PAX TWO MOTION
PRIVATE AUTOMATIC EXCHANGES
UNLIMITED CAPACITY. EXTENSIBLE OPEN RACK TYPE
The ultimate number of lines required for large, expanding establishments cannot always be accurately forecast. This P.A.X. is ideal for such establishments, as there is virtually no limit to its extension. We recommend its use where ultimates of 300 or more lines are envisaged. The minimum equipment is 100 lines.
The most economical and usual system employs uniselector type linefinders with two-motion group and final selectors mounted together on Line Units, but a system similar to that used for public exchanges working on a uniselector-per-line basis can be supplied if specified. Typical illustrations of both types of equipment are shown.
Equipment features are described in general terms, as they are varied in detail to provide the most economical arrangement for the particular exchange.
The maximum extension line loop resistance including the telephone is 1000 ohms, but long line equipment to extend this limit can be supplied.
NUMBERING AND FACILITIES
Full intercommunication by direct dialling, with complete secrecy except on party lines is given.
Any of the special facilities described for P.A.X. 50/400 can be provided, although not necessarily in precisely the same way. Should other facilities be required, we shall be pleased to make recommendations.
Racks are of open type but can be enclosed in dust-proof covers if specially ordered.
Switching equipment is normally provided on a basis of 1 lost call in 200 at the busy hour.
The general finish for racks and apparatus covers is cream enamel. Connecting wires are p.v.c. insulated, and cables have p.v.c. insulated conductors and a cream p.v.c. sheath.
Systems requiring a 4-digit numbering scheme, i.e. with second group selectors, have separate second selector racks each with capacity for 60 circuits.
Line Units and racks are 7 ft. 9 in. (236 em) high and 4 ft. 6 in. (137 cm) wide.
The distribution frame, equipped with connection strips, protectors and fuses as required, may be of single-sided wall/floor type or double-sided floor mounting type. The exchange side of the frame illustrated has 4 protector mountings and 4 connection strips per vertical, but in most cases the capacity is 3 of each (or 6 connection strips if protectors are not required).
Facility for extension is a feature of the system by virtue of the self-contained nature of the Line Unit, which reduces the amount of cabling work to be done at the exchange. Increased traffic demands also can quickly be met by jacking-in extra selectors.
We usually recommend a single battery with charging rectifier operating on the automatic full float principle, which enables the plant to be left unattended for long periods. Orders should specify the a.c. mains voltage and frequency.
A special telephone N23868A for executives is available.
Last revised: October 10, 2019