Crown Supercoach

Crown Supercoach
1977-1991 Supercoach (retired) at a UK bus rally
Overview
Manufacturer	Crown Coach Corporation
Body and chassis
Doors	Single-door
Floor type	High-floor
Chassis	Crown Coach; underfloor or rear engine Single or tandem rear axles
Powertrain
Engine	Gasoline Hall-Scott Waukesha International Harvester Ford Super Duty Diesel Cummins Detroit Diesel Caterpillar
Capacity	72-97
Power output	210-335 hp
Transmission	4-speed automatic 6-speed automatic 5-speed manual 10-speed manual
Dimensions
Length	35-40 feet
Width	96 inches

The Crown Supercoach is a bus that was constructed and marketed by Crown Coach Corporation from 1948 to 1991. While most examples were sold as yellow school buses, the Supercoach formed the basis for motorcoaches and other specialty vehicles using the same body and chassis. While technically available outside of the West Coast, nearly all Crown school buses were sold in California, Washington State, and Oregon.

From 1948 to 1984, the Supercoach was constructed at the Crown Coach facilities in Los Angeles, California; from 1984 to the 1991 closure of the company, the Supercoach was constructed in Chino, California.

Design History

1932-1948

Crown Coach first used the Supercoach model name in 1932 when it built its first transit-style school bus. The first Supercoach was of a front-engine design similar to today's Type D school buses; it predated the Blue Bird All American by 16 years. It was also one of the first buses whose body was constructed primarily of steel instead of wood. During the 1930s, Crown built motorcoaches alongside its school buses, and in an effort to increase passenger room, its first mid-engine bus (with a front-mounted radiator) was built in 1937. In 1939, the company built its school bus with a rear-mounted engine. Following World War II, Crown entered into several joint ventures to save on development costs and to restart bus production; the most notable involved Crown becoming the West Coast distributor for Indiana manufacturer Wayne Works.

1948-1960

Late 1950s Crown Supercoach (restored)

In 1946, development began on an all-new Supercoach. Originally designed as a sightseeing motorcoach, the Supercoach entered production in 1948; school bus production began a year later. Breaking from precedent, the chassis featured unibody construction. Although the frame itself was steel, the body panels were rust-resistant aluminum. In the early 1950s, two additions were made to the Supercoach lineup. In 1954, as diesel engines became popular in large trucks, Crown introduced diesel engines to the school bus industry with the option of the mid-mounted Cummins NHH inline-6. As student populations had risen through the 1950s, larger-capacity school buses had become popular out of necessity. In 1955, Crown introduced the tandem-axle Supercoach, with a 91 (with an option for 97)-student capacity; this was the highest capacity school bus ever mass-produced.

1960-1977

Retired 1960s Crown Supercoach in Mexico

In 1960, the body of the Supercoach underwent its first set of modifications since its introduction 12 years earlier. To enhance driver visibility, the windshield was enlarged. Also, the taillamps were moved from the doors of the luggage compartment to the rear corners of the bus.

Alongside the standard 220-hp Cummins NHH diesel, a turbocharged 262-hp variant was added; alongside the Cummins engine, Crown added the Detroit Diesel 671 as an option during the 1960s.

In 1973, the 743 cubic-inch Cummins NHH diesel was replaced by the 855 cubic-inch NHH diesel, requiring internal structural updates to the frame. From the outside, 1973-1977 Crown school buses are distinguishable by flat-topped wheel wells.

1977-1991

1978 Supercoach 90-passenger

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 lead to minor capacity reductions, the structure of the Supercoach needed relatively few changes to meet the new regulations; the company had gone on to claim 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' version (84-passenger) was introduced. In 1989, two new 40' versions were introduced: a rear-engine and a single rear axle mid-engine.

The Supercoach would outlive the Series II, ending production as Crown Coach closed its doors in March 1991.

Supercoach Series II

1989-1990 Crown Supercoach Series II

The Crown Supercoach Series II was introduced during 1989 during an effort to fit the Crown Supercoach with a methanol-fueled version of the Detroit Diesel 6V92. While the chassis accepted the V6 engine, it came at a cost, requiring significant modifications to the engine compartment to fit properly. However, Crown Coach saw this as the first opportunity to update the Supercoach school bus since it entered production in 1949. To minimize overall production costs, the body between the entry door and rear seats was common to the previous-generation Supercoach, which remained in production. The Series II was given a new driver's compartment (with an all-new instrument panel), new bodywork for the roof, rear compartment, and a flat-glass windshield.

Along with the methanol-fuel Detroit Diesel 6V92, the Series II became available with Cummins C8.3 and Caterpillar 3208 diesels in 40-foot rear-engine configurations. The Detroit Diesel 671 was fitted in 38-foot and 40-foot mid-engine units. During the 1990s, virtually all of the 6V92 units were converted from methanol to diesel.

Outlived by its predecessor, the last Series II was produced in 1990. After the closure of Crown Coach in 1991, the designs and tooling were acquired by Indiana-based Carpenter Body Works in the hopes of adopting the Series II as part of the Carpenter model line. As Carpenter could not produce the model at a competitive price, the project was abandoned; however, several elements of the Series II styling (and its left-hand control panel) lived on in the final product, the 1992-1993 Carpenter/Spartan Coach RE.

Powertrain

Engine	Configuration	Fuel	Production	Notes
Waukesha		Gasoline
Hall-Scott	590 cu in (9.7 L) OHC I6 779 cu in (12.8 L) OHC I6	Gasoline
International Harvester		Gasoline
Ford Super Duty	534 cu in (8.8 L) OHV V8	Gasoline
Caterpillar 3208	636 cu in (10.4 L) V8	Diesel	1989-1990	Rear-engine Supercoach Series II
Cummins 6C8.3	507 cu in (8.3 L) I6	Diesel	1989-1991	Rear-engine Supercoach and Supercoach Series II
Cummins NHH	743 cu in (12.2 L) I6 855 cu in (14.0 L) I6	Diesel	1954-1972 (743) 1973-1991 (855)	Mid-engine Supercoach; first diesel engine in a school bus Available in naturally-aspirated and turbocharged configurations
Detroit Diesel 6V53	318 cu in (5.2 L) V6	Diesel	1961	Produced as part of a customer-order rear-engine Crown Supercoach
Detroit Diesel 6N71	426 cu in (7.0 L) I6	Diesel	c.1963-1991	Mid-engine Supercoach; also produced for mid-engine Supercoach Series II Available in naturally-aspirated and turbocharged configurations Also used in Crown-Ikarus buses.
Detroit Diesel 8V71	568 cu in (9.3 L) V8	Diesel		Used in Crown motorcoaches; not used for school buses
Detroit Diesel 6V92	552 cu in (9.0 L) V6	Methanol Diesel	1989-1991	Rear-engine Supercoach Series II, bus body designed for use of engine Most methanol-fuel buses converted to diesel.
Detroit Diesel 8V92	736 cu in (12.1 L) V8	Diesel		Used in Crown motorcoaches; not used for school buses