Yellow Coach Model 720 and Model 735

THE STORY OF THE 1930s YELLOW COACH AMERICAN DOUBLE-DECKERS

We take the rear-engined double-deck bus for granted as the mainstay of urban operation in many British cities – especially London.  It seems to be a peculiarly British arrangement, yet its lineage can be traced back not to Leyland and the prototypes of the early 1950s, but to a revolutionary bus that that appeared in America twenty years before!  Here is the extraordinary story.

It starts in New York.  In 1885 the Fifth Avenue Transportation Company was established to run a horse bus service in Manhattan.  Horse buses were slow and old-fashioned alongside the competing electric streetcars.  After the trial of a domestically built Fischer petrol-electric single-decker around 1905, the now-named Fifth Avenue Coach Company imported a standard London General bus of the time – a DeDion-Bouton with a 34 seat double-deck LGOC body.

Its success was immediate, and within a year 24 additional DeDion-Boutons had been imported and fitted with American Brill double-deck bodies.  The entire horse bus fleet was retired, and the passenger appeal and lower running costs of the new buses allowed FACCo to expand rapidly.  Over the succeeding twenty years, the normal control arrangement with a rear platform was the standard bus across much of Manhattan.

The First World War interrupted chassis supply, and so the company began building its own buses in New York, producing over 600 by 1926 – including 170 sold to other operators. 

In 1924, J. D. Hertz (who owned Yellow Cabs) and his Chicago backers formed the Omnibus Corporation.  They put Chicago Motor Coach Corporation into it (which they already owned) and bought control of Fifth Avenue.  Yellow Coach Manufacturing Company was created in 1923 out of the bus building subsidiary of Chicago Motor Coach.  It reached the apotheosis of American normal control bus design in the Z-type and subsequent Y-type – many examples of both being built as double-deckers.

In September 1925 General Motors combined its truck building subsidiary with Yellow Coach Manufacturing, taking a majority share of the combined business – now called Yellow Coach Truck and Coach Manufacturing Company.  In 1928 bus manufacture moved to a new factory built by GM in Pontiac, Michigan.

Despite the Wall Street crash (or perhaps because of it) this period was to be one of extraordinary advances in American bus design by many companies.  Two in particular would allow the double-decker to move in a new direction.

The first came from California.  Pickwick Stages was a progressive operator of long distance coach services that built some of its own vehicles.  When Greyhound acquired Pickwick in 1929, its chief engineer, Dwight E. Austin, bought the factory.  He set up the Austin Utility Coach Company to build a medium sized single-decker which incorporated his key invention, the angle drive.  This allowed the engine and gearbox to be mounted transversely across the back, powering the rear axle through a gear set that turned the drive through 315 degrees.

The second innovation came from Pontiac.  The Yellow Type 700 single-decker was developed by George Green’s team in 1932 in response to the success of the Fageol Twin Coach of 1927, which featured two underfloor engines and placed the entrance door ahead of the front axle.  On the 700 though, the engine and gearbox were taken to the rear, running longitudinally under the saloon, thus placing them behind the rear axle, where they are fitted in the majority of city buses to this day.

Although single-deckers were much more common across the United States as a whole, by the early 1930s the double-decker was well established as a suitable layout for intensive urban routes, especially in a city like New York where sightseeing could be an important source of revenue. 

The question was whether the future lay with further development of normal control buses, or adoption of the new rear-engined layout.  Thus in 1933 the Omnibus Corporation received two prototypes from Yellow Coach to determine what their next generation of double-deckers would be.  Fifth Avenue were sent a 30 foot long closed top normal control Z type, seating 56.  But Chicago Motor Coach took delivery of a radical new design, the model 706, based on the model 700.  By the standards of the day it looks astonishing.

It was 33 feet long, 8 feet wide and 12 feet 11 inches tall, with a single 46 inch wide doorway ahead of the front axle.  The lower deck floor was stepless to the rear axle with a main floor height of 16½ inches above the road (much lower than on the 700).  There were 29 seats downstairs plus two spaces on an upholstered bench over one of the rear wheels.  Upstairs there were 41 seats, reached by a rearward ascending staircase over the left hand front wheel.  Owing to the tyre diameter of around 40 inches, wheelarch intrusion in the lower saloon was considerable, but otherwise the interiors were light and airy.  Headroom downstairs was a generous 74 inches, but a more cramped 63 inches upstairs.

