GENERAL MOTOR DIESEL LOCOMOTIVE. Manual - part 8

IRCAMTECH/2006/M/D/GM loco/1.0

Introduction hand book on GM locomotive February 2006

Fuel then goes to primary fuel filter. This primary filter

is provided with a 30-PSI bye pass valve with sight glass,
which should be normally empty. Whenever the primary filter is
Choked/clogged and the pressure difference reaches 30 PSI
this bye-pass value open allowing the fuel oil directly to the
system, which can be noticed by the flow of bye-pass fuel in
the sight glass. Under such cases the primary filter element is
changed.

The fuel then passes to 02 engine mounted secondary

filters, which are of spin-on type. Secondary fuel filters are also
provided with a bye-pas value, which is set at 60 PSI.
Whenever the filters are choked/clogged and the pressure
difference across the secondary filters reaches 60 PSI, this

bye-pass valve opens and
diverts the fuel oil back to
fuel tank, avoiding damage
to fuel injectors due to
unfiltered fuel oil. A bye-pass
sight glass is also provided
to indicate the condition of
the fuel secondary filters and
the sight glass should be
normally empty.
From the secondary filters
the fuel oil is supplied to all
unit injectors through fuel
supply manifolds located
inside the top deck on the
both banks. The governor
controls the quantity of fuel
to be injected through the
injectors to the engine.

At the end of the fuel supply manifolds, a regulating

valve with a sight glass is provided which is set to 10 PSI. The
regulating valve ensures constant fuel supply to all unit injector
in all working conditions. If the system is working properly the
sight glass should indicate clear and clean fuel oil flow all the

Secondary fuel oil filter

IRCAMTECH/2006/M/D/GM loco/1.0

Introduction hand book on GM locomotive February 2006

time. Air bubbles, interrupted fuel flow or no fuel flow in the
return sight glass indicates problem in the fuel feed system.

Fuel injection system :-

Fuel supplied by the fuel feed system is always

available at all the unit fuel injectors. The fuel oil available at
each injector are to be pressurized to very high pressure,
timed and to be injected in the cylinder in atomized form. The
timing of each unit injector is decided by the camshaft and the
fuel is pressurized by the in-built fuel injection pump which is
operated by individual cam lobe of the cam shaft.

The quantity of fuel to be injected will be regulated and

controlled by engine mounted wood word governor according
to the notch and load conditions. The governor operates fuel
control shaft, linkage mechanism and fuel racks. The individual
fuel injector nozzle does the atomization of the fuel to be
injected in the cylinder.

Alco locomotive Vs GM locomotive

Although the purpose for which the fuel oil system is

designed is same for Alco locomotive and GM locomotive, but
the design of the fuel oil system differs in Alco and GM
locomotive in respect of general arrangement, position of
various components, make and design of components etc.
The important comparisons between the two locomotives are
given below-

1. The fuel tank capacity in GM loco is 6000 lts. and in Alco

loco is 5000 lts.

2. Both have a strainer with wire mesh element.
3. Both the locomotives have a positive displacement gear

type fuel feed pump.

4. Both the locomotives have a relief valve for fuel feed pump

safety.

IRCAMTECH/2006/M/D/GM loco/1.0

Introduction hand book on GM locomotive February 2006

5. Both the locomotives have a regulating valve after the fuel

manifold for the safety of the fuel system and to maintain
adequate fuel supply to fuel injectors.

6. Both the locomotives have a paper type primary filter. In

GM locomotive a sight glass is also provided on the
primary filter housing.

7. Both the locomotives have a secondary filter but in GM

locomotive a spin-on type 02 secondary filters with return
sight glass and bypass sight glass are provided on the filter
housing.

8. In Alco locomotive fuel injection pumps and injectors

connected by high pressure tube are separate units but
GM locomotive a unit type fuel injection pump with injector
is provided, and there is no provision of HP tube.

Fuel oil pressure (Alco loco)

5.0 Kg/Cm

(Idle)

3.2 Kg/Cm

Notch and Full
load)

Fuel oil pressure (GM loco)

There is no
pressure gauge in
system

IRCAMTECH/2006/M/D/GM loco/1.0

Introduction hand book on GM locomotive February 2006

COOLING WATER SYSTEM

Engine cooling water system is a closed loop

pressurized water cooling system. The water cooling system
cools – All the engine cylinder liners, cylinder heads, after
cooler, lube oil cooler and compressor.

LINE DIAGRAM OF THE COOLING WATER SYSTEM

In the water cooling system, there are 02 nos. engine

mounted water pumps (centrifugal type). The water pump
receive water from the radiator through lube oil cooler. Water
from the water pump is sent to the two (left and right Bank)
water main header (also called water inlet manifold) . From the
water main header water enter to all the cylinder liner jackets
through water jumper. After cooling the cylinder liners water
enter in the cylinder head through 12 holes which are matched
to cylinder liner with “O” rings and cools the combustion

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