Question about partial piston stroke
 

My team wants to make a partial stroke.
What I mean is the following:
A joystick button is pressed-->piston starts to open
Another joystick button is pressed while pitons opens-->piston stops.

How do we do that?

We have tried to put another single solenoid after the main double solenoid.
It partly worked: when we pressed the second button, the piston stopped, but then started to come back slowly.

We are trying to do this to prevent the smack of the piston on the robot (it raises an arm).

Re: Question about partial piston stroke
 

I think that you must to use a special valve to regulate the flow pressure!!!!

Re: Question about partial piston stroke
 

Cause the control of the solenoid is made with spike, and spike unfortunately haven't break condition as Victor :(

But, if you can control the flow pressure, you can stop you piston in any position...

Re: Question about partial piston stroke
 

The pneumatic cylinders we use (please don't call them pistons) are designed to be fully open or fully closed. It is possible to stop one mid-stroke but it's not very easy.

It would make a great off-season project but I wouldn't attempt it this far into the build season.

If you are worried about speed you can use the flow control valves.

If you want to achieve multi-stroke just put two cylinders together.

Good luck.

Re: Question about partial piston stroke
 

There is no way to control the position of a pneumatic cylinder without mechanical stops. Once air enters the cylinder, the piston will move based on the air pressure and the force it is trying to move. If it can overcome the force it is trying to move, it will move until it comes to the end of it's travel (a mechanical stop inside the cylinder). You can control the speed at which the cylinder is moved by using flow control valves at the ports of the cylinder. There is a tradeoff in the time it takes to travel.

Re: Question about partial piston stroke
 

You can use a double solenoid valve with a spring return center off position to stop a piston in mid stroke. You can get vavles from SMC that look nearly identical to the double solenoid valves we recieved in the kit but are about 1 cm longer that will accomplish what you want.

Re: Question about partial piston stroke
 

Hey...

I don't know if allowed to use Norgren valves on robots, but, they have some Proportional Valves...

I think that theses valves can satisfy your case!!!!

Re: Question about partial piston stroke
 

You want an smc SY3340-6H, which is a three position, close center valve. The one in the KOP is a two position, so it won't stop in the middle. Warning: when a cylinder stops halfway, it will be "spongy" because its air holding it. If its a light load, it might be OK. Be forewarned, when it drops, it will drop quickly for a small amount until the air is compressed on the drop side.

Re: Question about partial piston stroke
 

You can send the vent from the first valve to another valve. The first controls direction and the second is stop/go. There are some nuances to this method but and old team I was on used it with moderate success.

Re: Question about partial piston stroke
 

Do you mean the regulator? I tried to put down the pressure so it'll move slower, but no success.. It just didn't move because it didn't have enough force.

Re: Question about partial piston stroke
 

This is the flow control fitting that comes with the kit. You use it instead of the standard fitting. The little white knob controls how fast the air fills the cylinder giving you control of the speed but it will still deliver the full 60psi.