Slowing down a power functions m motor

[danim]

Hi

I am not sure if this is in the correct area but how would you go about slowing down one of the power functions m motor

thanks in advance

[lightningtiger]

'Damin' there are two ways you can do this apart from using IR controls which are pricey.

1. Mechanical - effort gear much larger than the idler and load gear, you'll need an idler to keep the gears turning in the direction you want.

2. Electrical - reducing the voltage, but not losing current supply ability. An electronic voltage regulator which has variable voltage settings, you want to reduce speed not lose torque. Speed is dependent on voltage, torque is dependent on current, gee it's handy to be a electronics tech who watches Discovery Channel and National Geographic Channel isn't.

[danim]

I would like to use gears but I am not sure what gears I should use to slow it down as it is for a working lift in a police station

P.S it does help to be a techie, I am currently doing a degree in embedded systems (also I love the discovery channel)

Edited December 10, 2009 by danim

[soc399]

The mechanical method that lightningtiger mentioned will probably be the simplest, since Lego doesn't make a PF voltage regulator. Basically, have the M motor connected to a small gear that drives a larger gear. The greater the difference between the small gear and the large, the slower the speed of the large gear will be.

EDIT: Have you thought about using a linear actuator? I don't have any, but I think they extend and retract when connected to an M motor. They are a bit pricey but contain a built in clutch, which you will need with something like a lift that has to stop at the top and bottom

Edited December 10, 2009 by soc399

[danim]

I now have a much slower large gear but once I connect it to the lift the string that holds the lift pulls the gear of the bricks that hold it on, does anyone have any ideas

[Milan]

I now have a much slower large gear but once I connect it to the lift the string that holds the lift pulls the gear of the bricks that hold it on, does anyone have any ideas

It is a common problem with motors and the devices that they are powering, when torque is to great, it will brake apart the structure of the MOC, so you have to...

Brace it.

Can you post a small picture of motor and lift assembly? How is string connected to the lift?

[Big Cam]

The mechanical method that lightningtiger mentioned will probably be the simplest, since Lego doesn't make a PF voltage regulator. Basically, have the M motor connected to a small gear that drives a larger gear. The greater the difference between the small gear and the large, the slower the speed of the large gear will be.

EDIT: Have you thought about using a linear actuator? I don't have any, but I think they extend and retract when connected to an M motor. They are a bit pricey but contain a built in clutch, which you will need with something like a lift that has to stop at the top and bottom

That's what I was going to say, if you can constantly control the voltage, it's as good as having a speed control switch. Just don't ever go over the recomended voltage or you'll likely fry the circuit.

[danim]

I want to use gears and the motor

here is the connection to the lift

and here is the gearing

the two gears together on the same axle will be replaced with the thing that the string connects to on lego sets

Edited December 11, 2009 by danim

[Davey]

So far, your gearing looks pretty good. Although I don't understand what the second large gear (on the right) is doing. To further slow the motor down, you could look at picking up the 8878 Power Functions Rechargeable Battery Box. If you look at the picture below, you will see the orange rotary dial in the middle of the battery box. That controls the voltage and will help you really slow down that motor. The downside is that you will lose power as well, but you aren't lifting much so I can't imagine it would be an issue.

Good luck!

-Dave

Edited December 11, 2009 by Cyclone Breezerider

[Milan]

I wouldn't suggest him to use that battery box, simply because it cost 45 up to 60usd!!!

For a town guy, not so good, as he can get lots of other stuff for that money.

I have two of that battery boxes, and it works perfect, but I am using it constantly...

If he does buy it, and use it to decrease the speed, torque will remain the same 3.63 N.cm.

Power will slightly decrease, but for the lift it is sufficient!

Danim, based on your pictures that piece that string attaches to, is very weak. use more robust system, like building a brick support directly on your current setup, or use technic brick, tie string to its hole, and brace that technic brick to the lift even more...

Edited December 11, 2009 by Milan

[JohnnyPopper]

having the same problem in technic with 2 worm gears but my dad just told me it wouldent work so ive figured out i have to use a bigger gear