Charing Cross Signals and Cabin



(Improved Spring Catch Lever and Tappet with Duplex Plunger.)

The locking is actuated by Spring Catch and Lever in combination, the security of both, with the advantage of preliminary action.
The locking gear "Tappet and Plunger" is of the strongest and most durable kind, and the "Duplex Plunger" prevents the possibility of Tappets being moved into notches at cross purposes to the intended locking arrangements.
Special or Conditional locking combinations can be arranged in the troughs of the ordinary locking without any additional Plungers being required.   
The Levers are all alike and can be used indiscriminately for Points or Signals, or Facing Point Locks. Each Lever has its own segment plate and carries its own locking gear, so that additional levers can be introduced with perfect facility.

The reduced space between the levers admits of economy in the size of Cabins, and the position of the locking gear beneath the floor gives perfect freedom of access for inspection, cleaning, alterations, &c.
The importance of " Preliminary Action" of locking is now generally recognised, and that principle is exclusively adopted on the London and North Western Railway.

Objections to Spring Catch actuation suggested and fostered by those not entitled to use it—viz., that too much strain is thrown upon the spring catch, by its having to move spindles, slides, &c, &c, are all set aside in this new type of Frame—as those connections are dispensed with altogether, and the preliminary action of locking is obtained by a  "combination of Spring Catch and Lever with Tappets,"—reducing the number of parts to a minimum, and those parts being of the most simple, solid and durable kind.

Locking Frame The new Frame, therefore, possesses all the solidity of ordinary Lever Locking Frames, and still retains the principle of "Preliminary Action," without which no Locking Frame is or can be perfect.

The new Frame has recently been inspected and highly commended by the officers of the Board of Trade, and is being largely supplied to English and Foreign Railways.   

" The importance of this improvement (preliminary action of Locking Gear) may be best appreciated by considering the class of miscarriage of interlocking which might take place in the older locking apparatus, in which, the effect of great wear and tear would be, that the locking might not act as soon as a Lever began to be moved, and consequently that a partial movement of another Lever, which ought to have been locked immediately the first Lever was moved, would be possible; and further, that the locking set in motion by a Lever might be released before the movement of the first or actuating Lever had been completed. In the former case, supposing the actuating Lever in question were a Signal Lever, a pair of Points might be moved out of their exact position while the signal was down, during which time the Points should have been locked; and in the second case, if the actuating Lever in question were a Point Lever, the signal might be put to allright before the adjustment of the appropriate Points was accurately completed.  Both these dangers, which were found serious in practice, are obviated by actuating the locking gear by motion of the spring catch rod."  -- Vide Barry's "Railway Appliances"

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Union of Block and Interlocking

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Sidan uppdaterad den 18 augusti 2013