Mercedes-Benz O500U Review

A rejuvenated Mercedes-Benz Bus and Coach group, complete with a new general manager and new product, is hungry for market share in Australia. Gary Worrall took the first of the new low floor route buses for a test drive

Funny thing about prodding one of the world’s biggest vehicle manufacturers, they may take a little while to respond, but when they do, be ready for fireworks.

This is particularly the case with the bus division of Mercedes-Benz. It may have eased out of the city bus stoush for a while, but now it is back with a new 7-litre power plant and a new chassis, and a determination to take a bigger piece of the pie.

Recently-arrived General Manager Jan Moreth says the company is a leader in the 12-litre engine segment, and is now chasing market share from Swedish rival Volvo in the 7-litre arena.

Armed with the Euro 5 version of the O500U low entry route bus, Moreth and National Sales Manager Grant Simmonds are excited about the prospect of conquest sales, and believe they have the right bus for the right task.

Not surprisingly the issue of oddball Australian regulations entered the conversation early, with Moreth pointing out Mercedes-Benz restricts itself to supplying buggy kits into Australia because of the maximum body width of 2.5m on local roads.

Mercedes-Benz builds a 2.55m wide version of the O500U for Europe and other markets which could be offered locally, however governments would need to allow the extra 5cm of body width for it to be legal.

While Moreth did not say it, the reality is mass production buses conforming to a global standard could be sold for less than a re-engineered model with low production runs incorporating numerous ‘one-off’ components such as body panels and windows.

Despite the recent problems with Sydney Transit Authority (STA) buses running on compressed natural gas (CNG), Moreth says CNG remains an integral part of the Benz line-up.

“CNG is part of our armoury, we can supply whatever the customer needs, whether it is CNG, diesel or even fuel cells,” Moreth says.

“There is some resistance to SCR and AdBlue, but the majority are accepting it is part of the future.”

Terminus, all change

Instead, Mercedes-Benz works closely with local and international body builders including Custom Coaches, Volgren and Marcopolo to develop Australian-only solutions, such as noise and heat issues.

“We work with the body manufacturer to ensure noise, or dirt and dust contamination is not an issue, things like drive-by noise levels, or ensuring the body helps keeps the radiator clean,” Moreth says.

The buggy kits are sent to the body builders for construction, along with a set of directions on how certain elements must be fitted, to ensure compliance and correct operation, with a local engineering manager checking on the ‘chassis/body interface’ before the bus enters service.

Moreth says two versions of the O500 chassis are imported from the South American factory, the low floor ‘U’ and the ‘R’, which includes extras such as seat belt mounts and is supplied generally as a school or charter bus, with a number seeing service in regional areas carrying miners to and from worksites.

The buses share common specifications, including the 7.2-litre OM 926LA engine, a six cylinder, three valve per cylinder design, running SCR for the emission control, with a ZF Ecomat 6-speed automatic putting the power to the ground.

This allows Benz to run a common spare parts catalogue, helping control the ‘whole of life’ costs of the bus, something that Grant Simmonds says is not being properly considered in all bus contracts.

“Governments are looking at the capital cost of the vehicle, not the whole of life cost, and that is making the market price sensitive,” Simmonds says.

All aboard

The first of the O500U models to arrive went to Volgren to have an Australian-spec route service body fitted, complete with wheelchair access ramp and seating area.

This is a body Volgren has built for numerous transport contracts and includes a common control panel, fitted regardless of chassis supplier to ensure driver familiarity across different brands.

While there was no questioning the fitout and overall body construction, which was of the highest order, there were a number of faults that should have been identified prior to delivery.

The most audible was a hammering noise – similar to ‘water hammer’ when an air bubble is trapped in a sealed water pipe – when the air suspension raised and lowered the bus.

The other significant issue was the actual switches for the air suspension, the raise and kneel button appeared to be cross-wired so that to lower the bus the rocker switch was pushed towards ‘raise’, and then the ‘kneel’ button was pushed to bring it back to normal ride height.

While this would undoubtedly be rectified before entering service, it was annoying that it had not been spotted before hand over to Mercedes-Benz.

The third, and probably most significant problem centred on the transmission retarder, which Simmonds says drivers should be able to set so that the first stage of retardation activates when the throttle is released, as a speed regulator.

Unfortunately, on this bus it appears the switch is set so that it only cut in when the brakes are used, shortening the life of brake linings and decreasing the ride quality for passengers as the combined brake effort tends to throw people forward in their seats.

