Tractor Units with Retarder
Tractorheads with retarder
A retarder, also known as an auxiliary brake or continuous brake, is a sustained braking system that supplements conventional service brakes. In long-distance heavy transport, the retarder is the most valued piece of equipment among professional drivers, as it allows maintaining constant speed on long descents without overheating disc or drum brakes.
Types of retarder
There are three main retarder technologies for tractorheads, each with specific advantages depending on the type of operation:
- Hydrodynamic retarder (Voith, ZF): Uses pressurised oil inside a chamber with rotating vanes to create resistance against driveline rotation. The Voith VR 115 and VR 120 are the most commonly fitted models in Europe. Delivers braking power up to 500 kW (680 HP) and is particularly effective at high motorway speeds. Its main advantage is constant braking power independent of engine speed.
- Intarder (ZF, Mercedes): Hydrodynamic retarder integrated directly into the automated gearbox. The ZF Intarder is available in TraXon gearboxes (DAF, MAN, Iveco) and the Mercedes Intarder in PowerShift units. Integration reduces weight and space compared to an independent retarder. Braking power up to 600 kW on the latest models.
- Decompression engine brake (Jake Brake): Not a retarder per se, but a braking system that opens exhaust valves during the compression stroke to turn the engine into a compressor that slows the vehicle. The Volvo VEB+ reaches 375 kW, MAN EVBec 400 kW and Scania Retarder (electronic) 500 kW. Its advantage is adding no weight to the vehicle.
Why the retarder matters
On a typical mountain crossing such as the Brenner Pass (Austria-Italy) or the Somport tunnel route (Spain-France), a 40-tonne truck may face 20-30 km of continuous descent. Without a retarder, service brakes overheat (brake fade), losing effectiveness and compromising safety. With a retarder, 80-90% of braking is performed by the auxiliary system, keeping service brakes cool and available for emergencies. Additionally, brake pads can last 400,000-500,000 km instead of 150,000-200,000 km, representing significant maintenance savings.
Retarder by brand
Each manufacturer offers differentiated retarder solutions:
- Volvo: VEB+ (Volvo Engine Brake Plus) standard on many FH configurations. 375 kW engine brake combinable with optional Voith retarder.
- Scania: Own integrated retarder up to 500 kW, considered the best on the market for its progressiveness and quietness. Available as standard on most R and S configurations.
- Mercedes: Intarder integrated into PowerShift 3 gearbox with up to 600 kW. The Actros also offers the 475 kW High Performance Engine Brake.
- DAF: ZF Intarder integrated into TraXon or independent Voith retarder. The MX Engine Brake delivers 360 kW.
- MAN: EVBec (Extra Valve Brake with compression release) at 400 kW integrated into the D26 engine. Combinable with Voith VR 115.
- Renault: Optibrake+ (320 kW engine brake) as standard. Optional Voith retarder across the T range.
- Iveco: ZF Intarder in the HI-TRONIX gearbox. Iveco Turbo Brake engine brake at 400 kW.
How to check the retarder when buying a used tractor unit
Before closing a purchase of a tractor unit with retarder, verify on a road test that the system acts progressively at each level (typically 3-5 steps on the stalk) and that no warnings appear on the dashboard. On Voith or ZF hydrodynamic retarders, check the oil is not contaminated and there are no leaks in the chamber; a retarder repair can cost 1,500-3,500 €. On engine brakes (VEB+, EVBec) listen for uniform braking without abnormal valve noises. At Coatrucks we test the retarder on every unit and record it in the documented inspection.
Retarder or engine brake: which suits your route
If you run international transport over Alpine or Pyrenean passes regularly, a Voith hydrodynamic retarder or ZF Intarder (up to 500-600 kW) is the safest option thanks to its constant braking power at high speed. If your operation is more domestic with less mountain, a powerful decompression engine brake (Scania Retarder, Volvo VEB+, MAN EVBec) usually suffices and adds no weight or retarder maintenance cost. For 40 tonnes on long haul we always recommend at least a good engine brake; at Coatrucks we advise based on your real routes.
Used tractorheads with retarder
Buy used tractorheads with retarder: Voith, ZF Intarder and engine brake. Safety on mountain routes.
Frequently asked questions
What is the difference between a hydrodynamic retarder and an engine brake?
The hydrodynamic retarder (Voith, ZF Intarder) uses pressurised oil to brake the driveline and delivers constant power at high speed, up to 500-600 kW, ideal for long mountain descents. The decompression engine brake (Volvo VEB+, MAN EVBec, Scania Retarder) turns the engine into a compressor and adds no weight. The hydrodynamic retarder brakes more on the motorway; the engine brake is more effective at high revs. At Coatrucks we advise based on your routes.How much does a retarder extend brake life?
A retarder performs 80-90% of braking on descents, so pads and discs can last 400,000-500,000 km instead of 150,000-200,000 km without one. On regular mountain routes (Brenner, Somport, Alps) the difference is even greater. The savings in brake maintenance more than offset the premium of a tractor unit with retarder, plus the added safety. It is the most valued piece of equipment among long-distance drivers.Is it worth paying more for a used tractor unit with retarder?
Yes, if you run long haul or routes with elevation. The premium is recovered through lower brake wear and greater safety, and a tractor unit with retarder resells better because almost all professional buyers demand it. For urban distribution or flat routes the return is lower. At Coatrucks most of our long-distance tractor units have a retarder or high-power engine brake.Which brand has the best retarder?
Scania's integrated retarder is considered the best in the sector for its progressiveness, quietness and power up to 500 kW. The ZF Intarder (DAF, MAN, Iveco) and the Mercedes Intarder up to 600 kW are also excellent. The Volvo VEB+ (375 kW engine brake) is highly valued for adding no weight. Each brand has its solution; what matters is that it is in good condition. At Coatrucks we test the retarder on every unit before sale.How do I know if a used tractor unit's retarder works well?
On a road test the retarder should brake progressively at each step of the stalk, without jerks or dashboard warnings. On hydrodynamic retarders you must check the oil is not contaminated and there are no leaks; a repair can cost 1,500-3,500 €. At Coatrucks we verify the retarder operation on every tractor unit and record it in the documented inspection we deliver with the vehicle.Does the retarder use more fuel or wear the engine?
No. The hydrodynamic retarder is independent of the engine and uses no fuel when braking; it only adds some weight. The decompression engine brake also uses no fuel and does not wear the engine beyond normal, as it is designed for it. On the contrary, using the retarder instead of the service brakes reduces overall vehicle wear and improves safety on long descents.Can I import a tractor unit with retarder from Europe with Coatrucks?
Yes. Most long-distance tractor units from Germany, the Netherlands, France or Sweden that we import have a retarder or high-power engine brake as standard. We handle transport, reduced homologation in Spain (technical sheet with COC, 24-48 h) and registration fees, with a fixed quote before we start. As an intra-EU transaction, VAT is 0% via VIES if your company is on the ROI register. Typical timeline: 7-15 days.