Setra presents four powerful models
The number one among urban regular-service buses is now even more attractive: in the new Citaro NGT, Mercedes-Benz offers an attractive alternative to the diesel-powered Citaro. The Citaro NGT (Natural Gas Technology) impresses with its quiet running and reduced CO2 emissions – both are crucial advantages in the heavy traffic of city centres. Practical people will be convinced furthermore by the Citaro NGT’s low weight and a correspondingly large number of passenger seats, the engine’s strong performance, low fuel consumption and extended maintenance intervals. Mercedes-Benz offers the new powertrain variant as a Citaro NGT solo bus and as a Citaro G NGT articulated bus. The Citaro NGT can be operated on natural gas or on renewable natural gas – in the latter case, the Citaro NGT is actually virtually CO2 neutral.
Clean and quiet through the city
The Mercedes-Benz Bus and Coach unit moves into high gear: the new Citaro NGT with natural gas engine sets standards in terms of environmental friendliness. The Citaro NGT is also approved for the use of renewable natural gas pursuant to DIN 51624 without restrictions. This makes the carbon footprint even more attractive because in this case the natural gas bus operates virtually CO2 neutral.
The natural gas engine has even lower noise levels than the already smooth-running and quiet OM 936 diesel engine, noticeable over the entire engine rev range. Depending on the driving status, its noise emissions are up to 4 dB(A) lower, which corresponds to the subjectively perceived noise level almost being cut by half.
Both factors – low CO2 emissions and noise levels – predestine the new Citaro NGT especially for use in packed city centres and for driving through residential areas.
Lightweight and robust gas bottles made of composite material
Under the cover are the newly developed gas bottles of the Citaro NGT. They are made of a composite material with a plastic core, a casing made of carbon fibres and – a new feature – additional glass fibres. This combination of materials is very lightweight on one hand and highly robust on the other. The gas bottles are filled from the engine compartment of the bus as standard. Optionally, the filler neck can be repositioned above the front right wheel arch, which corresponds to the position of the filler neck of the diesel-powered Citaro.
At the same time, the capacity of the new-generation gas bottles was increased considerably from 190 to 227 l. The advantage: the number of containers can be reduced while the overall volume remains the same. Compared with the predecessor model, the Citaro NGT therefore requires one gas bottle less while offering an unchanged operating range. This results in noticeable weight savings of 15 to 45 kg, depending on the number of gas bottles.
Low extra weight means more passengers
The additional weight of the Citaro NGT resulting primarily from the gas bottles has been reduced considerably compared with the predecessor. On a solo bus, this additional weight will be just 485 kg. Apart from the new gas bottle system, this also comes courtesy of the considerably more compact engine.
The passenger compartment of the Citaro is not affected at all by the natural gas drive. On the contrary: due to the weight savings, the passenger capacity of the Citaro NGT is significantly higher than that of the predecessor model. The Citaro NGT solo bus in standard specification now transports up to 96 instead of previously 93 passengers. The Citaro G NGT articulated bus has even a capacity of 153 passengers, up from 149 passengers previously.
New M 936 G gas engine: textbook example of downsizing
The new Mercedes-Benz M 936 G natural gas engine with a displacement of 7.7 l is presently the most compact natural gas engine in its class. It delivers the performance of a diesel engine while setting standards for noise and exhaust emissions. The engine is especially compact and lightweight. Weighing just 747 kg including the primary catalytic converter, it is about 230 kg or almost 25 percent lighter than the predecessor engine with a displacement of 12.0 l, making this engine a textbook example of successful downsizing.
The Mercedes-Benz M 936 G natural gas engine is based on the state-of-the-art OM 936 turbodiesel engine. This engine is already in successful use on board the Citaro and Citaro G Euro VI. The vertically installed six-cylinder mono-fuel engine runs on compressed natural gas (CNG). It has an output of 222 kW (302 hp) at 2000 rpm while delivering a peak torque of 1200 Nm consistently from 1200 to 1600 rpm. To some extent, it remains well below the Euro VI emission limits.
Fuel consumption reduced by about 15 to 20 percent
The new natural gas engine is extremely efficient. In concert with more intelligent control of the ancillaries, this results in a savings potential of around 15 to 20 percent for the Citaro NGT over the predecessor model. Even more energy savings can be expected in conjunction with the optional energy recovery module.
