Welcome to our locomotives
When running, the Maybach MD655 engine (1) rotates a cardan shaft coupled to the transmission (2). Using internal gears, two smaller cardan shafts mounted on top of the transmission rotate the dynostarter and hydrostatic oil pump (these are not shown). The dynostarter provides 110 volts for the electrical systems operating on the locomotive and acts as the starter motor for the diesel engine. The hydrostatic oil pump (not shown) works constantly and a small electrically operated valve diverts oil to the cooling fans to turn them as required.
When the driver selects "forward" (or "reverse") direction and then "notch one" on the power controller, the transmission (2) convertor 1st stage (gear) fills with oil and the diesel engine now begins to rotate this oil, rather like a ships propeller in water. Face to face with this "propeller" is another similar "propeller" which begins to rotate too and this is coupled to another cardan shaft leading to the bogie mounted intermediate gearbox (3). In this gearbox, a combination of bevel and wheel gears transmit the drive downwards. From there a cardan shaft (6) transmits the drive to the axle mounted final drive gearboxes (4). The locomotive will begin to move foward as soon as the brakes have been released.
As more power is applied by the driver (up to notch 9) on the power controller, the locomotive moves forward gaining speed and the converters within the transmission automatically change (1st to 2nd; 2nd to 3rd), each convertor decreasing in physical size until the 3rd convertor is used. This, the smallest of the three converters, then drives the train forward in the speed range between 63 and 90 mph.
The two locomotives owned by the Western Locomotive Association Limited are based on the Severn Valley Railway, which operates over 16 miles of track between Bridgnorth and Kidderminster. They are “Western” class 52 diesel hydraulics, D1013 Western Ranger and D1062 Western Courier. Both locomotives were retired from service with British Rail more than forty years ago.
The Western class are a historically and technically significant design as they replaced the famous King and Castle classes of steam locomotive on the former Great Western Railway in the 1960’s before being replaced in turn by the Inter City 125 High Speed Trains. Most of the seventy four locomotives were broken up for scrap, but seven survived, including the two WLA locos.
How does a Western Diesel Locomotive work?
A Western has two 65 litre Maybach MD 655 diesel engines each driving a Voith hydraulic transmission which turn the wheels via a gearbox. The cylinders are arranged in a V formation driving a common crankshaft. The Maybach MD655 has twelve cylinders and produces 1380 hp at 1,500 rpm. Maybach diesel engines were also used in marine installations such as motor torpedo boats and fishing boats.
Maybach diesel engines operate on a four-stroke cycle; that is two up strokes and two down strokes. An inlet valve and an outlet valve are operated from a camshaft and control the air into the cylinder and the exhaust gas out.The piston sequence is as follows:-
First stroke-Induction. This begins as the piston commences the down stroke with the inlet valve open. As the piston commences downward, it draws air past the open inlet valve into the cylinder. The exhaust valve is closed at this stage.
Second stroke-Compression. When the piston has completed the down stroke, the inlet valve closes, and as the exhaust valve is already closed, the air contained in the cylinder is trapped. The revolving crankshaft pushes the piston up and as it rises, the air trapped in the cylinder is compressed up into the combustion chamber. As the air is compressed it becomes extremely hot.
Third stroke-Power. With the valves still closed, fuel oil is sprayed through an injector into the top of the cylinder at the point of greatest compression and heat. The heat from the compressed air causes the atomised oil to ignite and greatly expand in volume. This forces the piston down the cylinder.
Fourth stroke-Exhaust. At the end of the power stroke, the exhaust valve opens and during the following up stroke of the piston the waste gases are pushed past the valve and out of the engine. The first photgraph below shows the four strokes.
A turbo-charger is used in order to obtain the maximum power from the engine. This is a device which contains a turbine that sucks in air from the atmosphere and forces it into the engine through the inlet valve. The turbo-charger is driven from a turbine powered by the exhaust gases of the engine.
