Mercedes-Benz O405
Bus 86: SBS Transit Mercedes-Benz O405 CAC (SBS3921Z)
Manufacturer	Mercedes-Benz
Bodywork	Walter Alexander Duple Metsec
Years in operation	1990-2011
Operators	SBS Transit Former: SBS
Technical Data
Length	12 metre
Engine	Mercedes-Benz OM 447 h
Transmission	Mercedes-Benz W3E 110/2.2 R Voith DIWA 851.2 ZF Ecomat 4HP 500
Accessibility	High Floor
Emission Standard	NA

The Mercedes-Benz O405 is a rear-engined single-deck transit bus built by Mercedes-Benz from the mid-1980s to the early 2000s. As the successor of the Mercedes-Benz O305 chassis, it was highly successful, with many units operating in Europe, Australia and Singapore.

Both major public bus operators in Singapore, Singapore Bus Services (SBS) and Trans-Island Bus Services (TIBS), acquired a total of over 1000 units between 1990 and 2000 over many different variants of bodywork. 700 units obtained by SBS were of the Mark-I make, while the 323 units obtained by TIBS were of the Mark-II make.

This article will only cover Mercedes-Benz O405 buses in SBS’ and SBS Transit’s fleet only.

Technical Information:

The Mercedes-Benz O405 was the successor to the Mercedes-Benz O305, which ceased production in 1987. It was sold to many bus operators in Europe, Australia and Singapore. The O405 was produced in two generations, designated as O405 MkI and O405 MkII.

The O405 MkI (mid-1980s to early-1990s) featured a naturally aspirated Mercedes-Benz OM447h engine with either a 210-horsepower or 250-horsepower output, coupled with a Mercedes-Benz W3E110/2.2R or W3E112/2.2R gearbox. A compressed natural gas (CNG) 205-horsepower Mercedes-Benz M447hG engine was also offered. Gearbox options included other Voith, ZF or Allison gearboxes. All units acquired by SBS were of the Mk I type.

The O405 MkII (early-1990s to early-2000s) featured a turbocharged 250-horsepower Mercedes-Benz OM447hA engine. Naturally aspirated engines, turbocharged+inter-cooled engines & CNG engine options were available. Gearbox options included other Voith or ZF gearboxes. All units acquired by TIBS were of the Mk II type.

Apart from providing an integral bodywork, the O405 is compatible with many other types of bodywork. An articulated version of this chassis was also produced, the Mercedes-Benz O405G. The low-floor version of the O405 was known as the O405N (or O 405 GN for articulated version). A low-entry variant, the O405NH, was also produced, targeted towards the Australia market.

The Mercedes-Benz O405 and O405N series were superseded by the Citaro, and the O405NH was superseded by the OC500LE.

SBS Transit Mercedes-Benz O405 [Overview]

A total of 700 units of the Mercedes-Benz O405 was procured by SBS Transit’s predecessor, Singapore Bus Services (SBS), in two bodywork variants.

Between the Duple Metsec bodied units, two specifications emerged: Original Air-conditioned (OAC) buses with full-sized windows (300 units), and Non-air-conditioned (NAC) buses with sliding windows (200 units), to give commuters a choice between buses back when air-conditioned buses were regarded as a luxury (and charge higher fares). Eventually, when AC buses were becoming standard, air-conditioning units were installed onto existing NAC buses, earning them the designation Converted Air-conditioned (CAC).

Finally, the remaining 200 units were bodied with the Walter Alexander bodywork, all of which were delivered as air-conditioned buses.

Many Mercedes-Benz O405 buses share similar technical specifications. Here’s a table at a glance:

