Window Locking Mechanisms

Window locking mechanisms are essential components in modern uPVC windows, providing secure multi-point locking for homes across Sutton and beyond. These window parts ensure your windows close firmly and resist forced entry. If yours are faulty, identifying them accurately is the first step towards reliable replacement.

What It Is

Window locking mechanisms, often called multipoint locks or espagnolettes, are the core systems that secure uPVC windows. They typically consist of a central gearbox operated by a handle, connected to multiple locking points via rods or strips that engage with keeps and strike plates on the frame.

These uPVC window parts distribute pressure evenly across the window, improving security and weatherproofing. Unlike single-point locks, they engage at several points—usually three to eight—for a tight seal. Replacement window parts like these are common in casement windows.

How To Identify It

Spotting a window locking mechanism starts with the handle and its operation. Open the window and turn the handle: if it lifts a central mushroom cam or hook that pulls in rods to multiple points, it’s likely an espagnolettes system with a window gearbox.

Look for:

• Metal strips running vertically along the window edge.
• Hooks, rollers, or mushrooms at intervals (e.g., top, middle, bottom).
• Keeps and strike plates fixed to the frame that receive these points.
• Engravings on the gearbox faceplate, such as brand names like Maco, Avocet, or Mila.

Remove the handle (often a screw) to expose the gearbox spindle hole. A square drive indicates a standard multipoint window lock.

Compatibility Factors

Not all window locking mechanisms fit every uPVC window. Key factors include the window’s profile (e.g., Rehau, Spectalock, or freeform) and bevelled or squareo edge designs.

Consider:

• Brand matching: Mechanisms from the same manufacturer as your window reduce fitting issues.
• Handing: Left or right-hand operation based on hinge side.
• Operation type: Inline espagnolette for standard casement; tilt-before-turn for vented windows (though we focus on standard uPVC casements).
• Profile compatibility: Chamfered edges need specific faceplates.

Exclusions like sash, sliding, tilt-and-turn, or inward-opening windows use different systems—we specialise in standard uPVC. Always match the original for seamless integration.

Measurements That Matter

Precise measurements prevent costly mismatches in replacement window parts. Start with the backset: distance from the edge of the faceplate to the spindle centre (common sizes: 30mm or 35mm).

Essential dimensions:

• Spindle size: Length (typically 15-40mm each side) and type (PZ euro profile, 7mm square).
• Faceplate length: Overall strip length, e.g., 1700-2400mm.
• Locking point spacing: Distance between hooks/rollers (e.g., 600mm centres).
• Case depth: Gearbox depth into the window (20-25mm standard).
• Frame hook distance: From frame edge to keep centre.

Use a digital caliper for accuracy. Photos with a ruler help when sourcing uPVC window parts.

Common Naming Confusion

Window locking mechanisms spark frequent mix-ups. Many call the entire strip a “lock,” but it’s the gearbox that drives it—think of the gearbox as the engine.

Other confusions:

• Gearbox vs multipoint window lock: Gearbox is the handle-operated core; the full system is the multipoint lock.
• Window keeps vs strike plates: Keeps are frame-mounted receivers; strikes are often the same but specify by shape (hook or flat).
• Espagnolette vs roller cam: Espagnolette refers to the rod system; rollers are a subtype for smoother action.

Clarifying these avoids ordering the wrong replacement window parts.

Symptoms It Can Cause

Faulty window locking mechanisms lead to everyday frustrations and security risks. Common signs include handles spinning freely without engaging locks, indicating a worn window gearbox.

Watch for:

• Window not closing flush or drooping at the bottom.
• Partial locking where only some points engage.
• Rattling or draughts from misaligned keeps and strike plates.
• Jammed window from seized rods or broken hooks.

These issues worsen over time, compromising insulation and safety. Early identification prevents escalation.

Related Repairs

At Window Repairs Sutton, we handle window lock and locking mechanism repairs as a core service, backed by 10+ years’ experience and public liability insurance. Our DBS-checked technicians replace gearboxes, full espagnolette strips, or window keeps on-site for standard uPVC casements.

We cover:

• Fault diagnosis and part matching.
• Adjustments for alignment.
• Full replacements using compatible uPVC window parts.

No sash, sliding, or wooden window work—see our services offered for details. For a no-obligation assessment, contact us on 020 8138 0796 or info@window-repairs-sutton.co.uk.

FAQs

What are window locking mechanisms made of?

Primarily zinc die-cast for gearboxes and steel for rods and hooks, with plastic rollers for durability. Galvanised components resist corrosion in uPVC frames.

How do I know if I need new window keeps or strike plates?

If the window engages but pops open easily, or points don’t align, inspect keeps for wear or bending. Replace as a set with the mechanism for best results.

Can I replace a window locking mechanism myself?

DIY suits simple handle swaps, but full multipoint replacements need tools for frame adjustments. Professional fitting ensures security—book via /repairs/window-lock-repair/.

Are all multipoint window locks the same size?

No—backset, spindle length, and point config vary. Measure as outlined to match replacement window parts.

How long do window locking mechanisms last?

10-20 years with moderate use, depending on exposure. Regular lubrication extends life.

Do you repair tilt-and-turn window locks?

We focus on standard uPVC casement locks; tilt-and-turn are excluded. Check our services for alignments and draught proofing.