Leyland Titan

Leyland
Leyland Titan with Metro Cammell Weymann body structure in use at London Transport
titanium
Manufacturer	Leyland Motors Ashok Leyland
design type	double-decker bus
Production period	1927-1942, 1945-1969
engine	Petrol engine : 6.8 liter Leyland 6-cylinder (until 1939) 7.4 liter Leyland 6-cylinder from 1937 Diesel engines : 8.6 liter Leyland 6-cylinder (1933–1941) Leyland O.600 9.8 liter Leyland O. 680 11.1 liters each with direct injection
successor	Leyland Titan (B15)

The Leyland titanium was a COE - bus chassis with front engine , the Leyland Motors as a chassis for double decker buses developed. Various body manufacturers mounted their self-developed bodies on it for the series specially designed for the United Kingdom . The Titan first appeared in 1927, and production was discontinued in 1942 due to the Second World War . In 1945 this was resumed and continued with revisions until 1969. The production facilities then moved to India , where Ashok Leyland still produces the model as Ashok Leyland Titan for the Asian market today.

Titan was used in many places in the United Kingdom and has also been successfully exported to Australia , Ireland , India , Spain , South Africa and many other countries. From 1946, specific export models were introduced, but all Titans were built as right-hand drive , regardless of the status of the buyer countries.

Model history

Before 1924, Leyland Motors and the majority of other British commercial vehicle manufacturers had similar chassis for buses and trucks , mostly a simple straight ladder steel frame. The disadvantage with buses here was a relatively high body floor with a correspondingly high and difficult access for the passengers. In addition, there were problems with the stability due to the height of the double-deckers, which are increasingly in demand. The first double-deckers in Britain were used by the Widnes Corporation in 1909 . The first chassis specially designed for double-deckers was created by the Associated Equipment Company (AEC) in 1923 for the London General Omnibus Company (both then part of the Railways Company of London ). This AEC-405 model had a frame with raised longitudinal members welded at fastening points above the axle, which meant that the lower floor was about a foot lower than the other double-decker variants AEC 301 and 401. However, the Metropolitan Police refused , which was then for the legal Supervising the building and safety regulations in bus traffic from London was responsible for a number of years to issue a general operating license. The AEC 405, powered by a backward four-cylinder side valve engine with a three-speed chain transmission, was only used at London General .

In 1925, Leyland Motors introduced its own double-decker model for general sale. To distinguish it from the competition, Leyland named its omnibus models with animal names. For example the single deck buses Leyland Leveret (20 to 23 seats), Leyland Lioness (26–30 seats), Leyland Lion (32–36 seats) and Leyland Leopard (38 seats). This gave the double-decker the mythical name Leyland Leviathan , which had up to 48 seats, just like the AEC 405. Pneumatic tires for commercial vehicles were at an early stage of development and mostly only available as options. That is why Leyland equipped the Leviathan with six solid rubber tires as standard, two on the front axle and four on the rear axle. The Leviathan was not a sales miracle, in contrast to the AEC model with its monopoly market, nevertheless around sixty copies were sold by 1927, most of them to municipal operators in Lancashire and Cheshire . This made Leyland the market leader in the free market.

From Leviathan to Titan

The electric trams were becoming increasingly obsolete in the 1920s, and the high space requirements also meant that the routes were abandoned and increasingly replaced by bus lines. The trams also had double-decker cars, which also had to be replaced. Guy Motors from 1925 and Karrier from 1926 offered transport companies a three-axle double-decker to replace the double-decker tram cars. In contrast to the Leviathan and the AEC 405, these were up to 30 meters long, depending on the local building regulations. At that time there were no national regulations, but the rules were prescribed by the municipalities. Due to their greater length, they could offer the same or even higher passenger capacity than the double-decker trams. Other manufacturers, especially AEC in cooperation with the Daimler Motor Company , only had double-decker models with three axles as a drawing model.

