Elvisnake's Lego Technic Offroad Shark RC Trophy Truck

[DLuders]

On SeTechnic, Elvisnake recently posted his Lego Technic Offroad Shark RC vehicle. In the original French (and in this English translation), he wrote:

"It is based on...the modified frame of Baja Truck of Nico71." It uses two Lego RC Buggy motors coupled to a Lego Power Functions XL motor with a differential. It does "drifting" well on a tiled floor -- see this

:

There are 9 pictures on is Brickshelf gallery. "Here the detail of the transmission:"

Edited February 11, 2012 by DLuders

[Sariel]

That black hand scares me.

It's a very nice MOC, but I wonder if with XL motor added to the RC unit's output any of the motors in the truck is actually running at full power.

[timslegos]

What is the purpose of the xl motor? I am a bit confused. And where is the blue line connected to?

tim

[jorgeopesi]

Blue line steering?, XL decreases RC motors speed???

[sama]

I think the guy was just trying to get some extra power to the wheels. I would have just left it with two buggy motors geared down to 1:1.66 or 1:3, depending which is better suited for the intended job.

[BobBongo1895]

The truck itself looks good and got a got speed and suspension, but the steering should be fixed.

The steering radius looks like 10 feet or so.

And Sariel is right, the black hand is disturbing.

[T_Tank]

I think because the motors are connected via differential the XL motor runs the grunt of the low speed while the buggy motors take over for the higher speed, Just looking at the design I can understand it similar to a low speed an high speed turbo one is tuned to work better for the lower rpm while the other kicks in more for when your at the max top speed of the slower one....if that makes sence

[Bulle]

Think he decided to have it for weight distribution. the front would have been to light without the xl motor maybe..

[Finntech]

Cool MOC, but I'm wondering how long the batteries will last with 2 buggy + 1 XL-motor... However in the video it runs great!

[timslegos]

Where does the blue line connect to? Sorry i do not have that rc unit so i dont know what is on it. Si ther an axle hole in the front for steering ?

tim

[DLuders]

@ timr: The 8475 RC Race Buggy set was one of several that used the RC steering module, shown below in the 8475 Building Instructions. In that set, the 6272c01 "Black Electric, RC Race Buggy Battery / Receiver Unit with Auxiliary Output" mates up to the 6282 "Electric, RC Race Buggy Steering Unit":

Edited February 12, 2012 by DLuders

[timslegos]

Okay that makes more sense. thank you

tim

[T_Tank]

I wish I had a spare XL motor to test my theory with the differential being connected to the rc motor an XL. I'm thinking that its somehow keeps the RC motors from stalling at low speed an thats where the XL motor kicks in an once the vehicle gets up to speed faster then the xl motor can handle is when the diff starts directing power from the rc motors so it could speed up an since there is a diff between the motors the xl motor won't mechanically slow down the rc motor.