Need to pull item against a spring, fast. 3 times a second fast

Discussion in 'The Projects Forum' started by swatti, Dec 25, 2015.

  1. swatti

    Thread Starter New Member

    Dec 25, 2015
    Hi, im new and sorry for my bad english, i kinda lack the specifig "terms" needed...

    I have a mechanical "gearbox" with a certain part in it, "spring-loaded" and moved by gears. I want to move this part via electricity and not the gears.

    Here is the part:

    Its the black plastic "plate" there with the spring below it. It moves maybe 3-5 cm backwards.

    Here it is, moved at the far back where it needs to go. Other components will stop its movement, the spring will pull it back.

    What i need, is SOMETHING to able to pull against that spring, aprox three to four times a second. The spring is quite strong for its size, about two to three times as powerfull as pencil spring. I maybe able find a slightly less stiff spring for this aplication.
    This device would be mounted OUTSIDE the gearbox and it has multiple potential locations depending on its size. Width should not be much more then the coin in the picture, more will cause problems, length is a lesser issue.
    I can use for example, use piano-wire to attach the device to the plastic part, there are options. Leave that to me.

    What i have:
    Lipo-battery power, 3-4 cell lipo, 11.1-14.8 volts - Comparable to RC car batteries, should have enough juice to run most things.
    CONTROLL CIRCUIT. The important part! I have a friend whos able to make and program a circuit to move the device, but sadly neighter of us know what to buy as the device to move that part. We have a circuit controlling the gearbox, it has room to add thigns to it.
  2. swatti

    Thread Starter New Member

    Dec 25, 2015
    Cant edit posts?

    Googling things, i believe the device i need a "linear solenoid" - Preferrably one what has a hole all the way thru it so i could pull the piano-wire thru it and mount the device itself against the back of the pictured gearbox.
  3. sailorjoe

    Active Member

    Jun 4, 2013
    Yes, swatti, you need a linear solenoid. It needs to have enough power to pull the spring all the way back. You'll need to measure the force required to pull the spring all the way back. You can do that with a spring type scale, like used to measure fish or food.,k:spring scales&tag=duckduckgo-osx-20
    Then find a solenoid that has at least 20% more force available for pulling.
    I like your idea of piano wire hook up. The solenoid won't be as narrow as the coin, so it will have to go outside the mechanism. Run the piano wire to the end of the moving rod on the solenoid, and connect it mechanically. Other end of the wire goes to the spring, or the lever, as you choose.
    Your friend will be able to make a switched power source for the solenoid, and you'll be in business.
  4. swatti

    Thread Starter New Member

    Dec 25, 2015
    Measured things: Movement needed, ONLY 10mm. I overshoot that estimate a bit earlier. Once all parts are in, only 10mm is needed.

    I pushed down the fully assembled setup to a scale and it was 2.2g kilos when the part reached it furthest point, as in where it needed to go.

    Now, link me something that will do the trick.