Andy Mark Supershifter with Pneumatic shifters

[jspatz1]

Originally Posted by Coffeeism

Well for a 20PSI 1/2 inch cylinder you would get about 4.5 lbs. Here's a random solenoid close to spec that is about 2.2 lb push, 6.6 lb pull. Could probably alter the spring to even out the force?

This solenoid is one-directional, push only. The spring return is only minimal to return the armature to the retracted position when de-energized. It is also intermitant duty, which means it can be energized no more than 50% of the time without overheating. A shifting actuator must maintain force in either direction at all times. This is one reason an air cylinder is well suited to the job. A continuous duty solenoid of this same wattage would have about 1/3 the force.

[jspatz1]

Originally Posted by Ravage457

What diameter pin should I use after I had drilled it out?

Hmmmm....I think the solenoid shifter is my next project, thank you for the input and advice

What teams had used this solenoid set up?

3/32.

As I mentioned this is the first year solenoid actuators have even been permitted on a FRC robot, so there is no history of them being used for shifting that I know of. If someone successfully did this in 2012 I would be curious to hear about it.

[Ravage457]

Yes i agree with jspatz1 about this conversaion, but im also wondering about this solenoid shifter, if anyone has use this setup,please feel free to add to this conversation, i see the pros and cons about using pneumatic shifters......what are the pros and cons using solenoid shifters

[MichaelBick]

pros: less weight(no compressor and tanks)

cons: slower

[kevin.li.rit]

Originally Posted by jspatz1

All my comments are assuming a pneumatic system is already available. Comparisons to air shifting should be done at 60 psi, not 20 psi. The solenoid wattage which was allowed in 2012 would not begin to approach the force of an air cylinder for a continuous duty solenoid. Keep in mind that solenoids are one-directional, and their "rated" force exists only in a small fraction of their total stroke.

Why should it be 60 PSI? Shouldn't it be closer to the actual force required?

Our own shifters we had, we've always run at 20 PSI for the solenoid valves sake. I was under the assumption that it took less force than the 12 lbs to shift but I could be wrong about this as I have no experience with the super shifters.

[protoserge]

Originally Posted by Coffeeism

Why should it be 60 PSI? Shouldn't it be closer to the actual force required?

The own shifters we had we've always run at 20 PSI for the solenoid valves sake. I was under the assumption that it took less force than the 12 lbs to shift but I could be wrong about this as I have no experience with the super shifters.

We run our SuperShifters at 20 psi as well without issue. 60psi shifts with 27 lbs of force (force = pressure*area, where the Bimba 040.5-DP has a 3/4" bore).

Another setup that I've heard of is using a window motor coupled to both transmissions with a spring setup to engage the gear if it is not lined up during the initial gear change request. I do not know what team had this setup, but it is definitely worth researching some more as it could offset the weight of a pneumatics system, even those with pvc air reservoirs.

[AdamHeard]

Originally Posted by stinglikeabee

We run our SuperShifters at 20 psi as well. 60psi shifts with 76lbs of force (force = pressure/area).

Another setup that I've heard of is using a window motor coupled to both transmissions with a spring setup to engage the gear if it is not lined up during the initial gear change request. I do not know what team had this setup, but it is definitely worth researching some more as it could offset the weight of a pneumatics system, even those with pvc air reservoirs.

Force = Pressure * Area. Much smaller force there.

[David Doerr]

Originally Posted by stinglikeabee

Another setup that I've heard of is using a window motor coupled to both transmissions with a spring setup to engage the gear if it is not lined up during the initial gear change request. I do not know what team had this setup, but it is definitely worth researching some more as it could offset the weight of a pneumatics system, even those with pvc air reservoirs.

That would be Team 67...

[protoserge]

Originally Posted by AdamHeard

Force = Pressure * Area. Much smaller force there.

That's a clue that I should go to bed.

Fixed for posterity, thanks.

[jspatz1]

Originally Posted by Coffeeism

Why should it be 60 PSI? Shouldn't it be closer to the actual force required?

Our own shifters we had, we've always run at 20 PSI for the solenoid valves sake. I was under the assumption that it took less force than the 12 lbs to shift but I could be wrong about this as I have no experience with the super shifters.

Pneumatic solenoid valves of the type used in FRC are internally piloted valves, which means the pressurized supply air is used to actuate the valve spool, not the solenoid. The solenoid is very small and only opens a tiny port to trigger the pilot air. Such valves have a minimum pressure that will allow it to operate, usually around 30-40 psi. So they actually prefer a high pressure and only function reliably when it is sufficient. So a note to teams: If you have a valve that is not responding when you are certain it is getting a proper electrical input, and you are using low pressure, chances are the pressure too low for the valve to operate.

[kevin.li.rit]

Originally Posted by jspatz1

Pneumatic solenoid valves of the type used in FRC are internally piloted valves, which means the pressurized supply air is used to actuate the valve spool, not the solenoid. The solenoid is very small and only opens a tiny port to trigger the pilot air. Such valves have a minimum pressure that will allow it to operate, usually around 30-40 psi. So they actually prefer a high pressure and only function reliably when it is sufficient. So a note to teams: If you have a valve that is not responding when you are certain it is getting a proper electrical input, and you are using low pressure, chances are the pressure too low for the valve to operate.

Right, and the minimum pressure for the valve we were using was at 20PSI. For me, that's not a good reason to say that you need to generate the same force as a 60psi 1/2" piston with a push/pull solenoid to make the thing work.