1. IRS POINT MACHINE
IRS POINT MACHINE is rotary locking type point machine and designed to comply with IRS specification S-24/2000 and RDSO Dr.No.S
it is designed operate all type of points /switches.
It is available in two model low stroke (143mm) and high stroke (220mm)
It is non-trailable type point machine

2. Important feature Sr Nob Description remark 1 Type
D.C. high thrust (stroke 143mm) 2
Other model
High stroke 220mm 3
Type of Locking
Rotary type 4
Locking of switches
Independent (two lock slides) 5
Arrangement for Locking of switches
Indirect through ground connections (rods) in side machine 6
Thrust
700 Kg 7
Over load protection
Friction clutch self adjustable 8
Snubbing
Mechanical 9
Locking of throw
Available 10
Number of control contact
2+2 11
Number of detection contact 12
Greasing nipple 13
weight
220 Kg 14
packing
Wooden skeleton 15
Number of ground connections
Five (02 lock+ 02 detection + 01 through)

3. General Features of point machine
The basic design of point machine generally comprises of
Cast iron casing and cover with locking arrangement
Motor
Reduction gear
Crank handle mechanism
Friction clutch
Contact assembly with spring loaded rollers and Detection slides
Rotary to linear conversion mechanism
Locking and throw assembly

5. Cast iron case accommodates all the parts of point machine
is made of cast iron and designed to fix all parts at required place.
provide access to/ slots for different lock and detection slides
facilitate fixing of machine on sleepers
Provides an arrangement to drain out water/ oil in bottom of casting.
Provides cable entry.

6. Cast iron case

7. COVER OF POINT MACHINE
Made up of thick iron sheet and fixed on cast iron casting (case)
Contain lock ( S&T maintainer's lock) on inner side surface to lock it with cast iron casting (case).
Secure all the parts of machine in weather proof environment and prevents un-authorosed interference.
Provides access only to nominated (ward &feather) crank handle insertion.
All the apertures for keys and crank handle are secured by flaps
All flaps has a locking arrangement

8. COVER OF POINT MACHINE Cover top view Cover inner view
Flap for crank handle key
lock
Flap
For
Cover
key
Flap
For Crank
handle
Cover top view
Cover inner view

9. MOTOR
DC motor IRS: S 37 Motors for Electric Point Machine.
shall comply with the requirements of IRS: S 37 'Motor for Electric Point machine.
Motor comprises of
crank handle cutout contact assembly,
DC motor
reduction gear

10. CRANK HANDLE AND CRANK HANDLE MECHANISM
It allows Manual operation (without power) of point
It require in case of failures of point/ point machine OR for the purpose of maintenance of point machine.
It contain
CRANK HANDLE AND KEY
CRANK HANDLE CUTOUT CONTACT ASSEMBLY

11. CRANK HANDLE
This apparatus is used for manual operation of point machine
It is a “Z” shape structure made of steel pipe and has wooden handle on one end to have better gripe.
Wards &feathers are welded on other end of pipe
facilitates coding (insertion of only to nominated crank handle).
A stud is intrude in the pipe, it get engage in forked shaft of motor
Wooden
handle
Ward &
feather
Crank handle

12. CRANK HANDLE CUTOUT CONTACT ASSEMBLY
It disallows simultaneous power and manual operation of point machine to protect staff performing crank handling.
Ordinarily crank handle can not be inserted in machine
Turing of crank handle key permits/ allows insertion of crank handle in the machine.
Turning of crank handle key isolates the negative power path of motor.
It comprise of
Crank handle cutout contacts
flap cover plate
Crank handle key

13. Crank handle cutout contacts1 1
There are two sets of contact
These contacts are wired in negative path of power supply to motor.
Contacts break / open with insertion and turning of crank handle key
Makes when crank handle key is taken out. 2
Crank handle contact closed & Flap in front of shaft
Crank handle contact open &Flap displaced & shaft visible

14. Flap cover plate & key
controls the entry of crank handle in the machine for manual operation
metal flaps attached to a lock
hangs/ placed in front of motor shaft at the entry point of crank handle.
flap cover plate is displaced by means of a crank handle key
The insertion and turning of crank handle key
displace the flap cover plate to allow insertion of crank handle
open crank handle cutout contacts.
Removal of the crank handle key
replaces flap cover in front of motor shaft
makes the crank handle contact.
Crank handle key

