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I bought a new letterbox lock (Burgwächter ZBK-70, pdf datasheet/drawing), but the bar is too short.

I'd like to exchange that bar, but I have no clue how to loosen the bolt. So far, I tried it with telecom pliers, but it didn't work.

What is this black washer-like thing underneath the nut, by the way?

enter image description here

Alaska Man
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dodi
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    Does this answer your question? [What is this nut clamp called and how do you remove it?](https://diy.stackexchange.com/questions/95451/what-is-this-nut-clamp-called-and-how-do-you-remove-it) – Peter Duniho Nov 08 '20 at 19:45
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    Even a blind squirrel finds a "circlip" once in a while. – Alaska Man Nov 08 '20 at 23:44

2 Answers2

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That is a circlip.

Just use a small flat screwdriver in the gap to prise it off - make sure you keep hold of it because it can ping away.

If you put the screwdriver in the gap at 3 o’clock and twist it will force the circlip over the diameter of the shaft.

Solar Mike
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  • I've seen them a few times for sprockets on smaller engines, the tool I am typically using is a pin punch: https://upload.wikimedia.org/wikipedia/commons/f/fb/Chasse_clou.png – Yanick Salzmann Nov 08 '20 at 18:25
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    I've also heard of them as "e-clips" because the three little toothy bits on the inside look vaguely like an E. – Criggie Nov 08 '20 at 19:01
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    @Criggie: They _are_ "e-clips". A circlip is something similar, but different. See e.g. https://diy.stackexchange.com/a/122883. One can use circlip pliers to remove a circlip, but there's no holes in the ends of an e-clip. – Peter Duniho Nov 08 '20 at 19:44
  • I've never heard them called e-clips. Is "Circlip" a (genericised) trademark? – Mark Morgan Lloyd Nov 08 '20 at 19:59
  • @PeterDuniho there sre clips without holes as well just open or incomplete loops... – Solar Mike Nov 08 '20 at 20:03
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    I've also seen them used inside locks, to hold the cylinder inside the lock body. – Criggie Nov 08 '20 at 21:25
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What is this black washer-like thing underneath the nut, by the way?

It is a "circlip". - Operate on it under a hanky or something because they can fly pretty far when pushed out of their notch.

The "black thing" isn't a nut, there is no nut in this application.

Place a small blade screwdriver in the exposed gap between the black c-shaped clip, and give the driver a little twist. You'll see the clip starts to ease away from the rotational axis of the tumbler.

If you don't do that carefully with some covering, you can lose that clip quickly.

This "nut" cannot be tightened, but theoretically you can add some shim stock under it to tighten up the assembly.

Alaska Man
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me.here
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