Externally the bus appeared very modern, with continuous glazing around both decks, although there were thirteen window bays on each side – part of a semi-integral body structure strong enough to make up for the lack of deep chassis rails.  Least successful was the front, completely flat and vertical to the upper deck floor line then angled straight back up to the roof.  The stark appearance was compounded by ventilation flaps and a rectangular destination box that stuck out above the windscreen.

The rear mounted engine was a General Motors 616 series petrol unit, producing 149 BHP at 2,100 rpm, with a radiator mounted at the left rear corner.  Drive was taken through a three speed semi-automatic transmission, with electric solenoid selection.  As on the model 700, the engine and gearbox were mounted longitudinally.  The engine, transmission and rear axle assembly were mounted on a sub frame to facilitate removal.  Suspension was by leaf springs and air brakes were fitted.  There was no rear bulkhead, so the bus interior was probably quite noisy.

The single type 706 was exhibited at the Chicago World’s Fair in 1933 and entered service as Chicago Motor Coach’s fleet number 103.  It quickly showed that it represented the right way forward.  It had much greater capacity and passenger appeal than the Z type and must have proved reliable enough in service, despite its exotic design.  But Green recognised that the type 700 single-decker was only a step towards the optimum design.  In 1934, GM recruited Dwight Austin and acquired the patents for the angle drive.  This quickly led to the model 718 – which could have a transverse rear engine. 

Thus when the production version of the 706 followed later that year – this time designated the model 720 – it incorporated five major changes, starting with the angle drive.  A GM 707 petrol engine producing 165 bhp at 2,000 rpm gave a useful increase in power, but the Banker semi-automatic transmission ultimately proved too complicated and unreliable. As for the body, the lower deck window line was dropped in the wheelbase to give passengers a better view and the upper deck sliding windows were replaced with ones with top vents. 

Presumably after some in-service testing revealed delays in unloading lower deck passengers, a second narrow exit door was fitted ahead of the rear wheels. The loss of seats due to the second door was offset by fitting a single seat just inside the front entrance and three side facing seats over the rear wheels.  This was possible because having a transverse rather than longitudinal engine created more passenger space in the rear of the lower deck.  The total unladen weight was 21,460 lbs, against a gross weight of 32,560 lbs.

The pre-production model 720 entered service as CMC’s number 104, after spending some time in New York to prove its suitability for FACCo’s operations.

In 1936 serial production began at Yellow Coach’s factory in Pontiac.  Chicago Motor Coach and Fifth Avenue each took 100.

FACCo had looked into whether the new buses could be run with more headroom in the upper deck along routes that had no clearance problems.  This led to the model 735, which appeared exactly the same as the 720 except that the roof had a more pronounced curvature, allowing a headroom of 68 inches over the gangway – the same as contemporary British regulations stipulated.  This took the overall height to 13 feet 5 inches.

75 of the first New York order were 735s.  Further batches arrived in 1938 when FACCo took delivery of 25 model 735s and 35 model 720s.  Chicago went on to take another 40 model 720s.  These later builds featured revised battery and fuel tank locations to reduce the risk of fires (which had in fact consumed two of the early Chicago buses in 1937).

Following a welcoming ceremony for the first buses on 15 July 1936 the Chicago 720s began work on some of the major boulevards running out of the central business district.  Several routes ran up North Michigan Avenue, and then along the shore of Lake Michigan to destinations up to ten miles from the city wherever overhead clearances would allow.

The fleet was painted dark green up to the lower deck waist line, and cream above that.  On the sides between the decks was the legend ‘Chicago Motor Coach Company’, with ‘See Chicago – The City Beautiful’ on the lower panels, and ‘Go The Motor Coach Way’ on the front and back.

Advertising was rarely carried, and generally confined to a small area towards the rear of each side between the decks.  Exceptions were buses 117 and 134, which carried perhaps the first all over advertisements on a double-decker anywhere – exhorting Chicagoans not to travel on holiday but to ‘Relax in Chicago’ as part of the war effort in the early 1940s.

In New York, the new buses quickly became a symbol of the city.  Their length and size led them to being christened the Queen Marys, after the world’s largest liner, which had recently begun transatlantic services.  Also painted green up to the waist and cream up to the roof, their side slogan was ‘See New York – The Wonder City’.

They carried thousands of people past brand new skyscrapers like the Empire State Building and the Rockefeller Centre on Fifth Avenue, as well as up past Central Park and into Harlem.  Although all their standard routes were in Manhattan, they did stray further afield, including carrying visitors to the 1940 World’s Fair in Queens.  And they were certainly marketed at tourists; a 1940 Fifth Avenue Visitor’s Guide and map shows only pictures of these buses and recommends riding them as the best way to get “a general idea of the city”.  

