Design history
1932–1948
In 1932, Crown Motor Carriage Company built its first complete school bus, in a shift from building bus bodies on cowled truck chassis. Externally modeled after1948–1960
In 1946, Crown began development on a new generation of vehicles. Starting life as a sightseeing bus for a motorcoach customer, the new-generation Supercoach (renamed as a single word) entered production in 1948, with Crown producing its first school bus example in late 1949. In a move back to the mid-engine layout, the design of the 1950 Crown Supercoach broke many precedents in school bus construction. Although built on a steel frame, to fight corrosion, the body panels of the Supercoach were of aluminum. In place of the traditional ladder truck-style frame, the Supercoach featured a monocque-style integrated frame. In the early 1950s, Crown made several additions to the Supercoach model line. In 1951, the1960–1977
In 1960, the body of the Crown Supercoach underwent its first set of modifications since its introduction in late 1949. To enhance visibility, the windshield, driver window, and entry door windows were redesigned. To make the bus more visible, Crown moved the taillamps and brakelights from the doors of the luggage compartment towards the rear corners of the body. Although overtaken by school bus production, Crown continued production of the Supercoach as an intercity coach in various lengths. Designed similar to a1977–1991
During the 1977 model year, federal regulations took effect that forever changed school bus design in the United States. To better protect passengers from crashes and rollovers, the structures of many school buses had to be updated; the metal-backed seats seen for decades were replaced by thickly padded, taller seats. Aside from the redesign of the passenger seats, which led to minor capacity reductions, the structure of the Supercoach needed relatively few changes to meet the new regulations; the company claimed that the Supercoach was compliant as far back as 1950. Post-1977 Supercoaches are distinguished by larger pillars behind the drivers' window and entry door as well as the fixed window next to the side emergency door. In the late 1980s, along with the Crown Supercoach Series II, Crown began to expand the Supercoach lineup beyond its traditional two models. In 1988, a 38-foot version (84-passenger) was introduced. In 1989, two new 40-foot versions were introduced: a rear-engine and a single rear axle mid-engine. In March 1991, Crown Coach closed its doors; the final vehicle produced was a 36-foot mid-engine Supercoach (with standard body).Supercoach II (1989–1991)
During 1989, Crown Coach introduced the Crown Supercoach Series II (internally designated N-body). Developed for Crown to participate in a multi-yearCalifornia Energy Commission program
Produced for the first phase of the CEC study, 153 Crown Series II buses were acquired, including 103 "advanced diesel" and 50 methanol-fuel buses. Crown was going to offer a CNG option ( John Deere 8.1L) to replace the methanol option, but due to the closure of Crown Coach Corporation in 1991, the CNG option was cancelled. As a secondary objective of the study, the buses researched the practicality of advanced safety features for school districts replacing buses manufactured before 1977, including fire suppression systems, an increase in emergency exits, taller seats (made of additional flame-retardant material), anti-lock brakes (ABS), and automatic parking brakes. During the 1990s, as the California Energy Commission program moved into its advanced stages, methanol was abandoned as an alternative fuel (in favor of further development of compressed natural gas and diesel buses); virtually all of the 50 methanol-fueled Supercoach II vehicles were converted to operate on diesel fuel. Crown was unable to offer the CNG option due to closure.Design overview
During the late 1980s, the only methanol-fuel engine that complied with California emissions standards was the Detroit Diesel 6V92. To accommodate the engine in the rear of the Crown Supercoach, substantial revisions were required for the chassis and rear bodywork. As the 6V92 V6 was wider than previous inline engines, the rear body panels were widened aft of the rear axle, creating a new rear roofline (with a vertical rear window). To match the modified rear bodywork, the front body was also revised, including a squared off body above the entry door, enlarged windshield (four-piece flat glass), and flat front bodywork (with horizontal quad headlights). During the early 1990s, the only CNG engine that complied with California emissions standards was the 8.1L John Deere engine. Since methanol was abandoned as an alternative fuel, Crown Coach Corporation was planning to replace that alternative fuel option by compressed natural gas. From the mid-1990s Crown was going to offer a John Deere CNG engine option on the Series II, but due to the closure of Crown Coach Corporation, no Series II was offered with CNG. To maintain production commonality with the standard commonality with the standard Supercoach, the Supercoach II shared nearly all of its bodywork between the entry door and the rear seats with its predecessor. The drivers' compartment underwent a substantial redesign, grouping secondary controls together left of the driver. Following the production of the 153 CEC buses, the Supercoach II continued as a regular production model alongside the standard Crown Supercoach. The Detroit Diesel 6V92 V6 diesel remained, with Crown adding a Cummins C8.3 inline-6 and Caterpillar 3208 V8, and a John Deere 8.1L inline-6 (no longer offered). A mid-engine version was introduced, including the Detroit Diesel 6-71. Produced primarily in a 40-foot rear-engine configuration, the Supercoach II was also offered in a 38-foot length; both rear-engine and mid-engine versions were produced (no tandem-axle examples are known to have ever been produced).Design epilogue
The Supercoach II was offered by Crown Coach through its closure in 1991; however, many of the 1991 vehicles produced by the Crown were of original Crown Supercoach body design. Following the closure of the company, the designs and tooling of Crown Coach were acquired by Indiana-based Carpenter Body Works, who sought to replace its discontinued Corsair with a revived Supercoach II. Carpenter would soon abandon the project, as it could not produce the complex Crown Coach design at a competitive price (a diesel Supercoach II cost over $125,000 in 1990). Also, Carpenter did not offer a John Deere CNG option since it was also more expensive. While Carpenter would abandon production of the Supercoach II as a whole, several elements of its design would live on in a successive product, the 1992 Carpenter/Spartan Coach RE, including its left-hand driver control panel and its headlight layout. The bus was offered with diesel engine options only; the Detroit Diesel 6V92, Caterpillar 3208, and Cummins C8.3. No Methanol or John Deere CNG.Powertrain
References
External links
{{School Bus Chassis School buses Vehicles introduced in 1948 Buses of the United States