Driving Basics

These driving instructions cover the basic elements of driving a train, in any country, on any gauge of track, and specifically apply to diesel, electric, and diesel-electric powered locomotives (engines) or railcar sets.

Steam trains are somewhat different, and because the techniques used in driving a steam engine are not similar, a seperate section for them will be written for posting here at a later date.

There are basically two main and different operations - applying or reducing power (traction) to some or many of the wheels of the train - and applying or reducing braking to all wheels.

We should point out that the way in which a train is driven is totally different from a car, a bus, a road truck, or any other vehicle.

Different types of power
Diesel-electric, Diesel-Hydraulic, and Direct-drive Diesel locomotives are similar in the practical operation of their power control. They have a throttle control which steps through a number of positions (called "Notches") from idle speed up to the maximum engine speed permitted. The number of notches depends largely upon the manufacturer.

In the case of diesel engines of U.S. origin (General Motors, General Electric, and American Locomotive Company being probably the best known) there are eight running positions. The British built engines often had twelve.

The throttle control is precisely that... the higher the running "notch", the more fuel is metered into the engine. If these notches are correctly set up, the same increase in power is developed in each increased throttle position, meaning that several similarly constructed engines can be connected together and run from one of the cabs.

The engine with the driver is called the "local" locomotive, and the others (without drivers) are called "remote" locomotives - and in the case of very long train some may be half-way down the length of the train, and controlled by radio (Locotrol). Sometimes they are referred to as "leading" (or "lead") and "trailing" (or "trail").

Electric locomotives use control equipment similar in appearance to diesel locomotives, but frequently with a larger number of power "notches". They do not usually run "in multiple" with diesel power. There are always exceptions; the Danish State Railways (DSB) designed their IC3 diesel powered self-propelled trains to run in multiple with their ER4 electric powered self-propelled trains!

Train Brakes
The original trains built, when fitted with brakes at all, were of the vacuum variety, a totally fail-safe system developed by the British. There was a quite large diameter pipe (called the "Train Pipe") that ran for the entire length of the train, with flexible hoses connecting each vehicle. The large diameter pipe was needed because of the necessity to move large volumes of air as the pipe was evacuated to release the brakes, or to open it to the atmosphere to apply the brakes.

If the train broke into two or more sections, the vacuum in the "Train Pipe" would immediately disappear, and the brakes would be applied, bringing each portion of the train to rest.

However, because they relied on the very small difference in pressure between the atmosphere and the nearest they could approach to a vacuum - a maximum of 14 pounds per square inch (or 150 kilopascals) at sea level, and less the higher one climbed above sea level, they were not very efficient. A larger pressure differential was needed, which in turn would allow smaller sized pipes and hoses.

Various systems were tried, and thus we arrive at the Westinghouse Air Brake system, which the majority of countries nowadays use; this system was originally developed by Westinghouse, and uses compressed air, but which will also fail safe due to its ingenious design.

There is a quite high pressure in the pipe to keep the brake shoes released, and an air tank on each wagon (passenger or goods) whose tank is kept charged from the brake pipe. When the pressure in the brake pipe reduces below that in the receivers on the wagons, braking takes place, the greater the pressure difference, the greater the brake application. On releasing the brakes, the pipe is recharged with air, and this refills that lost from the tanks down the train.

Whereas the vacuum system had a maximum of 14 pounds per square inch of vacuum with which to both signal the brakes on each vehicle and apply braking pressure, the Westinghouse system runs typically with 100 pounds per square inch as the maximum pressure... a typical brake application to gently slow a train being 10 or 20 psi.

The type of braking system used by train driving simulators is basically that controlled by a five-position air brake control similar to those developed by Westinghouse and similar companies. There is no graduated control... the brake application is made, and then "lapped" to cut off any further reduction, followed by a full release operation - a partial release is not possible.

Graduated brakes such as the Westinghouse 26L type, which offers almost a rheostat type adjustment to brake application probably require more skill in correct operation, but are not offered in RailSim (nor indeed in TrainMaster).