The intervals for changing the engine oil and spark plugs have been extended substantially in comparison with the previous engine, from 45,000 km to 60,000 km. Based on this practical metric, this means that a Citaro NGT driven for a typical urban-bus distance of about 60,000 km a year only has to be taken in for servicing once every 12 months.
Automatic transmission with torque converter
The power is transferred as usual by automatic transmissions with torque converter from ZF and Voith. The shift points and the use of the torque converter have been specially tailored to suit the new gas engine’s characteristics.The same applies to the available final drive ratios. Due to the different engine speeds, the development engineers have chosen standard final drive ratios that are one step shorter than those of the diesel engine in both cases, ergo i = 6.19 for the solo bus and i = 6.98 for the articulated bus.
With more than 7000 vehicles since its introduction in 2011, the current model series of the Citaro has not only continued the unmatched success of the predecessor model, it has even expanded on it. The basis for this success lies in the outstanding characteristics of the low-floor urban bus.
Setra line up
Setra demonstrated its prowess in design and comfort by lining up four powerful models – S 516 HDH of the TopClass 500, Double-decker coach S 431 DT, S 511 HD of the ComfortClass 500 and the low-entry bus S 415 LE business.
The S 516 HDH of the TopClass 500 embodies contemporary elegance and sophisticated vehicle technology in Kortrijk. The vehicles of this model series debuted in spring 2014. With the premium three-axle models, the brand presents a new travel experience which blends luxury and functionality at the highest level – with even more lengths. The 12.5-m S 515 HDH, the S 516 HDH with a length of 13.3 m plus the 14.2-m S 517 HDH embody the design, value appeal and safety aspects in a unique way and form.
Enlarged wheelbases compared with the predecessor model series ensure a luggage compartment volume enlarged by 0.6 m3 for all three variants. In the interior, the passengers relax on comfortable chair-like seats and enjoy a superior travel experience with a widened TopSky Panorama glass roof, homogeneous climate control and a new lighting concept. They are the flagships of the Setra product range that also convince renowned designers. The Setra TopClass 500 touring coaches were already honoured with the “Red Dot Product Design Award 2014”, one of the world’s most coveted quality seals for outstanding design.
The S 431 DT double-decker coaches, the largest in the Setra family, with a Euro VI powertrain of the “Blue Efficiency Power” engine generation continue to be integral components of the current product range. These Setra TopClass 400 buses boast more than 40 new features compared with their Euro V predecessors. These include a revised cockpit with a new multifunction steering wheel, two staircases as standard and a luggage compartment door that is 23 cm wider. The popularity of the three-axle vehicle in Europe is demonstrated by a proud number. Italian bus operator “Autolinee Marino” took possession of the 2500th doubler-decker Setra made in Neu-Ulm just a few weeks ago. The anniversary bus was also the 250th vehicle of this model equipped with a Euro VI engine.
In the S 511 HD, Setra puts a vehicle in the limelight that makes the tradition of the club bus come alive in a new dimension. Exactly 60 years after the world premiere of the first Setra compact bus, an S 6 introduced at the Geneva Motor Show in 1955, visitors to this year’s Busworld show got an idea of what a modern bus all has to offer for exclusive club journeys or excursions. The S 511 HD is a member of the Setra ComfortClass 500 presented in 2012, which in a spectacular Record Run event has demonstrated maximum energy efficiency with fuel savings of 8.2 percent over the reference model.
Just a year after its market launch, this innovative generation of coaches was voted “Coach of the Year 2014” on top of receiving the “Green Coach Award 2014” in recognition of its low fuel consumption. In the autumn of 2014, Setra presented another four vehicles of the ComfortClass 500, which means that the model series is now complete with a total of eight models. Setra delivered the 500th vehicle of the ComfortClass 500 to a German customer just a few short weeks ago.
The interior of the S 415 LE business is efficient and robust. The efficient low-entry regular-service intercity vehicle of the Setra MultiClass combines low-floor and high-floor technology as well as economic efficiency and functionality in an unprecedented manner. It is perfect for winning tenders. Bus operators can choose from two MultiClass LE business models as two-axle vehicles, three MultiClass UL business models as two-axle vehicles and five classic MultiClass UL and two H models.
Under the bonnet of the S 415 LE business is a Euro VI Mercedes-Benz OM 936 with a displacement of 7.7 l and a rated output of 260 kW (354 hp), which provides fuel-efficient propulsion in conjunction with a six-speed ZF automatic transmission. The vehicle on display is equipped with the Electronic Stability Program ESP, the acceleration skid control system ASR and BA Brake Assist.