But let us return to the mid-nineties with their tremendous innovative leap forward. Things were happening at the upper end of the van scale too.
The Vario (formerly T2 and now with an upgraded exterior) defined its sphere of operation as the broad field between 4.8 and 7.5 tonnes gross vehicle weight. The model range now extended from the 507 D to the heavyweight 811 D. More spectacular than the touch-up work to the sheet metal and interior, however, was what happened under the small bonnet of the Vario. A representative of the new 900 series now did service there, superseding the highly respected and regularly updated pair of veterans, the OM 364 and OM 366.
Premiere of the 900 engines in the van
The 900 series engines were all-new developments that had recently been premiered in the light-duty class. The engine used three valves per cylinder for breathing: two were intake valves, the third an exhaust valve. Individual pumps per cylinder drove the diesel fuel, metered with extreme precision, into the combustion chambers at high pressure, atomising the fuel with a maximum pressure of 1600 bar. An additional constantly open throttle valve (the 400 series engines stood model) was an option available to beef up the engine brake. And the engine management system made use of advanced electronics. From the outset these engines were prepared for the Euro 3 emission standard coming in 2000.
These engines were based on a modular system that gave rise to a four-cylinder with 4.25 litres and a six-cylinder with 6.4 litres displacement. In relation to displacement, their torque was remarkable. Outputs ranged from 90 to 205 kW. Christened “Eco Power” engines, these power plants were designed both for high mileage and long maintenance intervals. An all-electronic monitoring system prevented engine overload.
The 2.9-litre diesel with direct injection and charge air cooling (OM 602 LA) already had proven itself in the Vario’s little brother, the Sprinter. The five-cylinder with a rated output of 90 kW at 3800 rpm and peak torque of 280 Nm at 2000-2300 rpm impressed with high torque, economical operation, low pollutant emissions, very smooth running characteristics, and low noise generation. A distributor pump handled the supply of diesel fuel.
The internally ventilated disc brakes on all four wheels were a boon to active safety. A hydraulic dual-circuit brake system with vacuum assist was the production configuration; for the 612 D model upwards, an air/hydraulic brake system was available. A compressed-air spring brake served as parking brake.
All-wheel drive not long in coming
Shortly after the Vario was launched, Mercedes-Benz presented the large-capacity van also in an all-wheel-drive version (814 DA). As it is, the Vario was improved upon several times during its career. Through load uprating and load derating it covered a gross weight span from 4.8 to 8.2 tonnes. In 1998 all models were fitted with ABS and the output of the most powerful engine changed to 112 kW. From autumn 2000 the Vario was available with engines built to satisfy the Euro 3 emissions standard. The compact five-cylinder was dropped, replaced by an 85 kW variant of the big four-cylinder. Two years later the output range was reshuffled and featured engines with 100 kW, 110 kW and 130 kW, the most powerful of these being combined with a six-speed manual transmission as standard.
The Vario got its last spate of innovations for the time being at the 2006 International Commercial Vehicle Show (IAA): BlueTEC diesel engines with SCR technology to enable it to comply with the Euro 4 emissions standard. The engine outputs are now 95 kW, 115 kW and 130 kW. All Vario models now have a six-speed manual transmission as standard and can be optionally equipped with a five-speed automatic transmission with torque converter. New trim panels enhance the interior of the cab.
Source: Daimler AG