To keep the engines and turbo-chargers cool, the locomotive has large fans mounted in the roof. These draw air through the louvres in the body-side and through radiators mounted above the engines. The turning action of a diesel engine cannot be linked directly to the wheel. It has to be controlled so that the locomotive can start from rest with a train and cope with different gradients and loads. This is achieved on a Western by using a hydraulic transmission. Most locomotives nowadays use diesel electric transmission where the diesel engine turns a generator and the power produced drives electric motors, which turn the wheels.
A diesel hydraulic locomotive has a torque converter, which is rather like a hydraulic pump revolving inside a housing filled with oil, which transmits power to the rails. It has three main parts, of which two rotate and one is fixed. Each part consists of a ring with specially shaped blades. The blades are curved to control the direction of the flow of oil. The three parts of a torque converter are the impeller (a centrifugal pump), the turbine wheel (or driven wheel) and the fixed guide wheel (or reaction wheel). The diesel engine drives the impeller and its power is passed on to the oil in the converter. The impeller blades pump the oil onto the turbine wheel blades, causing the turbine wheel to rotate. The turbine wheel is connected by a shaft to the locomotive wheels so when the turbine wheel rotates the locomotive wheels rotate. The second photograph below shows a hydraulic transmission.
The advantage of a diesel hydraulic system was its lightweight construction. Also the torque converter is so designed so that the lower the speed the greater the pulling power. A hydraulic drive also provides a shock free connection between the engine and locomotive wheels over the whole range of engine power.
Building the Westerns
Building the Westerns
The Westerns were built at Swindon Works in Wiltshire and Crewe Works in Cheshire. A total of 74 were produced between 1961 and 1964, 35 at Swindon and 39 at Crewe. The Westerns employed a stressed skin body shell rather than the heavy frame that had been used previously on earlier diesel locomotives. This comprised two substantial steel tubes running from end to end of the locomotive. A steel honeycomb was built up from these tubes to create a lightweight yet rigid structure very similar to a motorcar chassis. This technique had been pioneered by the American civil engineer Stepan Timoshenko and is based upon the premise that thin metal sheet, if folded and shaped can be made to serve a load bearing function.
The Westerns were essentially a British development of a prototype locomotive built by Krauss-Maffei in 1957. This locomotive, known as ML3000 was an enlarged version of the successful V200 design but with six wheel bogies giving greater traction and braking effort. The design had to be compressed to fit within the British loading gauge and 74 locomotives were ordered in October 1959. The unit cost of each locomotive was given as £115,500. Remarkably no prototype was developed or evaluated. The class was ordered before the detailed design had been finalised.
Structurally, the Westerns were very similar to the earlier Warship design. They were however proportionately longer and heavier.
The first of the class, D1000 Western Enterprise, was delivered in December 1961 and the last one was completed in April 1964. It was no coincidence that the first of the celebrated Great Western King class locomotives was withdrawn in February 1962 with the class being completely withdrawn by the end of the year. The Westerns were initially allocated to Laira Depot in Plymouth, Canton Depot in Cardiff and Old Oak Common Depot in London. Eventually the whole fleet was based at Laira.
What did the Westerns do?
The Westerns were “mixed traffic” locomotives, that is they worked on both passenger and freight trains. For instance, Western could haul the Cornish Riviera Express passenger train on one day and then a 1000 tonne stone train the following day. Modern locomotives are specifically designed for either one role or the other.
In their early days, Westerns worked trains from London Paddington through to Birmingham Snow Hill, Wolverhampton Low Level, Shrewsbury, Chester and Birkenhead. These duties ceased in the late 1960's with the closure of Birmingham Snow Hill, although in later years they regularly worked to Birmingham New Street via Oxford and Reading. Westerns regularly worked on passenger services from London Paddington to and from Bristol, Cardiff, Swansea, Plymouth and Penzance. It was relatively rare for them to go further afield. Freight duties included working stone trains out of Merehead Quarry in Somerset, China Clay trains to and from Cornwall and Milk trains from the West Country to London.
