Dipl. Ing. Martin Hrdlička, PhD.
ŠKODA AUTO,Technical Development
What do engineers have to consider when developing all-wheel-drive models?
To optimally design all-wheel-drive vehicles, the variants must be an integral part of vehicle development right from the very start. For its current models, ŠKODA AUTO uses Volkswagen Group’s modern modular transverse matrix, the MQB, which not only makes development easier, but also faster. Every variant in a model range has its own specific design. To this end, the optimal components are chosen, including the shock absorbers, springs, stabilizers, wheels, tyres or all of the electrical system settings. The chosen solution then undergoes a variety of tests. All-wheel drive also has an influence on where components are positioned including, for example, the fuel tank, exhaust system and not least the bodywork. The 4×4 drive system fundamentally changes the vehicle’s weight distribution on its axles, the centre of gravity and thereby the vehicle’s driving dynamics as well.
The all-wheel-drive system used in the current ŠKODA OCTAVIA, SUPERB, KAROQ and KODIAQ models comes with an electronically controlled multi-plate clutch. Are there variations between different models?
The electronically controlled multi-plate clutch is structurally identical in every ŠKODA model. Every model does, however, feature individual calibration for the all-wheel-drive software that corresponds to parameters for each vehicle such as the wheelbase, centre of gravity or engine.
What other differences are there between the ŠKODA 4×4 models, besides the multi-plate clutch?
As well as the components used in the all-wheel-drive system itself, that is to say the front differential, the propshaft featuring a Hardy coupling or the 4×4 coupling with the rear transmission, numerous other components have to be modified. These include chassis settings or the rear axle with its independent suspension and in some cases it could even be the fuel tank, exhaust system and parts of the floor assembly.
Can you provide specific examples that illustrate the technical progress in ŠKODA 4×4 vehicles since 1999?
Thanks to the multi-plate clutch’s predictive behavior and the ESC, XDS+ and TCS electronic stability systems’ gentle interventions, the driver can also drive safely in situations that would have previously required them to considerably reduce their speed. The first generation of the 4×4 multi-plate clutch could only regulate the difference in speeds at the axles. In comparison to that first generation, the current 4×4 drive system is 6 kg lighter, which, amongst other things, has noticeably reduced fuel consumption. The centrifugal valve integrated into the electronic pump enables the clutch to be fully engaged even when the vehicle is stationary.
It has also improved traction when pulling away, regardless of the conditions, but particularly when towing a trailer or performing a hill start on snow. We offer Off-Road mode in several models, which significantly improves the driving characteristics on rough terrain at speeds up to 30 km/h. This even applies in difficult conditions, including on steep descents or when driving on slippery surfaces. Any driving maneuver can easily be mastered in all-wheel-drive vehicle – whether on motorways or on challenging terrain.
How has the clutch switching speed changed between the 1st and 5th generations?
The clutch switching speed for the current 5th generation is, for example at a differential speed between the front and rear axle of 25 rpm, three times faster than that of the 1st generation.
Does the 4×4 drive system have specific maintenance or service intervals?
The progressive development of the multi-plate clutch has significantly reduced the need for maintenance in 4×4 vehicles. Previously, the clutch required an oil change every 60,000 km, and the oil filter also had to be changed. Now, only the oil in the multi-plate clutch has to be changed every three years. Nowadays, the modern all-wheel-drive system requires no further maintenance.