Patent GB-190429471-A (GB)
Title: Improvements in or relating to the Interlocking of Railway Points or Signals by Means of Keys.
Inventor: MACKENZIE JOHN WILLIAM
Filed: 1904-12-31
Granted: 1905-05-11
Abstract: 29,471. Mackenzie, J. W., [Hepper, H. A. L.]. Dec. 31. Controlling traffic on railways, staff and ticket systems for; interlocking.-A key is delivered for use at points or switches from an electrically-controlled mechanical lock. The key may be released either from a similar distant apparatus or by action of an interlocking frame arranged to control a number of such locks. The key locking and delivering apparatus is shown in Fig. 4. The key is shown inserted and turned through 180‹. This action has lifted the bolt I, which is held up by the lever J, and also by the pin O, which is part of the bolt I, being held by the projection on the arm N of the armature M. The bolt Q is normally held in its highest position by the spring R. The key cannot be removed except by being turned to the left, and this is only possible when the magnet BC has attracted its armature M and released the pin 0 so as to allow the bolt I to move. Pins T, U are attached to, but insulated from, the bolts I, Q. The pin T, when the bolt I is raised by the key, makes contact between the line from distant apparatus, which is fixed to the terminal A, and the electromagnet BC, which is connected to the terminal B. When the bolt Q is in its normal position, the pin U connects the electromagnet terminal C to the terminal D, and when the bolt Q is depressed the pin U connects the terminal C to the terminal E. The terminal D is connected through a bell to earth, and the terminal E through a battery to earth. A tappet lock S prevents the bolts I, Q from being both depressed at one time. An apparatus at stations at the ends of a line can be used to deliver a key for use at one station if the similar key is in position at the other end. The key at one station being free and that at the other being required for use, that at the first station is inserted and turned to the right. This action first lifts the bolt I and locks the key in, then depresses the bolt Q against the action of the spring R, and completes a circuit from the battery at the first station to and through the terminals E, C, electromagnet BC, and the terminals B, A at this station, along the line to the second station, to and through the terminals A, B, electromagnet BC, terminals C, D, and the bell at this station to earth, and so back to the battery. The magnets at both stations are energized and deflect a soft iron needle which is placed in the cover of the apparatus opposite the smaller and staggered poles V<3>, V<4> of the magnet BC. The operator at the second station, on seeing the needle deflected, turns his key to the left. This removes the pin on the lever J from the lever N, and allows the armature M to be drawn up by the main pole-pieces of the magnet, thus releasing the pin 0 ; the key at this station can then be turned to the position for removal. The pin T is withdrawn from the contacts A, B, and so breaks the circuit, and the needles are then no longer deflected, indicating to the operator at the first station that the key at the other is free ; he then lets his key return by the action of the spring R to the normal locked position. A partition is fixed under the cover to prevent interference with the contacts by bodies introduced through the keyhole. If a number of keys are to be controlled from one station, a miniature interlocking frame may be used to liberate the keys from the locks, the interlocking being arranged to prevent two conflicting keys from being liberated at one time. An extra lever may be added to lock the whole frame, this lever being locked by a key kept by the person responsible for the road. Each lever moves a bar W, Fig. 2, which carries two contacts, insulated from the bar W, over contact-plates B, A, E, C, and normally is in the position shown. When a key is to be released from a distant box, the bar W is pulled over as far as it will go. The plates A, E are then connected, and current passes from the battery at the lever frame to the distant key box, ringing the bell there, energizing the distant magnet, and allowing the key to be withdrawn. Both indicating-needles are deflected until the key is withdrawn.. The pawl PL falls on the bar W moving and prevents the bar W from returning to its normal position. It returns under the action of counterweights only so far as to bridge the contact-plates A, B, and is held by a catch on the lever. When the key at the distant box is replaced and turned to the right, the bell at the frame is rung, the indicating-needles deflected, and the magnet BM energized. The pawl PL is lifted, and the lever may be replaced in its normal position. The circuit is then broken and both needles resume their normal position, showing the operator at the distant end that the lever is returned to its normal position, and he then releases his key from the bolt Q. It is preferable to use wire instead of earth returns. The miniature lever frame may be extended, if desired, to include a mechanical release for keys which are for use close to the lever frame, and so afford the security of interlocking among all the keys whether released electrically or mechanically.