Even in the mid-1930s the Chicago Motor Coach fleet operated without conductors.  CMC had been converting its normal control buses to driver operation from 1930, and so the rear-engined buses were run this way from the beginning.  The original intention was that the Fifth Avenue buses in New York would also have driver only operation – collecting fares upstairs on the model 720s was awkward when the headroom was a mere 63 inches.  In actual fact a union contract prevented this until 1946.  When it was finally introduced boarding and fare collection became very slow at busy stops, so ‘loaders’ were employed to speed things up by collecting fares on the sidewalk.

In the late 1930s General Motors was developing the combination of the two cycle diesel engine and torque converter transmission.  The last FACCo bus, number 2124, went back to Pontiac in 1939 to be fitted with a 6-71 Detroit Diesel engine and a Spicer automatic transmission, in place of its petrol engine and semi-automatic gearbox.  It ran for a period in Philadelphia, before returning to New York. 

It probably also ran in Chicago because CMC converted all 40 of its second batch of 720s to diesel-hydraulic in 1941, whereas only 25 FACCo examples were converted.

In the 1930s streetcar operators began to replace their trams with buses, typically modern single-deckers like the Fageol Twin Coach and the Yellow 700 series.  These buses had smaller capacities than streetcars, up to 45 seats in a 35 foot long vehicle.  The quest was to build a bus that could carry an equivalent number of people to a streetcar.

In 1939 Yellow Coach began work on a 42 foot long single-decker that could seat 55 passengers and carry many more standing.  This appeared in October 1940 as the TD-55, featuring a streamlined look which emulated the styling of the latest PCC streetcars.  It came to Fifth Avenue in 1942 and stayed until 1946, proving that a large single-decker could operate successfully in city service.  It also featured a transverse power pack and angle drive.

After the war the double-deck fleets in New York and Chicago came under increasing pressure.  Reduced ridership meant that the high seating capacity was unnecessary, and slow boarding and poor acceleration continued to hinder operation.  The new single-deckers were economical and powerful, and the big double-deckers looked worn out after years of intensive service.  In New York this was not helped by the decision in 1947 to fit a blanking panel across the lower half of the upper deck front windows to prevent passengers falling out.

General Motors (the Yellow Coach brand went in 1943) pressed ahead with production of a 40 foot long single-deck bus suitable for service almost everywhere.  Chicago Motor Coach purchased 260 examples between 1945 and 1948, plus 100 TD-55s, many of which were bought specially to replace the double-deckers.  Fifth Avenue had built up a fleet of 81 GM, Mack and White 40 footers by 1952, plus over 150 new 35 foot long GMs. Double-deck service ended in Chicago on 25^th July 1950 and the last FACCo example was retired on 27^th April 1953.  The future was with big single-deckers.

Not many examples passed on to other operators. Two 735s ran in Philadelphia, and a further seventeen went to two small operators in New York and New Jersey.  Three or four were apparently preserved, including Fifth Avenue number 2124, the very last model 735.  This is maintained by the New York City Transit Authority and in November 2007 I got the opportunity to inspect it at a bus depot in Brooklyn.

The first thing that struck me was how modern the bus looked despite being seventy years old.  You step straight on board through the wide front door and the floor is completely flat into the lower saloon (yes, a low floor bus built in 1938!).  The driver’s area is spartan, with no partitions and few controls.  On the forward side of the right front wheel arch is perched a single seat; the staircase rises rearwards over the left wheel.  Behind the front wheels are pairs of opposite facing twin seats, and then forward facing seats towards the rear. Headroom is a generous 76 inches until the floor starts to rise just aft of mid wheelbase.

This, combined with a ten inch step ahead of the rear axle, means that headroom is only 60 inches at the rear of the lower deck.  There is a narrow exit door ahead of the rear wheels.  Over the rear wheels are inward facing seats, and a bench seat across the back.  The engine compartment cover is inside the body so there is no rear bulkhead.  Upstairs all the seats are forward facing, and the headroom is more than adequate.

The seats are upholstered in a kind of faux leather material (possibly not original) and are mostly at a generous 31 inch pitch.  The interior panels are painted metal and the saloons are illuminated by quite stylish art deco ceiling lamps.  The side windows can be opened by lifting the lower half up into the body.  This is particularly clever upstairs as the pane disappears into the curved roof panels.  Compared with modern buses there are very few internal partitions and screens.

The engine compartment is reached by a series of access doors around the back of the bus.  The engine is connected straight on to the transmission, and there is an angle drive that conveys power to the straight rear axle. Everything is packed in tight, with little room between the radiator and the engine, and the angle drive hard up against the edge of the bodywork.  Suspension consists of leaf springs at the rear and a single transverse leaf spring at the front; one hopes the roads were kept in good condition.

