Abstract: A gas turbine engine casing apparatus includes annular first and second annular cases connected by a spigot joint. The spigot joint includes an annular projection of the first annular case fitted into an annular recess of the second annular case. A plurality of circumferentially spaced apart scallops are formed on one of surfaces of the annular projection or of the annular recess, and are located in selective circumferential locations adjacent respective enhanced stiff areas of the first and second annular cases.

Abstract: A transmitter for transmitting cab signal and track signal currents to a pair of rails includes the circuitry for mitigating runby currents which are not fully shunted by the rail vehicle. High runby currents at the leaving end of a block are reduced by sensing the presence of a railway vehicle in the leaving end of the block. In response to sensing the rail vehicle the cab signal voltage is reduced to a lower level. The lower level and the position at which the railway vehicle is sensed are adjusted so as to permit a lead vehicle to receive at least a minimum cab signal value throughout its journey while assuring that following trains receive less than the minimum cab value required to activate the vehicle based receiver. The train is sensed by the voltage drop across the rails as the train approaches. A relay is used to respond to the presence of the train by applying a lower cab signal to the rails.