Leyland made huge losses in the early 1920s. The Leyland Lion was always the best-selling single-decker bus, and an extended version of this was introduced in early 1926. As a result, Leyland returned to profitability after three years and became the market leader among bus manufacturers. The then Leyland chairman Henry Spurrier decided to recruit design talents and engineers so that Leyland could remain technical supremacy and market leader not only temporarily but also in the long term. He appointed GJ John Rackham chief engineer in the summer of 1926 and commissioned him to launch a whole new range of products with a new double-decker bus. He did so because AEC was now able to manufacture a double decker bus with a conventional transmission and improved engine for general sale. At the same time, AEC was able to offer these at a low price and compensate for these losses with the guaranteed London bus orders. This and the competition from Guy Motors and Karrier with higher capacities would clearly give the Leviathan no chance and result in production being discontinued.

Rackham had for AEC in the prewar period of the First World War worked. During the First World War he worked, among other things, on the Mark I (tanks) together with other talented engineers such as Walter Gordon Wilson . After the war, he designed a series of fast, relatively light chassis with powerful engines with different vehicle floor heights in the USA under chief designer John Hertz for the Yellow Coach Company , one of the leading bus manufacturers in the American states.

Based on preliminary work at Leyland, a new range of models was developed under Rackham's leadership, and the first model was the Leyland Titan.

Leyland Titan prewar

TD1

The T-Type as Rackham's first Leyland development was called the Titan TD1 double-decker bus. (Mythological names for double-deckers and animal names for single-deckers and trucks became a Leyland tradition from 1925 onwards.) A single-decker Leyland Tiger was also developed, and both three-axle models were presented at the London Olympia Motor Show in 1927 after a brief but intensive period of development. At that time they were both the most modern models in the world in terms of design and handling in their categories.

They represented immense progress in contrast to what was previously on the market at Leyland or elsewhere. It wasn't so much that the functions were all new, but their combination in one vehicle and the overall concept of the vehicles gave them a huge lead over the competition, which mostly took years to catch up. This is what former AEC employee Alan Townsin said in retrospect.

An important feature of the new Leyland buses was the engine, a six-cylinder overhead camshaft gasoline engine with a displacement of 6.8 liters with 90–98 hp at up to 2200 revolutions per minute. The four-speed gearbox had a simple multi-plate clutch and was produced as a single unit with the engine. The power was transmitted to the rear wheels by means of a cardan shaft. There the drive shafts and the differential gear in worm gear construction were located under the specially shaped rear axles. This construction ensured a low vehicle floor and traction . Vacuum servo brakes on all four wheels were standard on the Tiger and Titan , but in favor of the vehicle floor , these were built into the vehicle frame at the rear in a special angular teardrop shape.

Leyland Motors was already building its own bodies shortly after World War I, next to Leyland in the neighboring community of Farington. Most of the Lion s and many Lioness received their superstructures there. In addition, Leyland Motors also issued licenses for body manufacturers to replicate. But there were also pirated copies of the Leyland design, which is why Leyland patented the body design of the Titan . The body was the first model to have an upper deck with four seats next to each other on the passenger side with 48 or more seats. The height was about two meters less than the Leviathan or the AEC 405. A Titan with pneumatic tires and the standard body weighed less than 5 tons curb weight. This meant that a standard titanium could carry pneumatic tires of the same type as the Lion and other competing monoplane. Pneumatic tires on a heavy vehicle at the time legally meant a maximum speed of 20 miles per hour (mph) instead of 12 for tires with surfaces made of solid materials. Not only the size but also the weight were lower than competing three-axle buses.

Up to 1932 2352 TD1s had been produced, most of them with Leyland's own construction or those of licensed manufacturers. From 1929 there was also a version with closed rear stairs based on contemporary tram practice.

TD2

By 1931, the competition had mostly caught up, especially AEC, which introduced its rival model AEC Regent in 1930 . This was developed by Rackham, who switched to AEC after completing the development of the T series, lured by a much higher salary than Leyland.

Due to their unreliability, additional maintenance costs during maintenance and high fuel consumption, the three-axle vehicles from Guy Motors and Karrier fell behind after the appearance of the Titan. Guy Motors was only able to survive thanks to orders from the British Army, while Karrier went bankrupt and was bought out by the Rootes group .

In 1930 a general highway code was introduced and a consolidation between bus operators now brought standard values for the maximum dimensions and gross weight for buses and commercial vehicles in Great Britain and Northern Ireland. The maximum width was now 7 feet 6 inches, the maximum length for a two-axle double-decker 26 meters with a gross vehicle weight of 10 tons. Thus about a foot more than the original development of the Titan. As a result of these changes, Leyland increased the bore of the engine, revised the rear axle and introduced a three-circuit braking system. Larger tires were also used.