The body structure is clearly semi-integral.  The steel understructure consists of longitudinal beams about 4 inches deep, connected to transverse beams that taper to the body side.  The floor is structural.  Inside the body, tapering beams beneath the seats reinforce the connection between the floor and the body side.  Up to lower deck waist rail level the vehicle appears to be constructed like a stiff boat hull.  Above the rail closely spaced body pillars add further strength.  Much of the structure is made from aluminium alloy. 

The overall impression is of a very ingenious design that produced a bus that was striking to look at and airy and spacious inside – and certainly a long way ahead of its time.  Considering they were so advanced, bus 2124 and its compatriots did well to last from the 1930s up to as late as 1953.  Some would have been fifteen or even seventeen years old when they were retired, and their service life included very intensive service through the war years when overcrowding was commonplace and maintenance limited.

One interesting sidelight on this story is the appearance of these buses in Hollywood films.  The solitary model 706 prototype found its way to California in 1945 and appeared in at least three popular movies.  On The Town is a 1949 musical set in New York.  Early in the film is a short location shot with model 735s in service at Columbus Circle.  A later dance sequence was filmed in Hollywood and features the prototype model 706 in Fifth Avenue livery driving away from us behind Frank Sinatra, Gene Kelly and the other stars.

Two years later it turned up in The Day the Earth Stood Still, a science fiction film starring Michael Rennie as a visitor from a distant planet.  At one point Rennie demonstrates his power by stopping virtually every machine on earth; there are several street scenes full of stationary traffic and puzzled crowds.  One is in New York, with people hanging out of the bus’s windows wondering what is going on, and another is in London, where the same bus carries a ‘Piccadilly Circus’ destination board!

Its last appearance was even more extraordinary.  In the Hitchcock thriller Torn Curtain, made in 1966, it carries a protruding snout-like bonnet to make it look something like a 1930s Berlin Bussing or Mercedes-Benz doppeldecker!

It wound up at the Orange Empire Trolley Museum in Perris, California, but sadly succumbed to an arson attack and is no more.

The Fifth Avenue buses turned up in exterior shots on their home turf in several popular films, including Gentleman’s Contract (1947) and The Snake Pit (1948). There is also a very short but full colour excerpt of a couple of New York’s 720s in a film about the liner Normandie. Go to 38:58 in https://www.youtube.com/watch?v=SJDLl2RbS_c

The best way to see the Chicago buses in action is to track down a 1942 promotional film called To Market, To Market which looks at billboard advertising around the Windy City.  Both the Prelinger Archive and Handy Jam Organization have this film on-line.  See https://archive.org/details/ToMarket1942

To conclude this story let’s finish in the best Hollywood tradition with a twist in the tale

Just as British bus design influenced American practice early in the twentieth century, by the mid-1930s the opposite force was at work. Leyland Motors had a strong record of innovation and also a dominant position in the British urban bus market. It was paying close attention to what was happening in Canada and the United States where big single-deck buses were becoming popular in most major cities. Prior to the introduction of the Yellow Coach 718 in 1934, the underfloor-engine layout was prevalent, and the company even imported a White transit bus to the UK in 1936 to examine and test it.

Leyland was also well aware of AEC’s attempt to redefine bus design with its side-engined Q type and began to consider ways in which maximum use could be made of a vehicle’s exterior dimensions while still having a reasonably low floor. The monthly reports of the Engineering Department reveal how this resulted in a unique prototype

Work began in February 1935 and Leyland independently came up with the same layout as Yellow Coach – transverse rear power pack, with an angle drive to the rear axle – but using an 8.6 litre diesel engine. After all their effort the design team were dismayed to find that General Motors had already published a patent for such a layout. They took advice from Sefton, Jones, O’dell and Stephens – Leyland’s patent agents – who confirmed their design at that point infringed the patent.

Leyland was aware they were not the only British bus-builders looking at the potential of a transverse rear engine layout. The Birmingham and Midland Motor Omnibus Company (‘Midland Red’) built most of its own fleet, and in 1935 produced the S.O.S. REC (Rear Engined Coach), which featured a petrol engine and French Cotal epicyclic transmission. How the drive ran from the engine to the wheels is unclear.

Back at Leyland work proceeded apace and by April the Experimental Department was starting to build the prototype chassis. The 7 foot 6 inch width restriction at the time meant that the radiator and angle drive protruded outside the body line, and only single rear tyres were fitted. Meanwhile the design team pressed on looking for ways to get round the patent and improve on the American solution.

