Signal Reverser For Railway Signaling

1

TEACHING NOTES ON REVERSER, ALR & LLCC

SIGNAL & TELECOMMUNICATION TRAINING CENTRE, BYCULLA, MUMBAI ( I S O 9001-2000 CERTIFIED )

2 CONTENTS

PAGE NO.

REVERSER 1. Introduction

03

2. Main Parts of Reverser

03

3. Electrical Parameters

04

4. Function of various parts

04

5. Checks to be carried out before installation.

06

6. Performance Test

06

7. Trouble Shooting and Maintenance

07

8. DO’s and Don’ts

09

ARMS LIGHT REPEATER 1. Introduction purpose

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2. Working Principle of Arm Repeater and Main parts.

10

3. Light Repeater, Main Parts, and working

11

4. Alarm circuit and working

12

5. Indoor and outdoor equipment

12

6. Maintenance and Testing

12

7. Trouble shooting

13

LEVER LOCK AND CIRCUIT CONTROLLER 1. Introduction and working of lever lock

14

2. Types of Lever Locks

14

3. Circuit Controllers

15

4. Force drop arrangement

15

5. Economizer contact

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6. Checks for Maintenance

16

7. Trouble Shooting

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ELECTRICAL SIGNAL REVERSER In Electro-Mechanical signaling territory an Electrical Signal reverser is used to establish an electrical control over semaphore signal by one or more controlling agencies where the transmission is mechanical. Reverse is one of the methods to achieve slotting system. Types of Reverser: a) Cabin type b) Post type I)

Post Type Style ”A”

II)

Post type style “B”

In cabin type reverser the signal arm may be taken “OFF” by pulling signal wire from out side even in absence of control (slot). To avoid this unsafe working post type reverser was developed.

Style “A” type has so many

demerits hence RDSO has standardized only post type style “B” reverser. Main Parts of Style “B” reverse i)

Electro Magnet

ii)

Armature

iii)

Semaphore arm lever

iv)

Operating arm lever

v)

Spectacle crank

vi)

Operating crank

vii)

Coupling lever

viii)

Support lever

ix)

Lock pawl

x)

Dash pot

xi)

Terminal Block & Lighting Arrestor

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Electrical parameter: Coil resistance 600 ohms Min. operating voltage 7.5 volts Normal working voltage 10 volts Normal working current 16.5 ma NOTE: There is no basic difference between “UQ” & “LQ” reversers. The reverser fit for UQ signal can be made fit for LQ simply by turning the spectacle crank & operating crank by 180 degree. FUNCTIONS OF VARIOUS PARTS: Electro Magnet: It is laminated core winding which gets energized through the concerned controls. Armature: Armature picking up does two things. i) Sliding bar lifts up and so the lock pawl releases the spectacle lever for operation. ii) The ball bearing connected with support lever rests with armature lever hence the spectacle and operating lever gets rigidly connected. SEMAPHORE ARM LEVER: Normally this lever remains locked through lock pawl. It is connected with spectacle crank on other side. Signal arm cannot be operated due to this locking from out side interference. OPERATING ARM LEVER:

This lever can be freely operated without

operating the semaphore arm lever. Its operation operates the signal arm only when it gets coupled with the arm lever. SPCTACLE CRANK: Down rod of the semaphore signal arm is connected with this crank. Arm can be taken OFF only when this crank operates & this it self will operate when semaphore arm lever operates. OPERATING CRANK: It is connected with pull wire of the transmission and can be operated freely without operating the semaphore arm lever.

