GM Buffalo bus - AbsoluteAstronomy.com

GM Buffalo bus is the slang term for several models of intercity motorcoaches built by the GM Truck and Coach Division

GMC (General Motors division)

GMC is a manufacturer of trucks, vans, military vehicles, and SUVs marketed in North America and the Middle East by General Motors Company. In January 2007, GMC was GM's second-largest-selling North American vehicle division after Chevrolet, ahead of Pontiac....

of the General Motors Corporation at Pontiac, Michigan

Pontiac, Michigan

Pontiac is a city in the U.S. state of Michigan named after the Ottawa Chief Pontiac, located within the Detroit metropolitan area. As of the 2010 census, the city had a total population of 59,515. It is the county seat of Oakland County...

between 1966 and 1980. "Buffalo" buses have a stepped roof in front, and the first three rows of seats are at different levels, mounted on stepped floors similar to some theatre seating.

Scenicruiser
PD-4501 Scenicruiser
The GMC PD-4501 Scenicruiser, manufactured exclusively for Greyhound Lines, was a three-axle monocoque two-level coach used by Greyhound from 1954 to the 1970s...

The GM Buffalo bus models were strongly influenced by the PD-4501 Scenicruiser

PD-4501 Scenicruiser

The GMC PD-4501 Scenicruiser, manufactured exclusively for Greyhound Lines, was a three-axle monocoque two-level coach used by Greyhound from 1954 to the 1970s...

, produced by GM exclusively for Greyhound Lines

Greyhound Lines

Greyhound Lines, Inc., based in Dallas, Texas, is an intercity common carrier of passengers by bus serving over 3,700 destinations in the United States, Canada and Mexico, operating under the well-known logo of a leaping greyhound. It was founded in Hibbing, Minnesota, USA, in 1914 and...

between 1954 to 1956, in limited run.

The Scenicruiser was a split-level model, with a lower level at the front containing the driving console and 10 seats behind it, and upper level containing 33 seats. This also allows a baggage compartment underneath the second level, while providing 360-degree view for the upper level. A lavatory was located in the rear of the first level. Scenicruisers were equipped with an air-ride suspension utilizing air bags at each wheel, and were air conditioned. Later on, model PD-4106 a new design was incorporated, such as having air conditioning powered off the engine, a patented V-drive engine-transmission design, and the 8V71 Detroit diesel motor.

As Scenicruisers became a familiar sight around the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

and in advertising, competing bus companies including members of the National Trailways Bus System sought a vehicle to compete. One of the product designs developed in response to this market demand was the GM Buffalo bus. Unlike the Scenicruiser, these models were available for sale to all operators, and in fact, Greyhound only purchased a few of them, the last GM bus purchased by Greyhound was a 1967 PD4107. Many features, such as the split-level design and the revision introduced in PD-4106 model, was included in the Buffalo bus.

Fishbowl transit and suburbans

The GM New Look Transit Coach series (nicknamed "fishbowl" for the six-piece rounded windshield) was introduced in 1959. In the early 1960s and later, thousands were built in the transit

Transit bus

A transit bus , also known as a commuter bus, city bus, or public bus, is a bus used for short-distance public transport purposes...

and suburban bus models. When designed and put into production, the Buffalo intercity products shared many body and mechanical parts with these "fishbowl" buses, which were assembled in the same plant in Pontiac, Michigan

Pontiac, Michigan

.

This aspect, a sensible production economy at first, would negatively impact the future of the Buffalo models years later when GM switched transit production at the Pontiac plant to the modular RTS

Rapid Transit Series

The Rapid Transit Series bus is a long-running series of transit buses originally manufactured by General Motors and is currently produced by Millennium Transit Services as the RTS Legend. Millennium had produced the buses from 2006 until it shut down production in 2009, only to be bought back...

design, a radical change beginning in the late 1970s.

First buffalo models: GM PD-4107 and PD-4903

In 1966, GM introduced the PD-4107. Also known informally as "decks", these buses were similar in some ways to the Scenicruiser design, but had a larger "second level" with the first level reduced, and the lavatory was located at the rear. The 4107 was 35 feet (10.7 m) in length, and nominally (without lavatory) would seat 41 passengers (38 or 39 with lavatory). In 1968, the PD-4903 was introduced, a 40 feet (12.2 m) long version of the 4107 which nominally would seat 49 passengers (46 or 47 with lavatory). The PD-4903 was the first GM bus to use a 24 volt electrical system and was 40 feet long with a third luggage bay. For states with lower axle load limits, a factory option used the third bay to hold a retractable two-tire axle.

In the Buffalo design, the driver sat higher than in a Scenicruiser, but the passenger compartment was no higher than the Scenicruiser deck, so the Buffalo did not look like a double decker. The difference in the height of the front and rear roof was approximately one foot, giving a sleeker, more aerodynamic shape.

