TAV2 COMET Bidirectional rotation?

[genlokked]

Hello,

I'm building an electric ATV and currently making my specs list.

Since I never had a CVT, especially a TAV2 in my hands, I can't tell if it can spin both ways or if they are intended for one rotational direction only.

The reason why I ask is simple. The electric motor spins both ways, so if I want to drive in reverse, I can do it electronically, instead of mechanically.

Since I intend to use a CVT, I wonder if it is possible for it to do its job in both directions, or if I need a gearbox.

Thanks

 

[mckutzy]

As far as I know... You won't need the TC as the controler will be the "cvt"...
Also, afaik all electric drives are directly gear(an actual geared ratio , or chain drive).

But this is a project that needs alot of money... If on a budget or wanting to do the cheapest possible way... You'll be better off going gas engine...

 

[KartFab]

My opinion is that the drive unit would work in either direction.

The driven unit, however, is held by a compression spring that forces the cam/wear tab to stick together. This is directional. If you were to make it spin the opposite direction it the cam and wear button may not contact each-other and it may force the spring to go twice as far 'backward' is it is intended to go.

Im not saying that it wont work, but it will not work as it is intended and may cause the spring to warp or fail. Just my opinion.

 

[anickode]

There is also no need to use a torque converter with an electric motor.

Electric motors, unlike engines, can deliver their full torque through the full rpm range. Torque converter are designed to allow an engine to operate in its power band even at lower speeds

 

[itsid]

yeah... not really..

Instead electric motors have their maximum torque near stall speeds (close to zero rpm)
and it drops off from there (slightly but noteworthy)

Either way, a TC makes no sense, since highest torque is already at lowest speed
(unlike with a gas engine, where highest torque is somewher mid rpm)
and the TC transforms rotational speed in torque when needed.

What might make sense would be a ratio reversed TC (which is not in existence)
that instead of a 270% reduction and a 10% advantage,
would provide you with a 10% reduction and a 270% advantage
(yeah that'd be extreme and unlikely usefull but you get the idea)

But there is no such thing that I know of at least.

So, w/o any TC is still the way to go.
Adding a reverse gearbox is utterly pointless, since a proper controller can reverse the motor direction.

with an ATV however you might need a rather large motorpower
("all terrain" to me always sounds like nasty sinks and rocks to climb)
So be prepared to carry a lot of batteries (dead weight)

'sid

 

[genlokked]

Thank you for the input.

My plan so far, was a chinese bldc 3kw, 5.5Nm. Since it is chinese watt, i dont really know what i will get. My intention was enough torque, for slow driving with high inclination but not totally sacrificing a decent top speed on flat terrain.

TC seemed to enable both worlds.

Is there anybody having experience with 3kw chinese my1020 lookalike?

General Data:

Kart weight with human payload. 160kg
wheel diameter 420mm
3kw, 5.5nm, 5800 rpm
LiPo 25Ah @60v

intended gear ratio 17:1
Intended top speed: 30km/h

Greetings

 

[anickode]

Another consideration with torque converters is the 20% inefficiency. On an engine that can't make much torque at low rpms, the torque converter makes up more than it loses until you've accelerated above the power band. Engines are also easy to upgrade to negate some of the loss.

Motors on the other hand, are what they are. Short of over-volting your motor (which is a pretty terrible idea), there's not really any way to make up that power loss.

 

[itsid]

General Data:

Kart weight with human payload. 160kg
wheel diameter 420cm
3kw, 5.5nm, 5800 rpm
LiPo 25Ah @60v

intended gear ratio 17:1
Intended top speed: 30km/h

Greetings

420cm wheel diameter??
4.2 meters? 9 foot 4 inches?

No I think you have a mistake there

'sid