How do diesel locomotives work

The controls will usually include a maintenance management system of some sort which can be used to download data to a portable or hand-held computer. This is the principal man-machine interface, known as a control desk in the UK or control stand in the US. The common US type of stand is positioned at an angle on the left side of the driving position and, it is said, is much preferred by drivers to the modern desk type of control layout usual in Europe and now being offered on some locomotives in the US.

The standard configuration of US-designed locomotives is to have a cab at one end of the locomotive only. Since most the US structure gauge is large enough to allow the locomotive to have a walkway on either side, there is enough visibility for the locomotive to be worked in reverse.

However, it is normal for the locomotive to operate with the cab forwards. In the UK and many European countries, locomotives are full width to the structure gauge and cabs are therefore provided at both ends. Just like an automobile, the diesel engine needs a battery to start it and to provide electrical power for lights and controls when the engine is switched off and the alternator is not running.

Since the diesel-electric locomotive uses electric transmission, traction motors are provided on the axles to give the final drive.

These motors were traditionally DC but the development of modern power and control electronics has led to the introduction of 3-phase AC motors. For a description of how this technology works, go to the Electronic Power Page on this site.

There are between four and six motors on most diesel-electric locomotives. A modern AC motor with air blowing can provide up to 1, hp. The traction motor drives the axle through a reduction gear of a range between 3 to 1 freight and 4 to 1 passenger. A diesel locomotive has to carry its own fuel around with it and there has to be enough for a reasonable length of trip.

The new ACs have 5, gallon tanks. In addition to fuel, the locomotive will carry around, typically about US gallons of cooling water and gallons of lubricating oil for the diesel engine. Air reservoirs containing compressed air at high pressure are required for the train braking and some other systems on the locomotive.

These are often mounted next to the fuel tank under the floor of the locomotive. The air compressor is required to provide a constant supply of compressed air for the locomotive and train brakes.

In the US, it is standard practice to drive the compressor off the diesel engine drive shaft. In the UK, the compressor is usually electrically driven and can therefore be mounted anywhere. The Class 60 compressor is under the frame, whereas the Class 37 has the compressors in the nose.

The main output from the diesel engine is transmitted by the drive shaft to the alternators at one end and the radiator fans and compressor at the other end. The radiator and its cooling fan is often located in the roof of the locomotive. Drive to the fan is therefore through a gearbox to change the direction of the drive upwards. The radiator works the same way as in an automobile.

Water is distributed around the engine block to keep the temperature within the most efficient range for the engine. The water is cooled by passing it through a radiator blown by a fan driven by the diesel engine. See Cooling for more information. The amount of power obtained from a cylinder in a diesel engine depends on how much fuel can be burnt in it. The amount of fuel which can be burnt depends on the amount of air available in the cylinder.

So, if you can get more air into the cylinder, more fuel will be burnt and you will get more power out of your ignition. Turbo charging is used to increase the amount of air pushed into each cylinder. The turbocharger is driven by exhaust gas from the engine. This gas drives a fan which, in turn, drives a small compressor which pushes the additional air into the cylinder. The main advantage of the turbocharger is that it gives more power with no increase in fuel costs because it uses exhaust gas as drive power.

It does need additional maintenance, however, so there are some type of lower power locomotives which are built without it. Locomotives always carry sand to assist adhesion in bad rail conditions. Sand is not often provided on multiple unit trains because the adhesion requirements are lower and there are normally more driven axles.

Figure 3: A diesel-mechanical locomotive is the simplest type of diesel locomotive. It has a direct mechanical link between the diesel engine and the wheels instead of electric transmission. The diesel engine is usually in the hp range and the transmission is similar to that of an automobile with a four speed gearbox.

Other parts are similar to the diesel-electric locomotive but there are some variations and often the wheels are coupled. In a diesel-mechanical transmission, the main drive shaft is coupled to the engine by a fluid coupling. This is a hydraulic clutch, consisting of a case filled with oil, a rotating disc with curved blades driven by the engine and another connected to the road wheels. As the engine turns the fan, the oil is driven by one disc towards the other. This turns under the force of the oil and thus turns the drive shaft.

Of course, the start up is gradual until the fan speed is almost matched by the blades. The whole system acts like an automatic clutch to allow a graduated start for the locomotive. This does the same job as that on an automobile. It varies the gear ratio between the engine and the road wheels so that the appropriate level of power can be applied to the wheels. Gear change is manual.

There is no need for a separate clutch because the functions of a clutch are already provided in the fluid coupling. The diesel-mechanical locomotive uses a final drive similar to that of a steam engine. The wheels are coupled to each other to provide more adhesion.

