Passenger and freight locomotive – what’s the difference?
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Passenger and freight locomotive – what’s the difference?

There are many types of locomotives used on the railway. They differ in the method of traction (electric or thermal) and purpose. In addition to passenger and freight, there are also shunting and universal machines.


It would seem: does it really matter what a locomotive pulls: passenger cars or oil tanks? It turns out there is a difference, although there is an exception to every rule. But let's look at everything in more detail.

Passenger diesel locomotives


The first external difference is the number of sections: in this case, there is only one. And it is made in the form of a one-piece body, which has a complex structure of transverse, longitudinal metal profiles, rods. From the outside, all this is covered with cladding. The role of the power plant is usually played by a 16-cylinder diesel engine, developing a capacity of 4 thousand "horses".

Passenger and freight locomotive – what’s the difference?TEP70 – classic single-section passenger diesel locomotive. Photo: youtube.com

The passenger locomotive is initially designed with high dynamic performance in mind. The speed is 160 km/h (this is largely due to the wheels with a diameter of 1220 mm), the load on the rails from the axle reaches 245 kN, and the traction in continuous mode is from 130 to 180 kN (47-50 km/h). The turning radius is 125 m. A classic example is the TEP70, TEP70BS diesel locomotives. Another important feature of the passenger train consists of the presence of electro-pneumatic brakes.

Larger diameter wheels, pneumatic brakes. Photo: youtube.com

We will not go into detail about their design, we will only say that they work simultaneously on all cars and the locomotive. This allows the entire train to stop relatively quickly during emergency braking. If we take regular pneumatic brakes, they act twice as slowly. Well, there are also "minor household" differences in the form of power cables through which the cars are supplied with electricity.

What if you attach a freight train to a passenger locomotive?


It is "not supposed" to do this even in theory. But in practice, although rarely, it happens. The locomotive of a passenger train is a single unit in terms of body design. And therefore it is not designed for heavy carriages capable of creating a longitudinal-dynamic "wave": many have probably noticed it when, for example, the train just starts moving.

In the cabin of the TEP70 locomotive – the driver is responsible for the passengers. Photo: youtube.com

The large mass of the train will create difficulties during towing: the total weight of passenger cars is much less. The increased diameter of the locomotive wheels makes it problematic even to move off the spot. In principle, it is possible to tow freight cars with a passenger car if their mass is not too great.

Freight diesel locomotives


They have more than one section: two, three, or even more. The diameter of the wheels is smaller and equals 1050 mm. But the power of the power plant is greater (as well as the axles) and reaches 8 thousand "horses". The load on the rails of such a diesel locomotive, due to the increased number of wheels, is almost the same as a passenger locomotive. But the traction is in the range from 250 to 300 kN (24-27 km / h): this is on average twice as much. True, the design speed is lower - up to 100 km / h. But for a freight train it is not as important as traction.

VL80 – freight locomotive with two sections. Photo: youtube.com

The body has a different design: it is removable, the frame is load-bearing, reinforced. The latter is especially important at the start of movement: at this moment, a jerk occurs, heavily loading the body structure. The brakes are pneumatic and deceleration begins "in a chain": first the locomotive stops, then, one after another, the cars. As an example, we can consider the brands 2TE25KM, 2M62 and others.

Is it possible to pull passenger cars with a freight locomotive?


Theoretically, yes, but in practice this is rarely done. For this, the locomotive must have the ability to connect electrical equipment to the cars. The second point is the "liberal" schedule. If you need to "catch up" with the schedule somewhere on the stretch, then it will be difficult to do this on a freight locomotive with its low speed.

A two-section freight locomotive hauls a passenger train. Photo: youtube.com

But there is an advantage: if the power unit breaks down in one section, the train can be pulled to the second (such cases have happened). The mass of passenger cars (there are always fewer of them) is several times less than that of freight cars. If necessary (for example, in the event of an accident), the 2M62 can also move two trains with people.

Shunting locomotives


The work associated with operating these machines is jokingly called "elite" by railroad workers. Such diesel locomotives have one cabin, a bonnet-type body, removable, and a supporting frame. The diesel engine is inferior in power to the above-mentioned ones: it develops only 1200 "horses". However, the shunting machine is capable of providing traction of up to 350 kN at a speed of 10 km/h for a long time.

Shunting TEM2s can often be seen at large enterprises. Photo: youtube.com

The diesel locomotive is quite nimble and it is not for nothing that it is called a shunting locomotive, since it is capable of fitting into curves with a radius of 80 meters. At the same time, the load on the rails is slightly less: up to 220 kN. This allows the machine to pull trains on tracks with a weak base - for example, at industrial enterprises. But the speed of the shunting locomotive is the same as that of the "trucks» – up to 100 km/h. Therefore, as an exception, such diesel locomotives sometimes haul cars over long distances, but only on sections where there is no strict schedule, and if the mass of the train does not exceed operational tolerances. In Russia, shunting diesel locomotives are branded as ChMEZ, TEM18D, TEM2, etc.

Universal locomotives


Their name says it all: they are designed to drive both passenger and freight cars. And in addition, they are capable of performing shunting operations. Only one series of universal machines is currently used on Russian railways.

M62 – a universal machine. Photo: youtube.com

These are the M62 and its modernized version, the DM62. Their technical characteristics, compared to the diesel locomotives described above, are average.

At one time, the cargo-passenger DM62 hauled a BZhRK train with nuclear missiles.

The engine power, for example, is 2 thousand hp, the braking system is exactly the same as in passenger cars.

What about electric locomotives?


Here the differences are approximately the same as for diesel-fueled locomotives. The traction gearbox, or rather its gear ratio, is larger in freight locomotives than in passenger locomotives. Universal electric locomotives have an average value. The gearbox here plays the same role as the gearbox on the car. As with diesel locomotives, a reinforced frame is typical for freight locomotives. Passenger locomotives differ in the power supply system, so that, for example, the doors can be opened simultaneously in all cars of the electric train, and the driver can communicate with the people being transported.

The ChS200, as its name suggests, reaches 200 km/h. Photo: youtube.com

Among the freight locomotives powered by the contact network, we can highlight the VL80S, and the passenger locomotives are the ChS200 and ChS7. Among the universal locomotives is the Re-420 made in Switzerland. Previously, shunting machines were made only with diesel traction. But today, exceptions have begun to appear. An example is the Russian hybrid EMKA2, the prototype of which was first shown at the PRO//Movement.Expo exhibition in 2023. Externally, the machine is similar to the serial TEM23: the difference lies in the current collector on the cabin.

Testing of the first Russian shunting hybrid EMKA2

The batteries were developed by the capital's Technospark, and the new product was assembled at the Novocherkassk plant. The shunting electric locomotive receives energy through the contact network or batteries. In the latter case, the cruising range with a train weighing up to 2 thousand tons will be 14 km. The power of the traction electric motors reaches 500 kW, of which 300 are batteries. The average speed of the EMKA2 is 90 km/h. Progress is moving forward and now "battery-powered" locomotives are no longer news.
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