I am looking at a motor like this: https://www.amazon.com/vanpro-Brushless-Outrunner-Motor-Electric/dp/B07FNHQ3JK/ref=sr_1_2_sspa?keywords=brushless+scooter+motor&qid=1561407288&s=gateway&sr=8-2-spons&psc=1

Please feel free to suggest other solutions if this does not seem reasonable as I am still new to electrical and mechanical engineering.

Thanks, Maanit

• Your question is likely to be closed as too broad and you are requiring your readers to follow two links just to understand your question. I haven't checked but I can guess that because they are Amazon links there won't be a proper datasheet for either so detailed specifications will be missing. Our recommendation is, "No datasheet? No sale!". – Transistor Jun 24 '19 at 20:54
• I'm voting to close this question as off-topic because this is a question about the properties of a device that can only be answered with information from the datasheet of the device, but no datasheet is available, due to OP's purchasing decisions. – Marcus Müller Jun 24 '19 at 21:20

I was wondering if an outrunner brushless motor with a belt to a larger gear would be effective

No, a single gearing would not be sufficient. You'd really need either multiple levels of gear reduction, a worm gear drive, or a different type of motor.

The motor you're looking at is specified with a nominal speed of 6000 RPM.

Most wheelchairs have wheels with a diameter of 24 inches (61 cm). To move at a reasonably fast speed of 5 mph (8 kph, 2.2 m/s), the wheels would need to rotate at ~70 RPM. (This is probably too fast for a wheelchair, but setting a lower top speed would make the analysis come out even worse.)

For a 6000 RPM motor to drive a wheel at 70 RPM, you'd need a gear ratio of roughly 85:1 -- e.g. if the large gear were the same size as the wheelchair's wheel, the small gear would be about a quarter of an inch (~7 mm) across. This is smaller than the drive shaft of the motor -- it's not clear that a gear (or pulley) this small would even be mechanically sound, let alone that it could transmit enough torque to drive a wheelchair.

Note that what I haven't analyzed here is whether this motor can even provide enough torque to move a wheelchair. This is because there are no torque specifications available for the motor you're looking at.

• 24 kilometers per hour? Holy moly! It must be no more than 2.4 kilometers per hour or you can't control the damn thing. (In wheelchair sports, they use a model specifically designed for higher speeds up to roughly 10 kilometers per hour. Faster at your own risk.) – Janka Jun 24 '19 at 21:37
• @Janka Make sure to augment the handling and suspension when you increase your wheelchair nominal speed to 24km/h so you can make it around corners. – DKNguyen Jun 24 '19 at 21:51
• @Janka LOL, fair point -- I suppose this is a wheelchair, not an electric scooter. I've dropped the target speed to 5 mph, which shrinks the drive gear to a clearly unreasonable diameter of 7mm. – duskwuff -inactive- Jun 24 '19 at 21:55
• The most important part you need for any kind of motorized wheelchair are rear wheels. At least as "training wheels". Skipping those is a recipe for disaster. – Janka Jun 24 '19 at 22:16
• A diameter of 24 inches? That seems smaller than most wheelchairs I've seen, though perhaps power wheelchairs use smaller wheels. – Hearth Jun 24 '19 at 23:38

The published specifications seem to be:

Brushless Outrunner Motor Power N5065 270KV 1450W for DIY Electric Skate Board Bicycle Scooter

1.Max Efficiency Current: 80A

2.Motor Dimensions: Φ50 x 65mm

3.Shaft Diameter: Φ8mm The shaft length: 20mm

4.Rotational Speed: 270 (kv) 6000RPM/V

5.Electric Skate Board Vehicles Remote Control Toys Manned bicycle

1450 W / 80 A = 18.1 V

270 X 18.1 = 4890 RPM

Torque = 1450 X 9.549 / 4890 = 2.83 Nm

The maximum efficiency point may or may not be the rating for continuous operation. It appears that the motor has sufficient power to drive a wheelchair including an allowance for substantial losses in an appropriate speed reduction gear. A 1450 W motor will likely need to dissipate 150 to 200 watts of losses. To dissipate that power and avoid overheating the motor is likely needs the air flow generated by a propellor.

The motor is called an out-runner, but the picture of the motor mounted on a skateboard seems to show an in-runner. The details also show a shaft.