“150”, Aptitude Test Questions and Answers for Technician II (Electro-Mechanical) – TRC.
ABSTRACT
This preparation material contains 150
premium multiple-choice aptitude test questions and answers designed for
candidates preparing for the Technician II (Electro-Mechanical) position at
Tanzania Railways Corporation (TRC). The questions cover key areas
including electric and diesel locomotive maintenance, fault diagnosis,
electrical testing, wiring and connectors, rotating machinery, cooling systems,
refrigeration and air conditioning, batteries, preventive maintenance, safety,
maintenance records, and basic engineering calculations. Emphasis is placed on
practical application, technical reasoning, and fault-solving scenarios, with
closely related answer choices designed to reflect the demanding nature of
public service online aptitude tests in Tanzania. The material aims to
strengthen candidates' technical understanding, analytical ability, and
confidence before undertaking the assessment.
Prepared by Technician II (Electro-Mechanical)
– TRC.
Compiled by Technician II (Electro-Mechanical)
– TRC.
0628729934.
Date: September 18, 2026
Dear applicants,
This collection of questions and answers
has been prepared to help all of you to understand the key areas tested during
the interview. The goal is to provide a useful, and practical study guide so
you can all perform confidently and fairly in the selection process. I wish you
the best of luck, and may this resource support you in achieving success!
Warm regards,
Technician II (Electro-Mechanical) – TRC.
For Personal Use by Applicants Preparing
for Technician II (Electro-Mechanical) – TRC - at Public Service Recruitment
Service.
Technician II
(Electro-Mechanical) – TRC.
150 Aptitude
Test Questions and Answers
1. During routine inspection of a locomotive
traction motor, the motor has acceptable winding continuity, but an
insulation-resistance test between the winding and the motor frame gives a
significantly low reading. Which condition is MOST directly indicated by this
result?
A. An open
circuit exists within the motor winding B. The winding insulation is
deteriorating toward earth C. The motor commutator has excessive mechanical
wear D. The motor bearing has developed excessive running clearance
Answer: B
Rationale: An insulation-resistance test evaluates
the effectiveness of electrical insulation between energized conductors and
earth or the equipment frame. A significantly low reading indicates that
leakage toward the frame is possible because the insulation has deteriorated,
become contaminated, or absorbed moisture. Continuity can still be completely
normal because continuity only confirms that an electrical path exists through
the winding; it does not establish that the winding is adequately insulated
from earth. Bearing clearance and commutator wear are mechanical conditions
that cannot directly explain a low winding-to-frame insulation reading.
2. A diesel-electric locomotive shows
progressively reduced traction power during operation. Engine speed and fuel
supply remain normal, but measurements show that the traction motor current on
one motor is significantly higher than that of comparable motors under the same
operating condition. Which finding would MOST strongly support an electrical
fault in that motor circuit?
A. Abnormal
current imbalance between comparable traction motors B. Slightly reduced
gearbox lubricant level C. Increased vibration from the driver's cab fan D.
Normal temperature of the locomotive cooling system
Answer: A
Rationale: A significant current imbalance between
traction motors operating under comparable conditions can indicate an
electrical abnormality affecting one motor or its associated circuit. Possible
causes include winding faults, poor electrical connections, abnormal control,
or other circuit conditions that cause unequal current distribution. The
finding does not by itself identify the exact fault, so further measurements
are required, but it provides substantially stronger evidence of an electrical
problem than unrelated mechanical or auxiliary-system observations.
3. While checking a locomotive control
circuit, a technician finds that voltage is present at the supply side of a
control device but absent at its output when the device is commanded to
operate. The device is properly connected and the upstream protection is
healthy. What should be investigated FIRST?
A. The condition
of the locomotive suspension components B. The lubrication condition of the
traction gearbox C. The operation or internal contacts of the control device D.
The refrigerant level within the air-conditioning system
Answer: C
Rationale: When the expected input voltage is
present but the output is absent during a commanded operating condition, the
control device itself or its internal switching contacts become an immediate
point of investigation. Depending on the equipment, the device could be a
relay, contactor, switch, or another controlled switching component. The
technician should verify the control signal and then assess whether the device
operates and establishes the intended electrical path. Suspension, gearbox
lubrication, and refrigerant level are unrelated to this specific electrical
symptom and therefore should not be the first diagnostic focus.
