PAKISTAN RAILWAY LOCOMOTIVE
WORKSHOPS
LOCOMOTIVES:
A locomotive or engine is a rail transport vehicle that provides the motive power for
a train. If a locomotive is capable of carrying a payload, it is usually rather referred
to as multiple units, motor coaches, railcars or power cars; the use of these self-
propelled vehicles is increasingly common for passenger trains.
DIESEL CLASSIFIED REPAIR SHOP:
In this shop different types of engines come for maintenance in different sections of
this shop. Engines sometimes face problems like extra fuel consumption, radiator
leakage and damages caused by long routes on engine pistons etc.
DISEL ENGINE:
An Internal-combustion engine in which air is compressed to a sufficiently high
temperature to ignite diesel fuel injected into the cylinder, where combustion and
expansion actuate a piston. It converts the chemical energy stored in the fuel into
mechanical energy, which can be used to power freight trucks, large tractors,
locomotives, and marine vessels. A limited number of automobiles also are diesel-
powered, as are some electric-power generator sets.
WORKING OF DIESEL ENGINE:
The diesel engine gains its energy by burning fuel injected or sprayed into the
compressed, hot air charge within the cylinder. The air must be heated to a
temperature greater than the temperature at which the injected fuel can ignite. Fuel
sprayed into air that has a temperature higher than the “auto-ignition” temperature
of the fuel spontaneously reacts with the oxygen in the air and burns. Air
temperatures are typically in excess of 526 °C (979 °F); however, at engine start-up,
supplemental heating of the cylinders is sometimes employed, since the temperature
of the air within the cylinders is determined by both the engine’s compression ratio
and its current operating temperature. Diesel engines are sometimes called
compression-ignition engines because initiation of combustion relies on air heated
by compression rather than on an electric spark.
STEP BY STEP PROCESS:
TYPES OF DIESEL ENGINES:
By power output
Small <188 kW (252 hp)
Medium 188–750 kW
Large >750 kW
By cylinder bore
Passenger car engines: 75...100 mm
Lorry and commercial vehicle engines: 90...170 mm
High-performance high-speed engines: 165...280 mm
Medium-speed engines: 240...620 mm
Low-speed two-stroke engines: 260...900 mm
By number of strokes
Four-stroke cycle
Two-stroke cycle
By piston and connecting rod
Crosshead piston
Double-acting piston
Opposed piston
Trunk piston
By cylinder arrangement
Regular cylinder configurations such as straight (inline), V, and boxer (flat)
configurations can be used for diesel engines. The inline-six-cylinder design is the
most prolific in light- to medium-duty engines, though inline-four engines are also
common. Small-capacity engines (generally considered to be those below five liters
in capacity) are generally four- or six-cylinder types, with the four-cylinder being
the most common type found in automotive uses. The V configuration used to be
common for commercial vehicles, but it has been abandoned in favor of the inline
configuration.
By engine speeds:
High-speed engines (> 1,000 rpm),
Medium-speed engines (300–1,000 rpm), and
Slow-speed engines (< 300 rpm).
Parts of Diesel Engines:
Cylinders or Liners
Nozzles or Fuel Injectors
Connecting Rod
Fuel Pump
Cam shaft
Crank shaft
Piston
Engine Block
Lube oil
Radiator
ENGINES USED IN LOCOMOTIVES:
16-cylinders Caterpillar Diesel Engine producing 550HP.
8-cylinders Cummins Diesel Engine producing 450HP, etc.
ELECTRIC and DIESEL COMPONENT SHOP:
In this workshop all parts related to diesel engine are prepared and machined here:
Parts that are machined here are:
Oil seal
Friction plate
Discharge valve
Valve guide
Bearing shell
SECTIONS OF E AND DC:
Grinding section
Milling section
Lathe Section
MACHINES USED IN E AND DC SHOP:
Hydraulic machines
Vertical milling machines
Bench lathes
Centre lathes
FURTHER PRODUCTIONS OF E AND DC SHOP:
Suspension Bearings D29 Model (prevents high temperature of axle and is
used in motors)
Pins V2281 Model (used in making connections)
Crank shaft (it is made by turning operation, threading operation and grinding)
Hub and Gears (used in gear box)
Water pump shaft (used in air compressors)
Re-boring and Re-bushing of connecting rods
Axial taps (drilling and tapping which used for covering axles)
Weight rings (used in motors and winding processes)
Removing of old bushes and fitting of new bushes in bodies of starting
motors)
Pinion Gutters (used in winding shops)
High pressure and low pressure pistons
Maintenance of turbo rotors
FOUNDRY SHOP:
In Foundry shop different types of parts are produced using casting process. After
casting the work pieces are machined to convert them into various parts according
to structure. Various types of furnaces are available at loco shops of railway industry
to cast different number of parts according to demand.