15. Flap cover plate and crank handle key
Flap cover plate in front of crank handle Entry
& shaft of motor
Crank handle insertion
Insertion & turning of key displaces flap Cover plate

16. DC motor is a series split field DC motor
Is design to work on 110volt DC
Is a series motor to meet high initial torque requirement
Is split field so that motor can be rotated in both direction
contains four field windings and two windings are connected in series to form a set of winding.
Use carbon brushes

17. Technical parameters of motorSr
Nob
Description
Remarks 1
Type
D.C. Series split field 2
Operating voltage
110 Volt DC (60 volt mini) 3
current
2 to 2.5 Amps 4
Thrust
700 Kg 5
Power
0.48KWt 6
Reduction ratio (in side motor)
20.8 :1 7
AC immunity
160 , 300, 400 volts 8
Power supply terminals 03 9
Insulation grade of windings
More than 10 M Ohms

18. DC MOTOR main parts Armature and commutator Field winding
Carbon brushes
Motor body
Groove for crank handle

19. DC motor
Reduction Gear
Rec
Power Terminal
Pinion
Commutator & brush

20. Armature and commutator
Function of armature
To carry current crossing the field thus creating shaft toque
To generate an electromotive force
Function of Commutator
Reverse the current in moving coil of motor’s armature and generate a steady rotating force (torque)

21. Field winding
The function of the field winding create magnetic field for armature
motor contains four field windings
two windings are connected in series to form a set of winding.
one set of winding rotate motor clockwise and other set of winding rotate motor anticlockwise direction

22. Carbon brushes
Brush is rectangular carbon block and spring loaded in holder
Brush provides the electric connectivity between field windings and rotating commutator
the holders should be mounted a maximum of .125" above the contact surface.
Proper functioning of the holder depend upon,
Inside holder dimensions
equally Holder spacing
Holder angle (20 to 30 deg.)
Holder height
Spring force ( PSI)
Electrical connections
Carbon brush

23. Reduction gear
It is trail of gears which provides reduction ratio 20.8:1
Number of teeth on driver
Reduction Ratio =
Number of teeth on drive
Reduction ratio provides a torque-speed conversion from a higher speed motor to a slower but more forceful output.
Motor rotate at very high speed and Load can not be directly placed on motor shaft.
Appropriate reduction gear ratio is used
to get require mechanical advantage/ thrust
to syncronised various functions
to change direction of rotation
to get desire power as

24. Reduction Gear
Oil entry
pinion
pinion
Hover flow pipe

25. Friction Clutch
Friction clutch is an assembly of spring loaded Gear, shaft and disks which are placed between motor and Load (point throw / transmission assembly).
Functions of friction clutch are
To protect the motor from overload
To achieve mechanical (dynamic) snubbing
To follow the sequence of point operation.

26. Transmission assembly
Lift out
disc
Control
disc
Drive disc
Lock segment
Gear
rim
slip
rim
pinion

27. Feature of friction clutch
The friction clutch designed to
extend stroke (force) from motor to load (point) if load is within Specified limit (700 Kg)
de-clutch (separate) motor and Load (point) if load is more Specified limit (700 Kg).
De-clutching of friction clutch can be adjusted to suite Specified limit of load (700 Kg) by loosening Or tightening spring.
Friction clutch require / needs an adjustment if
slipping current /obstruction current shall not be more than 1.6 to 2 times of normal working current
difference between normal working current and slipping current /obstruction current is less than 0.5 Amps.
The friction clutch shall adjusted in workshop only (not at site).

28. Parts of friction clutch
Friction clutch comprises of
Control disc
Lift out disc
Drive disc
Gear rim and slip rim
Shoe expansion (locking plate)
Helical spring

29. Sequence of rotation of gear &disc
How different gear and disc rotate in side friction clutch
Pinion of motor rotates
Gear rim, then Gear rim rotates
slip rim then slip rim rotates
shoe expansion, then shoe rotates
lift out disc and
drive disc, then d.disc rotate
control disc and
shaft with pinion & lock pawl

30. Control disc It is a circular disc with notch on outer periphery
Notch for top roller
It is a circular disc with notch on outer periphery
Edges of notch are vertical
Function of control disc are
Allow the top roller (roller A) to fall in side respective notch at end friction clutch rotation
Prevent upward movement of top roller (lock the top roller)
Control disc outer view
Studs for non trail able
block
Control disc inner view

31. Lift out disc It is circular disc with notch on outer periphery.
It has notch on inner periphery also which engages with shoe expansion.
It has two grooves which are fill with grease & fitted with two grease nipples.
It is first disc to rotate in friction clutch.
Function
To lift the top roller (roller A) to open detection contacts at beginning of point operation
Notch on inner
periphery
Inner view
Grease
Nipple
Outer view

32. Drive Disc Drive disc is a Thick circular disc & has
Two projections on outer and inner periphery.
A shaft keyed in the center
Lock pawl and pinion fixed on one end of shaft
Lock pawl and pinion fixed at180 degree opposite
A circular offset on outer periphery on which gear rim rests
Two studs which engaged with non trailable block.
A Small window to have access to friction clutch adjustment nut.