The output from the 4-speed gearbox is coupled to a final drive and reversing gearbox which is provided with a transverse drive shaft and balance weights. This is connected to the driving wheels by connecting rods. Hydraulic transmission works on the same principal as the fluid coupling but it allows a wider range of "slip" between the engine and wheels. It is known as a "torque converter". When the train speed has increased sufficiently to match the engine speed, the fluid is drained out of the torque converter so that the engine is virtually coupled directly to the locomotive wheels.

It is virtually direct because the coupling is usually a fluid coupling, to give some "slip". Higher speed locomotives use two or three torque converters in a sequence similar to gear changing in a mechanical transmission and some have used a combination of torque converters and gears. Some designs of diesel-hydraulic locomotives had two diesel engines and two transmission systems, one for each bogie.

The design was poplar in Germany the V series of locomotives, for example in the s and was imported into parts of the UK in the s.

However, it did not work well in heavy or express locomotive designs and has largely been replaced by diesel-electric transmission. Wheels slip is the bane of the driver trying to get a train away smoothly. The tenuous contact between steel wheel and steel rail is one of the weakest parts of the railway system. Traditionally, the only cure has been a combination of the skill of the driver and the selective use of sand to improve the adhesion.

Today, modern electronic control has produced a very effective answer to this age old problem. The system is called creep control. Extensive research into wheel slip showed that, even after a wheelset starts to slip, there is still a considerable amount of useable adhesion available for traction.

The adhesion is available up to a peak, when it will rapidly fall away to an uncontrolled spin. Monitoring the early stages of slip can be used to adjust the power being applied to the wheels so that the adhesion is kept within the limits of the "creep" towards the peak level before the uncontrolled spin sets in. Single phase motors are the most familiar of all electric motors because they are extensively…. Your email address will not be published.

Remember Me. Not a member yet? Register now. Enter something special:. Are you a member? Login now. Table of Contents. A Diesel Locomotive Construction. The hand brake is a crank that pulls a chain. It takes many turns of the crank to tighten the chain. The chain pulls the piston out to apply the brakes. You don't just hop in the cab, turn the key and drive away in a diesel locomotive. Starting a train is a little more complicated than starting your car.

The engineer climbs an 8-foot 2. He or she engages a knife switch like the ones in old Frankenstein movies that connects the batteries to the starter circuit. Then the engineer flips about a hundred switches on a circuit-breaker panel, providing power to everything from the lights to the fuel pump. Next, the engineer walks down a corridor into the engine room. He turns and holds a switch there, which primes the fuel system, making sure that all of the air is out of the system.

He then turns the switch the other way and the starter motor engages. The engine cranks over and starts running. Next, he goes up to the cab to monitor the gauges and set the brakes once the compressor has pressurized the brake system. He can then head to the back of the train to release the hand brake. Finally he can head back up to the cab and take over control from there.

Once he has permission from the conductor of the train to move, he engages the bell , which rings continuously, and sounds the air horns twice indicating forward motion. The throttle control has eight positions, plus an idle position. Each of the throttle positions is called a " notch. To get the train moving, the engineer releases the brakes and puts the throttle into notch 1. In this General Motors EMD series engine, putting the throttle into notch 1 engages a set of contactors giant electrical relays.

These contactors hook the main generator to the traction motors. Each notch engages a different combination of contactors, producing a different voltage. Some combinations of contactors put certain parts of the generator winding into a series configuration that results in a higher voltage. Others put certain parts in parallel, resulting in a lower voltage. The traction motors produce more power at higher voltages. As the contactors engage, the computerized engine controls adjust the fuel injectors to start producing more engine power.

The brake control varies the air pressure in the brake cylinders to apply pressure to the brake shoes. At the same time, it blends in the dynamic braking, using the motors to slow the train down as well. A computerized readout displays data from sensors all over the locomotive. It can provide the engineer or mechanics with information that can help diagnose problems. For instance, if the pressure in the fuel lines is getting too high, this may mean that a fuel filter is clogged. The accommodations inside a passenger train are quite plush.

The seats on this train recline more than airline seats and have more leg room. They also have footrests. Although taking the train might be slower than flying, it's definitely a lot more comfortable. There is plenty of room to walk around, and you can eat in a dining car or look at the view from the the top of the lounge car.

Some trains even have private rooms for first-class passengers -- not a bad way to get from here to there. For more information on diesel locomotives and related topics, check out the links on the next page.

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How Diesel Locomotives Work. By: Karim Nice. Contents Why Hybrid? Why Diesel? Why Hybrid? Steel Wheels " ". Some engineers worked to reduce the noise and the smoke exhaust caused by burning oil. Modern locomotives can have HP in just one engine. The collapse of ALCO happened as a result of business problems, General Motors and General Electric were able to secure deals with Union Pacific and other railroads using both the fact that they could act as a bank providing the loan.

Diesel-Electric Locomotives 1. History 1. How They Work: Below: a simple diagram of the major parts of an original s era direct current power diesel electric locomotive.