Nevertheless, compared to its predecessor, sales fell. The now heavier TD2 version is much more technically behind the competition. A body with an additional row of seats was optionally offered by changing the engine position, but the front design of the TD1 also looked out of date, and so production was stopped as early as 1933 after around 1000 TD2s.

TD3

The TD3 series from mid-1933, like the contemporary Tiger TS6 series, had a newly designed, more compact body and a modified arrangement of the engine, which means that the additional row of seats that was optional on the TD2 was now standard equipment. For the first time, an 8.6-liter diesel engine with direct injection was optionally available, as was a torque converter . With this it became the TD3c and had the lettering Getriebeloser Bus on the radiator. The tuning of the standard gearbox has also been improved, and steel is now used instead of hardwood for the body.

TD4

In 1935 the TD4 appeared with a change in the braking system from vacuum to hydraulic . The 8.6-liter diesel engine was now the standard engine, and the body was redesigned by Metro Cammell Weymann , among others .

TD5

The TD5 from 1937 received a 24-volt electrical system and the engines had continuous oil lubrication, both of which were previously only available as options. The frame had a greater depth in the front wheel arches for a lower vehicle floor. A 7.4 liter gasoline engine with OHV valve control , known as the Leyland Mark III, was installed for the bus companies from Bournemouth and Eastbourne.

TD6

This series was only built for Birmingham Transport from 1938 to 1939. This was a TD5c with a torque converter and flexible engine mount.

TD7

The last pre-war Titan had a flexible engine mount and a larger flywheel. It was produced in parallel to the TD5. By order of the government in early 1940, production of most of the copies ordered was frozen. The remaining orders were carried out until the end of 1941, after which the titanium production line was closed. to get capacity to build tanks .

TD8

Originally, Leyland received an order from the Ministry of Supply to produce 500 standard buses from October 1941. However, due to a change in government policy, Guy Motors was commissioned to build 500 chassis based on the same drawings as TD8, while Leyland should concentrate on building tanks. The buses manufactured by Guy from the spring of 1942 were the first of the models later known as Guy Arab.

Leyland Titan post-war period

PD1

In contrast to AEC, which initially reintroduced pre-war models, Leyland presented a completely new Titan in 1945. On the PD1 only the front axle was similar to the TD7. All other components were new, even if the structure and arrangement of the standard steel frame was similar to the pre-war model, the body was slightly elongated and widened and the lower rows of seats were anchored differently. There were also larger side windows and the upper roof could be ordered with cladding on the inside for the first time. In Leyland, the “P” stood for passenger car and “D” for double deck. The Titan PD1, which was originally developed as the TD9, also got a "single decker" version of the Tiger PS1 .

The new features included the E181 7.4-liter gasoline engine. A further development of a pre-war 6.2 liter unit that was already used in some TD8 Tigers and prototypes. Leyland adopted the revised bore dimensions from the Matilda (tank) . The E181 was a six-cylinder OHV that made 100 hp at 1800 rpm and 328 Nm of torque at 1150 rpm. These values were slightly better than the larger pre-war 8.6 liter OHC engine and the fuel consumption was lower. The flexible engine mount available on the TD7 was not entirely successful and the PD1 reverted to a rigid engine mount as a result. A 4 + 1 spur gear was used as the gear. The braking system consisted of three vacuum braking circuits with servo assistance. A new, larger radiator has now been installed, with the filler neck being moved to the passenger side in favor of a wider driver's cab .

The dimensions of the PD1 were 26 meters in length and 7 ft 6 inches in width. The PD1 series was produced until 1952, partly parallel to the successor PD2 from 1948 to 1952. Over 5000 Leyland buses equipped with the 7.4 liter engine were built, but most of them were Tigers, largely because the Tiger PS1 had been in series production for a longer period of time. Still, over 1950 PD1 Titans were built, mostly between 1945 and 1948.