5 COUPLING LEVER: This lever couples semaphore arm lever and operating arm lever when the armature picks up. Under energized condition of Reverser, pulling the signal lever not only operating crank and lever operates buy t semaphore arm also operates lever through coupling lever. SUPPORT LEVER: It is attached with coupling lever. The coupling lever couples both the lever only when the armature lever restricts the movement of this lever. The ball bearing of this lever eliminates the possibility of armature lever pitting. LOCK PAWL: Locks the semaphore lever is normal condition and allows the movement of this lever only after energisation of electro magnet. DASH POT: It consists of sliding cylinder, plunger nozzle, plunger and a spring. It absorbs the shop offered to the system when the signal arm flies back/comes to “ON”. TERMINAL BLOCK: For electrical connections inside. LIGHTENING ARRESTOR:

It is used to avoid risk of damage due to

thundering & lightening because of overhead line used. CONTACT ASSEMBLY:

It is used to provide indications at panel & for

controlling other electrical circuits as per requirement it can be 2 ways or 3 or 6 way and is connected with spectacle lever through link and crank. WORKING: To operate a signal, controlling agency releases its control first. Now electromagnet gets energized, the armature lever attracted. sliding bar moves up the lock pawl releases semaphore arm lever.

In turn

6 When signal lever is operated, the roller B of operating lever comes in contact with CAM surface of coupling lever.

Since armature lever holds the ball

bearing of support lever this can semaphore arm lever moves down. Resulting spectacle crank moves towards down side, this movement gives stoke to the down rod of signal arm an signal arm taken off. As soon as current through coils ceases the armature drops so ball bearing leaves it base. Now coupling lever gets detached and the weight of the signal arm pulls the operating lever due to gravity. For next operation it is necessary to put back the signal lever to normal. Checks to be carried out before installation: i)

Check oil level in the dash pot. It should be at least 35 mm above the bottom of sliding cylinder.

ii)

Check tightness of all nuts and bolts. All split pins are in position and their ends are properly opened.

iii)

Check the correctness of internal wiring.

iv)

Ensure smooth working by lubricating and greasing the moving parts.

v)

Check the proper connection of signal down rod to the semaphore crank and the transmission wire with the operating crank.

vi)

Check the alignment of arrow mark of the bridge with the marks on operating and semaphore lever.

vii)

Check that the armature houses properly on the core phase of the electromagnet in normal position.

viii)

Check that the clearance between lock pawl teeth and spectacle lever gear is not more than 1mm.

ix)

Check that in the normal position spectacle lever touches the bottom surface of dash pot.

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PERFORMANCE TEST 1) Energize the electromagnet at 10 volts supply, operate the signal lever and see that signal arm is taken “OFF”. Ensure that signal arm does not return to “ON” due to any obstruction on the transmission line. 2) Cut of the supply of electromagnet, signal should return to “ON” smoothly. 3) Apply external force to lower the signal. It must not come to “OFF” position. 4) Replace the signal lever to normal. Check that arrow on the operating a semaphore lever aligns with arrows on bridge. 5) With releasing control, pull the signal lever. Signal does not resume “OFF” position. 6) Replace the signal lever to normal. Ensure that any strain in transmission line must not lower the signal and lock pawl has logged the spectacle lever. TROUBLE SHOOTING AND MAINTENANCE 1) To avoid unsafe effect of residual magnetism, change polarity of the coil at every fortnight (every maintenance round). 2) Use grafted grease for smooth working of ball bearing. 3) Oil all moving parts with light grade oil once in 15 days for smooth working. 4) Check Dashpot oil lever & oil condition once in a year. 5) Dashpot spring must be checked once in 15 days, replace if necessary. 6) Sliding bar should move freely so apply oil here. 7) There must not be any dust, oil or grease on armature & core. 8) For cleaning the contacts, armature & core use chamois leather. 9) Align arrow of bridge with levers arrow.

8 FAILURES I)

SIGNAL FAILS TO OFF:

Probable cause: a) Battery connection to coil terminal is break or loose or fuse blown out. b) Weak batteries. c) Grease, oil or dust on armature and/or on core. d) Balling bearing jams and de-shaped. e) Operating lever roller jams and de-shaped. f) Lever & bridge connection is loose. g) Tension in mechanical transmission is more causing armature lever dropping form its normal position. h) Down rod connection infringing each other movement. i) Bride arrow not aligns with levers arrow. II)

SIGNAL DOES NOT RETURNS TO NORMAL AFTER: Unsafe side collapse of feed in reverser coil.

