Nothing works unless it is told to by its electrical or human master. In modern warfare the first thing to be attacked are the lines of communication. Likewise the most effective, quick, at expensive way to disable equipment is to disable the control systems. For example, how would you turn a computer on if someone removed its 'on/off' switch?

7.1 Controls/switchgear

A good way to disable any system is to disable/damage the control systems. Especially on more modern systems, where specialist control devices are made to order, this can be very expensive to fix.

Control systems essentially break down into three groups...

Note also that these switching systems need not be all electronic, or all mechanical - there are still a number of systems in operation using mechanical or electro-mechanical control systems.

How you tackle a system will depend mainly on its make-up. If you have a wholly mechanical control system, for example on a aggregate grading screen, you would either go for the levers that control the system, or the linkages from these levers. But if you were dealing with a more complex system, for example an electrical generator, it would make more sense to go for the electrical output controls (the switches, power meters, fuses, etc.) than to just go for the switch that starts the engine.

7.2 Mechanical controls

Mechanical controls are either very flimsy affairs, such as brake cables, or they are very tough, such as the levers on large earth movers. Sometimes brute force, or endless tooling away, is not the answer. Many hefty control systems, such as steering wheels, actually come of very easily if you take them apart rather than cut them apart.

As a very simple guide...

An issue to think of in all this is of course safety. You should never cut the brakes of a mobile vehicle - it is extremely dangerous to the operator and other people. Likewise never start cutting a control cable or control rod unless you are pretty certain that you can finish the job. Leaving cables and rods half cut is dangerous as they can fly apart and injure those nearby when the machine is operated. If you have any doubt about the effect of what you are doing - don't do it!

Examples of electrical control panel components (figure 22)

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7.3 Electronic controls

The illustration on the previous page shows a range of electrical control components - switches, knobs, meters, relays and fuses. How you tackle a control system is dependent upon how it is controlled, and so it is important to know how to tackle each element of the control panel.




Meters and displays:

Relays and PLCs:

At the bottom of the electrical controls illustration is a small control panel. This is a good example of what you might see - it has controls (knobs/switches) and instruments (panel meters/LEDs) - which need to be 'improved'. With any control box there are five options...

The purpose of the control panel is also important. With large earth movers it is sometimes easier to go for the controls than for the extremely well-engineered workings of the engine. You really have to apply the analysis explained at the beginning - the source, control and use of energy. Damaging the energy control systems is likely to immobilise the machinery, but is repairable. Damaging the engine or power source is often a much more serious matter to put right. You really have to make up you mind, as part of your scoping exercise (see Volume I) as to what you want to achieve from your work.

7.4 Computer systems

Computer systems were dealt with in general in Volume I, and there is little to add.

In general you should always try to take on the main computer unit - damaging computer screens or keyboards has little effect as they are easily and cheaply replaced. But if you damage the main unit, this gives a bigger "£ per hammer blow cost" - some of the computer chips cost £300 to £800, and a replacement hard disk can cost three times the cost of a keyboard.

A very annoying tactic is to get a floppy disk, cover it in glue, and stick it into the disk drive. This not only means that the computer is effectively disabled in a simple, quick and quiet manner, but it is difficult to get the data stored on the hard disk out of the system without paying a lot of money to a computer engineer to remove the hard disk and read the data off it, or replace the disk drive.

With larger computers, where the circuit boards inside are easily accessible, the simplest option of to just open the cabinets, pull out the boards and snap them in two - this can be difficult by hand but if you prop them on a block or against the wall and stamp in the middle this is easily achieved.

7.5 Basic sabotage of instrumentation and switchgear

As noted above, you have to make a judgement before you start about what you want to achieve. Going for the control systems can be quick, simple, and more importantly quieter, but you may not have the permanent effect that damaging the sources or sinks of energy might have. The exception to this general rule is the more complicated systems controlled by PLCs - damaging the PLC effective renders the whole unit useless until it can be replaced, normally at great expense.

With mechanical systems, you have a option to cut or dismantle. Dismantling is quieter, but takes longer. Also, by cutting or smashing the controls you often creates "collateral damage" which take more time and money to put right than dismantling would.

With electrical systems you need to make sure that the damage you are doing will have some effect. Quite often the electrical control boxes are mass produced, and they can just bring another out and plug it in. In these cases it might be better to spend your time on other parts of the system.

I generally apply the following hierarchy of options when tackling control systems...

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