THE NEW LEVER LOCKING FRAME, 1888
(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.
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"
Saxby & Farmer page
Union of Block and Interlocking
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Sidan uppdaterad den 18 augusti 2013
