In the following we illustrate our special system of Telephones for use on Electric Tramway System.
The illustrations will, no doubt, suggest that since introducing this speciality many developments have taken place, mainly the result of our having obtained a more intimate knowledge of the requirements of traction engineers, and our consequent endeavour to meet same. The list below, showing the different systems that are fitted with our Telephones, will be sufficient indication of their efficiency, many engineers only installing them after a prolonged test, necessary to exercise deeply rooted prejudices against telephones in feeder pillars, based on sad experience of instruments not specially designed for the purpose. We can only add that the manufacture of these telephones at our Manchester factory is carried on under the supervision of skilled telephone engineers, who know well the adverse conditions under which they are required to give service.
The Feeder Pillar Telephone K 710 and Plug Box K 700 are well known and require no comment. We have, however, found that it is not always convenient or desirable to fix the instruments in feeder pillars, and in such cases we advise the use of special cast iron boxes for fixing to poles, walls, or on the side of feeder pillars. See Figs. K 740 and K 760.
As regards the Central Station Equipment, if only one route of trains existed, this would consist of the K 905 telephone and a battery consisting of Eight No. 1 E.C.C. Dry Cells. This one set of batteries is all that would be required for signalling and speaking, our system being worked from this common battery at the central station.
It occasionally occurs that at the termination of a tramway, or somewhere along its route, sub-stations or depots are situated and that they also require to call the central station, and, as -a rule; the latter requires to call out to the sub-station. For this purpose we use a special instrument at the sub-station (see K 840). which is arranged with a polarised bell, telephone, and induction coil.
This instrument can be tapped off the same two wires as those which run to the feeder pillars, and will not interfere or be interfered with by them. To call the central, all that the sub-station attendant requires to do is to press the lever in the handle of the telephone. At the central station the K 905 instrument must be supplemented by a small magneto Generator (see K 910), by means of which the attendant can ring the polarised bell at the sub-station.
It is also-sometimes required to ring out to the terminus of a line, and in such cases the Street Telephone Post K 800 or Pole Box K 780 should be used. in conjunction with large magneto Bell K 790. This bell should be either on a pole or wall of a building. A hood of zinc or iron should be fixed over to afford protection from rain, &c.
In cases where a number of routes run from the central station, it would be necessary to fix an Annunciator Switchboard provided with an indicator and spring jack for each Route (see K 920). The K 905 instrument would not be required in this case, but instead the K 940, complete - with telephone and generator, would be used, being generally fixed immediately beneath the annunciator. The generator is provided with this set because it invariably occurs that in a system of several routes there are a number of sub-stations or depots which required to be called by the central in which case the Telephone K 840 would be used at these sub-stations as before. Very frequently the central station is divided up into a number of offices or departments, and if provision is made on the annunciator, and these departments provided with a sub-station or office telephone (see Figs. K 840, K 850, and K 860) they can call the attendant and be switched into communication with each other and also if necessary to the various sub-stations, and visa versa. In the latter case, a special through connecting board must be used as K 930, which is kept in stock with provision for a single through connection, and also for two through connections. For each connection a pair of plugs, listening key, ringing key, and needle indicator is provided, the object being that so long as a given through connection is in use the needle is deflected, but when the conversation is finished it regains and rests at the zero position. A bell will also be required for the purpose of attracting attention when a call is received.
In cases where an annunciator is used as above, we advise one set of batteries for signalling, a second set for speaking, and a third set of about four cells for ringing the local bell.
An alternative instrument to the K 840 is K 860 Wall Pattern and K 860 Table Pattern Telephones.
An alternative arrangement for the K 920, K 930, and K 940 apparatus is K 950 Switchboard, which combines the functions of the whole in one piece of apparatus, and is, in addition, made more substantially with larger indicator shutters and much more convenient arrangement generally.
With regard to (be telephone cables, they should, where possible, consist of twin conductors, separately insulated and twisted, in order to minimise any inductive disturbance which might otherwise occur.
The advantages of our system are as follows :-
We shall be pleased to estimate for complete Telephone equipments on being made acquainted with the requirements.
Last revised: November 06, 2022