Friday 1 December 2017

Volvo 8400 Hybrid Low-Floor City Bus – Tech Specs, Review

Priced at around INR 2.3 crores, the Volvo 8400 Hybrid is entitled for a subsidy of INR 61 lakhs under the union government’s FAME scheme. 

Volvo Buses is now offering the 8400 low-floor diesel-hybrid buses in India. Few buses are already in their trial runs in the cities of Mumbai and Bangalore, with the company persuading state-owned metropolitan transport corporations of different cities for orders. The 8400 hybrid makes a great proposition for a sustainable urban mobility solutions for our Indian cities plagued with vehicular pollution. Being a parallel-hybrid system, the bus needs no dedicated infrastructure and is quite affordable that pure-electric buses.

The Volvo 8400 Hybrid is no different from the regular, diesel-powered 8400 range of city buses that are already in operation across Indian cities, except for the hybrid powertrain and related electronics. Based on the global Volvo B5RLE platform, the body structure of the buses are locally assembled, with superior build quality and fit and finish. It can seat 32 passengers in 2×2 seating layout, features two pneumatically-operated doors, and a simple and functional driver’s cockpit with suspended seat and fully-adjustable steering wheel.

But the high point of this bus is its hybrid technology. The powertrain consists of a 5-litre Volvo D5 4-cylinder turbo-diesel engine producing 215 hp and an electric motor of 160 hpoutput. Together, they produce a peak torque of 800 Nm. The longitudinally-placed diesel engine is paired to a 12-speed automatic transmission. An Electronic Control Module (ECM) regulates the synchronization of electric and the diesel motor, also influencing gear shifts, start/stop feature (for diesel engine), and battery recharging cycle.

The electric motor in the hybrid bus serves as both propulsion motor and as a generator. This permanent magnet motor is also the starter (integrated alternator) to the diesel engine using alternating current. It is aided by an energy converter for DC or AC conversion and a battery pack. While the brake-energy regeneration system charges the battery, something that is a boon for typical city-bus operations involving numerous stops and starts. The motor is said to offer considerable torque resulting in good performance at low speeds, especially when the bus starts from a standstill. Therefore, the diesel engine is not required for initial starts, bringing an operational benefit of reducing exhaust gases at bus stops with people nearby.

The hybrid system works this way.  Turn on the key, the electric power from the batteries are on your command. Remove the parking brake and accelerate, the bus moves without cranking the diesel engine. After reaching speeds between 20-25 kmph, the engine wakes up with seamless integration of power. The engine automatically shuts-off when the bus halts at stops or traffic lights, and comes alive whenever necessary. In case a failure in electric power, the bus can normally run on diesel power like a regular city-bus.

Volvo has concentrated more on energy-saving, by using individual electric motors for power-steering pump, AC compressor, and radiator cooling fan. They operate only when there is a need. The braking system is electrically-controlled, with all-disc brakes and ABS. The 8400 range is known for its pliant ride and optimum stability, with independent air suspension.

The Volvo 8400 Hybrid is one of the affordable ‘green’ city bus available on sale in India, with a promise of fuel saving up to 30 percent as against a diesel-powered bus. It’s lower emissions on travel and ‘zero-emissions’ when stationary perfectly matches urban bus operations in India, with frequent bumper-to-bumper traffic and stopping.