Window Gearbox Maintenance: Keeping Your Locks Working Smoothly

Window Gearbox Maintenance: Keeping Your Locks Working Smoothly

A well maintained window gearbox keeps casement and tilt-and-turn windows operating smoothly and prevents costly call-outs. This post covers practical inspection, lubrication and replacement steps for both homeowners and trade professionals; the advice is applicable to espagnolette-style locking systems commonly used across the UK. For technical background on the locking system itself, see our pillar page: espagnolette window locks.

What is a window gearbox and why it matters

The window gearbox is the internal mechanical unit that converts handle rotation into movement of the locking rod or multi-point system. It contains the spindle, gears and cams that operate keeps, striker plates and locking points. If the gearbox is worn or poorly maintained, you will experience stiff handles, incomplete locking, rattles, or stripped components that can compromise security and weather performance.

Recommended inspection frequency

Inspect gearboxes at least once a year as part of routine window servicing. For coastal properties, high-pollution areas or commercial buildings with frequent use, check every six months. Carry out a quick visual and functional check whenever you notice stiffness, noise or a change in handle travel.

Tools and materials you will need

• Screwdriver set including Pozidriv and Torx
• Allen keys or hex bits for handle spindles
• Clean lint-free cloths and a small brush
• Isopropyl alcohol or a mild solvent for cleaning
• White lithium grease or a light machine grease (suitable for metal gears)
• PTFE spray or silicone spray for keeps and gaskets
• Fine needle files or emery cloth for minor burr removal
• Replacement gearbox or spindle if necessary
• PPE: gloves and eye protection

Step-by-step maintenance: inspection and cleaning

Do not attempt work on a window that is under tension from cables or has broken components without isolating it first. For standard espagnolette systems follow these steps:

• Operate the handle slowly while observing the locking points: note any snagging, excessive play or missing engagement.
• Remove the handle: loosen grub screw or unscrew retaining screw and withdraw the handle. This gives clear access to the gearbox area and spindle.
• Remove the gearbox faceplate or cover if fitted: remove screws and gently prise the cover off to expose the gearbox. Keep screws in a labelled container.
• Clean visible dirt, grit and old grease using a brush and cloth dampened with isopropyl alcohol. Avoid over-wetting PVC frames.
• Check for corrosion, metal swarf and stripped gear teeth. Small burrs can be gently dressed with a file; replace the gearbox if teeth are significantly damaged.

Lubrication: what to use and where to apply

Choosing the correct lubricant is important. For the internal gearbox and cams use a white lithium grease or light machine grease that will adhere to metal gears without attracting excessive dust. For keeps, striker plates and external moving faces use a PTFE spray or silicone spray which provides a dry, low-friction finish and is kind to PVC gaskets.

• Apply a small amount of white lithium grease to the gear teeth and the spindle. Work the handle to distribute the grease.
• Use PTFE or silicone spray sparingly on the locking points and striker plates to reduce wear and noise.
• Do not use general-purpose penetrating oils such as WD-40 as a long-term lubricant; they are solvents that will wash away and may attract dirt.
• Avoid thick tar-like greases that can gum up in cold weather; choose greases specified by reputable hardware manufacturers or window suppliers.

Adjustment and minor repairs

Often a gearbox fault is compounded by misaligned keeps or loose fixings rather than a failed gearbox. Follow these checks:

• Tighten faceplate and gearbox mounting screws to take up any movement. Over-tightening can distort the profile so use firm but controlled torque.
• Adjust keeps and striker plates: raise or lower keeps by small increments to ensure locking points engage smoothly. Use a feel test rather than forcing the handle.
• If the spindle shows play in the gearbox or the handle wiggles, check for worn bushes or a loose retaining clip; replace the gearbox if internal bushings are worn.
• For uPVC windows with multi-point rods, ensure the rods are straight and the end caps are secure; damaged rods can cause gearbox overload.

When to replace a window gearbox

Replace the gearbox when any of the following apply:

• Stripped or broken gear teeth that prevent reliable operation
• Excessive play in the spindle or worn internal bushes
• Visible corrosion or metal fatigue
• Repeated failures despite adjustment and lubrication

When replacing, match the new gearbox to the original: check spindle size (7mm square is common in the UK), spindle length, backset and screw hole positions. Many gearboxes are reversible but confirm left or right handed versions; carry common sizes on-site if you are a trade operative to avoid returns.

Practical trade tips

• Keep a small service kit with spare grub screws, grease and a selection of common gearbox types for first-fix repairs.
• Note the manufacturer and part number where possible before ordering replacements to ensure compatibility; small variations can cause misalignment.
• Record adjustments and parts replaced on service reports; customers value documented maintenance and you reduce repeat visits.
• Use a torque-limited driver for repeatable screw clamping; this avoids crushed frames or distorted faceplates.

DIY safety and do-not-do items

• Do not force a stuck handle; forcing can strip gears or bend rods.
• Do not paint over gearbox covers or moving parts; paint jams mechanisms.
• Do not use corrosive cleaners that can damage plated finishes or gaskets.
• If in doubt about removal of multi-point rods or sash tension, contact a professional; incorrect reassembly can create security or water ingress issues.

Recommended Products

Based on this article, you may find these products helpful:

• ERAB Espagnolette Window Lock Universal Lock Replacement
• Avocet Slimline Offset Window Espag
• In-Line Window Mechanism
• Offset Window Mechanism
• Multipoint Gearbox GU Old Style

Conclusion and next steps

Regular inspection, appropriate cleaning and correct lubrication will extend the life of a window gearbox and maintain a smooth, secure operation. For homeowners, perform a basic check and lubrication annually and call a reputable fitter if you find stripped gears or persistent stiffness. For trade professionals, stock common gearbox sizes, use suitable greases and document your work. If you need compatible gearboxes, spare parts or technical specifications for espagnolette systems, visit our product pages or contact our trade support team for assistance.