The products used an airplane-like stressed-skin construction

Monocoque

Monocoque is a construction technique that supports structural load by using an object's external skin, as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin or coachwork...

in which an aluminum riveted skin supported the weight of the bus. The wooden floor kept the bus' shape. The engine cradle was hung off the back of the roof.

GM's Buffalo models were powered by the eight cylinder Detroit Diesel

Detroit Diesel

As a corporation, Daimler Trucks North America has decided to rename the company "DETROIT".Detroit Diesel Corporation is an American-based diesel engine producer headquartered in Detroit, Michigan, USA...

71-series supercharged two-cycle diesel engines known as the 8V71. GM buses used a unique "V-drive" configuration with a transverse mounted engine. The transmission angled off at a 45-or-so degree angle to connect to the rear axle. The left hand rotating engines were canted backwards for maintenance access; in fact the only major components not accessible from outside the bus were the right-hand exhaust manifold

Exhaust manifold

In automotive engineering, an exhaust manifold collects the exhaust gases from multiple cylinders into one pipe. The word manifold comes from the Old English word manigfeald and refers to the folding together of multiple inputs and outputs.In contrast, an inlet manifold is the part of an engine...

and the starter

Starter

- Science and technology :* Starter motors, used to start internal-combustion engines* Motor starters, used to start large electric motors* Fluorescent lamp starters, used to initiate operation of fluorescent lights- Food and meals :...

, which were accessible from underneath and through access panels under the rear bench seat. The entire engine

Engine

An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...

-transmission

Transmission (mechanics)

A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...

-radiator

Radiator

Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics...

assembly was mounted on a cradle that could be quickly removed and replaced, allowing the bus to return to service rapidly, leaving the powertrain in the shop for repairs. The original transmissions were a 4-speed non-synchronized manual transmission

Manual transmission

A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...

with solenoid reverse. Late in production, an Allison automatic version was offered.

The 4107 and 4903 models were notorious for being difficult to shift gears, routinely making loud, grinding noises which tended to upset the passengers. Double-clutching reduced these embarrassing noises, but even the most skilled driver would occasionally have problems, especially when changing buses (or powertrains) meant an unfamiliar feel to clutch and shifter.

Second generation: GM PD-4108 and PD-4905

In 1970, design improvements came with the updated versions, PD-4108 (35 ft) and PD-4905 (40 ft) both with a 24 volt electrical system. The driver's controls were updated for both. The biggest gripe about the 4905 and 4903, from the drivers' point of view, was that the extra 5 feet (1.5 m) of length was all between the front and rear axles. It was very easy to scrape the baggage bins on tight turns. The 4905s looked just like 4108s but with 3 baggage bins. Some 4905s had a tag axle, with a single extra wheel on each side, located in the third baggage bin, but it was forward of the drive axle, so turning radius was not affected.

Additional updates in models

In 1972, the PD-4108 was redesignated P8M4108A, and the PD-4905 became P8M4905A. In 1979 and 1980, the P8M4905A was replaced with the short-lived model H8H649.

Markets

The GM Buffalo models were purchased primarily by affiliates of the National Trailways Bus System and many smaller operators. After the Scenicruiser arrangement with GM, Greyhound had purchased an interest in Canadian bus manufacturer Motor Coach Industries

Motor Coach Industries

Motor Coach Industries International Inc. is an American bus manufacturer based in Schaumburg, Illinois, and is a leading participant in the North American coach bus industry. It has various operating subsidiaries:...

(MCI), and by the mid-1960s, had switched most of its purchasing to MCI products. In the 1970s, MCI products began to overtake the GM Buffalo models in sales volumes, especially after the introduction of the popular MC-8 at the Transpo 72

Transpo 72

U.S. International Transportation Exposition, better known as Transpo '72, was a trade show held on of land at Dulles International Airport outside Washington, D.C. for nine days from May 27 to June 4, 1972. The $10 million event, sponsored by the U.S. Department of Transportation, was a showcase...

exhibition held at Dulles Airport near Washington, DC in 1972.

As the market share declined, GM lost interest in updating its motorcoach products. When the GM RTS

Rapid Transit Series

bus models replaced the fishbowl models in GM's transit bus offerings, the future discontinuation of the Buffalo models, which shared many common parts with the fishbowl, was sealed. The final Buffalo models were built in 1980.

Total production for 35-foot models was: PD-4107 1,267 (1966-69), PD-4108 65 (1970-71), PD-4108A 232 (1972-79);
and for 40-foot models was: PD-4903 401 (1968-69), PD-4905 330 (1970-71), P8M-4905A 2,002 (1972-79), H8H-649A 233 (1979-80).

External links

http://www.coachinfo.com/Manuals/Coach/GMC/4103.html

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

ScenicruiserPD-4501 ScenicruiserThe GMC PD-4501 Scenicruiser, manufactured exclusively for Greyhound Lines, was a three-axle monocoque two-level coach used by Greyhound from 1954 to the 1970s...