Shopping at LEGO or Amazon?
Please use our links: LEGO.comAmazon
As an Amazon Associate we earn from qualifying purchases.

Power functions help!

Hey, everyone! I recently purchased the Power Functions set #8293 and have a question. What is the large white gear used for in the set? It appears to have a bushing in the center that turns independently from the gear itself. Does the motor have that much torque? Anyway, any help is greatly appreciated.


  • plasmodiumplasmodium Member Posts: 1,956
    I don't have that exact set, but I did used to have an older version which had that same gear. According to the little pictograms in the instructions, it was a sort of 'safety gear' to stop the motor from damaging itself if whatever mechanism you had built got jammed.
  • scarecrow2400scarecrow2400 Member Posts: 99
    Thanks! I was thinking that was it. I just didn't realize the motor could have that much power.
  • rancorbaitrancorbait Member Posts: 1,842
    ^ They don't have a lot of power, but still enough to wreck themselves.
  • TheLoneTensorTheLoneTensor Member Posts: 3,937
    With a title like that! I was expecting a much greater problem than a simple gear identification.
  • graphitegraphite Member Posts: 3,275
    I believe it is titled a clutch gear. It does keep the motor from fighting something that won't move anymore. Also useful in designs where you want something to move till it hits something and stops and keeps the motor turning (although with some clicking that doesn't always sound good but is fine) allowing you to stop the motor or reverse directions.
  • ShibShib Member Posts: 5,459
    On the subject of power functions I'm thinking of starting to get together bits and pieces for a Lego train set for when we have the room - currently saving to buy a house which I've been told I'm allowed to convert the attic to a Lego room.
    I think I'd quite like to have more of an imaginative train set rather than a basic city one, but definitely want power function. After having had a quick look it seems that only the City ones tend to really come with power functions.
    What sets/bits and pieces would people recommend me looking out for?

    I'm in no hurry to get these as I won't have room for it for about a year or two but think it might be wise to start putting bits away for it.
    Also if anyone has any pics or videos of their own Lego train sets (particularly MOCs or modded from non power function sets) I'd love to see them for a bit of inspiration!
  • TheLoneTensorTheLoneTensor Member Posts: 3,937
    You could start with buying a City train set for the PF "guts," because they come with everything you need to run a train (except for maybe lights - depending on the set). Then, modify it to whatever you want. Even if you don't have room for the layout yet, you can still begin modifying the engine/cars to your liking.
  • ShibShib Member Posts: 5,459
    That's what I was thinking, unfortunately I don't think I've ever seen a set to really look at in store so hoping for some advice on what set might give a good staring point to give me the basic workings and a little bit of track.
  • scarecrow2400scarecrow2400 Member Posts: 99
    Last years cargo train came with power functions and track.
  • TheLoneTensorTheLoneTensor Member Posts: 3,937
    edited March 2014
    #7939 is a good start. As for seeing in-store, are you talking about the box or the set out and running? The box can be seen in most TRUs. As for a functioning train, you'll have to go to an event of some sort to get a real feel for how PF works. If you go to a model train show, chances are you'll find a local Lego train group displaying stuff, and from my experience, those guys love to talk about their craft.

    Nevertheless, here's a PF primer:
    • You have a battery box, either AA or rechargeable. The rechargeable is WAY more expensive, but imho, totally worth it
    • The IR module connects to the battery box
    • The IR module has red and blue connections on it, which correspond to the left and right side of the handheld speed remote (the one that looks like a gamepad with two dials on it). The red dial controls things connected to the red connect, likewise for the blue.
    • You connect a motor to one of the IR connections, let's say the red one
    • Turn on the battery, and now when you spin the red dial one way, it'll run the motor in one direction incrementally for every indent, up to max speed (7 I think)
    • Spin the red dial back the other way and the speed will decrease, eventually to 0
    • Keep spinning in the reverse way and the motor will run in reverse, up to speed 7, repeat
    • You can connect lights to the IR's blue connection and now the blue dial will control that (it'll actually start out dim and brighten as you select more "speed")
    • The speed remote lets you reverse the polarity of each dial
    • The speed remote has emergency red stop switches for each dial
    Other things:

    Jumper wires - to extend or split the power for running more lights/motors
    Switches - to manually control power flowing to different branches from the battery
    Motors - Other than the basic train truck motor housing, there are 3 different sizes to be used, plus a servo (useful for advanced stuff)

    Things can get pretty advanced, but the biggest pain is making room for the equipment and routing those wires around in train engines/cars.
  • oldtodd33oldtodd33 Member Posts: 2,683
    edited March 2014
    ^ The power functions trains all take AAA batteries, not AA. Three for the controller and 6 for the battery box.
  • DublinBay15DublinBay15 Member Posts: 7
    I run my High Speed Train with 2 lego engines. One has the old engine with metal wheels and an electric track, the other runs off a battery box (I have it plugged into the first engine through a short lego power cord, since they both have the 2x2 block power connectors, so my plastic engine runs off the power from the first one) It is able to climb hills that i build and it retains more balance around the corners since there is more weight by the track. However, i don't know where you are able to purchase these things
  • ShibShib Member Posts: 5,459
    Think it'd be quite a while to get to the point of looking for a dual engine but interesting. Thanks for the advise so far guys. Would love to see pictures/videos of what people have got set up, seen some interesting conversions on youtube.
  • PaperballparkPaperballpark Member Posts: 4,260
    Can anyone tell me what the length is (in studs) of the Power Functions M-Motor (#8883), L-Motor (#88003), and XL-Motor (#8882)?

  • ColoradoBricksColoradoBricks Member Posts: 1,659
    @Paperballpark, #8883 and #8882 are 6 in length, #88003 is 7.
  • PaperballparkPaperballpark Member Posts: 4,260
    Thanks! I was kinda hoping one would be 5 in length. Oh well.
  • ColoradoBricksColoradoBricks Member Posts: 1,659
    You want to look at this 9V motor, it is 5 studs long, and can be bought at a reasonable price on BrickLink.

    Philo's page is a great reference for motors and their power/torque/weight, etc
  • PaperballparkPaperballpark Member Posts: 4,260
    Thanks. Not sure it would work with PF though! I can cope with 6 long. Just. Probably!
Sign In or Register to comment.

Shopping at or Amazon?

Please use our links: Amazon

Recent discussions Categories Privacy Policy

Howdy, Stranger!

It looks like you're new here. Sign in or register to get started. is a participant in the Amazon Services LLC Associates Program, the, Inc. Associates Program and the Amazon EU Associates Programme, which are affiliate advertising programs designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.

As an Amazon Associate we earn from qualifying purchases.