Scheuerle from Pfedelbach is the first manufacturer in the world to employ hydraulic disc brakes for heavy-duty pendulum axle bogies. The prototype was devised and developed to the series production stage in collaboration with Knott GmbH. This puts Scheuerle at the forefront in terms of techno-logical development in tractor units, buses and light-weight semi-trailers. This world innovation will be presented for the first time at the IAA 2000 exhibition in Frankfurt at the Scheuerle Fahrzeugfabrik GmbH stand.

The advantages of disc brakes over drum brakes are indisputable, and it is not without good reason that - after conquering the car - they are now continuing their conquest and starting to appear in commercial vehicles as well. Scheuerle joined forces with Knott to devise disc brakes for the heavy- duty, hydraulically supported and controlled pendulum axle bogies of the INTER, EURO and FLAT COMBI series of platform trailers. With these vehicles, however, the low wheel and rim diameters proved tricky, particularly since the FLAT COMBI platform trailer is fitted with tyres measuring a mere 205/65x17.5. For this reason, Scheuerle called upon the specialists from Knott to help tackle this project.

The chief benefits of disc brakes include enhanced braking action, favourable fading behaviour, high ther-mal loading capacity and improved braking action when hot, high thermal shock resistance of the brake disc, low thermal strain on the tyre base, plus a distinct reduction in squealing and rattling. What is more, they permit a very fine and precise dosing of the brake power, which - with payloads of up to 1,000 tons and high loading points of gravity - provides additional safety. This is due to the high fficiency of the hydraulic brake application stroke and the low hysteresis coefficient. Compared with drum brakes, the steering is no longer caused to swerve or jerk when braking at high speeds, since there is no servo action. Furthermore, the new axles are capable of crossing water. For the average haulier, this is perhaps not so relevant, although it does offer him the distinct advantage of enhanced braking action on wet road surfaces.

Compared with pneumatic brakes, the brake power is available to be applied more quickly with hydraulic disc brakes. This is particularly true when driving long combinations com-prising numerous axle lines.

Compared with drum brakes, changing the brake pads on brake discs is virtually child`s play, saving as much as 10 hours per axle line. With combinations that normally comprise 6 to 20 axle lines, this translates into huge cost savings for the haulier. No special tools are required any longer for changing the brake pads. The simple design leads to lower failure rates when replacing the brake pads. A further advantage in terms of maintenance is the reduction by 4 lubricating points per pendulum axle, i.e. 8 lubricating points per axle line and the lower number of mechanical components, with the brake anchor shafts and slack adjusters disappearing completely. The ABS sensors are easily accessible from the outside and can also be removed and replaced with ease. There is no danger of damaging the brake cylinders when running over high roadside curbs, as the brake cylinders no longer protrude over the dynamic wheel diameter.

Particular attention was devoted to retaining the ability to couple these with older bogies still fitted with drum brakes. This ensures that the haulier does not encounter problems in build-ing up and augmenting his existing fleet with modular units. The necessary EU certificates for 12.0 to 16.0 ton axle loads at speeds of up to 80 km/h have already been obtained. The deployment of disc brakes in ultra-heavy trailers and semi-trailers marks a further milestone towards greater transport safety and reduced running costs for hauliers.