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Vickers-Hall Lighting System

The following is an extract of a booklet published in 1905 titled "Train Lighting", "The Vickers-Hall System" from Vickers, Sons & Maxim Ltd., 32 Victoria Street, London. Are any examples of this system still in used on preserved lines?

Vickers-Hall dynamo


  • 1. Removable Cover giving access to Governor, Pole-Changer, etc.
  • 2. Removable Cover giving access to Commutator and Brush Gear.
  • 3. Governor actuating Regulating Mechanism.
  • 4. Governor Body.
  • 5. Governor Weights.
  • 6. Governor Rollers.
  • 7. Governor Springs.
  • 8. Spring Box.
  • 9. Ball Race.
  • 10. Cap of Ball Race.
  • 11. Nut lacking Cap of Ball Race.
  • 12. Governor Chains.
  • 13. Aluminium Cup of Ball Race, carrying Slide Brushes.
  • 14. Regulating Slide.
  • 15. Lamp Resistance Slide.
  • 16. Slide Brushes and Carriers.
  • 17. Pole-Changer Actuator.
  • 18. Actuator Weights. These strike the trigger of the Pole-Changing Switch when the dynamo first starts, thus ensuring that the switch is in the proper position. As soon as the machine has reached an appreciable speed the weights fly out to the end of their travel, and so clear the trigger, thus avoiding unnecessary grinding away of the wearing surfaces.
  • 19. Pole Changing Switch. The frame of this carries the Slides also, so that the Pole-Changer and Slides can be removed from the machine in one piece.
  • 20. Centre Piece, carrying Blades.
  • 21. Trigger. This, when struck by the actuator weight, forces the switch over one way or the other according to the direction of rotation of the armature.
  • 22. Governor end frame and bearing.
  • 23. Bearing Brass.
  • 24. Oil Rings.
  • 25. Oil Well.
  • 26. Plug at bottom of oil-well for removing oil.
  • 27. Field Clamps.
  • 28. Field Laminations.
  • 29. Shunt Field Windings.
  • 30. Series Field Windings (these are inversely wound, and are cut in and out as required by the Governor and Regulating Slide).
  • 31. Armature.
  • 32. Armature Core.
  • 33. Armature End Plates.
  • 34. Armature End Barrels.
  • 35. Armature Nut.
  • 36. Armature Coils.
  • 37. Commutator.
  • 38. Commutator Sleeve.
  • 39. Commutator Nut.
  • 40. Commutator Ring.
  • 41. Mica Insulating Rings.
  • 42. Brush Gear.
  • 43. Brush Rocker.
  • 44. Brush Spindle.
  • 45. Brush-holders.
  • 46. Carbons.
  • 47. Tension Adjusters. (To increase tension, remove spring, screw hook further up stem and replace spring.)
  • 49. Nuts for fixing connections.
  • 50. Pulley-end frame and bearing.
  • 51. Bearing Brass.
  • 53. Oil Well.
  • 54. Plug for running off oil.
  • 55. Shaft.
  • 56. Pulley.
  • 57. Pulley fixing nuts.
  • 58. Set screws to secure lock-nut.
  • 59. Box-type Brush Gear.
  • 60. Rocker for same.
  • 61. Brush-holders.
  • 62. Carbons.


The system, entirely automatic in operation, is well adapted to meet the most widely varying conditions of train lighting service.

The regulator is designed to provide complete automatic control of the generator at all speeds above that at which full output is obtained, giving initial CONSTANT CURRENT until the battery or batteries are nearly fully charged, and ultimate CONSTANT VOLTAGE to ensure the ideal tapering charge. By this means, rapid battery reconditioning is obtained and overcharging prevented.

The Lamps and all parts of the equipment are fully protected in the event of accidental break in the battery circuit ; in such circumstances the regulator will immediately take charge of the generator, which will then run CONSTANT VOLTAGE throughout its speed range.


The limitation of voltage at the battery terminals, imposed by the regulator, greatly facilitates lamp voltage regulation. The high charging voltage which may occur in other systems is positively precluded in this, and the final voltage to be corrected is small enough to permit an abbreviated form of lamp resistance to be used, even with extensive switching of individual lamps.


When the generator is at rest, both Cut-in (UR) and Regulator (UM) Relays are in the open position and the main contactor in the "OFF'' position. The Generator is disconnected from the battery ; under these conditions the lamp resistance is short-circuited so that the lighting current may be taken direct from the battery.

When the train accelerates and the generator has developed the required Cut-in voltage the Cut-in (UR) Relay operates, closing its contacts thereby operating the Cut-in comtactor (U300). Under these conditions the Generator is connected to the battery, the lighting load being taken through the lamp resistance.

lt wilI be observed that the Regulator Voltage Coil (MJ1) is connected to the battery side of the Cut-in. Therefore the Regulator is not attempting to control the Generator voltage prior to cut-in, although the Regulation Carbon Pile is connected in the field circuit.

lf the lights are of "OFF'' the Regulator Voltage coil is connected to the battery when the generator voltage reaches a low value, by operation of the in Regulator Relay (UM) (REL).

When the lights are "ON'' the regulator voltage coil (MJ1) is always connected to the battery.

It follows from this arrangement that with a battery of average standing voltage the Carbon Pile is fully compressed before cut-in, irrespective of the cut-in voltage. Further, if the battery is just off charge and standing at a high voltage, and the Regulator operating at less than this value, the Regulator pile will be fully open, and prevent cut-in until the battery voltage has fallen to the Regulator setting.

When the train slows down, and the generator voltage falls below that of the battery, the Cut-in Relay opens by virtue of a normal series coil. Hence the Cut-in Contactor opens, disconnecting the generator from the battery and cutting out the lamp resistance so that lighting current is obtained direct from the battery.

It will be seen from the connection diagram that the lamp switch is provided with auxiliary contacts whereby part of the resistance in series with the shunt coil of the regulator is short-circuited when the lamps are "ON". The effect of this is to cause the regulator to operate at a rather lower voltage. The generator voltage, however, is raised with increase of lamp load to a degree depending on the lamp resistance drop and the selected tapping point of the Voltage Dividing Resistance (VR), except when position 4 of resistance (VDR) is chosen. At the same time the Iamp voltage will fall with increase in lamp load except where position 1 of resistance (VDR) is chosen. The most popular setting of resistance (VDR) is position 2.

With a discharged battery, the regulator operates at constant current corresponding to the full load rating of the generator. This current value is constant whether lamps are '"ON" or "OFF" so that with lamps "ON" the entire generator output, less the lamp Ioad, is available for charging the fbattery. This is a very valuable feature of the dual regulator system as it ensures the generator capacity being utilised in the most advantageous manner.

The Regulators described in this publication are of the dual operating type in which independent magnet systems impose initially constant current and ultimately constant voltage upon shunt wound Train Lighting Generators, and should not be confused with Regulators having single magnet systems and Compound Windings, which can only provide progressively falling current with rising battery voltage.

For a detailed description of how the system is configured (single and double battery versions), click here.