Lego PF Accelerator Module

[cgg199]

I'm in the process of building a MOC car, which I want to have as many features as possible. I know that Sheepo has made a way of his Supercar 2011 accelerating more like a real car. I would also like to do this, and have half of an idea how to.

Using the rechargeable battery box, and the cars drive motors, it would be possible to gradually change the settings of the power controller, to slower deliver more power to the motors. The only two problems I have are; It would need a way of stopping when maximum power was reached, otherwise parts would get damaged. The other is returning to 0 power once the accelerator is not being pressed. Does anyone have a solution?

[Alasdair Ryan]

What about a gearbox?

[cgg199]

I'm having that too, but in a normal car, you don't press the accelerator and suddenly go the top speed in that gear. I want the car to start off slowly, and accelerate up to the speed.

Edited June 22, 2013 by cgg199

[Junpei]

So let me get this straight. You are using a geared down m-motor to slowly turn the speed dial on the rechargeable battery to slowly accelerate. If that is the case it will look really cool because when the m-motor makes the battery box output give more power and the motor is connected to the battery the motor that is turning the speed dial will slowly increase its own speed making the speed dial move faster and eventually get to the highest setting very realistically. If you are worried about damaging the parts, you can use a 24t clutch gear or this gear block to gear it down and slip when the torque on it is maxed out however if you do not want a horrendous loud clicking noise like from LA's from the gear block's clutch you need to use a 24t clutch gear as they are not very loud, but I think unless the output of the gear block has an 8t gear powering the 24t clutch gear the gear block will slip first. However the gear block has a very large gear reduction (20x) and I do not know which speed you want, you can always figure it out by measuring the rpm of the motor and using Sariel's gear ratio calculator. I am not sure what you can do from preventing the motor from running after the speed dial has finished turning though, it seems like it would just be a waste of power without a mechanism to stop it. If you put a 3l axle in the speed dial, put the driving gear in the middle, and put an engine crankshaft center on the end you could make a linkage to a pf switch connected to only the motor used for moving the speed dial with a 1x2 liftarm with axle and pin hole and a beam to link the cranks. That .5 stud to 1 stud linkage will give you a 45 degree angle with the pf switch therefore turning the motor off and effectively not wasting power at all. So never mind I think that will work, ignore that one sentence. Sorry for the long post and run on sentences, hope this helps.

[cgg199]

Thanks for the help, I'll take all of that on board.

Now the only problem is returning it to the neutral position when no power is being given.

[KopMaister]

well... you could take the short route and use the 8879 speed controller.

or connect a servo motor to the rechargable battery box and use a 8879 speed controller to regulate the servo motor :P

kinda unnessesary tho.....

[cgg199]

That wouldn't really be an option, but thanks anyway.

[Alasdair Ryan]

I only way I can think of doing it,is by using another battery box (you could use a old 9v battery) which is connected to a motor that controls the rechargeable battery box's speed out-put.

[cgg199]

What I mean is, the battery boxes power adjuster would be controlled by the same motor that drives the car, but would be geared down. Then, to stop it from damaging the battery box, I would have a 24 tooth clutch gear in between the motor and the battery box. Now that all of that has been solved, I just need to think of a way to return the power adjuster back to zero.