SBS Transit Mercedes-Benz O405
	Mercedes-Benz O405 (Walter Alexander)	Mercedes-Benz O405 (Duple Metsec, OAC)	Mercedes-Benz O405 (Duple Metsec, CAC)
Registration No.	SBS82P – SBS281R	SBS282D – SBS581R	SBS3723D – SBS3922X
Quantity	200	300	200
Registered Date	02 Jul 1990 – 02 Sep 1991	04 Jan 1991 – 06 Nov 1992	13 Oct 1990 – 02 Apr 1992
	Technical Specifications
Engine	Mercedes-Benz OM 447 h engine, 11967cc turbocharged Power /Torque rating of 250 hp (184 kW) @ 2200 rpm / 890 Nm @ 1300 rpm
Transmission	Mercedes-Benz W3E 110/2.2 R Voith DIWA 851.2* ZF Ecomat 4HP 500**
Bodywork	Walter Alexander PS	Duple Metsec	Duple Metsec
Capacity	Seating: 47 + Standing: 30 = 87 total After Refurbishment: Seating: 41 + Standing: 42 = 83 total	Seating: 47 + Standing: 38 = 85 total After Refurbishment:*** Seating: 41 + Standing: 50 = 91 total	Seating: 47 + Standing: 38 = 85 total After Refurbishment: Seating: 41 + Standing: 50 = 91 total
Air-conditioning	Webasto and Fuji (SBS182J – SBS281G)	Fuji and Sütrak AC 35	Webasto and Carrier Sütrak AC 350
Remarks	All buses were originally fitted with the Mercedes-Benz W3E 110/2.2 R transmission, with Voith and ZF units later replacing them on several buses: * Voith DIWA 851.2 buses: (SBS87B, SBS549K, SBS550E, SBS552A – SBS554U, SBS557L – SBS559G, SBS562X – SBS581R) ZF Ecomat 4HP 500 buses: (SBS414R, SBS441L, SBS484M, SBS496D, SBS497B, SBS530M, SBS533E, SBS551C, SBS3836L, SBS3841X, SBS3899E, SBS3922X) * All buses except SBS293Y and SBS310G

All 700 buses were assembled in Singapore using complete-knock-down (CKD) kits. Roughly half were assembled by SBS’ own engineering division based out of Woodlands Depot, while the remainder was subcontracted to local coachbuilder Soon Chow.

SBS Mercedes-Benz O405 (Walter Alexander) OAC:

In 1990, Singapore Bus Service (SBS) brought in 200 units of the Mercedes-Benz O405 of the Mark-I type. They were registered between 02 Jul 1990 – 02 Sep 1991 as SBS82P – SBS281R. Bodywork was supplied by Walter Alexander Coachbuilders of Scotland and all buses were delivered with air-conditioning.

Following their retirement, selected units were sold as second-hand buses to Bangkok, where they were retrofitted with Compressed Natural Gas (CNG) engines and put into service on air-conditioned local bus routes.

SBS Mercedes-Benz O405 (Duple Metsec) OAC:

Following the 200 Walter Alexander-bodied units, a further 500 Mercedes-Benz O405 buses were brought in with the Duple Metsec bodywork. Singapore Bus Service (SBS) brought in 300 units fitted with air-conditioning, registered between 04 Jan 1991 – 06 Nov 1992 as SBS282D – SBS581R. Bodywork was supplied by Duple Metsec of England and all buses were delivered with air-conditioning. The remaining 200 buses would not be delivered with air-conditioning.

SBS468K was converted into a mobile library following its retirement. “Molly, The Mobile Library”, an initiative by the National Library Board, was launched on 3 April 2008 and registered XD2037B. It would be replaced by a Volvo B10M MkIV Strider in 2012.

SBS Mercedes-Benz O405 (Duple Metsec) CAC:

Following the 200 Walter Alexander-bodied units, a further 500 Mercedes-Benz O405 buses were brought in with the Duple Metsec bodywork. Among these buses, Singapore Bus Service (SBS) brought in 200 units fitted without air-conditioning, registered between 13 Oct 1990 – 02 Apr 1992 as SBS3723D – SBS3922X. Bodywork was supplied by Duple Metsec of England.

Originally non-air-conditioned, they were introduced in an era where air-conditioned travel was a comfort and air-conditioned buses charged higher fares. Such non-air-conditioned (NAC) buses provided commuters with a choice between AC and NAC buses. Eventually, when AC buses were becoming standard, air-conditioning units were installed onto existing NAC buses, giving them the converted air-con (CAC) designation. Sliding windows were also replaced with full window panes.

Some of these buses were re-registered as Private Hire Buses (bearing the PA prefix) and re-deployed to Jurong Island Bus Services which SBS operated under contract. They also bore the SBS Leisure livery of red curved lines over a white background; a slight deviation from the standard SBS livery of the time. These buses were reverted back to their original registration plates following the end of the contract period, but retained the SBS Leisure for a period of time thereafter.