PROBABLE CAUSE: a) Residual magnetism b) Foreign feed c) Sliding bar jamming iii) Signal taken ‘OFF” without releasing Unsafe side control PROBABLE CAUSE: a) Residual magnetism b) Foreign feed c) Slide bar jamming

9 iv) A lowered signal returns to “ON” without safe side putting back control to normal. PROBABLE CAUSE: a) Weak battery b) Fuse or lightening arrestor blown out c) Weak reverser coil v) Reverser connection with signal post frequency looses: Safe side PROBABLE CAUSE: a) Oil level is not adequate in Dashpot. b) Oil mud in sliding cylinder c) Dashpot spring loose or cracked. DO’S AND DON’T’S DO’S 1) Change the coil polarity at every fortnight. 2) Maintain correct oil level in Dashpot. 3) In normal position bridge arrow align with levers arrow. 4) Tight all nut & bolts and open split pins properly. 5) Oil the sliding bar for its free movement. 6) Performance test periodically. 7) Locking and sealing of it. DON’TS 1) Forget to change the polarity. 2) Stuck armature with foreign means. 3) Oil the ball bearing only graphite – grease it. 4) Clean armature or core with emery paper. 5) Over energize the electro magnet. 6) Forget to disconnect for any adjustment. 7) Forget locking & sealing.

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ARM AND LIGHT REPEATER 1. PURPOSE: If the Arm or light or both of a semaphore arm signal is not visible to operating man from the place of operation due to any obstruction like, tree, or any structure or curvature, in such case the arm and light of the semaphore arm signal is repeated in the office of operating /controlling staff. So that SM cabin man/switchman could know about position of semaphore signal arm & light in night. 2. WORKING PRINCIPPLE OF ARM REPEATER: It works on the principle of electromagnetic induction.

When the arm of signal is at “ON” or OFF

position then depending upon the circuit controller contact the current flows through the electromagnet coil and its is magnetized and the signal arm position is shown by the small arm of arm repeater. When semaphore arm is in other position then “ON” or “OFF” position then electromagnet coil is not energized and the arm repeater shows wrong position of semaphore arm of signal. Main Parts 1. Dial 2. Small Arm showing 3 positions. “ON” “OFF” wrong 3. Indicator coil 300 ohms (3 to 5mA) 4. Permanent Magnet 5. Needle 6. Armature 7. Light repeater coil 150 + 150 ohms In arm repeater, Arm position (For two aspects LQ) (i)

“ON” – when the signal arm is at +/- 50 from horizontal position.

(ii)

“OFF”–when the signal arm is at 400– 600 below the horizontal position

(iii)

“WRONG” – When the signal Arm is in any other position then the above two position i.e. signal arm is in between 50 – 400 from the horizontal position. When any open circuits failure.

11 FOR MULTIPLE ASPECT SIGNALLING (I)

“ON” when the Arm is +/- 50 from the horizontal position.

(II)

“OFF” when the arm is 400 – 900 from the horizontal position.

(III)

WRONG – When the arm is in between 50 – 400 from horizontal position and any open circuit fault. 3. LIGHT REPEATER:

Light repeater is used to know that the

semaphore Arm signal lamp is lit or not. It is provided below the Arm repeater.

It is in the form of a “Pointer”. It shows two

positions. i.e. out, and “in”. The construction of pointer is such that in normal position due to its weight it remains out side and indicates that signal lamp is not lit to and when signal is lit it comes towards In side and indicates that signal lamp is lit. Main Parts 1. Dial with a pointer 2. Contact bell 3. Armature 4. A coil of 300 ohms (150 ohms + 150 ohms in series) Current 8 to 10 mA 5. Bell circuit contact WORKING- When signal lamp is burning, the thermostat contacts are made and a current flows through less resistive path. Electromagnet coil of repeater is energized and pointer moves toward ‘In’ and indicates that signal lamp is in lit position.

