Patent GB-191004997-A (GB)
Title: Improvements in Signalling and Interlocking for Railways and Tramways.
IPC: B61L23/22
Filed: 1910-02-28
Granted: 1911-02-16
Abstract: 4997. McKenzie & Holland, Hudd, A. E., and Haywood, T. E. Feb. 28. Combined electrical and mechanical systems, non-automatic; single-track systems; signalling- instruments; signalling-instruments, interlocking; hand - levers; track apparatus actuating signals other than on trains; staff and ticket systems. - In a combined electrical and mechanical system for single-line railways and tramways having loops at the ends of each section, a home signal is provided at the entrance, and a starting-signal at the exit, of each loop. The signal hand-levers are normally locked, and are electrically controlled from the cabin in advance. The lever is also interlocked with the signalling-instrument, which is provided with a polarized relay arranged to control a lock; this, on release, permits the actuation of a handle, which is then operated to unlock the signal-lever. Track treadles are provided over which the train passes operating electric contacts which control signal reversers to restore the semaphores to ' danger ' behind the train. The instruments may be locked against actuation by a special key, which is then carried by the driver of a ballast train passing into a section, and is restored to the signalman when the train passes out of the section. The interlocking-mechanism for the signalling-instrument and starting-signal lever comprises a blade 2, Fig. 5, attached bv links to the tail of the lever, and provided with two notches 3, 4 for engagement with two locking-pieces 5, 6. The lever is front locked in the normal position, when the piece 6 engages the end 2<a> of the blade 2. The blade slides through the base of the pedestal 7 of the instrument, and is guided by means of a slot 10 about a pin 8. A pair of plates 12 mounted on the pin 8 carry the locking-piece 6, and also a wiper 14. If, when the parts are in the normal position shown, the signalling-instrument is operated, and the rod 17 thereby raised, the attached plates 12 are moved to move the piece 6 clear of the end of the blade 2, and the lock 5, mounted on a pivot 15, falls against the blade 2. When the lever is operated to lower the signal, the lock 5 rests against the edge of the blade 2, but moves into the notch 3 to lock the lever when it is returned nearly to its normal position, i.e. the lever is back-locked and the signal has returned to ' danger.' If then the instrument is returned to normal position, the rod 17 moves, and actuates the plates 12 and wiper 14 to restore the lock 5 to its normal position, and the lock 6 then abuts against the face 4<a> of the blade 2. The weight of the parts retains them in this position until the lever is returned fully to its normal position when the surface 4<a> descends below the lock 6. When the lever is backlocked, and the instrument has been operated to remove the lock 5 from the notch 3, the signal cannot again be lowered because the lock 6 engages the shoulder 4 to prevent this. The rod 17 is connected to a pin 19, Fig. 1, on a crank 20 operated by a handle outside the instrument. The crank spindle 22 carries disks 21, 21<a> having locking-notches cut in their peripheries, in which move locking-pieces 23 operated by the armature 26 of a permanent magnet 24 provided with lock coils 25, which thus act as polarized coils. An additional locking-piece 39 is moved by the armature 36 of an electro-magnet 37. The sending-commutator 30 is mounted on the crank spindle 22, and another commutator 31 called the receiving-commu- ' tator ' is carried by a disk 32 mounted on a spindle 33 and notched so that its periphery intersects that of the disks 21, 21<a>. The disk 32, or the pair of disks 21, 21<a>, may be rotated separately in certain positions, but both cannot be rotated together. In the normal position, the commutator 31 may be moved by a handle 34, but in the operated position it may be locked by an arm 35 on the armature 36 engaging a notch 38 in the disk 32. A plunger knob 40 is pressed to operate bell signals, and locks at the next cabin by controlling contacts 79. An electro-magnet 42 controls the circuit of a constant-current signal-reverser 41 on the starting- signal, and the armature 43 is connected by a rod 45 to a lever 45b, one end of which rests against a cam 46 on the disk 21, so that, in the normal position, the armature 43 is held midway between its lowest and highest points, and the word ' closed ' is shown by the flag 47 at an aperture in the case. The spring contacts 70, 136, 59, 73, 74, 84, controlled by the electromagnets 42, 54, 37, are adapted to be opened when the corresponding armatures are attracted, and closed when the armatures are released. Assume that an ' up ' train is to be sent from the loop at station A through the section of single track to station B, similar instruments being provided at each station and connected by a line wire 82. The signalman A first transmits bell signals to B by pressing his plunger 40, which operates the bell magnet 61, and sends a negative current through the lock coils 25 at B. The signalman B then turns his receiving- commutator handle 34 until the disk 32 becomes locked by the piece 35 engaging a projection 38, and the flag 62 indicates " train accepted." B then acknowledges the bell signal by pressing his plunger 40 to operate the bell magnet 61 at A, and transmits a positive current through the magnet coils 54 and lock coils 25 at A. The coils 25 then act with the permanent magnet 24 to raise the locks 23 and release the disks 21, 21<a>, the additional lock 39 being also raised by the magnet 37, which is energized by the battery 51 together with the magnet 42, which causes the flag 47 to indicate " clear." The magnet 42 also closes a circuit to the signal reverser 41 through track treadle contacts 49. The armature 26 at A is retained in the attracted position by the permanent magnet 24 even when the lock coils 25 are de-energized. The signalman A then operates the handle to rotate the crank 20 and removes the front lock from the starting signal lever, which is then operated to lower the signal. The rotation of the spindle 22 also forces the armature back to its normal position, and the locks 23, 39 then fall into notches 94 in the disks 21, 21<a>, backlocking the spindle 22. The train proceeds into the section of single track, and passing over the treadle 50 breaks the contacts 49 to de-energize the reverser 41 and restore the signal to ' danger,' (the armature 43 simultaneously falling so that the flag 47 indicates ' train ' going ') and also closes the treadle contacts 69 to energize the magnet 54, which disconnects the line wire 82 and breaks the circuit of the magnet 54 at B, which then closes a circuit through the lock coils 25 at B, the armature 26 of which is attracted and removes a projection 64 from a catch 67 allowing the flag 62 to show 'train coming.' The projection 64 strikes against the inside of the cam-slot 68<a>, which prevents the full movement of the armature 26 necessary to release the locks 23, 29. As the flag 62 falls the cam-slot 68<a> forces the armature 26 back to its normal position, and when the coils 25 are next energized by a positive current, the locks 23, 29 may then be raised. When the train arrives at B, the treadle contacts 69 are closed, and the magnet 54 at B is energized to close a circuit including the lock coils 25 at B and the bell at A. The train passing into the loop at B operates the treadle 75 to close a circuit through the magnet 37, which raises the locks 38 out of the notches in the disks 21, 21<a>, which may then be returned to the normal position, and the flag 62 may also be returned to the normal position indicating " closed." To clear the section, the signalman B now transmits a bell signal to A, and energizes the lock coils 25 at A, which remove the locks from the disks 21, 21<a>, and the instrument and signal lever at A may be returned to normal condition. The instruments may be locked up by a special key under circumstances such, for instance, as when a ballast train passes into the section and returns. This key operates a lock which moves the disk 21<a>, Fig. 1, backwards slightly to cause the projection 21b to lock the disk 32 and the receiving-commutator. The end of the slot 29 also locks the armature 26 of the lock magnet 25. The special shunting-key may then be turned a quarter turn within its lock to cause the body of the lock to engage with a notch in the disk 21<a>, and the shunting-key may then be removed and carried by the driver of the ballast train. The necessary operations of circuits involved in cancelling permission for a train to enter a section, which cancellation may be done only when the spindle 22 has not been operated, are also described.