UPVC Door Lock – Gearbox Identification (Fast Match)

Handles & Hinges UPVC Maintenance Ltd helps you replace just the gearbox (centre case) when the strip and locking points are fine. Record the sizes below and you’ll know exactly which gearbox to order.

Before you start: Open the door. Work with the latch not under load. Keep all screws safe.

What to note (in order)

Brand / stamp
Check the faceplate and the gearbox for a name or code (ERA, GU, Yale, Winkhaus, Mila, Roto, Avocet, Fuhr, etc.).
Backset
Measure from the faceplate edge to the centre of the spindle square. Common: 35 mm or 45 mm on UPVC (others exist — 28/30/40/55 mm, etc.).
PZ (centres)
Distance from spindle centre to cylinder/keyhole centre. Typical: 92 mm (modern), 70/68 mm (older).
Operation type
Lift-lever (lift handle to throw points) or key-wind/double spindle (key throws points). Note split-spindle or lever/pad outside if fitted.
Case shape & fixings
Note the gearbox outline (round/rectangular latch area), latch direction (reversible or not), and the positions of the fixing screws through the case.
Faceplate width / profile
Flat 16–20 mm strip, or U-profile? (Useful for confirming family.)

Quick reference table

Measurement	How to take it	Why it matters
Backset	Faceplate edge → spindle centre	Core size — most critical pick
PZ (centres)	Spindle centre → cylinder centre	Must match handle/lock geometry
Operation	Lift-lever or key-wind; split spindle?	Chooses the correct gearbox family
Fixing layout	Positions of case screws	Ensures holes line up
Faceplate style	Flat or U-profile; width	Confirms system compatibility

When a gearbox is all you need

Strip and locking points (hooks/rollers) are intact; only the centre mechanism jams or freewheels.
Handle springs back normally (or is fixed by a sprung handle) but the door won’t latch/lock.
You want the most economical repair with minimal cutting and waste.

Measuring tips

Photograph the brand stamp and the whole centre case next to a tape.
If the latch is reversible, note the current handing before removal.
Most handles use an 8 mm spindle; confirm if yours differs.

Shop Door Lock Gearboxes Full Multipoint Measuring Guide Door Handle Measuring Guide