The document provides details about an electrical point machine. It discusses: 1. The point machine has a cast iron casing and cover that houses the motor, reduction gear, contact assembly, and locking/throw assembly. 2. The DC motor is a series split-field motor that operates on 110V DC and provides high initial torque. It has a reduction ratio of 20.8:1 to convert high-speed motor rotation to slower, higher-torque output. 3. A friction clutch between the motor and load protects the motor from overload and provides mechanical snubbing of the point movement. That covers the key components and functions of the electrical point machine in under 3 sentences.

1. ELECTRICAL POINT MACHINE
POINT MACHINE
BY
V.V.KRISHNA
IOS-5/ODS

2. 1) NON TRAILABLE TRAILABLE
2) SINGLE FIELD SPLIT FIELD
(GRS5A,NIPPON) GRS5E,IRS,SIEMENS,PODNUR
STYLE 63,ALSTOM,CG.
3) LOW VOLTAGE HIGH VOLTAGE
24—36V 6AMP 110V,DC 3AMP
4) SEPARATE TYPE COMBINED TYPE
5) LOCKING WISE IN & OUT TYPE
STRAIGHT THROUGH TYPE
ROTARY TYPE
6) LOW SPEED 5SEC. HIGH SPEED 3SEC.

3. TRAILABLE POINTMACHINE

4. 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.S10.800.
it is designed to 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

5. Sr
No
b
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 2+2
12 Greasing nipple 10+1
13 weight 220 Kg
14 packing Wooden skeleton
15 Number of ground connections Five (02 lock+ 02 detection + 01 through)
Important feature

6. 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

8. Cast iron case

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

19. Transmission assembly
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23. 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.

24. 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

25. 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
1. crank handle cutout contact
assembly,
2. DC motor
3. reduction gear

26. DC motor
 It is a series split field motor
 It is designed to work on 110V DC
 It is a series motor to meet high initial torque
requirement
 Split field so that motor can be rotated in both
directions (N/R)
 contains four field windings and two windings are

27. 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 prevents simultaneous operation of
power as well as manual.
 It contains.
1. CRANK HANDLE AND KEY
2. CRANK HANDLE CUTOUT CONTACT
ASSEMBLY

28. 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
Crank handle
Wooden
handle
Ward &
feather

29. 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
1. Crank handle cutout contacts
2. flap cover plate
3. Crank handle key

30. Crank handle cutout contacts
 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.
1
2
Crank handle contact closed & Flap in front of shaft
Crank handle contact open &Flap displaced & shaft visible

31. 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

32. DC motor
 is a series split field DC motor
 Is designed 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

33. Sr
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 0.44KWt
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
Technical parameters of motor

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

35. Armature and commutator
Function of armature
 To carry current crossing
the field thus creating
shaft torque
 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)

36. 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

37. Carbon brushes
Brush is rectangular carbon
block and spring loaded placed
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 (4.0-6.0 PSI)
 Electrical connections
Carbon brush

38. Reduction gear
 It is trail of gears which provides reduction ratio 20.8:1
No of teeth on driven 75*75=5625
Reduction Ratio = ------------------------------------=20.8:1
No of teeth on driver 18*15=270
 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 synchronized various functions
 to get desire power as

39. 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.
 To transmit the motion
from motor to load

40. Transmission assembly
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41. GEAR RIM & SPRING LOADED SLIP RIM
Shoe expansion
Helical spring
gear rim
slip rim

42. 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 than 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 1.5 to 2 times of normal working current
difference between normal working current and
slipping current /obstruction current should not be less
than 0.5 Amps.
The friction clutch shall adjusted in workshop only (not
at site).

43. 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

44. 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 (3mm)
drive disc(12mm) then drive
disc rotates
control disc and shaft
with pinion & lock pawl

45. Control disc
It is a circular disc
with(120mm) 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 of friction
clutch rotation
Prevent upward movement
of top roller (lock the top
roller)
Control disc inner view
Control disc outer view
Notch for top roller
Studs for non trail able
block

46. Lift out disc
It is circular disc with
notchof158mm on outer
periphery.
It has notch on inner
periphery also which engages
with shoe expansion.
It has two grooves which are
fill with (20 grease gun
stroke) grease & fitted with
two grease nipples.
It is first disc to rotate with
friction clutch.
Function
 To lift the top roller (roller A)
to open detection contacts at
beginning of point operation
Inner view
Outer view
Grease
Nipple
Notch on outer periphery
Notch on inner
periphery

47. 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 to one another.
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.

