relay controls for an air cylinder

Thread Starter

b.alan

Joined Dec 28, 2007
5
I would like some other ideas for the controls for an air cylinder. the cylinder
has prox switches and will constantly extend and retract using two 120v air valves if not 120v ac may consider using 24v dc thanks for any input
 

beenthere

Joined Apr 20, 2004
15,808
What kind of control? Full on/off or proportioning? You said the air valves were up for grabs - is there something you would prefer to use?
 

Thread Starter

b.alan

Joined Dec 28, 2007
5
full on I guess, when the unit is on the cylinder will be in constant cycle. the cylinder will be set up with A set of fully extended and fully retracted switches witch will control direction through relay's and maybe even A thought on using flipflop. the air valves will be either 24v dc or maybe 120v ac not sure at this point for starters will go with 24v dc. If I use relay logic what do you think my logic setup should be?
 

beenthere

Joined Apr 20, 2004
15,808
It sounds like a pair of microswitches will work. One to start extending the air cylinder when fully closed, and the other to start closing it when fully extended. If it is just going to stroke open and closed while operating, this should be enough. Voltage is not significant. The microswitches will set the state of a latching relay that will operate the air valve.
 

Thread Starter

b.alan

Joined Dec 28, 2007
5
on start up the air valve in it's off state will extend the cylinder until it reaches the extended switch, help me on the relay latching setup. for the two switches to change the latching state what do I need in a relay to acomplish this. thanks for your time.
 

beenthere

Joined Apr 20, 2004
15,808
Look at a P & B S89R11DAC1-12. Or S89R11AAC1-120. They are impulse latching realys, with 12 and 120 VAC coils. A brief application of voltage on the coil terminals will put the relay into the opposite state, which will be maintained until the next voltage pulse. The contacts are actually two microswitches, and the arrangement is so the relay is DPDT. They are available from Digi-Key as part #'s PB513 @ $45.38 & PB585 @ $47.64. Pick a microswitch with an actuator to suit.

The relay contacts will apply voltage in the necessary direction to drive the air valve. The limit microswitches will be arranged so the cylinder or the door will trip one at either limit. That will put the voltage to the impulse relay and will reverse the operation.
 

Ron H

Joined Apr 14, 2005
7,012
If this project is a one-off, Here is a 24VDC, dual coil latching relay for $9.95. All you need is a limit switch on each end to reverse directions.
 
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