HKT
It is a time saving electrical arrangement for transmitting keys over long distances. A cast iron case with an indicating needle and a key hole is kept at both the places concerned. One of the key remains locked in one of those instruments at one time.
If ‘A’ wants to transmit the key to ‘B’ he will insert it in the key hold of the transmitter and turn it in the clock wise direction. This causes both the needles deflect and a bell to ring at “b”, “b” will then turn the key at his end in the anti clock wise direction and take it out.
This stops the bell and bring the indicators to normal. “A’ leaves the key in the transmitter which gets locked up ‘B’ will return the key to ‘A’ after the work by repeating the procedure.
HKT is useful in interlocking a number of outside siding points, gates, slip siding etc with reception or dispatch signals. It is also used to connect LSS with the block instrument.