When signal lamp is extinguished then

thermostat contacts gets break and current flows though high resistive path and current flowing in the repeater coil is reduced the pointer comes towards out.

12 4. ALARM CIRCUIT- There is day and night switch which is provide on bottom side of the equipment this switch is connected in series of the bell circuit during day. Switch is turned towards day and it disconnects the bell circuit. During night it is turned toward night and close the Bell circuit. Bell coil resistance – 5 ohms Voltage – 3 V DC Current – 600mA WORKING: In night when signal lamp is extinguished thermostat contact breaks and pointer moves towards out and the strips above pointer makes and completes the electrical circuit and buzzer stats to ring which indicates that signal lamp is extinguished. The arm and light repeater both are provided in a single unit itself it is installed in office of signal operating / controlling body. 5. INDOOR UNIT: Arm and light repeater unit is called indoor unit. OUTDOOR UNIT: 1. Thermostat Rod ( above the signal lamp) with bimetallic strip. 2. Circuit controller (4way). 6. MAINTENANCE: 1. Circuit Controller band should be neat and clean 2. Circuit controller should be filed with signal post strongly. 3. “ON” “OFF” “WRONG” ‘IN’ and out of the Arm light repeater should correspond the signal Arm and light position. 4. Thermostat contact should be adjusted properly. 5. L. D. and fuse should be cleaned. 6. Earth should be proper (not more than 10 ohms earth resistance) 7. Battery terminal should be clean and tight. 8. There should be no loose connection. 9. Color and shape of Arm repeater should be accordingly to signal Arm it repeaters.

13 TESTING 1. Signal Arm at “ON” – (+) in on linen (-) to earth. Signal arm at “OFF” – (+) to earth (-) on line. 2.

When no current through Arm repeater coil Arm shows wrong

position. 4. When signal lamp lit, pointer should be towards “IN” and when signal lamp not lit pointer should be towards out. 5. When light repeater is at OUT and day/night switch is at day, buzzer should not ring. When switch kept at night then buzzer should ring. TROUBLE SHOOTING SL. TROUBLE 1. L. D. Short 2.

3.

4.

5.

6.

7.

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SYMPTOMS Connection between line circuit & earth Arm repeater will indicate “wrong” position. Light repeater will show “out” indication. No current in line

a. Break in line wire b. Arm and light repeater coil open c. Open earth d. Break in circuit controller band. Reverse polarity of No correspondence battery between the signal arm and arm repeater position Faulty Battery 1. Arm repeater will show “Wrong”. Light repeater will show out position, No current in circuit. Or less current in circuit Signal Arm in High resistance in OFF ‘OFF” position but position circuit controller Arm repeater in contact. wrong position High resistance in 1. Arm repeater OK but thermostat contact light repeater in out position or break High resistance in Current will be less in circuit over head line and arm light repeater will not work Loose connection Do

REMEDY Check the reason of short circuit. Remove it. 1. Check the coil continuity and earth wire connection remove the fault

Check the battery. Change the polarity of battery Check the battery. If required replaces it.

Check the controller band .if required clean and adjust it. Clean the thermostats contact and adjust it. Check the reason for high resistance and rectify it. Clean the terminal and tight it.

