What is a window brake?

A window brake is a mechanical brake that allows a window or door to stop in the position you open it. When you press down on the handle, the brake is activated and creates friction in the brake rod.

This prevents the door from blowing open or slamming shut, which both increases comfort and reduces wear on the door and fittings.

When do you need to replace window brakes?

A window brake is a wearing part and may need to be replaced after many years of use.

Common signs that the brake is worn out are:

• The balcony door does not stay in the open position
• The window slides back by itself
• The brake does not engage when the handle is pressed down.
• The door opens too easily.

When this happens, it is usually easiest to replace the brake with a new model.

Common models of window brakes

Most homes in Sweden use brakes from Assa Abloy. The most common models are:

• Assa Fix 150
• Assa Fix 160
• Assa Fix 160S
• Assa 750
• Assa 760

Which model you need usually depends on which brake is already installed in your door or window.

Window brake for patio doors and balcony doors

Window brakes are often used in patio doors and balcony doors where it is important that the door can remain open. A functioning brake prevents the door from slamming shut in wind or drafts.

Models like Assa Fix 150 and Assa Fix 160 are very common in Swedish patio doors.

How do you know which window brake you have?

The easiest way is to check the brake that is already installed in the door or window.

You can identify the model by:

• look for markings on the brake housing
• measure the length of the brake
• compare with product images

If you are unsure, you can compare your brake with the products in this category.

Can a window brake be adjusted?

In some cases, the brake can be adjusted, but if it is worn out, it usually needs to be replaced. Brakes contain mechanical parts that wear out over time.

Replacing the brake is usually a simple operation and can often be done yourself with basic tools.

Frequently asked questions about window brakes

Why doesn't my patio door stay open?

If your patio door won't stay open, it's usually the window brake that's worn out. When the brake wears out, the friction disappears and the door starts to slide again.

How do I know if the brake should be right or left?

Turn the brake box so that the short side is facing you and you can see inside the mechanism.

• If the locking pin is on the left side, it is a left-hand variant
• If the locking pin is on the right side, it is a right-hand variant.

In many cases, the left-hand version fits both left- and right-hand hung doors.

What does the length of the brake box mean?

The brake box length indicates the length of the brake box itself, not the pin or door/window. Common lengths are, for example, 252 mm, 347 mm, 352 mm, 447 mm and 452 mm.

You can easily filter out the right size by using the filters on the page.

Do I have to cut the brake rod?

In some installations, the brake rod may need to be cut slightly to fit perfectly in the door or window. This is usually done with an angle grinder or other metal cutter.

This is a normal part of the installation and does not affect the function of the brake.

Can you replace the window brake yourself?

Yes, in most cases a window brake can be replaced without any special tools. It usually only requires a few screws and basic tools.

If you want to see the whole process, you can read our guide:

How to change a window brake

Guides and help

• How to change a window brake
• Balcony door won't stop – solution
• The difference between Assa Fix 150 and Fix 160