TRACK CIRCUIT ACUTATORS Flashcards
What do track circuit actuators do?
They detect the passage of trains, showing the signaller that a train is present in the section.
In normal circumstances, what else effectively transfers electrical signals across to the other rail?
The train wheels.
What impairs (short circuits) the train wheels on the rail?
Contaminants such as rust, leaves or other debris.
What do track circuit actuators create between the rail and the wheels?
An electric current that forces the track circuit’s electrical signal across to the other rail.
What is the risk without track circuit actuators?
There is a risk the trains could ‘disappear’ off track circuits, affecting the visibility of your train to the signaller and preventing the correct operation of signals, signalling systems and level crossings.
How could you identify a fault with TCAs? (6 answers)
Warning lights on cab desk Illuminated exterior orange hazard lights TCA warning lights TCA MCB tripped TCA system isolated Missing or defective TCA equipment
You must not allow a train to start a journey from a maintenance depot if the TCA: (3 answers)
is isolated in any vehicle
the isolating switch is unsealed
a warning light indicates a system fault
A train can start a journey with one or more defective or isolated TCAs, as long as: (2 answers)
A train is formed of one or two vehicles and there is at least one TCA working on the train.
In a train formed of three or more vehicles, there is at least one TCA working on either of the first two vehicles or at least one TCA working on either of the last vehicles.
If there is defective TCA equipment that prevents the train from continuing normally, whom do you contact and when?
You must contact the signaller immediately.
If defective TCA equipment does not prevent the train from continuing normally, who do you contact and when?
Contact the signaller at the next convenient opportunity.
Once you have reported to the signaller, whom do you report the circumstances to next?
Maintenance control.
If you are told to approach any level crossing at caution, what must you do with the warning horn?
You must sound the horn continuously until the front of the train is on the crossing
