Opening fail-safe electrical strike door with a spring

Question

I have a 12V fail-safe electrical strike currently installed and working on a door, but I want it to open slightly when it is powered down, but a spring apparently won't do as my strikes keep themself locked if they have a constant force acting on them (so after unlocking, you either have to pull the door and the spring pushes it away, or push the door in place and the spring pushes it on you)

The question is: is there a way to open slightly the door with another type of electrical strike or is this kind of security on every one of them ? I need it to stay fail-safe though.

The other options I see are a solenoid pushing the door after the strike is opened, or a magnetic lock with a spring. Are there easier workarounds I didn't thought of ?

what does `open slightly` mean? ... your question has nothing to do with electronics ... it appears to be a mechanics related question — jsotola, Jul 06 '20 at 15:09
I am tring to get past that "security" that keeps me from opening this door with a spring. @jsotola that means 5 to 10 cm, enough to see the door is open — Neil, Jul 06 '20 at 15:12
@jsotola is there a stackexchange my question might fit in ? maybe engineering ? — Neil, Jul 06 '20 at 15:15
click the blue icon, that has three horizontal lines, at the top of this page — jsotola, Jul 06 '20 at 15:32
You also need to define what "fail-safe" means in your application. Does "safe" mean doors lock (as in a prison) or that doors open (as in a fire escape). [Edit] it into your quesiton - don't bury it in the comments. — Transistor, Jul 06 '20 at 16:05
And they do define the fail-safe. "Want to open when powered down". — Passerby, Jul 06 '20 at 18:08
@Passerby: It may depend on which side of the bars you're on. — Transistor, Jul 06 '20 at 18:28

score 1 · Answer 1 · answered Jul 06 '20 at 17:44

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You may want to consider using a magnetic lock rather than an electric door strike. These are used in many applications such as holding fire doors open until a fire alarm is triggered.

One common use of magnetic locks is holding doors closed in security areas.

The specific advantage of a magnetic lock is that it releases completely upon removal of power.

answered Jul 06 '20 at 17:44

Dwayne Reid

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There are energise-to-release maglocks too. The coil counters the permanent magnets. See https://electronics.stackexchange.com/a/245575/73158. – Transistor Jul 06 '20 at 18:27

Passerby · Accepted Answer · 2020-07-06T18:24:41.820

The keyword you are looking for is "preload". Loading the keeper on an electric strike will cause it to bind, preventing the solenoid to release the keeper. Once pressure is released, it's free to move again. It's not really a security feature, but a mechanical problem with the design. It's a minor problem in most cases that's easily overcome by behavior changes, so manufacturers dont put in the time/research/money to engineer a better fix.

There are electric strikes made to work in environments where preload exists (misaligned doors/walls, high air pressure from HVAC, etc). Or you can chose a different type of locking mechanism that does not have this physical problem.

To get the existing one working, you could add an active system, like your own solenoid that will push the door after 1s of power loss.

That is definitely what i am looking for, i was worried it was a design flaw, but relieved there are strikes that counter this issue, will look into that :D — Neil, Jul 06 '20 at 22:05

Opening fail-safe electrical strike door with a spring

2 Answers2