Alex Jackson Coupling - page 2
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How it works
Coupling
The action of coupling may be followed by reference to the drawing
below in which wagon 'B' approaches wagon 'A' and the noses of the
couplings slide against each other. Further movement of 'B' leads
to contact of the tails of the couplings and a gradual sliding movement
in the horizontal plane takes place until the tails pass each other.
The wires then spring back to the central position with the shanks
in line. The coupling hooks are now in the correct relationship
for engagement and at this point the buffers should make contact.
Upon reversing the motion of 'B', the tails of the couplings slide
along the shanks and engage, whereupon wagon 'A' is also drawn along
with wagon 'B'.
It is important that the couplings spring together before the buffers
make contact, and to ensure this, the end of the hook tail should
be 0.25mm (0.010in.) from the buffer face as shown in the drawings.
There should not, however be excessive clearance, otherwise when
the locomotive is pulling a train the gaps between the vehicles
will be unrealistic. Note that it may be necessary to add weight
to a free running vehicle of light construction in order to provide
enough inertia to allow the springing of the coupling wires to take
place, otherwise wagon 'A' might simply be pushed along by the friction
of the coupling tails.
From the foregoing it will have been seen that two wagons may be
coupled simply by bringing them together and that the magnetic field
plays no part in the operation. Coupling may therefore take place
anywhere on the layout, except on sharp curves. (a problem which
will be discussed later). It will be realised that for two vehicles
to come together and the coupling hooks to engage correctly (i.e.centrally),
sideplay of the vehicle on the track must be small. The wheel and
track relationship of P4, EM, or OO finescale (but not necessarily
proprietary) is satisfactory; however sideplay of axles in their
bearings must be held to a minimum. Greater offset than 1mm from
centre line may cause the tails or noses of the hook to pass without
making contact.
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Wagons approach each other with couplings
lined up. |
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Coupling tails slide over each other
and the buffers touch. |
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The train pulls away and the coupling tails
engage. |
Uncoupling
Referring to the drawing we see that wagon 'B' is pushing wagon
'A'' by contact of the buffers and the couplings are therefore slackened
off. Vertical movement of either coupling will disengage the hook,
and in the electro-magnetic system we arrange for one coupling to
be pulled downwards by arranging an electro-magnet between the rails.
After having passed through the magnetic field, the coupling springs
back upwards but now the tail is on the opposite side of the shank.
Upon reversing the direction of motion of wagon 'B' the tails slide
past the noses of the hooks and wagon 'A' is released. It will be
found that one gets a less jerky action if the coupling of wagon
'B' is pulled down to release wagon 'A'. Note that the path of coupling
'B' is downwards with a slight horizontal movement and that of coupling
'A' mainly horizontal.
After uncoupling in the magnetic field, the wagons may then be pushed
along until a desired location is reached, at which they may be parted
without further ado. Uncoupling and parting of vehicles are therefore
separate and distinct operations which take place at quite different
locations. This means that one electro-magnet positioned at the start
of a number of sidings is all that is required to split a whole train.
Herein lies the ingenuity of the original design, which distinguishes
it from most other types of coupling device. By leaving the magnet
energised, the whole train would of course become uncoupled as it
passed over the magnet position. If wagon 'A' is of light construction
and free running it can happen that as wagon 'B' draws away from it,
having been uncoupled, the friction of disengaging may draw wagon
'A' along. As mentioned earlier, the inertia of wagon 'A' should then
be increased by adding weight to it.
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Wagons propelled and couplings slacken
off.
Solenoid is energised, pulling one coupling downwards.
|
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Solenoid current is released and the coupling
springs back leaving the tails disengaged.
When one wagon is moved the
head of one coupling simply slides over the other one.
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