OPD1

The Titan OPD1 was the first Leyland bus specifically designed for export. “O” stood for “overseas”. This export version had a similar frame, but made of slightly thicker steel, and the dimensions were larger. The wheelbase was 17 feet 6 inches compared to 16 feet 3 inches, and the body was 18 inches longer than local regulations allowed. The other big difference to the PD1 (as well as the similar Tiger OPS1) was the equipment with the pre-war 8.6-liter OHC gasoline engine.

PD2

Leyland installed the E181 as an interim solution until a better engine was available. This is how the first post-war Leyland truck, the (internally called) Interim Beaver, was launched . From 1946 Leyland gradually began to produce its Beaver, Leyland Steer , Leyland Octopus and Leyland Hippo truck models again. At the same time, the E-numbering for engines ended. The new engines were named after the conversion into cubic inches (due to US influence during World War II). The Leyland was called O.600, O for oil (British engine parlance for compression ignition engines instead of the German designation diesel ) and 600 for 600 cubic inch displacement, which corresponds to 9.8 liters. The only contemporary heavy vehicle compression ignition engines in Great Britain with equivalent displacement were the AEC 9.6 liter diesel engine (from 1939) and the 9.1 liter Albion Motor Car (from 1937). They had the O.600 with 125 hp at 1800 rpm. and a maximum torque of 410 Nm at just 900 revolutions per minute. This engine now offered fast acceleration in the Titan PD2 with great economy at the same time. As a result, it also impressed with its high mileage and high reliability. So it is not surprising that this engine was used until the end of production in the Titan series in 1969 and in other models until the 1970s. An important structural feature of the O.600 was that the cylinder block and crankcase were manufactured as one unit. The cylinder head was divided into two parts, with each head and gasket assembly, three cylinder bores and other important functions driven by a gear instead of a chain to improve reliability. For the latter, the camshaft was also installed at the bottom of the engine block.

In addition to the new diesel engine, the PD2 also received a redesigned frame with side members carefully staggered in depth. Nobody should be overused or underused. The O.600 was attached to the chassis at three points for flexible assembly. An enlarged clutch and a new transmission with now synchronized second and third gear were further pioneering functions in British bus chassis construction.

PD3

The British building and usage regulations were relaxed in July 1956, with a maximum double-decker bus length on two axles of 30 m and a total weight of up to 14 tons. Leyland reacted immediately to these relaxed regulations by announcing a new titanium model range PD3 with corresponding model configurations. There was no longer a special export model. Thick steel for the frame and a special rear axle were now standard. The first presentation of the new series took place in 1956 at the Commercial Motor Show. After Leyland had finished manufacturing its own bodies in 1954, the exhibition model carried a Metro-Cammell - "Orion" body. It was shown with 74 seats, but delivered with 68 seats.

The Leyland O.680 11.1 liter diesel engine with 150 hp and power steering were now also available as an option . The bodies now produced by different manufacturers differed considerably in the number of seats, the use for special requirements such as airport traffic with a rear trunk or special designs. Leyland only supplied the chassis and the customer chose the body, hydraulic or compressed air braking system, engine variant and manual or automatic transmission . In addition, there were customers who only ordered the chassis and equipped them with drive variants from other manufacturers or who had new technical developments installed. As a rule, batches were ordered that made the respective individual model correspondingly cheaper.

In 1967 the last revision took place, which took over many components of the larger Leyland Atlantean such as the new dual-circuit air brake system and semi-automatic transmission.

Through the merger to form the British Leyland Motor Corporation , production of the series in Great Britain was discontinued in 1969. However, a few years later new prototypes were tested, which later resulted in the successor model Leyland Titan (B15) . The last export model of the Titan PD series went to Indonesia , the last domestic model had an East Lancs body and was ordered by the Ramsbottom company and delivered to its subsidiary SELNEC PTE in November 1969 . The production facilities were brought to Ashok Leyland in India , where the series is still manufactured today as Ashok Leyland Titan .

London Passenger Transport (RTL) on duty
RTL554 restored in 1991
An RTL exports to South Africa
Titan PD3 with Northern Counties Motor and Engineering Company body structure
Titan PD2 with Willowbrook body structure

literature

The best of British buses. No.1, Leyland Titans 1927-1942 . Transport Publishing Company, Glossop 1981, ISBN 0-903839-56-3

Web links

Commons : Leyland Titan - collection of images, videos and audio files