Patent GB-295679-A (GB)
Title: Improvements in or relating to train control systems
IPC: B61L3/12
Filed: 1928-06-08
Abstract: 295,679. Associated Telephone & Telegraph Co. Aug. 17, 1927, [Convention date]. Fuid-pressure. - Relates to track apparatus for stopping trains. At the exit end of each section, a permanent magnet and one or more electromagnets controlled in accordance with traffic conditions ahead, actuate a polarized armature pivoted near four pole-pieces carried by the train to control the circuits to lamp signals and an electromagnetic valve which controls the air supply to a whistle and to a cylinder operating the driver's valve. A forestalling and resetting lever is provided by which the driver may avoid a brake application by acting within a predetermined time interval; after an application has been made, the apparatus can be reset only after stopping the train. The apparatus described and shown is identical with that described in Specification 303,415 and 303,416. In one form of train-carried apparatus, a speedgovernor renders the brake application dependent on the speed of the train. The driver's valve 10, Fig. 1, is operable manually or by the piston 5 compresses a spring 6 at the end of its stroke in order to avoid throwing the valve beyond the service position. Air is supplied to the cylinder 12 through a valve 1 acted upon by main reservoir pressure on one side and by pressure in the reservoir 28 on the piston 36 which keeps the valve closed only so long as it remains above 40 pounds. Each inductive collector on the train is similar to that described in Specification 291,115 and normally closes the circuit to the magnet 2 and the green lamp G over the wire 34. In its reversed position, the relay 11 is energized over wire 33. The magnet 2 keeps closed the valve 2<1> which closes the exhaust from the timing reservoir 28 through the whistle 4. At a clear signal, the armature of the inductive collector is reversed and restored at once and magnet 2 and lamp G are de-energized only momentarily. At a caution signal the armature is not reset so that the valve 2<1> remains open, and air from reservoir 28 exhausts through pipe 24 and whistle 4 quicker than it is admitted from the main reservoir through pipe 31 and the restricted orifice 35. After a given interval the valve 1 will be opened unless the driver acknowledges the signal by depressing the lever 14. The tail of the lever causes the arm 19<1> to lift and lock the contact 20 to light the purple lamp P. Depression of the lever 14 also opens valve 15 and if the driver acts within the prescribed time, a rush of air from reservoir 29 lifts the lever 18 and closes contact 19 to energize the resetting coils on the receiver R and close the circuit to magnet 2 which shuts the valve 2<1>. The armature of magnet 11 is locked to maintain the purple lamp P as a warning that the train is under a caution signal, although magnet 11 is not energized. If the next track magnet is passed before pressure has built up in reservoir 28 or if the driver does not acknowledge within the given time, the contact 19 cannot be closed and a brake application follows. The apparatus can then be reset only after the train is stopped, by further operation of the lever 14 to open valve 16 to supply pressure to the conduit 17, which can only occur if the pipe 22 remains closed at the stop detector device SD, situated close to a train wheel. This device is described in Specification 285,804. At a subsequent clear signal, the reenergization of the magnet 11 allows the lever 19<1> to fall away and the green lamp G is relighted. The coa.cting train apparatus may include a speed governor contact-maker for permitting running at low speeds only under caution conditions.