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TRACKSIDE EQUIPMENT
CRANK HANDLE BOX, TYPE 2
The crank handle box is a trackside enclosure that houses
and controls the points machine crank handle.
It provides automatic electrical indication when the crank
handle is removed. The box complies with Transnet's standards.
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Operation
The crank handle is secured so that only authorised crews
can remove it. A special key is required to fit the pad lock,
which forms part of the inner cover. The cover cannot be closed
until the crank handle has been replaced.
Maintenance personnel enter by opening a separate pad lock,
which gives access to all operating parts of the box.
The crank handle box has two electrical contacts. These open
when the crank handle is removed and close when it is replaced.
A set of screw-type terminals provides internal and external
connections.
Materials and finishes
The box is constructed of robust galvanised and mild steel
- stainless steel is available on request. The inner case
is cast iron to give durability and protection. Installation
is simple. A support post bolts to a concrete foundation.
The crank handle box is virtually maintenance-free.
JUNCTION BOX
The junction box is a multipurpose trackside enclosure designed
primarily as a cable termination box for points machines.
It provides a convenient test and isolation point to facilitate
maintenance work.
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Mechanical and electrical description
The junction box is available in single or double entry versions.
The underground power feed and detection cables are terminated
at clip-on terminals, in the junction box.
Materials and finishes
The junction boxes are available in galvanised mild steel
or 304 stainless steel.
Installation
The support post is normally buried in the ground so that
the junction box lid is level with the top of the points machine
box lid.
APPARATUS CASE
The apparatus case is a multipurpose trackside enclosure.
It may house external control equipment for trackside points
and signal control. It may also house 24-volt DC batteries
and chargers. A power annex case may also be fixed to the
side for power requirements.
Mechanical and electrical description
The apparatus case is available in a number of standard sizes,
related to the equipment it is intended to house. The cases
have a swing door at the front and at the back to simplify
access for testing. Underground cables brought into the case
for termination run in conduits.
Materials and finishes
The cases are available in galvanised mild steel or 304 stainless
steel.
Installation
The apparatus cases are supported on concrete legs buried
in the ground in accordance with standard installation specifications.
MECHANICAL POINTS INDICATOR
The mechanical points indicator is designed to meet the demands
for safety and reliability required of railway signalling
equipment in a crossing loop situation. The points indicator
is manufactured by ALSTOM Transport. With the exception of
on-condition inspection cycles, the mechanism is maintenance
free. The purpose of this type of indicator is to provide
train personnel with a positive indication of the points position
to be negotiated by the train. The indicator is mounted on
a steel cradle fixed to two sleepers.
Ordering details
The points indicator is supplied in two forms:
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two-way
points indicator (for crossing loops) |
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one-way
points indicator (for sidings) |
Operational data
The points indicator is coupled to the points set via a ground
rod configuration and hand tumbler. The indicator is split into
three sections, namely
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Base section
- housing the detection slides, lever slides and vertical
plunger |
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Centre section
- housing the connecting rods between the mechanism and
indicator disc arms making up the distance section between
the base and top sections |
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Top section
- houses and supports the indicator disc arms as well
as the cranks for the connecting rods from the base and
to the disc arms. |
When the points are operated by the hand tumbler, the indicator
lever slide lifts the vertical plunger clear of the detector
slides and allows the detector slide to move across as the switches
move to the other position.
When the movement has been completed and the points are properly
closed, i.e. switch to stock, the vertical plunger will drop
by means of gravity into the respective notch in the detector
slide and all-safe indication will be given. If the points switch
is not properly closed to the stock, i.e. tolerance of 0 - 3
mm, the detector notch will foul with the plunger preventing
indication. The result will be that both arms will remain in
the 'danger' position.
For self-normalising trailable points, the indicator is designed
to provide positive indication of the lock of the rail mounted
points lock as well as detection of each individual switch to
stock position.
Applications
Two-way indicator used at crossing loops
One-way indicator used at sidings
The indicator incorporating separate detection slides for each
switch that is used in conjunction with the self-normalising
trailable cylinder.
SELF-NORMALISING TRAILABLE CYLINDER
The self-normalising cylinder is designed to fulfil the strict
requirements for safety and reliability required of railway
signalling equipment. The trailable cylinder is an ALSTOM Transport
design manufactured in South Africa.
Incorporated in the design is an internal, easily adjustable
time delay mechanism whereby the normalising action can be pre-set
over a wide range of time settings.
The trailable cylinder is a hydro mechanical device and requires
no electric power.
The trailable cylinder's mounting arrangement is on a steel
cradle, fixed on two sleepers. The cylinder has overall compact
dimensions and can be conveniently handled in the field.
Operational data
Internal time delay mechanism, easily adjustable from 3 seconds
to 10 hours.
Stroke
245 mm, giving a minimum points opening of 90 mm and a maximum
points opening of 210 mm.
Environmental condition
Operating from ~36o C to +800 C
Dimensions
Length 1000 mm
Diameter 140 mm
Weight 90kg
Manual operation
For shunting purposes or opposing train movements, the points
can be operated in the conventional manner with a hand tumbler.
Applications
The trailable cylinder is used as the prime mechanism of the
points at crossing loops, in conjunction with the rail mounted
points lock assemblies and hand tumbler.
The trailable cylinder can also be used in conjunction with
a mechanical points indicator where no electric signalling is
available.
Operation
The trailable cylinder's sequence of operation is as follows,
with a train trailing through a points set:
The open switch is forced closed with the first wheel of the
train unlocking the Cl clamp lock and opening the closed blade
- at the same time activating the self-normalising trailable
cylinder.
Once the wheel has cleared the blade, the time mechanism begins
operating.
Dependent on the preset time adjustment of the self-normalising
trailable cylinder for the complete train set to clear the points,
the operation rod of the trailable cylinder retracts slowly,
pulling the blades towards the set position.
At a preset distance from the end of the stroke no resistance
is present internally of the cylinder, allowing the operating
rod of the cylinder to close and lock the switch to the stock
rail and so preparing for the next train movement.
Ordering details
Self-normalising trailable cylinder.
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