TYPES OF FURNACES:
There are different types of furnaces available at Foundry shop:
Cupola Furnace
Tilt Furnace
Rotary Furnace
CUPOLA FURNACE:
A cupola furnace is a melting device used in foundries that can be used to melt cast
iron and some bronzes. The cupola can be made almost any practical size. The shell
of the cupola, being usually made of steel and has refractory brick. The bottom is
lined with a similar manner but often a clay and sand mixture. It can hold a
temperature of 3000F.
TILTING FURNACE:
A tilt furnace is also a melting device used in foundries that can be used to melt
aluminum and some bronzes, it is called tilt furnace because we can get molten metal
by tilting the furnace. This furnace can be made almost any practical size.
Temperature for aluminum(550F-600F) and Brass temperature(1050F-1150F).
ROTARY FURNACE:
Rotary melting furnace is very flexible and universal equipment used for recycling
many non-ferrous metals. It is designed according to capacity. In rotary furnace the
required quantity of raw material is filled along with a proportionate charge of
additives. It is used to melt raw iron.
PARTS MADE IN FOUNDRY SHOP:
BRASS FOUNDRY:
Sliding door handle
Upper birth handle
Coat hook
Window catcher
Window stopper
Window panel
Glass stand
Motor cover
IRON FOUNDRY:
L.P cylinder for D.E loco
H.P cylinder for D.E loco
Oil tank cock body
Disk brakes
China brakes
Brake shoes
Caps for alternator body
Brake block
Plug for oil tank
Hooks
I-Pads
Vacuum brake
Excel collar
Master valve
TYPES OF SAND USED IN FOUNDRY SHOP:
Green sand (River sand+ Water+ Kamoki sand binders)
Dry sand (Opposite of green sand)
Molasses sand (waste of sugar mill and is mixture of molasses and dried river
sand)
Cow-dung sand (cow-dung +water+ kamoki sand)
Fire clay (Mixture of fire bricks powder)
Silica sand (For making cores, buffers and plungers)
TYPES OF FOUNDRIES:
FERROUS FOUNDRY
Carbon is used
Brick block model V775 used
Disk brakes are made
H.P and L.P cylinders are made
Liver weights are made
NON-FERROUS FOUNDRY:
No coal is used
Brass and copper casting is done
Lead is used
Tin, Zinc and aluminum used
No hard cock is used
PAKISTAN RAILWAY CARRAIGE
WORKSHOPS:
MACHINE SHOP:
Machine shop is a large workshop having different machining apparatuses. This
shop includes machines such as milling, boring, lathes, drilling, shaper, planer and
slotter etc. Many machines have three to four tool posts i.e. many jobs could be done
in less time. Moreover, large components are machined in this shop which could
only be lifted by cranes only. Components included are:
Engine blocks
Coupling rods
Bearing
Axles
Rail wheels
Rail joints
Fish plates
Bogie components
MACHINE ANALYSIS:
Some machines were analyzed in detail, such as: -shaper and planner machines,
drilling and boring machine etc. Their structure, parts and working were focused.
The criteria to study every machine is:
Base
Table
Column
Tool head
Feed
Speed
FURTHER PRODUCTIONS OF MACHINE SHOP:
Safety Pin B.S 1151
B.T 527 Bolt
Bolt for disc B.T 525
T/Nut D.G 647
Hand brake T. Nut
Bogie center Pivot w601
Center pivot B.T 58
Buffer spindle
Buffer plug
Dummy coupling
Center pin 22inch
Master valve rod 7inch
Draft link
Floating leaver pin
Bar locating pin
Bogie Block
Floating leaver small pin
Coupler knuckle pin
Hager bolt
Bogie block nut
T. Bar end
SPRING SHOP:
In this shop all types of springs are produced and manufactured. Springs are flexible
machine element used for controlled application of force or torque or for storing and
releasing mechanical energy.
