Signalling Turnouts

National Turnouts WorkshopMay 2014

Paul ZammitAsset Standards Authority

• Track & Signals• Signalling Principles• Turnout Stability• Points Locking• Points Detection• Turnout Types

• Switch Rollers• Back Drives• Points Strategy• Achieving Maintainability• Signalling Controls• Emergency Operation

Contents

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Signals construction

Track construction

Track & Signals

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Turnouts are required to be:• Safe• Functional• Reliable• Maintainable

Turnouts are challenged

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Signalling Principles

• Large steel structures that require significant force to move• Exposed to rolling stock forces• Exposed to the elements• Points operate occasionally or frequently, but their availability (locking

and detection) is 24/7

• Effective track stability and geometry• Simpler effective signalling design • Proper installation (track and signalling)• Regular testing to ensure continued operation within specifications• Achieving maintainability objectives (track and signalling)

Solution

• In accordance with the desired route request or overlap

Operate the switches

• Mechanically secure (lock) points in correct position• Fail the lock if points obstructed• Detect the position of the lock

Provide & prove locking

The aim of signalling turnouts

• Lock the point position with train approaching• Hold the points in the route until train has passed

Lock the route

Detect the switch position

• Prove the closed-switch and open-switch positions

Designed on fail safe principles-including mechanical components

Regularly maintained by competent personnel to ensure it performs its

designed safety and functional requirement

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Signalling Principles

The steel in-bearer arrangement is engineered to provide a solid

square box

Avoids the points goingout of square

Anchored fixings keeps the signalling

square with the switch and stock rails

Turnout Stability

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• Closed-switch cannot open by 3.2 mm* or more, nor can the point lock enter if the closed-switchis open by 3.2 mm* or more

• For reliability, the point lock is adjusted to fully enter with a closed-switch opening of at least 1.6 mm**

Power operated points

Point lock test

Exception for Claw Lock points

* Extended to 4.8 mm** Extended to 3.2 mm

Points Locking

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• Open-switch openings (at the switch-tip) checked-typically 125 mm

• Rear flangeway clearances checked to 60 mm +/-5 mm

Points Locking

Switch-tip & Rear flangeway

Switch openings test

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Points Locking

• The point lock does not permit the open-switch to close by less than 100 mm

• The point lock is prevented from engaging if the open-switch opening is less than 100 mm Less Than 100mm

1. Point Lock Fails

2. Detector Contacts Broken (Open Circuit)

Catchpoints switch-tip

Switch openings test

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Flank Protection

The amount of coveragethe operating bar provides

to the point lock

(measured at the moment detection is broken)

Points Locking

Maximum CoveragePoint Lock Coverage

Operating Bar

Point Lock

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Point lock coverage test

Points LockingMinimum point lock coverage

• Measured at the moment detection is broken

Spherolock points

>=25 mm

Lock Coverage

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>=25 mm

Lock Coverage

Claw Lock points

Points Detection

• Closed-switch / Open-switch• Mechanical detection• Electrical detection

• Combined with points mechanism• Stand alone• Dependant/independent on point lock

Closed-switch

Go at 3.2mm or lessNo-go at 4.8mm or moreExceptions available for trailing (only) points

Detecting the switch position

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Points DetectionDetecting other vital movements

• Point lock position• Bolt lock position• Point lock coverage (operating bar)• Electro pneumatic types

• Plunger lock position• Control valve spool position• Pos & neg motor air pressure• Back drive (in some cases)

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Points Detection

Plunger Lock Dog

Contacts Made Normal (NWKR) when Locking Plunger

Contacts Made Reverse (Cut-off Valve) when Clear of Plunger

Plunger Clearance

Electro pneumatic points- Detecting plunger lock position

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Points DetectionElectro pneumatic points- Detecting control valve spool position

Air Motor

Main Spool

Micro SwitchMicro Switch

Control Spool

Cut-off Valve

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Points DetectionElectro pneumatic points- Detecting pos/neg motor air pressure

Negative Air PressurePositive Air Pressure

Back Contact Made Front Contact Made

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Turnout Types

Electric combined mechanism

Claw Lock mechanism

Spherolock mechanism

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Turnout TypesConventional combined mechanism

M3aCombined

Mechanism

Internal Point Lock& Detection

Deflection Ramp

Points Rodding

Detector is dependentwith the point lock

Both switches areoperated simultaneously

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Turnout TypesClaw Lock mechanism

Switches operate independently

84MElectric

Mechanism

InternalDetection

ExternalPoint Lock

Steel In-Bearer(contains rodding)

Independent switch position & point lock detection

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Turnout TypesClaw Lock operation

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Turnout Types

Steel In-Bearer(contains rodding)

T Style Crank

Back Drive

Spherolock mechanism

External Lock

Switches operate independently

Independent switch position & point lock detection +

Turnout TypesSpherolock operation

Spherolockinternal workings

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Schreck-Mieves (Teksol) switch rollerfor 60kg rail full height switches

RotorRail switch rollertype RIC294 toe end

CDP in-plate switch roller

CDP switch roller assembly

Schreck-Mieves EKOS (Teksol)switch roller for conventional switches

Switch Rollers

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Back Drives

Single rodding back drive Spring assist mechanism

Older types

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Back DrivesNewer type

Double rodding using T cranks

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• Spherolock or Claw Lock mechanisms• D84M electric machines or Electro pneumatic type• Trailable mechanisms in yards• Standardised layouts and switch drillings • T crank style double rod back drives

Preferences

• Improved stability …integrity & reliability• Facilitate tamping and mechanised track maintenance• Efficient due to reduced maintenance time• Safer due to minimal trackside infrastructure

Benefits

Points Strategy

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for Sydney metropolitan area

Achieving Maintainability

• On-track access and duration• Point mechanisms located on the safest side of the track• Affect on adjacent tracks• Spare parts standardisation• Turnout components and drillings standardisation• Familiarisation

• Limit the number of different types• Provide specific performance requirements

• Signals / Track co-ordination• Simplicity of mechanisms

Considerations for achieving objectives

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Achieving MaintainabilityPhysical Position M3A Mechanism 84M Mechanism Electro Pneumatic

Mechanism

On-trackin danger zone

Points detectorLock detectorDrive detectorElectric motor

ClutchCut out crank

Points detector…………………..

Drive detectorElectric motor

ClutchCut out crank

Points detector…………………..…………………..

Air motor…………………..…………………..

Off-trackout of danger

zone

Fuse and SwitchCut out timer

ESML

Fuse and SwitchCut out timer

EOL

Control valvesShuttle valves

Pressure switchEOL

(integrated within unit)

Note: Circuitry on the interlocking side is considered similar for all applications

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Achieving MaintainabilitySupporting mechanised track maintenance

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Signalling ControlsEvolution

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Emergency Operation

ESML- Emergency Switch Machine Lock

EOL- Emergency Operation Lock

• Electric PointsTrackside cupboard containing an indexed crank handle or fortress key that fits into specific points

• Electro pneumatic (EP) PointsNewer style EP points provide push button release & operation of the points

Older style EP points do not have provision for emergency operation except by the maintainer

Points can be manually operated in the field under failure conditions

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Thank you