When I bought my house, it was fitted with multi-point locking systems on the windows. One or two of these have failed - an internal cast-metal half-cog has disintegrated. There is no manufacturer's name or other marking on the parts, that I can find.

My wife thinks it must be possible to source replacement parts. I suspect I'll have to try to fabricate parts or replace the window frames because I think these parts are proprietary and unlikely to be standardised.

Here's a photo of the mechanism, there is a metal bar with three locking studs (one visible at right of photo) each stud engages with a locking point on the outer frame. The metal bar slides vertically up and down. It is driven by the toothed insert to the left of the photo. The rectangular part with three holes should contain a half-cog that engages with the toothed section and which has a square hole. This square part sits in a rebate in the edge of the opening window frame (PVC). The window handle (with a key lock) fits into the square hole so that turning the handle turns the half-cog thus moving the locking bar up or down.

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The square part is a metal sheet folded around the sliding bar (over which it slides freely) and bent at right angles. From the side it is L-shaped (two layers). The machine-screw inserts appear to be acting like rivets to hold the folded metal together.

Is likely that parts such as the missing half-cog can be sourced or fabricated?

  • Are there any manufacturer markings on it (or do you know the window manufacturer)? A lot of the higher end ones have replacement parts available.
    – Comintern
    Commented Aug 3, 2014 at 18:06
  • @Comintern: I can't find any markings and I don't know the manufacturer. Commented Aug 3, 2014 at 20:16
  • Nice pics - well documented!
    – FreeMan
    Commented Mar 22, 2016 at 17:27

1 Answer 1



For reference, what I eventually discovered was that these parts are called espagnolettes (in the UK at least) and that you can buy generic replacements that can be cut to fit.

There are a limited range of common rail-widths and lock-backsets that you need to measure before ordering. Fashions change, so older style parts are harder to find.

enter image description here

Dimension A - Backset
Dimension B - Mushroom Height
Dimension C - Rail Length
Dimension D - Rail Width

A suitable search term might be "upvc window espagnolette"

  • And 18 months later he has an answer! Hope it didn't take you that long to find what you were looking for!!
    – FreeMan
    Commented Mar 22, 2016 at 17:28
  • @FreeMan: Never give up hope! I bought the replacement parts long ago but kinda forgot about this Q. I just happened to look at my list of Q's on my profile page today and saw this had 0 answers. Commented Mar 22, 2016 at 17:31

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