33. Shaft pinion Window Lock pawl Projection on outer periphery
Projections on
Inner periphery
Shaft
pinion
Locking face
For throw slid
Window
Circular groove
For gear rim
Lock pawl
Locking face
For lock slids

34. Functions of Drive Disc
Extend movement to shaft hence rotate pinion and lock pawl.
Restrict rotary movement to 270° and provide subbing
Hold gear rim on outer periphery
Convert rotary movement in to linear movement

35. Gear rim & spring loaded slip rim
It is main part of friction clutch where
rotary movement of motor is extended to other parts of machine
Overload protection to motor achieved
Snubbing is achieved
The main parts are
Gear rim
Slip rim
Shoe expansion with helical spring

36. GEAR RIM & SPRING LOADED SLIP RIM
Shoe expansion
gear rim
Helical spring

37. Gear Rim A circular gear having 92 teeth on it’s outer periphery
It engages with pinion of the Motor
It Accommodate slip rim and spring loaded shoe expansion.
When rotated by motor It transmits rotary motion to shoe expansion through slip rim

38. Slip rim It is semicircular rim with grips on it’s outer surface.
It’s width is less than the width of gear rim
Rotate freely within gear rim when not loaded by spring.
When spring loaded it rotate with gear rim

39. Shoe expansion (locking plate right & left) and helical spring
Two rectangular steel strips hold by a clamp at one end.
Other end butted against slip rim ends.
Shoe expansion extends rotary movement of gear rim to lift out & drive disc.
Helical spring placed between shoe expansion in compressed condition.
Compressed spring compel gear rim and slip rim to act as one piece

40. Sequence of rotation of gear &disc
How different gear and disc rotate in side friction clutch
Pinion of motor rotates
Gear rim, then Gear rim rotates
slip rim then slip rim rotates
shoe expansion, then shoe rotates
lift out disc and
drive disc, then d.disc rotate
control disc and
shaft with pinion & lock pawl

41. How friction clutch performs?
During normal course of operation
During obstruction
At end of operation

42. Friction clutch during normal course of operation
Pinion operates gear rim
slip rim & shoe expansion rotates along with gear rim as these are spring loaded in side gear rim
the edge of one shoe expansion engages in the notch on inner periphery of lift out disc & lift out disc rotates
the same edge of one shoe expansion engages with projection on drive disc also & drive disc rotates
shaft rotates along with drive disc & stroke of 143mm generated

43. Friction clutch during normal course of operation
Gear Rim
Projection
on Inner
periphery
Of drive disk
Slip Rim
Shoe expansion

44. During obstruction
The drive disc cannot rotate, as throw bar/gear rack is stationary
Hence shoe expansion engages with projection on drive disc also cannot rotate.
But pinion of motor forced to rotate gear rim
Hence rotary force will appear on other shoe expansion
The helical spring get compressed & slip rim collapse to reduce circumference of slip rim
The gear rim alone rotates with slight friction between gear rim& slip rim.

45. During obstruction Gear Rim Projection on Inner periphery s
Of drive disk
Slip Rim
Shoe expansion

46. Friction clutch at end of operation
At end of operation projection on outer periphery buts with bottom rod
Obstruction is generated inside the machine
Friction clutch slips & snubbing is achieved.