Interestingly, the wheelchair ramp is manually lowered and raised by the driver, requiring them to leave the bus, particularly to raise the ramp after use, with potential health and safety implications, not to mention timetable discrepancies.

This is not to say ramps should not be offered, but perhaps a hydraulically operated ramp may be a better solution for route service operations.

Move to the back please

The driving seat offers a good view of the bus interior, with a ‘periscope’ mirror arrangement where a front-mounted mirror picks up the reflection from another mirror above the centre door, allowing the driver to ensure the doorway is clear before the door is closed or the bus moves off.

The Isri suspension seat with integrated seatbelt is comfortable, offering good support for the driver as well as damping out the worst of the pot holes common to urban Australia.

The bus runs on airbag suspension, with two bags on the front end and four at the rear. With the back seat commandeered during the test the ride was declared comfortable, despite deliberately seeking some testing road surfaces to see how the suspension coped.

While similar size trucks are now offering reversing cameras on the option list, the O500U relies on pillar mounted mirrors, the driver’s side is mounted low, around eye level, while the passenger side sits high on the A-Pillar for a view down the body above passenger height, helping spot any blockages or hold ups around the centre door.

As expected when the engine is roughly 12m behind the driver, there is virtually no engine noise on start up, and only a distinct, but not troubling, thrum during normal driving.

The ZF auto uses a push-button console, with buttons for drive, neutral and reverse, to protect the transmission it must be neutralised when shifting between drive and reverse, although momentarily slower in operation it is significantly cheaper in maintenance bills.

With plenty of time driving ZF transmissions in buses and trucks I am a big fan, with lightly slurred shifts for optimum driver and passenger comfort, heavy acceleration does cause more defined shifts however even a slight easing of the throttle reduces driveline shock significantly.

As mentioned previously, the retarder switch was modified so that it only operated with the brakes, which Simmonds says is not the normal method, making brake applications harsher than planned and causing a bit of passenger discomfort.

The retarder is strong, providing plenty of brake assistance, while we managed to avoid using the ’emergency’ mode as traffic was with us and not against us, there is plenty in reserve for when things go bad.

The OM 926LA Benz motor offers 225kW of power, but more importantly there is 1,170Nm of torque, which propels the 16-tonne GVM O500U along city streets with minimal fuss.

Our test route took in the Mulgrave and Glen Waverly areas of suburban Melbourne, including a long stretch at 80km/h, and there was never a problem matching traffic speeds, even from a standing start in the traffic light grand prix.

Given Volgren’s years of experience in designing and building route buses the sightlines on the new Benz are exemplary, the massive windscreen offers plenty of vision not just ahead but also to the sides.

An example of this is the high mount left hand mirror, not only does it improve vision down the kerb side, but it provides drivers with a clearer line of sight at T-intersections, long a bugbear of buses fitted with Euro-style mirrors that sacrifice side vision for a clear rear view, where this offers the best of both worlds.

Mind your step

The other test for a route bus is to see how easy it is to get in and out for passengers, unfortunately this particular bus offered mixed results at best.

While there is no problem with pulling in and out of the kerb, courtesy of variable rate steering that tightens the turning circle as the driver applies more lock, the mis-labelled or cross-wired suspension switches made for a couple of interesting stops.

Pulling tight against the kerb allowed the suspension to be dropped to its lowest point, with editor Goeldner the crash-test dummy for stepping on and off to test step heights.

As expected these were deemed acceptable, it was just disappointing the suspension did not work according to the dash labels.

The other big surprise was the weight of the wheelchair ramp. It is quite heavy, obviously for strength, however a smaller stature driver could have issues with opening and closing it safely, as it fits into a floor recess so that the driver has to bend down to pick it up, with potential OH&S implications.

End of the line

With a solid chunk of the 12-litre market in their possession it is no surprise Mercedes-Benz is now chasing the 7-lite segment, and the O500U is a good starting point.

It has more than enough power for top weight route service operations, and rides and handles well, with solid braking, while the driver has good all-round vision to make it a stress-free day in the office.

While there are some questions over the specific body fitted to the demonstration unit that are not the fault of Mercedes-Benz, it is not hard to imagine they would want it perfect before it is handed over to potential customers.

As Grant Simmonds pointed out, the route service market with its attendant government contracts is price sensitive, so to justify every cent of cost to operators Simmonds and Moreth need to ensure they are showing a top quality product.

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