The reign of the Westerns came to an end with the completion of the electrification of the north part of the West Coast main line between Crewe and Glasgow. This released the fleet of fifty class 50 diesel electric locomotives, which had worked those services. The plan was to reallocate the Class 50 fleet to the Western Region in 1974 enabling the Western fleet to be made redundant; to be withdrawn from service and scrapped. The first Westerns were withdrawn in 1973 and it was planned to complete the process by 1975. The Warship fleet had been withdrawn by the end of 1972 and the Hymek fleet had been withdrawn by early 1975.
The class 50 fleet proved to be notoriously unreliable in service. They were often known as 50/50’s because they previously worked in pairs on occasions or because it was perceived that you had a 50% chance of getting to your destination without a failure! Whilst they were technologically advanced locomotives, the Western Region were unfamiliar with their foibles and at one point half the fleet were out of traffic waiting for repairs. This left the Western Region with a locomotive shortage and so the Westerns soldiered on.
In October 1976, the Inter City 125 High Speed Train (HST) entered service and subsequently formed the backbone of Western Region and later First Great Western express passenger services. It is interesting to note that the HST locomotives are now being re-engined with MTU power units. MTU are the successors to Maybach and the new Adelante class 180 of diesel multiple units have hydraulic transmissions.
Why preserve a Western?
The Western Locomotive Association was founded in1974, just one year after the first Western had been withdrawn. Railway preservation was in its infancy and most enthusiasts were preoccupied with the rescuing of steam locomotives from Barry Scrapyard in South Wales. The suggestion that a diesel locomotive should be preserved was greeted in some quarters with incredulity and derision. The Westerns were regarded amongst enthusiasts and railwaymen as being different from other diesel locomotives and after a successful public appeal, D1062 was successfully purchased for preservation in 1976. Richard Holdsworth initially purchased D1013 in 1977 and they were originally based on the Paignton and Dartmouth Railway at Kingswear. Although this was a route which Westerns had worked trains on, Kingswear was a residential area where the locomotives were exposed to sea air and so it was decided to move both locomotives to the Severn Valley Railway in 1978.
The reception given to the Westerns at the Severn Valley was mixed. Some ‘die-hard’ steam enthusiasts were openly hostile. However, the Westerns soon proved to be popular and useful locomotives and both of them have worked regularly since arriving. D1062 was the first preserved Western to travel under its own power on the mainline when it took part in the Liverpool and Manchester Railway celebrations in 1980 at Rainhill. D1013 has appeared in a number of television programmes and commercials including ‘L for Lester’ and advertisements for crunchy nut cornflakes and British Gas!
Both of our locomotives have been modelled by Hornby in OO gauge and Graham Farish in N gauge and D1013 features in the Severn Valley Railway add on to the Microsoft Train Simulator computer programme. The Western Locomotive Association has successfully operated two of these iconic locomotives for forty years, three times as long as they were operated by British Rail.
Five other Westerns have been preserved:-
D1010 Western Campaigner preserved by the DEPG on the West Somerset Railway.
D1015 Western Champion preserved by the Diesel Traction Group on the SVR.
D1023 Western Fusilier preserved by the National Railway Museum at York.
D1041 Western Prince preserved on the East Lancashire Railway.
D1048 Western Lady preserved at the Midland Railway Centre in Derbyshire.
The Western Locomotive Association is committed to the preservation of D1013 and D1062 as working locomotives on the Severn Valley Railway. Many people enjoy the aesthetically pleasing shape of the Western, which never seems dated and the epitome of good design. The power of a Western is something to be experienced especially when driving one yourself with 2,700 bhp and 76,000 lbs of tractive effort on tap – twice the power of a Castle Class steam engine. Then there is the sound – two throaty Maybach MD655 V12 engines that can be heard miles away on full power, not dissimilar to the glorious sound of a Spitfire or Lancaster Bomber. With your help, we certainly intend to be supplying ‘Maybach Music’ for many years to come.