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LEVER LOCK AND CIRCUIT CONTROLER LEVER LOCK FUNCTION: Electric lever lock is an electro-mechanical lock used to provide an electrical control on a mechanical lever. WORKING: A plunge (slide0 with notches cut in required locking positions of the lever is connected to the lever tail through a down rod. A lock bolt operated by the electromagnet (lever lock coil) when dropped inside the notch holds the lever mechanically. The lever can be operated only when the lock coil is energized, its armature is attracted and lock comes out of the notch on the lever slide. The coil gets energized only when the conditions for operating the lever are safe. SPECIAL FEATURES: (1) An economical contact to cut off the feed to the cols at the end of the lever operation to save power. This contact makes from ‘a’ to ‘E’ position of lever and remains open (Break) in full ‘N’ and ‘R’ position of lever. (2) A forced drop arrangement to ensure that the lever is locked after the deenergisaton of the lock coil. TYPES: (a) For S.W. lever framed (200 mm strokes) TYPE COIL RESISTANCE WORKING VOLTAGE S&F

7.5 + 7.5 Ohms

10 V D.C. coil in series 110 V A. C. coil in parallel

IRS

4.5 Ohms

10 V D. C. /110 V A. C.

(b) For D. w. lever frame (40 mm. stroke) TYPE COIL RESISTANCE WORKING VOLTAGE T2

150 ohm

10 V D. C.

15 USES: Used for Track/Indication/Approach/back locking. Slot control, Gate controls etc.

CIRCUIT CONTROLLER: Circuit controller is a device by which electrical circuits can be made or broken at different positions of levers according to the requirement. It has generally got two sets of fixed contacts and corresponding number of rotating segments called ‘bands. The segments (bands) position can be adjusted in steps and locked in that position. The linear motion of plunger is converted into circular motion through a rack & pinion. Different bands used are NA, NB. RE. RE. AR. A.E.B, C etc. (NB band is one, which makes from N to B position of lever and remains break (open in all other position.) FORCED DROP ARRANGEMENT FUNCTION: It is a mechanical arrangement adopted to ensure that the lock controlled by a lector-magnet become effective (i.e. equipment gets locked) after the deenergisation of the lock coil. NEED: Any lock controlled / operated by an electromagnet gets released whenever the lock coil is energized and the lock becomes effective (equipment gets locked) once the coil is de-energized. But if due to residual magnetism or mechanical friction the armature of the electromagnet remains stuck in energized position even after the supply to the coil is cut off, then the lock will become permanently free and will not be effected for further (further) operations which is unsafe. To prevent this “forced drop arrangement” is employed.

16 HOW ACHIEVED? In lever lock, it is achieved by the provision of forced drop pin riveted to the plunger and a triangular piece called “Ramp” riveted to lock dog. In lever lock it the lock fails to drop inside the notch after the deenergisation of lock coil, the forced drop pin strikes against the slope point of ramp when lever is operated and forces the lock to droop inside the notch. The effectiveness of forced drop arrangement should be tested periodically in all locking position. 5. ECONOMISER CONTACT One of the means to ensure supply to the electromagnet is available only during the operation of lever. The arm of economizer contact droops in to the depression of the plunger in Normal and Reverse position and contacts remain open, cutting of supply of the coil. This arm is pushes out of the depression when the lever is operated and the contact is make to complete the supply to the lever lock. Thus the economize contact ensures that the supply is available to the coil during the stroke of the lever ‘AE’ band is used in lieu of economizer contact.

CHECK LIST FOR MAINTENANCE AND SAFETY CHECKS TO BE CARRIED OUT ON LEVER LOCK CIRCUIT CONTROLLER. MONTHLY CHECKES BY Sis 1. There is no tapering on the locking face of the notches and that the notches are cut perfectly square. 2. The forced drop pins are riveted properly as required and their effectiveness checked for every locking position. 3. The economizer contacts are functioning properly.

17 4. The various contact segments provided are cut to proper size as required and they are securely fixed and adjusted properly. The segments do not make contact in any position other then the one intended. 5. In the case of LLCC having insulator with serrations, contact segments are so adjusted that the serrations properly mesh with the contact segment and in case of LLCC having contact segment with fixing screws for securing the segment on to the roller, the screw should be properly tightened to ensure that the band is in position at all times. 6. The insulated separators are not broken and are secured in position. 7. There will be no possibility of the bands making unintended contacts through the keepers, contact spring etc. 8. The keepers are kept in proper alignment and should never be bent to give tension to the contacts. 9. While the finger contacts are kept properly tensioned, it must be ensured that they do not get entangled with the LLCC rollers and get damaged.