At the end of September a temporary cab was fitted and weights were added to simulate a fully-laden bus. Preliminary tests were followed by mounting the top deck body of a Titan bus, ready for road tests. These results were not promising. There was a great deal of interior noise, much of it emanating from the spiral gears in the angle drive, and also from an ineffective silencer.

In the January 1936 report the prototype is referred to as the ‘Z Type’ and it is clear that interest in the idea is waning. Instead Leyland’s designers are putting much more effort into underfloor engined buses for London Transport – which became their TF type. In 1937, Leyland did produce a rear-engined bus. This was a small single-decker for London Transport which they designated the CR type, but this had a longitudinal engine.

Part of the reason why the ‘Z Type’ project fizzled out was perhaps because the supervisor, a highly gifted engineer called Percy Ellliot Biggar, left for the United States in early 1935 to join… General Motors.

From the early 1950s, the underfloor engine arrangement became the standard layout of Leyland and other British single-deckers for over a decade. But a new consideration of what double-deckers might look like led to the transverse rear engine arrangement re-emerging in 1952 with the Lowloader prototypes, which featured a Leyland O.350 engine at the rear, stepless access to the lower deck and a rear platform. The 1935 prototype was undoubtedly an influence, along with other pre-war work Leyland had done on a low-floor double-deck trolleybus. However the Lowloader prototypes were hampered by an awkward drive-line arrangement to get round the General Motors patent. When GM found itself facing US government action in the early 1950s over its alleged effective monopoly of the US city bus market, it has been suggested by Alan Townsin that it abandoned its patent. This enabled Leyland to create a much more elegant design.

Further development led to the Atlantean prototype displayed at the 1956 Commercial Motor Show, which bears an uncanny resemblance to the model 735. This had an Leyland O.600 engine fitted transversely, connected to a Leyland Pneumocyclic semi-automatic gearbox and thence via an angle drive to the rear axle. 78 seats were fitted in the 30 foot long body. The stepless entrance was ahead of the front axle with the stairway ascending over the offside front wheel. There was also no full width bulkhead between the engine compartment and the lower deck. Two important innovations over the Yellow Coach were independent front suspension and a drop centre rear axle. And even though the front of the bus was as vertical as that of its cousin, the MCW body showed a good deal more style and grace.

Alas, cracks appeared in the underframe of the prototype during testing, indicating a lack of strength in key parts of the structure.  So Leyland spent two years taking cost out of the Atlantean, and recreating it in chassis format.  It was a simpler design, the chassis necessitating a step into the saloon, but it also meant that it could be fitted with a body from many different firms. As we know, the Atlantean and its imitators rapidly built up large shares of the British bus market, as well as significant sales in places like Hong Kong and Singapore.

The Transport Act of 1966, which permitted driver only operation of double-deckers, heralded the domination of the transverse rear engine double-decker in Britain.  Like the models 720 and 735, the Atlantean was confronted with the challenge of big single-deckers, but managed to find an enduring niche in the market for over thirty years.

The 302 rear-engined double-deckers built by Yellow Coach did not lead to a widespread adoption of this type of bus in the United States, but did – I believe – lead indirectly to the construction of tens of thousands of similar vehicles in Britain.

A small number of these have made the return journey – eight Leyland Atlanteans in 1976, eleven Olympians in the mid-1980s, thirty Dennis Tridents in 2001 and fifty more in 2004, plus many second-hand examples for sightseeing and tourism.  Now a profitable niche market for new British-built double-deckers has been established across the United States and Canada for transit and tourist operations.  But that’s another story.

This article is based on material I prepared for two articles in Ray Stenning’s excellent Classic Bus magazine – issues 87 (February-March 2007) and 94 (April-May 2008). Thanks are due to a number of very knowledgeable people who helped me with this account, although I willingly accept responsibility for any errors and would welcome corrections and enhancements.  In particular I must thank John Kyros at the GM Media Archive, Albert E. Meier at the Motor Bus Society, Charles Sachs, senior curator at the New York Transit Museum and Malcolm Thwaite. Much useful detail came from an article by Alan Townsin and Michael Eyre in Classic Bus 73 and another by Alan Townsin in Classic Bus 95. Book sources include Chicago Motor Coach Company by John F. Doyle, The Leyland Atlantean by Ron Phillips of the British Commercial Vehicle Museum; and The Leyland Bus and Beyond Reality by Doug Jack. I also spent a very enjoyable and productive morning in the archive of the BCVM in Leyland.