Push-pull apparatus

Hello guys!
Nice to meet you here: this is my first post! :slight_smile:

I’m new with Arduino and I don’t know all kind of available mechanical stuff it can drive…

I’m looking for a simple, yet small, mechanism with just 1 DOF that pushes and/or pulls a lever.
I’d like to drive it with a simple PWM signal.
It should be a low voltage/low power motor I can plug directly to the 5V pin in Arduino.

At the begin I thought to a servo motor but I find only rotative engine.
At the moment the only think I find useful is a couple of coils with iron core I find in an electric lock…

Is there something more “comfortable” to be used for this purpose?

Thank in advance for your help!

Coil-Lock.jpg

I think you may be thinking of a Solenoid. They are spring loaded for 1 direction, and electrically controlled the other direction. They can not be powered from Arduino 5V pin, most solenoids/motors/servos need more current than the 5v regulator can supply. You would not drive it with PWM tho - it is either on, or off.

CrossRoads, thanks for your quick reply!

Mmmh, I was quite aware that the solution would need more power: ok I'll supply the needed voltage (and current). A solenoid would work (it was the first solution I found), simply I wonder if there is a device ready to use out-of-the-box. In case I have to built it by myself: do you have any suggestion?

What are you trying to push/pull to know what force is needed to move it. What stroke length must the device deliver (for far must it travel back and forward) How fast must it move. You can use a servo motor with a linkage arm to deliver linear movement.

The lock actuators from car doors are pretty good at pushing a lever. Travel is usually 25mm.

I would add to Riva's list "How often?" A car door lock actuator will overheat if it has to operate more than a dozen times per minute.

Thanks to all for the suggestions! This is the scenario: I have to push a small plastic lever inside a turntable (do you remember vinyl? :-) ) in order to remotely command start and stop. The room inside the chassis of the turntable is little, so I need a small device. The lever is very thin and easy to move: it is directly connected to the START/STOP push button in the front panel. The lever commands the arm in order for it to move on the disc. The problem is that all the system is servo assisted but the start and stop commands rely on this mechanics...

In my opinion a solenoid will do the job: I have only to find the right one... in the meanwhile, I think I'll try with a servo motor: I have to find the right way to arrange it inside the turntable...

FOUND! May this do the job: http://www.amazon.co.uk/Motors-Actuators-ROB-11015-Solenoid-small/dp/B007XEY570

  1. What travel do you need in mm?
  2. What peak force is required to push?
  3. What peak force does it need to pull?
  4. How fast does it have to complete the motion.

Most solenoids can be configured to push or pull but not both BTW.

@MarkT: I don’t know how to measure the peak force I need… I’ll follow the old try and error method. On the other hand it is not a problem of speed or direction of the movement: I can position the solenoid to pull or push as it works best.
Once I finish the tests I’ll publish the results - and some picture!
Stay tuned! :slight_smile:

You can bias a solenoid with a spring so that the spring works one way and the
coil the other. However that means the solenoid will have to be working hard
all the time it is operating, normally causing overheating (solenoids are typically
rated for intermittent operation). Again how fast does the motion have to be, how
many mm of travel, some idea of the force (compare it to something) would be useful,
otherwise I wouldn’t have askeed.