TYPES OF SPRINGS PRODUCED:
Buffer spring
Coil helical spring
Leaf spring
SPRING MAKING PROCESS:
Cut to size
End Tapering
Bar Heating (860C-900C)
Coiling
Setting of spacing of springs
Uniform Heating
Oil Quenching (190C-210C)
Tempering (480C-510C)
Scrage Testing
Grinding
Painting
Raw material Coiling
Setting Bar Heating
Tempering
Oil Quenching
Grinding/Finishing
LIFTING SHOP:
ROLLER AND BEARING SECTION:
In this section rollers and bearings of rail wheels are examined and repaired
Fitting of new bearings and rollers are done and damaged rollers and bearings
are removed from rail wheels
In this section both Chinese and German rail wheels are examined
Greasing of bearings is done
Washing of rail wheels and bearings
Flushing of bearings with white spirit is done
TYPES OF BEARINGS:
Deep-Groove Ball Bearings
Angular Contact Ball Bearings
Self-Aligning Ball Bearings
Thrust Ball Bearings
Spherical Roller Bearings
Cylindrical Roller Bearings
Tapered Roller Bearings
Needle Roller Bearings
PARTS OF BEARINGS:
Ruler
Outer
Inner
Cage
BEARINGS USED IN COACHES:
In German Coaches, spherical and tapper bearings are used in their wheels.
In Chinese Coaches, cylindrical bearings are used.
PARTS OF A RAIL WHEEL:
Cone (back cover)
First Bearing
Distance Piece
Second Bearing
Locking Plate
MAIN PROCESS IN ROLLER AND BEARING SECTION:
Transportation
Flushing
Checking
Greasing (Shell Envenia 3)
Excel box mounting
Examination
End
CC-16 CHINA SECTION:
In Chinese under carriage and under frame section, the Chinese trollies and
under frames are examined and repaired.
There are 3 types of Chinese Trollies:
1. CRC
2. CNR
3. Tancsion
Chinese bogies contain hydraulic pressure.
Secondary suspension in the form of circular tubes to damp motion.
MAINTENANCE TARGETS:
Suspension Tubes
Disc Brakes
Springs
Shocks
Pivot Pins
UNDERFRAME SECTION:
One sole bar is about 72 feet long.
Bogies are connected by pins and hooks.
One bogie weighs about 48 tons.
One underframe of a bogie contains Diagonal bar, Longitudinal bar and a
cross bar.
German bogies have springs in their buffers.
Chinese bogies have hydraulic pressure in brakes and shocks.
One sole bar is about 8 inches wide.
In this section damaged sole bars and other bars are repaired or removed when
required.
POWER PLANT SHOP:
Power plant shop is an important railway workshop in which all the work
related to power supply and energy storage is examined.
Every Rail has one or two power vans to store and generate electricity to all
the carriages or bogies.
One power van has the capacity to provide electric supply to lights, fans and
ACs of rest of the train carriages.
Each power van contains 3 engines, with 2 engines (450kw) and 1 of (150kw).
WORKING OF A GENERATOR:
An electric generator is a device that converts mechanical energy obtained from an
external source into electrical energy as the output. It is important to understand that
a generator does not actually ‘create’ electrical energy. Instead, it uses the
mechanical energy supplied to it to force the movement of electric charges present
in the wire of its windings through an external electric circuit. This flow of electric
charges constitutes the output electric current supplied by the generator. This
mechanism can be understood by considering the generator to be analogous to a
water pump, which causes the flow of water but does not actually ‘create’ the water
flowing through it. The modern-day generator works on the principle of
electromagnetic induction discovered by Michael Faraday in 1831-32. Faraday
discovered that the above flow of electric charges could be induced by moving an
electrical conductor, such as a wire that contains electric charges, in a magnetic field.
This movement creates a voltage difference between the two ends of the wire or
electrical conductor, which in turn causes the electric charges to flow, thus
generating electric current.
