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Harpers block instrument


Until the railways were nationalised in 1948, there was considerable variance between the working practices of the different railway companies although the underlying principles were the same.

In 1950, the first British Railways Rule Book was issued, and this was followed by the British Railways Regulations for Train Signalling in 1960, although a few regional variations persisted.

To describe all of the different companies' practices would be a mammoth and confusing task, so for consistency in the section, all details refer to the above publications unless otherwise stated.

A range of photographs of interesting signalling instruments is now included with this section.

There are several chapters to this section, and these are listed below.

Principles of Block Working

Instruments in the flesh - photographs

Bell signals

  1. Bell signals in use in 1960
    1. Universal bell signals
    2. Bell signals used only on the Southern Region
    3. London Midland Region special routing bell signals.
  2. Pre-1960 bell signal variations
    1. Pre-grouping (to 1923)
    2. Post-grouping (1923 - 1948)

Absolute Block

  1. The basic principles
    1. Principle
    2. Block Section
    3. Signals
    4. In Advance, or in Rear of
    5. On or Off
    6. Normal or Reverse
  2. Keeping the trains apart
    1. Block instruments
    2. Light relief
    3. Method of working
    4. Clearing point
    5. Tail lamp
    6. Train register book
    7. In practice
    8. Short sections
    9. Special instructions
  3. Fouling the clearing point
    1. Refusing trains
    2. Stationary obstructions
    3. Setting back
    4. Short sections
    5. Train already in section
    6. Swapping around
    7. Inside or outside
    8. Exemptions
  4. Working at junctions
    1. Clearing points
    2. Setting for alternative route
    3. Trains at a stand
    4. Facing point locks
    5. Outer home signals
    6. Indecision and errors
  5. The Warning Arrangement - Regulation 5
    1. Use only where authorised
    2. Acceptance
    3. Warning the driver
    4. The driver's duty
    5. Train out of section
    6. Blocking back
    7. If the clearing point later becomes available
    8. Use of Warning Arrangement in emergency
    9. Lever collars
  6. Distant signals and short sections
    1. Shared distant signals
  7. Different types of train
    1. Is line clear? signals
    2. Trolleys in tunnels
    3. Trains requiring to stop in section
    4. Cancelling trains
    5. Trains wrongly described
    6. Engines assisting in rear of train
    7. Light engines, and engines with brake vans, running together
  8. Shunting
    1. Shunting into forward section
    2. Running round trains in block sections
    3. Working in wrong direction
    4. Shunt train for following train to pass
  9. Alarms and excursions
    1. Obstruction danger
    2. Train passed without tail lamp
    3. Train divided
    4. Train or vehicles running away
    5. Stop and examine train
    6. Train an unusually long time in section
  10. Closing the box
    1. Where a closing switch is not provided
    2. Closing switches
    3. Switching in
    4. Time to go

Railway Companies

  1. British Railways (Scottish Region)
  2. Cheshire Lines Committee
  3. Glasgow & South Western
  4. Great Northern
  5. Great Western
  6. Lancashire & Yorkshire
  7. London & North Eastern
  8. London & North Western
  9. Midland
  10. South Eastern
  11. Southern


  1. Spagnoletti
  2. Sykes
  3. Tyer


  1. One Engine in Steam Staff

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