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The Silcox Code
Page 81
Page 82
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A WOULD-BE hijacker will need to be something of a mathematical genius to break the Silcox and Smith ignition code system. This serves as an immobiliser when a vehicle is left unattended and as antihijack when the driver is with the vehicle.
When either of the cab doors are opened the device is set without any action being required by the driver. This means that even if the driver leaves the cab with his engine running and the ignition key In the "switched on" position, the vehicle will still Immobilise itself after a predetermined time. Thus the vehicle can be driven for the pre-set time, after that the engine will stop. However, the engine can be switched off by the normal ignition start switch and the engine will stop immediately, the code being again scrambled.
To re-start the engine the code number will again have to be operated. This code number can be changed at any time by the engineers, or alternatively, at extra cost, the units can be fitted with a code plug exchange system which would give more flexibility to the operator as he could then change his code system frequently himself by having a supply of code plugs.
A code plug assigned to a company cannot under any circumstances be used by any other company. A company can have a separate system for each vehicle with its own set of code plugs, or, for instance, If it has a fleet of say ten vehicles a supply of 20 different code plugs would allow for a good interchange of code numbers, if required, between the fleet itself.
As the permutation of any three digits out of 10 is considerable, the choice of number sequence is also considerable.
The Elva Self-Contained System is designed to "hold off" while the vehicle is being driven or when the doors are open for loading purposes. When the ignition is switched off and all doors are closed, the impact system comes into operation automatically.
Any sharp knock on the body of the vehicle will trigger the alarm, thus serving as a protection against any attempt to break locks or bypassing of the doors by breaking in by the sides or roof of the vehicle. The alarm for trailers with closed van bodies consists of a fully automatic system complete with sirens and its own independent rechargeable battery. The battery Is of the tmspillable type rated at 10Ah. This alarm is designated the Elva Series '8' Fully Automatic Self Contained Trailer Unit, and has three independent closed circuits to allow for independent protection on three trailer openings, eg if a vehicle Is being unloaded from doors on one side of the vehicle, the other doors, If closed, will still be alarmed. There is also an independent open circuit facility to enable contacted locks to be alarmed If necessary. In addition, there is a circuit which will protect the main tractor batteries from disconnection when the tractor and trailer are coupled.
When the trailer is standing In a depot with the doors closed, it automatically enters an alarmed state.
Silent entry to the trailer is obtained by operating a keyswitch in the trailer.