Recumbent Trike with trailer & two hub motors

[recumbent]

Has anyone tried two front hub motors on a tadpole's steered wheels?

The problem is with the hub motor mounted to a stub axle. Although I've seen on solarbbq.com has a smaller geared hub motor which has a two piece axle that might be machined to fit.

 

[Freddyflatfoot]

Hmm, two hub motors on the front! Interesting concept. would work on my trike, coz, I have wheel stirrups.
However, I'm not that flush. I have got a small hub motor that is going on the back. Should be very stealth, especially with the panniers!
Rob

 

[cerewa]

Are you saying that there is something intrinsic to electric motors that will control this phenomenon without the need of additional hardware/software?

no, it's intrinsic to having separate motors and not having a single, solid axle.

I know that if you put a wheel on the front and back of a bike - in line - there is definitely no problem.

not exactly true. If you ride your bike in mud/snow and take a sharp right turn, you will see that the front wheel has left a track further to the left than the rear wheel... the rear wheel has taken a shorter path and traveled fewer inches in the same time. This is not a problem for a bicycle because there is no mechanism forcing the front wheel to turn at the same rate as the rear wheel.

If the wheels were both mechanically linked and non-freewheeling then you would have a problem. This is why automobiles with four wheels driven by one motor actually have to have a differential for the front wheels, another for the rear wheels, and a third differential to allow the (front wheel average speed) to be different from the (rear wheel average speed). That is how cars like the all-wheel-drive dodge caravan are designed. As far as I know the Honda CRV, also all-wheel-drive, uses a freewheel mechanism instead: going forward around a turn, the front wheels have to move forward further than the rear wheels. Unless the rear wheels lose traction, the front wheels will freewheel. If the rear wheels do lose traction the front freewheel mechanisms force the front wheels to turn.

In reverse, the rear wheels provide the power. The engine power is not transmitted to the front wheels, just like the pedal power is not transmitted to the rear wheel of a bike if you try to pedal backwards to reverse.

If you built a 4 wheel drive car with four gasoline engines, one for each wheel, then you would not need a differential. (people don't bother trying this, because they would have to attach a clutch and a multi-speed transmission to each gas engine... things an electric motor doesn't need.)

 

[Rassy]

Okay, I like fechter's (oops, where did it go?) "One test is worth a thousand opinions". So somebody down under should loan Freddyflatfoot a couple of matched hub motors (big ones with high voltage and high amp controllers, since he will be way over the legal limit with two motors anyway). Then he can run some tests and settle this discussion. And while he has these motors installed he can install some flashing lights and stop some speeding SUV's! I think the trike would go where it is pointed with no negative steering characteristics, except when going straight, if the motors were not really well matched there might be a slight pull to one side. Even one of my first Honda cars, a 1980 model, would pull to one side during heavy acceleration coming out of a sharp corner.

Edit: Now I see it. Apparently the sign-off info is not displayed while entering a post.

 

[Freddyflatfoot]

Any takers?
Actually, I don't think it would be an issue with the steering, as both motors are not mechanically linked. Just reckon the 'inside' motor in a turn might draw higher amps, as it will be loaded up a bit more.
Only problem I can see, is that the trike would then be front wheel drive, and I think that requires different steering geometry.

 

[fechter]

I think it would handle well. If you're running two controllers off a single throttle, it would be easy enough to add a "trim pot" to equalize the motors and compensate for any pull.

 

[Freddyflatfoot]

Hmmm, two rear motors anyone/
Check this one out!
http://cyclesantamonica.blogspot.com/2007/11/wike-wicycle.html

 

[Ben]

That's cool, but doesn't 4 wheels make it illegal to ride on the road or bicycle paths?

 

[Freddyflatfoot]

Yer, I thought that too!
Just looking at the concept! Ya know, more than one motor?

 

[docnjoj]

The only problem I see for the HD Sun Trike is the push/pull rod. I will be using a pulley and steel plastic coated cables to make the right side pull cable. It will definitlely make the steering more neutral! Otherwise it looks like a winner for 15 to 20 mph!
otherDoc