Sunlong SLK6121UF14H

Sunlong SLK6121UF14H
SBS Transit Sunlong SLK6121UF14H
SBS Transit Sunlong SLK6121UF14H
Manufacturer Sunlong Bus
Bodywork Sunlong Integral
(Assembled by Gemilang Coachwork)
Years in operation 2010 – 2019
Operators Republic Express
Travel GSH
SBS Transit (Former)
Technical Data
Length 12 metre
Engine Dongfeng Cummins ISDe230-41
Transmission Eaton UltraShift F0-6406A-ASW
Accessibility Low Entry & Wheelchair-accessible
Emission Standard Euro IV  (SCR)

The Sunlong SLK6121UF14H is a rear-engined single-deck hybrid city bus built by Chinese manufacturer Sunlong Bus. The chassis is derived from the SLK6111 line of urban city buses, with the addition of a hybrid drive system developed by Eaton.

SBS Transit acquired two units in 2010 for demonstration purposes. They were taken out of service after their one-year trial period and sold to other operators.

Technical Information:

The bus relies on a parallel hybrid system, running on both diesel and electricity, which achieves up to 30% fuel savings. By using electricity to power the bus during periods of high energy demand, less strain is put on the combustion engine, hence lowering fuel consumption and emissions.

Electricity is generated during cruising and regenerative braking, and stored in four Lithium-ion batteries. The energy in the batteries is released to assist the engine in powering the vehicle. Hence, the engine is less strained while accelerating or going up hills, reducing fuel consumption.

The bus uses a parallel hybrid system that is developed by Eaton Corporation of the United States, where a motor/generator is used to convert the electrical energy into mechanical energy and vice versa.

Introduced in 2010, a similar diesel-electric hybrid bus was trialled by SMRT Buses, with a Zhongtong LCK6121GHEV bus introduced the following year (SMB137A).

SBS Transit Sunlong SLK6121UF14H Demonstrators (SBS8000Z / SBS8001X):

Two¬†Sunlong SLK6121UF14H¬†buses were brought in by ComfortDelGro Engineering, in collaboration with Shanghai Sunlong Bus Company and Gemilang Coachworks of Malaysia.¬†They were both registered on¬†17 July 2010 as¬†SBS8000Z and SBS8001X, as SBS Transit’s first ever China-made buses and hybrid-electric buses.

Basic Technical Specifications
Engine Dongfeng Cummins ISDe230-41, 6700 cc
Power rating of 230 hp (169 kW) @ 2300 rpm
Torque rating of 900 Nm @ 1200 – 1700 rpm
Motor Eaton Hybrid Electric Power System
Electric motor rated at 60 hp (44 kW) / 420 Nm
Emissions control Euro IV compliant
Selective Catalytic Reduction (SCR) technology requiring diesel exhaust fluids such as AdBlue.
Transmission Eaton UltraShift F0-6406A-ASW gearbox
Six-speed automatic
Bodywork Sunlong Integral bodywork
Completely-knock-down (CKD) kits assembled by Gemilang Coachworks in Malaysia, and delivered to Singapore fully assembled
EDS Hanover Electronic Display Signage (EDS)
Orange LED matrix

The bus was launched on 20 Jul 2010 at Comfort Delgro headquarters within Braddell Bus Park. Both units began revenue service on 8 August 2010, on Bus Service 185 between Soon Lee Depot and Buona Vista, where they spent most of their trial period.

The year-long trial period saw both buses running on Bus Services 185, 334 and Express Services 502 and 502A.

Following the end of their trial in early 2012, both buses were deregistered and returned to ComfortDelgro Engineering. They were later sold to private operators. Their high cost and unproven reliability in the Singapore climate were reasons that the LTA chose not to adopt diesel hybrid buses on a wider scale at that time.

Trial Results

In May 2015,¬†Transport Minister Lui Tuck Yew revealed that¬†the Sunlong diesel-hybrid bus trial was estimated to cost¬†S$1.7 million. The figure, provided by ComfortDelGro Engineering, had partnered with the Land Transport Authority (LTA) for the trials, with LTA’s share amounting to about S$660,000.

The trials had indicated an improvement in fuel efficiency by about 25 per cent, while the results were less conclusive for emissions. Mr Lui added that fuel savings were also insufficient to offset the 140 percent higher cost compared to normal diesel-powered buses.

In 2015, SBS Transit trialled another diesel-hybrid bus, a Volvo B5RLE Hybrid, at the manufacturer’s initiative, with no government funding.

Republic Express:

SBS8000Z was acquired by private operator Republic Express and registered as PC2677D in 2014. It currently bears a white and brown corporate livery.

The bus is often sighted plying a shuttle service between HarbourFront Interchange and PCG/CDMC (Police Coast Guard / Civil Defence Marine Command) at Pulau Brani. It has also been sighted on the Tanah Merah MRT РChangi Airbase (East) shuttle, and the Marina Square Lunch Time shuttle service.

Travel GSH:

SBS8001X was initially acquired by Dnata and used as an apron bus, operating within the airside areas of Changi Airport. An exemption order [Road Traffic (Changi Airport Terminal Shuttle Bus) (Exemption) Order 2012] was made to allow this bus to operate from 25th September 2012 to 31st March 2013 (both dates inclusive).

It was later acquired by Travel GSH Pte Ltd and registered as PC3847Z. The same company also acquired the Zhongtong LCK6121GHEV diesel-hybrid bus previously operated by SMRT.

Additional Specifications:

SBS8000Z and SBS8001X each have a total licensed capacity of 80 passengers, including 33 seating, 47 standing, and one passenger-in-wheelchair. A manually-operated wheelchair ramp at the exit door allows for disabled access.

Both PC2677D and PC3847Z were de-registered in 2019.


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