Main components of a generator:
The main components of an electric generator can be broadly classified as follows:
(1) Engine
(2) Alternator
(3) Fuel System
(4) Voltage Regulator
(5) Cooling and Exhaust Systems
(6) Lubrication System
(7) Battery Charger
(8) Control Panel
(9) Main Assembly / Frame
ALTERNATOR:
The alternator, also known as the ‘genhead’, is the part of the generator that produces
the electrical output from the mechanical input supplied by the engine. It contains
an assembly of stationary and moving parts encased in a housing. The components
work together to cause relative movement between the magnetic and electric fields,
which in turn generates electricity.
Stator – This is the stationary component. It contains a set of electrical
conductors wound in coils over an iron core.
Rotor / Armature – This is the moving component that produces a rotating
magnetic field in any one of the following three ways:
1) By induction – These are known as brushless alternators and are usually used
in large generators.
2) By permanent magnets – This is common in small alternator units.
3) By using an exciter – An exciter is a small source of direct current (DC) that
energizes the rotor through an assembly of conducting slip rings and brushes.
The rotor generates a moving magnetic field around the stator, which induces a
voltage difference between the windings of the stator. This produces the alternating
current (AC) output of the generator. The following are the factors that you need to
keep in mind while assessing the alternator of a generator:
Metal versus Plastic Housing – An all-metal design ensures durability of
the alternator. Plastic housings get deformed with time and cause the moving
parts of the alternator to be exposed. This increases wear and tear and more
importantly, is hazardous to the user.
Ball Bearings versus Needle Bearings – Ball bearings are preferred and last
longer.
Brushless Design – An alternator that does not use brushes requires less
maintenance and also produces cleaner power.
BLACKSMITH SHOP:
A blacksmith is a metalsmith who creates objects from wrought iron or steel by
forging the metal, using tools to hammer, bend, and cut (cf. whitesmith).
Blacksmiths produce objects such as gates, grilles, railings, light fixtures, furniture,
sculpture, tools, agricultural implements, decorative and religious items, cooking
utensils, and weapons. While there are many people who work with metal such as
farriers, wheelwrights, and armorers, the blacksmith had a general knowledge of
how to make and repair many things, from the most complex of weapons and armor
to simple things like nails or lengths of chain
Smithing process:
Blacksmiths work by heating pieces of wrought iron or steel, until the metal becomes
soft enough to be shaped with hand tools, such as a hammer, anvil and chisel.
Heating is accomplished by the use of a forge fueled by propane, natural gas, coal,
charcoal, coke or oil.
Forging:
Forging is the process in which metal is shaped by hammering. Forging is different
from machining in that material is not removed by it; rather the iron is hammered
into shape. Even punching and cutting operations (except when trimming waste) by
smiths will usually re-arrange metal around the hole, rather than drilling it out as
swarf.
Drawing:
Drawing lengthens the metal by reducing one or both of the other two dimensions.
As the depth is reduced, or the width narrowed, the piece is lengthened or "drawn
out." As an example of drawing, a smith making a chisel might flatten a square bar
of steel, lengthening the metal, reducing its depth but keeping its width consistent.
Bending:
Heating iron to a "forging heat" allows bending as if it were a soft, ductile metal,
like copper or silver. Bending can be done with the hammer over the horn or edge
of the anvil or by inserting a bending fork into the Hardy Hole (the square hole in
the top of the anvil), placing the work piece between the tines of the fork, and
bending the material to the desired angle. Bends can be dressed and tightened, or
widened, by hammering them over the appropriately shaped part of the anvil.
Upsetting:
Upsetting is the process of making metal thicker in one dimension through
shortening in the other. One form is to heat the end of a rod and then hammer on it
as one would drive a nail: the rod gets shorter, and the hot part widens.
Punching:
Punching may be done to create a decorative pattern, or to make a hole. For example,
in preparation for making a hammerhead, a smith would punch a hole in a heavy bar
or rod for the hammer handle.
Combining processes:
The five basic forging processes are often combined to produce and refine the shapes
necessary for finished products. For example, to fashion a cross-peen hammer head
Welding:
Welding is the joining of the same or similar kind of metal.A modern blacksmith has
a range of options and tools to accomplish this. The basic types of welding
commonly employed in a modern workshop include traditional forge welding as
well as modern methods, including oxyacetylene and arc welding.
Finishing:
Depending on the intended use of the piece a blacksmith may finish.