47. Friction clutch at end of operation
Drive disc
Bottom bar

48. CONTACT ASSEMBLY WITH SPRING LOADED ROLLERS
Contact assembly comprises of two spring loaded contact groups which are fixed inside the casting.
Function of the contact assembly: - make and break the sets of contact.
One group Contains two sets of contact fixed side by side
Contact controls feed (Power) to motor and point indication relay

49. CONTACT ASSEMBLY WITH SPRING LOADED ROLLERS
Each Contact group comprises of
Eight terminals in two sets for wires termination
terminals sets fixed opposite to each other on the casting
Eight high tensile contact (metal strips) in two sets.
Two sets of contact are fixed back to back on spring loaded bracket / crank.
Two sets of roller are fixed on same spring loaded bracket / crank.
Bottom roller and top roller
A transparent cover protects all sets of contact and terminals
The transparent cover has sealing arrangement also.
Control
contacts
Control
contacts
Bottom roller
Top Roller

50. CONTACT ASSEMBLY WITH SPRING LOADED ROLLERS
Terminal and finger contacts are insulated from metal part of point machine.
Two Finger contacts are shorted at one end
Carbon tip is fixed on other end of Finger.
Outer side two sets of contact are known as Control contact and inner side two sets of contact are known as Detection contact.
These contacts are self wiping, they clean themselves during the process of making and opening.

51. PARTS OF CONTACT ASSEMBLY

52. Making of contacts
Making of contact depend upon position of top and bottom roller on the periphery of control disc and detection slid respectively.
Detection contact in one group & control contact in other group makes when
top roller fall in nominated notch on friction clutch
bottom roller fall in nominated notch on periphery detection slid
Falling of top roller in notch proves correct locking of point
Falling of bottom roller in notch on proves correct setting of switches / points.
Bottom
Roller
Inside
notch
top
Roller
Inside
notch
top
Roller
outside
notch

53. Detection contacts
Making of Detection contacts proves correct setting and locking of switches.
Detection contacts are classified as Normal detection contact (ND) and reverse detection (RD) contact.
ND contact make when point correctly set and lock in Normal.
RD contact make when point correctly set and lock in Reverse.
if point is not set correctly and/ or not correctly locked then both ND contact and RD contact are remain in open condition.
ND contact and RD contact are used circuit of point indication relay NWKR and RWKR respectively.

54. Check for Correct setting and locking of point
The notches on detection slides and friction clutch can be make available for bottom and top roller by moving lock slides and detection slides.
Dose it Mean that ND & RD contacts can make even though point is not lock and set?
proving of correct setting and locking of point by ND & RD contact is subject to condition that length of ground connections between point slides are accurately adjusted.
This is prime check to be done at site during installation & Maintenance

55. Control contact Feed to motor is control through these contacts
Control contact controls feed to motor in normal course of working Types of Control contacts
Normal Control contact (NC)
Reverse Control contact (RC).
When points set and lock in Normal then RC contact makes.
When points set and lock in Reverse then NC contact makes.
When point is not correctly set and/ or not correctly locked position than both NC contact &RC contact are remain in make condition.
NC contact controls feed for reveres to normal operation of point
RC contact controls feed for normal to reveres operation of point.
NC and RC opens as soon as point correctly set and lock in required position.

56. Detection slides D Type detection slid Threaded Stud Small notch
Brass stripe
Threaded Stud
Small notch
Wide notch
C Type Detection slid

57. Detection slides
These are two rectangular strong metal strips and two threaded rods are welded at one end.
Each slid have a small and a wide notch on its one of surface.
These slides are connected to switches of point and used to prove correct setting of switches.
Bottom Rollers of switching unit are mounted on surface of these slides.
Threaded studs welded sideways to avoid interchanging position of slides
Rectangular Brass strips are riveted on inner surface
Brass strips avoids transfer of movement to other slid which is supposed to be stationary in case of rod breakage

58. Lock slides

59. Lock slides
These are two rectangular strong metal strips and two threaded rods are welded at on end.
Each slid have a small and a wide semicircular notch ,
These slides are connected to switches of point and used to lock the switches.
Lock segment on drive disc engages in these notches
Threaded studs welded sideways to avoid interchanging position of slides
Rectangular Brass strips are riveted on inner surface
Brass strips avoids transfer of movement to other slid supposed to be stationary in case of rod breakage

60. Position of point/ Switches
Position of Notches on
Lock slid
Position of
top Roller
ND For RHS mounting RD
RHS mounting
NC RHS mounting
RC RHS mounting
Control/lift out disc
Bottom roller
LHS mounting
When switching unit is not fixed on machine
Make
Open
open
Set in normal but not locked
Available
On periphery of control disc & lift disc
1,1a
5,5a
2,2a
6,6a
Not Available
Hanging on notch of detection slides
Set and locked in normal
In the notch of control disc & lift disc
3,3a
7,7a
In the notch of detection slides
4 ,4a
8 ,8a
5 ,5a
Set in reverse but not locked
Set and locked in reverse