10. The fiber insulation provided for holding the wires inside the metallic clamp at the entrance to the LLCC are in position and that there is no possibility of the wires leading to the LLCC and their insulations due to abrasion at the clamp edges. 11. The insulation of the wires must be periodically checked to ensure that there is no deterioration in the insulation. 12. The LLCC lock holding spring has sufficient tension to keep the lock dog in the locking position, when the lever lock is not energized, and that the spring tension is not less than 390 grams/cm as specified. 13.All split pins, including limiting split pins, are of proper size and are properly split.

18 14. All working parts are cleaned and oiled and work freely. All terminal screws and looking screws are kept tight. It should be ensured that no metallic dust is allowed to accumulate in the LLCC. 15. Voltage in excess of the rates voltage is not applied to the lever locks. 16. Every individual LLCC has the last date of overhauling painted on both of its covers and that the covers are locked and sealed. 17. A record must be kept in every station/cabin having LLCC, indicating the type of LLCC provided, giving details of the make, date of overhauling, the detail of inspections done monthly and quarterly by the signal Inspectors. This record shall be maintained in the prescribed register. The contact segments shall be maintained at stations provided with LLCC for every individual LLCC, indicating the details of the contact segment number, type of contact segments and the circuit in which it is used duly indicating the relevant circuit diagram sheet in which it appear. This record shall be available for inspection at all times. 18. That the functional test are carried out to ensure the correct operation of the LLCC. It must further be ensure that operating staff as observe the check lock indicating as required while operating the lever from normal to reverse or from reverse to normal. 19.

The fixing bracket is properly anchored to the wall or ground so that

operation of the lever locks and circuit controller does not transmit vibrations to the adjacent LLCC and disturb the adjustment of their contact segment. 20. The LLCC is fixed securely to the brackets with its bolts an nuts tightened properly. 21. LLCC should be checked to ensure that the slide is properly aligned and its travel is smooth. 22. The functional test shall be carried out. CHECKS TO BE CARRIED OUT BY ESMs: ESMs during their maintenance rounds shall check the items listed at Sr. No. 1to 15 and shall keep a record there of in their diary or a History card maintained for this purpose.

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QUARTERLY CHECKS BY SI INCHARGE: It should be ensured that in addition to the checks refer to the above the following check should also be carried out. TROUBLE SHOOTING Failure 1. Lock released without proper feed

Observation

1. Lock armature not release due to residual magnetism and force droop mechanism not function 2. Armature mechanically held up in energized position 2. Lock released 1. the circuit controller in unwanted bands wrongly adjusted position of lever 2. False feed 3. Lock not 1. Notch edge are not effective at certain square position 2. Feed continuously available due to wrong adjustment of C.C. band 3. Armature held in released position due to residual flux or mechanical parts 4. Force drop mechanism defective 4. Frequent fuse Circuit controller cross blowing off in the protection contact wrong controlling circuit adjustment and shoring the supply 5. Contacts of Contacts band slipping due circuit controller to holding nut slack or working in serrations on holders warn unwanted position out and not holding the bands rigid 6.Circuit controller 1. The contact bands not contacts open cleaned properly circuit 2. Contact spring lost tension 3. Wrong adjustment of bans. 4. Lasting nut slack and band slipping

Action 1. Interchange the coil connection

1. RE-adjust 2. Check for false feed 1. Square the notch 2. Re adjust the band 3. Clean the same 4. Replace the mechanism Readjust the band.

Tighten the holding nut, remove the warn out bands replace with now one

1.Clean the contacts 2.Give tension at the end of spring 3.Readjust bands 4.Tighten the same.

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