Dual front wheel drive

[DanCooper]

I am an engineer and from seeing the photos, there are two motors, one driving each front wheel. Each motor has its own gearbox with a fixed gear ratio to match the motor RPM to the wheel RPM for best motor efficiency and power output.

[Rickb]

Like I said what do I know! Thanks Dan, good to know. Makes better sense coming from an engineer.

[paravil]

Thanks Dan ... as a down payment client, I expected the same info to have come from the company. Just out of interest, if the motors are not in the wheel hubs, but are placed towards the centre, wouldn´t it have been logical to just have one, larger electric motor with one gear box?

I understand why hub motors are not the ideal solution, as they are unsprung weight.

[DanCooper]

Arcimoto is doing it exactly right. Motors in wheel hubs are unsprung weight, and negatively affect handling. Besides, the SRK uses standard car wheels - saves cost and complexity and makes it a lot easier to fix tires. Two motors don't cost much more than one motor twice as large. One motor would require a more complex gearbox and differential. Two motors allow independent control of the wheel speeds, which can help stability and traction.

[paravil]

.... but needs to be regulated, so that the inner wheel in a turn compensates for a higher speed outer wheel. So I´d suppose that some form of differentiual is needed.

I still expect Arcimoto to inform customers of important technical details (there is no `Technical Specificatiuons´ information on the SRK on their web site. All I can find is that it has an `independent dual-motor front-wheeled drive system´, and if I remember correctly wheel hub drive was mentioned somewhere at an earlier date.

[DanCooper]

"The differential function happens in software, based on the reading of the steering angle sensor." - Arcimoto

This was posted earlier in this thread. What this means is that if one wheel slips, it will not spin like it would with a differential. If the vehicle skids, the relative wheel speeds will tend to make it follow the steering input. This is why I would expect better traction, stability, and controllability with this system than with a conventional system.

[Rickb]

.... but needs to be regulated, so that the inner wheel in a turn compensates for a higher speed outer wheel. So I´d suppose that some form of differentiual is needed.

I still expect Arcimoto to inform customers of important technical details (there is no `Technical Specificatiuons´ information on the SRK on their web site. All I can find is that it has an  `independent dual-motor front-wheeled drive system´, and if I remember correctly wheel hub drive was mentioned somewhere at an earlier date.

I've followed one concept that mentioned hub motors and that was Lit Motors in the C-1.  

We will no doubt see the SRK's finalized specs sometime after they have been finalized in the Signature Series Builds.   Specs changed dramatically from the Gen 8 to the ETC Build........leading up to the Signature Series builds.  There may be minor tweaks in specs after the Signature Series daily use road testing miles leading up to the Production Series.

[Eric Fritz]

Hi guys!

Sounds like you've got it figured out. Two motors, independently powering the two front wheels.


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As for posting relevant technical details on the site, we will of course do so as they become locked in for production.

[Kepesk]

Oh I get it! One gear box, but it has identical gears on both sides, one set for each motor! Actually that's pretty cool.

That makes way more sense after taking another look at the video too.

[Rickb]

Welcome Eric!  Thanks for posting the photo.