Thomas Saf-T-Liner C2
|Thomas Saf-T-Liner C2|
Front 3/4 view
Interior view, looking back
|Manufacturer||Thomas Built Buses|
|Assembly||High Point, North Carolina|
|Body and chassis|
|Related||Freightliner M2 Business Class|
|Width||96 in (2,438 mm)|
|Curb weight||18,000–35,000 lb (8,165–15,876 kg) (GVWR)|
The Thomas Saf-T-Liner C2 (often shortened to C2) is a Type C (conventional-style) school bus produced by Thomas Built Buses. In production since 2004, the C2 is based on a Freightliner C2 chassis, itself derived from the Freightliner M2 Business Class medium-duty conventional. It was introduced as the replacement for the Thomas Conventional and Thomas Saf-T-Liner FS-65; the latter was produced alongside the C2 until December 2006. Due to elements of its design, the C2 can also be considered the successor to the Vista line of Type C buses from the 1990s.
The C2 is unique in that it is available in capacities up to 81 passengers, the largest of any type C conventional school bus in current production. It is visually distinguished from its competitors' type C school buses by its low, sloped hood and a large, curved, bonded windshield, said to resist chips by more effectively deflecting objects. The windshield is sloped back and corners on the bus' front end are smoothed out to produce a more streamlined appearance. Even the flashing warning lights at the top of the vehicle are made flush with the windscreen.
In addition to a unique outward appearance, the C2 makes use of modern manufacturing techniques. Many joints use adhesive bonding, reducing or eliminating the need for welds or rivets in many cases. Where required, self-piercing rivets are used, which ideally do not punch through the bottom layer of the metals being joined together, thus reducing the chance that rivets will become the source of leaks in the future.
While the large windshield is an obvious place where there is more window area, other windows have been expanded on the C2 as well, both increasing viewing area and increasing the size of emergency exits which are in removable window frames. The rear windows and rear emergency exit door have also been expanded compared to previous Thomas buses.
Another claimed innovation is the introduction of a multiplexed wiring system, where multiple electrical devices communicate over the same wires, rather than being individually wired. This reduces the number of wires running through the vehicle, which can help reduce maintenance in the future. In the system used in the C2, it also has the advantage that switches on the control panel next to the driver can be rearranged to suit the driver and continue to function without any rewiring or reprogramming. An electrically-powered entrance door was an option in late 2012.
The first generation was produced from 2004 - early 2007. It did not have to extended passenger-side mirror bracket like the second generation. It used a CAT C7 or Mercedes MBE900 engine. It also had the smaller reverse lights in the rear light setup unlike the second generation which uses the equal-sized rear light setup.
The second generation was produced starting in late 2007 and is still in production. It has the extended mirror bracket for the passenger side mirror, equal-sized rear light setup and also features equal sized window sashes with the bottom now slightly larger to match the top unlike the first generation c2s . It runs either a Detroit Diesel MBE900 or Cummins ISB engine. The MBE900 engine has since been discontinued.
Currently, the C2 is available with a single engine, the Cummins ISB; previously, the MBE 900 from Mercedes-Benz was an option. There have been reports of excessive lube oil usage in 2007 emissions-compliant Mercedes-Benz engines. Apparently, the problem corrects itself after 20,000 miles of service. If the customer does not want to wait or does not see an improvement in oil consumption, they can opt to have the engine repaired with an extended warranty.
In 2007, Thomas introduced a hybrid-electric version of the Saf-T-Liner, named the C2e. Designed as a parallel hybrid, the C2e retains the Cummins ISB engine, adding a lithium-ion battery pack with an electric motor/generator. In the summer of 2013 Thomas removed the C2e product literature from their website; it is uncertain if the C2e remains an offered product.
In late 2012, Thomas introduced a propane-fueled variant of the Saf-T-Liner C2, utilizing an 8.0L V8 LPG engine from General Motors. This engine is completely different than the previous 8.1 liter GM truck engine. The two engines share no parts, as the new 8L engine was designed with water jackets between the cylinders, unlike the old 8.1. Propane has 18 times the hydrogen content of CNG, so the engine must run cool when operating on propane. The 8L engine was purpose-designed to operate in the high-temperature environment that burning propane creates. The new 8.0 liter engine is square, with both a 4.25 inch bore and stroke. GM has no plans to offer the new 8.0 liter industrial engine in its own trucks at this time. Original dyno development tests on the first GM 8.0 engine operating on gasoline, showed 518 Lb feet of max torque at 1,800 RPM with a slightly higher compression ratio than the old 8.1 which had a 9.1:1 CR. GM showed a 2 percent power increase on the old 8.1 liter on propane compared to gasoline on its Industrial version of the 8.1 engine at 511 Lb feet at 1,800 RPM. On CNG, natural gas, exactly the same engine on the same dyno reached only 460 Lb feet of torque at the same 1,800 RPM. Propane burns very hot and has 104.5 octane ( R+M ) so knocking and pinging are not a problem with higher than normal compression ratios. The higher the CR, the better the fuel mileage and power at all RPM levels. Propane is very widely distributed in North America and the standard automotive grade is HD5. The HD5 grade of propane is the most pure and consistent in the world as used for automotive fuel. It is limited to only 4 to 6 percent butane, unlike the LPG sold in Europe which has butane levels of about 30 percent.
- Yellow Bus, Thomas Saf-T-Liner C2 - Thomas Built Buses - manufacturer website
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