Tyre requirements for car trailers?
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Version 2.2
Is your car trailer no longer running on smoothly, are the brakes squealing or did the roadworthiness test flag defects? When it comes to the overrun brake, safety comes first. Whether it's a repair, maintenance or a complete replacement – here you'll find high-quality spare parts for all common brands plus practical expert advice.
1. Why the overrun brake is so important
The overrun brake is the heart of every braked trailer. When the towing vehicle brakes, it ensures that the trailer slows down by itself using its own overrun force.
Faulty or worn components not only increase the braking distance dramatically, they can also cause the vehicle combination to sway or the trailer to fail its roadworthiness test. Regular checks and replacing wear parts in good time keep you safe on the road.
2. The most important spare parts for overrun brakes
To get your overrun device working perfectly again, we offer you a comprehensive range of branded spare parts:
- Overrun damper / shock absorber: Controls the smooth retraction of the drawbar shaft. If the trailer runs on with a jolt, the damper is usually faulty.
- Bellows / gaiter: Protects the drawbar shaft and the interior from dirt, water and corrosion.
- Drawbar shaft / drawbar tube: The central link between the ball coupling and the brake linkage.
- Ball coupling / “coupling head”: The connection point to the tow bar of the towing vehicle.
- Handbrake lever & breakaway cable: Essential for the parking brake and for emergency braking if the trailer becomes detached.
- Slide bushes & reversing lever: Ensure smooth guidance and power transmission.
3. Spare parts for all leading manufacturers
Trailer brakes are not universal – the components must exactly match the type of overrun device fitted. With us you'll find spare parts for all well-known manufacturers:
- AL-KO (e.g. 251S, 161S, V-type above/below-frame mounting)
- KNOTT (e.g. KF13, KF20, KR series)
- BPW / Peitz (e.g. PAV series, X spare parts)
- Schlegl, Nieper & Tobisch
Tip: Before ordering, always check the type plate of your overrun device (not just the one on the axle!).
4. What should you look out for when buying?
To avoid buying the wrong part, have the following details ready when searching for the right spare part:
- Manufacturer of the overrun device (e.g. AL-KO or Knott)
- Exact type designation (e.g. KF 20-A)
- Version / ETI number / approval mark (often stamped on the housing)
- Gross vehicle weight (GVW) of the trailer
Special points when identifying parts
5. Questions about fitting? Expert knowledge in the trailer forum
Not sure about the installation, don't know how to adjust the drawbar shaft play or looking for step-by-step instructions? Tap into the combined experience of our community on anhaengerforum.de (German-language)! Right here below you can search the forum for your model, ask questions and swap ideas with experienced DIY mechanics and professionals.
Matching overrun brakes
Frequently asked questions
How do I find the right spare part for my overrun brake?
Answer: The easiest way to identify the right spare part is via the type plate of the overrun device. What matters is the manufacturer (e.g. AL-KO, Knott, BPW), the type designation and, if applicable, the serial number. Alternatively, measurements or photos of the overrun device can also help with identification.
Can I replace individual parts of the overrun brake or does the complete unit have to be replaced?
Answer: In many cases, individual components such as the overrun damper, bellows, drawbar shaft, reversing lever or brake cables can be replaced. However, if the housing is damaged or heavily corroded, or safety-relevant components are worn, the complete overrun device may need to be replaced.
How can I tell that the overrun damper is faulty?
Answer: A worn overrun damper often shows itself through heavy jerking when braking or pulling away. The drawbar shaft moves without sufficient resistance or springs back uncontrolled. A leaking damper or escaping oil are also clear signs of a defect.
Are spare parts from different manufacturers interchangeable?
Answer: Not as a rule. Even if components look similar, they often differ in dimensions, load capacity and type approval. Always choose spare parts to match the manufacturer and type designation of the overrun device to ensure correct function and keep the trailer's operating approval valid.
What information is needed to identify the right spare part?
Answer: The following details help with clear identification:
- Manufacturer of the overrun device
- Type designation
- Serial number (if available)
- Gross vehicle weight (GVW) of the trailer
- Photos of the type plate and the faulty assembly
- Dimensions of the part to be replaced if the type plate is no longer legible
With this information, the right spare part can be clearly identified in most cases.
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