Patent GB-190801517-A (GB)
Title: Improvements in Apparatus on Railway or Tramway Vehicles for Giving Warning and for Stopping the same in case of Failure of the Driver
Filed: 1908-01-22
Granted: 1908-08-27
Abstract: 1517. Siemens Bros. Dynamo Works, and Lydall, F. Jan. 22. Locomotives.-Relates to means for protecting railway and tramway vehicles in case of failure of the driver, and consists in track apparatus which operates on the vehicle to cut off the power and apply the brakes, unless the driver operates a lever to prevent this result. A ramp R, Fig. 1, on the rack raises the shoe H attached to a lever L on the train, thus breaking the contact between contacts k<1>, k<2>. A plunger P, normally held by the solenoid O, therefore falls and breaks the motor circuits, at the same time opening the train-pipe T at a valve V. By closing his switch s, the driver may prevent this actuation The apparatus shown in Fig. 2 is modified to give the driver a warning of his approach to a ramp, and for this purpose a second ramp R<1> is provided, which is placed in advance of the ramp R<2>. The ramp R<1> lifts a shoe H<1> and breaks the contact between wires 1, 2, thus breaking the circuit of a magnet M, the armature a of which falls and causes a hammer p to strike a bell b, at the same time breaking contacts k<7>, k<8>, and k<5>, k<6>. The circuit of the solenoid O is thus only completed through the contact k<2>, which is broken when the ramp R<2 >is reached. The power is then cut off, and the brakes are applied unless the driver has meanwhile replaced the armature a by means of a handle h, thereby remaking the contacts k<5>, k<6> and k<7>, k<8>. The apparatus may be further modified as shown in Fig. 3, to obtain these results with one ramp only, and also to prevent the driver from fixing the replacing-handle in such a position as to prevent the operation of the apparatus. For this purpose two wires normally kept hot by electric current, are introduced to serve as slow-acting relays. One wire HW is placed in series with the coils of the bell-operating magnet O, and controls the operation of the brakes and the cutting-off of the power, while the second wire hw is placed in series with a resistance q and controls the operation of a whistle W in the train-pipe T. A neutralizing-switch s for the driver is also provided, contact normally being made by a handle h<1> between contacts k<3>, k<4> therein. Current normally flows from the supply +, Fig. 3, and through a resistance Q, and from a battery B in parallel therewith, and through three circuits (1) through wires 1, 2, contacts k<1>, k<3>, wire 3, contacts k<9>, k<10>, which are completed by the contact k<2> on the armature a, hot wire HW, and coils of the magnet O, (2) through wires 1, 4, contacts k<3>, k<4>, wire 5, hot wire hw, and resistance q to earth ; and (3) through wire 1, contacts k<7>, k<8>, which are completed by the contact K<4> on the lever l<2>, and the coils of a magnet M to earth. When the shoe H is lifted by the ramp R, the circuit (1) is broken at contacts k<1>, k<2>, the armature a<1> falls, the bell b is rung, the contacts k<9>, k<10> are broken, and the wire HW begins to contract in cooling, thereby moving the lever l<1> against the spring s<2>. If the wire is allowed to cool sufficiently, the catch j in the lever l<1> releases the citch k, and the weight w falls and open the train-pipe at the valve v, simultaneously breaking the motor circuit W at the contacts K<3> of the switch S. To prevent this action, the driver reverses his switch 8, making circuit through wires 1, 6, contacts k<5>, k<6>, wire 7, hot wire HW, and magnet O, which attracts its armature and remakes the circuit (1) at contacts k<9>, k<10>. The moving of the switch s breaks the circuit of the wire hw, but, as this wire cools very slowly, the lever l<2> is not moved to break contact at k<7>, k<8> unless the switch s is held in its reversed position for more than the short time necessary. The magnet M therefore remains energized, and the whistle is not sounded. If however the driver fixes his switch over, the whistle is sounded continuously until the switch is replaced, since the handle h<2> is prevented by the stop t<2> from completely returning the armature a' unless the magnet M is energized. The apparatus may be used with steam-propelled vehicles, in which case the steam supply is cut off or throttled by electromagnetic means, instead of by breaking the motor circuit.