Emergency Brakes
The "Automatic Brake" has an emergency braking feature which quickly empties the brake pipe and causes a very rapid speed reduction. In real life, this attracts a time penalty during which it is not possible to reset the braking system and recharge the pipe and the reservoirs. This should only be used in a real emergency situation, although various automated processes on board can put the train into emergency braking.

These processes are...

A severe leak in the brake pipe
Braking initiated by the "guard" at the rear of the train
Braking initiated by a passenger operating an emergency braking lever
Failure to acknowledge the Vigilance timer (see later)
Failure to acknowledge an Automatic Train Control warning (if fitted)
Failure to acknowledge a trackside signal warning in ATC mode (if fitted)

Stopping takes time and distance
It is important to understand that braking is not instant. As you make a 20 pound reduction in the pipe to gently apply the brakes, those in the engine and first wagon apply immediately. The air reduction moves down the train progressively, and eventually the last vehicle is also braking. The train will "run in" behind the engine(s) while this is happening.

On releasing the brakes, the train has to be gently "stretched" under power - as otherwise if the slack is not taken up like that, the couplings or the draft gear they are mounted in can (and will) break.

This is a technique that takes some development by a "rookie" (novice) driver.

Locomotive Brakes
We have looked at what is usually called the "Automatic Brake" - the brake that is controlled by the main air brake lever in the leading locomotive.

The driver has a second brake lever in a locomotive (not usually so in railcars), called the "Independant Brake". When the train runs in behind the locomotive during a brake application, a wise driver will release the locomotive's brakes, keeping those on the train set. This ensures that the first set of couplings is stretched, and when the brakes are released, the slack is able to be taken up faster and with less shock to the couplings and draft gear.

RailSim does not feature an Independant Brake, but TrainMaster does.

Speeding up is not instant, either
Likewise with throttle adjustments... it is not possible to suddenly open the throttle to maximum. With diesel-hydraulic and direct drive power, there is usually a torque convertor or similar device that allows the hydraulic oil to be bypassed under too much load, rather like the automatic transmission of a car.

With Diesel-Electric drive, and Electric drive, the increase in engine throttle or power selected immediately translates into more current being applied to the traction motor mounted on each axle. "Wheel slip" will occur if too much power is applied, and it is only personal knowledge of the behaviour of the particular locomotives that will prompt the driver when it is safe to increase further power "notches".

In the case of small amounts of wheel slip, boxes of sand are mounted near each driving wheel, and a "sand" pedal on the floor will cause compressed air from the engine's main air reservoir to blow sand to the front of each driving wheel just above rail level, to increase traction momentarily.

Any wheel slip will cause rail wear and wheel wear, and should be avoided.

Braking using the engine
In an electric locomotive or railcar set, to save wear on wheels and brake shoes or disk pads, the traction motors are often used in a "regenerative braking" mode where the motors are converted into generators, and pump electricity back into the power system overhead (or third rail).

In a diesel engine or railcar set, the power generated cannot be fed anywhere except to resistor grids on the roof which are cooled by fans, and this braking mode is then called "Dynamic Braking".

Not all railcars or locomotives are so fitted.

It is important to understand that the slower the train is going, the less effect will dynamic braking have on the motion.

"Dead Man's" pedal/handle
Most railway systems have some form of automatic gadget which checks if the driver is awake - or even alive; the general English terminology for this is "Vigilance". It can take various forms. In Australia it is basically a pneumatic timer, and is not reperesented in the Australian version of RailSim.

However the European version of RailSim has an automatic function called "Sifa" which is very similar to the Australian Vigilance control, in that it requires the driver to press a dedicated button frequently to reset the safety system when required to do so. Failure to acknowledge results in an emergency brake application.

The British system used on electric commuter trains in the London area for many years (including the UndergrounD) relied on the driver's controller handle having to be held down in whatever position it was. The knob being sprung (to move upwards) this was considered to be foolproof.

Other systems have required the driver to sit or stand with one foot on a pedal on the floor, similar in construction to a sand pedal.

In all cases, these features have not always proved to be foolproof, but they are a compromise in ensuring safety of the train, its load (people or goods), its crew, and the infrastructure (track and signals etc).