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

49. 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 into linear
movement

50. 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

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

52. Gear Rim
A circular gear having 92
teeth on it’s outer
periphery
It engages with pinion (12
teeth) 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

53. 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

54. 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

55. 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

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

57. Friction clutch during normal course of operation
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
Drive disc rotates control disc with the help of non-traleble
block.

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

59. 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.

60. FRICTION CLUTCH
WITHOUT
OBSTRUCTION
WITH
OBSTRUCTION
Pinion
Gear Rim
Shoe expansion
Slip Rim
Drive disc

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

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

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

64. 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

65. 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.
Bottom roller
Top Roller
Control
contacts
Control
contacts

66. 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.

67. PARTS OF CONTACT ASSEMBLY

68. Making of contacts
Making of contact depend
upon position of top and
bottom roller on the
periphery of control disc and
detection slide 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 slide.
Falling of top roller in notch
proves correct locking of
point
Falling of bottom roller in
notch proves correct setting
of switches / points.
Bottom
Roller
Inside
notch
top
Roller
Inside
notch
top
Roller
outside
notch

69. 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.

70. 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

71. 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 or RC opens as soon as point correctly set and lock in
required position.

72. Top roller
Bottom
roller
Detection
slides
Open Detection
contact
Detection
contact
Short & wide notch
on slides
function of top Roller and Bottom roller of
switching assembly

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

74. 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

75. 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

76. mainteance sechdule
Sr.
No
Maintenance work to be done
Periodi
city
1 Check the machines are kept free from rust, dirt and fixtures. Check for tightness
2 Check lubrication of all gears and bearings
3 Check that machine is not slips from its place at starting and at end of operation
4 Check that both carbon brushes are resting on commutator with sufficient pressure
5 Check the proper ballasting and packing of sleepers
6 Tighten all nuts, check nuts & bolts. Tighten lock nuts holding the detector slides and lock slides with
lugs are kept tight. After tightening the nut and lock nut should be turned in opposite direction
towards each other to lock the nut
7 Track locking test is to be done, during every inspection
8 Gauge tie plate provided for motor point is properly fixed
9 Ensure all the bridge contacts make and break at the same time
10 At least 5 to 7 sleepers from SRJ chair plates should be in full tight condition.
11 All pins of ‘p’ bracket or ‘d’ bracket are of the standard type only,and there should not be any play.
12 Check the functioning of overload arrangement and out of correspondence
13 Gauge test is to be done during every inspection.
14 Check all grease nipples provided are in position Recommended type grease should be used
15 Check the setting of switches for having required amount of spring action.
16 Measure the voltage & current at motor terminals for both normal& reverse operations. These should
be within the specified limits according to the different types of point machines.

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

78. RC
NC
`A'END
POINT MACHINE
POINT MACHINE
`B'END
SA
SA
M
RC
NC
N110
B110
11
NWR
11
RWR
11
NWR
11
RWR
11
NWR
11
WCR
11
RWR
11
RWR
NWR
11
WCR
11

83. WNR
WRR
WWNR WRR
WWRR WNR
1.SM’S key in position to be proved
2. CH key is intact.
3. Pt zone Tr Cct are in pick up condition.
4. Emergency not applied.
5. Pt buttons not in pressed position.
6. Pt is free to operate.
WR

84. WNR
WRR

85. WNR
WRR

86. WNR
WRR

87. WNR
WRR

88. WNR
WRR

89. N/R
W(R)R
W(N)R
WNPR
WRPR
XR
N/R
N/R
50ohms
40watt
5000mfd
50volt
B-24V
W(N)R
W(N)R
W(R)R
W(R)R N/R WCR
W(R)R
W(N)R
N/R
XR
XR
WCR
N/R WCR
100ohms
25watt
N-24V

90. M
CH
NC
RC
NC
RC
W(N)R
W(R)R
W(R)R
WCR
W(N)R
WCR
PARALLEL OPERATION OF POINT
‘A’ END MACHINE ‘B’ END MACHINE
M
CH

91. WCR
WCR
N/R
N/R X/R
X/R
W(N)R
W(N)R
W(R)R
W(R)R
ND ND
RD
ND ND
RD
RD
RD
NWKR
RWKR
NWKR
RWKR

92. RD
SERIES OPERATION OF POINT
‘B’ END MACHINE ‘A’ END MACHINE
M M
N-24
N-110
B-110
B-24
WCR
WCR
W(R)R
W(R)R
W(N)R
WCR
RC
RC
RD
NWKR
RWKR
NC
ND
NC
ND
ND
ND
RD
RD
WCR

94. THANKS FOR YOUR KIND
ATTENTION
V.V.KRISHNA.