scope:

INTRODUCTION

The problems of high maintenance costs and unsuitability for very high speed running which affect fishplated joints in conventional track are at present being overcore by leading continuously welded rail.

Nevertheless, although in jointed track the Signal Engineer can easily define the limits of his track circuits by insulated block joints, in continuously welded rail these joints are a source of relative weekness, restricting the top speed for which the track is suitable.

The Aster type 'U' Jointless Track Circuit is one means of eliminating this weakness. It was developed from the Aster 1 watt jointless track circuit installed on the Eastern, London midland and Western Regions from 1967 to 1969.

In 1979, the SF 15 receiver and transmitter units were introduced to replace 'Aster type'U'units which are no longer available. These are identical in operational characteristics but have different internal circuitry.