MAN Truck & Bus

MAN HydroDrive

Grafik HydroDrive
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Main and functional components The main components in a MAN HydroDrive are A) hydrostatic wheel-hub motor B) hydraulic line C) hydro pump D) hydraulic fluid cooler. The functional diagram shows a) supply line b) drain pipe 1) cylinder block 2) piston 3) rollers 4) cam ring 5) distributor disc 6) drain hole 7) falling cam flank 8) rising cam flank 9) inlet hole 10) bottom dead centre 11) top dead centre. 

MAN HydroDrive is a switchable front-wheel drive for situations where traction is critical. In contrast to conventional (mechanical) all-wheel drive, which is designed for continuous operation at any speed, our MAN HydroDrive switchable hydrostatic front-wheel drive is an ideal drive for deployments with an occasional off-road element and for situations where additional, short-term traction is required on the front axle. Vehicles with MAN HydroDrive are therefore primarily road vehicles whose deployment range is expanded by the hydrostatic front-wheel drive. The transmissible torque from the HydroDrive wheel-hub motors is sufficient for all deployment cases to cover the maximum transmissible traction from the front axle. Typical applications are on unpaved roads, smooth surfaces and route profiles with mountainous topography. 


MAN HydroDrive compared to mechanical all-wheel drive 

MAN HydroDrive saves up to 400 kilogrammes weightcompared to conventional all-wheel drive because there is no need for transmission elements to the front axle, such as transfer case and cardan shaft. Fuel consumption during normal road operation (front axle drive switched off) is lower, since friction losses due to constant corresponding movements in transmission elements do not arise. A MAN HydroDrive with straight front axle (medium height body) is lower than a conventional all-wheel drive (high body), but offers the same ground clearance beneath the axles. The range of applications from long-distance traffic to special vehicles is wider, since MAN HydroDrive does not result in any restrictions regarding body height, manoeuvrability, cab choice or axles. 


MAN HydroDrive compared to rear-wheel drive 

MAN HydroDrive with a top-offset front axle (normal height body) has the same body height as a road vehicle. MAN HydroDrive offers a significant increase in traction on slippery surfaces. The effect of our MAN HydroDrive is particularly efficient when driving empty and manoeuvring with low rear axle loads. Climbing ability on a paved surface based on the example of an unladen tractor unit without all-wheel drive is only a maximum of around 7.5 per cent. Even gradients of 20 per cent can be overcome using our MAN HydroDrive. Deployment flexibility is greater, because even difficult driving situations and deployment conditions can be mastered by the selectable front-wheel drive. Payload and fuel consumption are at the level of a vehicle with pure rear-wheel drive.