Patent GB-211152-A (GB)
Abstract: 211,152. Hulfish, D. S. Feb. 9, 1923, [Convention date]. Automatic exchange systems and apparatus; selectors. - In a group selector in which the bank terminals are arranged in horizontal and vertical rows with brush sets for each horizontal row, the brushes are first stepped round by the numerical impulses to select a desired vertical row, and a brush-choosing switch is then operated more rapidly over an interrupter circuit to select a brush set associated with an idle outgoing line. The invention is described as applied to a group selector the terminals of which are divided into two half-banks, separate brush sets wiping over each half-bank and the brushes of each halfbank being alternately tested by the brush-choosing switch. The brushchoosing switch is mounted upon the brush carriage of the main switch. Arrangement of terminal bank. The terminals 34, Fig. 1, are mounted in a semi-cylindrical frame shown developed in Fig. 6, in twenty-six vertical rows of twenty-one terminals. The bank is divided into two halfbanks of thirteen vertical rows, of which the first and last rows are unused and the second row corresponds to the normal position of the brushes, leaving ten operative rows in each half-bank. The twenty-one terminals in each vertical row consist of six sets of three terminals for six outgoing lines, and one set of three terminals (the uppermost set) for closing circuits used in the operation of the switch. The switch thus has a capacity of ten groups of twelve outgoing lines, each group occupying a vertical row in both half-banks. Construction of switch. The main switch comprises a rotatable spindle 33 on which are mounted fourteen brush sets 31, 32, Figs. 1 and 2, arranged in two vertical rows at an angle to one another, each row being adapted to wipe over a terminal half-bank. A ratchet wheel 43 is also mounted on the spindle 33, and is engaged by a two-armed escapement lever 50 which is operated by a magnet 45, and permits a spring 49 to advance the brushes one half-step when the magnet is energized and a further half-step when it is de-energized. After the brushes have selected a vertical row in each half-bank, a brushset resting on an idle line is selected by the brushchoosing switch. This switch is mounted on the ratchet 43 of the main switch by means of a flange 53, Fig. 5, on the framework 48, which carries a circular bank of terminals 73 connected to the main switch brushes, and three arcuate contact strips 75, 76, 77, Figs. 4 and 6, connected to the uppermost main switch brush-set, the contacts engaged by which are strapped together and connected to the incoming conductors 92, 93. Journaled between tongues 68, 78, is a spindle 80 carrying a ratchet 83 and three pairs of interconnected wipers 84, Fig. 4, which as spindle 80 rotates, successively connect the terminals 73 to the arcuate contacts 75 - - 77 and thereby test in turn the outgoing lines engaged by the brushsets in both half-banks until an idle line is found. the brush-sets in each half-bank are so connected up to the terminals 73 that brushes in each halfbank are tested alternately. The wipers of the brush-choosing switch are rotated by a pawl 70, Fig. 5, operated by the armature of a magnet 67 mounted on the framework 48. The brushchoosing switch is of the no-normal type but is arranged to be advanced a step before testing. The main switch brushes are restored in the following manner. The ratchet wheel 43 has pivoted thereon an arm 57, Figs. 1 and 2, provided with teeth which are normally hedd out of engagement with a continuously-driven ratchet wheel 61 by a shoulder on a pivoted catch 56, although a spring 59 tends to raise the arm 57. To restore the switch, further impulses are sent to the magnet 45 and the ratchet 43 continues its rotation, moving the arm 57 to the left, until the step 55 passes the shoulder on the catch 56. The arm 57 is then lifted by the spring 59 and its teeth engage the ratchet 61, which moves the arm 57 to the right, thereby returning the ratchet 43 and restoring the brushes. During the return movement of the arm 57 the catch 56 is turned upon its pivot, permitting springs 52 to open and disconnect the magnet 45 from the impulse source. In the normal position of the brushes, a tooth of the ratchet 61 engages a flat-portion of the arm 57, which is thereby depressed and releases the catch 56 which is returned to its normal position by a spring 64. Circuit arrangements. The response of the line relay 101, Fig. 3, energizes the usual slow release relay 102, and interruptions in the circuit of the line relay are repeated to the stepping magnet 45, Fig. 6, which moves the two rows of brushes to selected vertical contact rows. The series relay 103 energizes a relay 104 which locks up over off-normal springs 88. On the relapse of the relay 103, parallel circuits are closed over the earthed holding wire 90, the lower armature of an interrupter relay 105, off normal contacts 88, and armatures of the relays 104, 103, 105, for the brush-choosing switch magnet 67 and for the relay 105, which interrupts its own circuit and that of the magnet 67 and the relay 104. If the test wiper 84 of the brush-choosing switch now engages a terminal 73 connected to a brush earthed over the test wire of a busy outgoing line, the relay 104 will again be energized over the arcuate contact 77, auxiliary brush 32 and the wire 92, and the cycle will be repeated, but if the tested outgoing line is idle, the relay 104 remains inert, closing a circuit for the switching relay 106 which cuts out the line relay 101 and extends the incoming line 85 over the conductors 93 and the arcuate contacts 75, 76 to the main switch brushes selected by the brush-choosing switch. The Specification as open to inspection under Sect. 91 (3) (a) states that the switch may be adapted for use as a connector by making the brush-choosing switch a normal-type switch. This subject-matter does not appear in the Specification as accepted.