4. A technician is replacing a damaged
locomotive cable. The replacement cable has the correct conductor size and
insulation rating, but its terminal connection is poorly crimped. Which
consequence is MOST likely during operation?
A. Increased
contact resistance and localized heating B. Reduced mechanical vibration
throughout the locomotive C. Increased refrigerant pressure within nearby
equipment D. Improved current distribution between unrelated circuits
Answer: A
Rationale: A poorly crimped terminal can create
inadequate contact between the conductor and terminal, increasing contact
resistance. When substantial current passes through that resistance, heat is
generated at the connection, potentially causing further deterioration,
discoloration, arcing, voltage drop, or eventual circuit failure. This is
particularly important in locomotive systems where some circuits carry
substantial current and experience vibration. Proper crimping therefore
requires the correct terminal, conductor size, tooling, and prescribed
procedure rather than simply securing the wire mechanically.
5. During inspection, a technician notices
that a rotating auxiliary machine has developed increasing vibration while its
operating speed remains approximately constant. There is no obvious electrical
alarm. Which mechanical condition should receive PARTICULAR attention?
A. Refrigerant
charge in the locomotive cab system B. Alignment and bearing condition of the
rotating assembly C. Insulation resistance of an unrelated lighting circuit D.
Capacity of the locomotive battery charging circuit
Answer: B
Rationale: Increasing vibration from rotating
equipment at approximately constant speed is strongly associated with
mechanical conditions such as shaft misalignment, bearing deterioration,
imbalance, looseness, or coupling problems. Alignment and bearing condition are
therefore logical early inspection points. An electrical alarm is not necessary
for a mechanical rotating-equipment fault to exist. Refrigerant charge,
lighting-circuit insulation, and battery charging capacity may be important
elsewhere on the locomotive, but they do not directly explain progressively
increasing vibration from a rotating machine.
6. A locomotive battery supplies the control
system during engine starting. The battery voltage appears acceptable before
starting, but drops sharply when the starter is engaged and the starting system
struggles to operate. Which condition would MOST reasonably explain this
observation?
A. Excessive
refrigerant flow through the evaporator B. Increased insulation resistance in
the control circuit C. Reduced lubrication of an unrelated traction gearbox D.
High internal resistance or inadequate battery capacity
Answer: D
Rationale: A battery may show an apparently
acceptable open-circuit voltage while still being unable to deliver the
required starting current. A sharp voltage drop under load can indicate high
internal resistance, deteriorated cells, inadequate state of charge, or
insufficient battery capacity. The key diagnostic principle is that battery
performance must be considered under the actual load rather than from
open-circuit voltage alone. The other conditions cannot directly account for
the characteristic voltage collapse when the starter demands substantial
current.
7. An operator reports that a locomotive
occasionally loses traction, but the traction system returns to normal after
vibration or movement of the equipment. Which investigation is MOST appropriate
as an early step?
A. Inspect
connectors, terminals, and wiring for intermittent contact B. Replace all
traction motors without performing electrical tests C. Increase the
refrigeration-system pressure to stabilize traction D. Replace the locomotive
gearbox lubricant regardless of its condition
Answer: A
Rationale: A fault that appears and disappears with
vibration or equipment movement strongly suggests an intermittent connection,
loose terminal, damaged conductor, poor connector engagement, or similar wiring
problem. Railway equipment is exposed to vibration, so electrical connections
require particular attention. The technician should inspect and test the
relevant wiring and connectors systematically rather than replacing major
components without evidence. Random component replacement increases maintenance
cost and may fail to address the actual fault.
8. Before reconnecting a locomotive control
circuit after maintenance, a technician wants to verify that two terminals
which should remain electrically isolated have not become unintentionally
connected. Which test is MOST appropriate?
A. Measure
insulation resistance between the specified terminals B. Measure the
mechanical length of each conductor C. Check the bearing temperature of the
nearest rotating machine D. Measure the refrigerant pressure in the
air-conditioning circuit
Answer: A
Rationale: When two conductors or terminals are
intended to remain electrically isolated, insulation-resistance testing can
determine whether an unintended conductive path exists between them. A
satisfactory insulation-resistance value indicates that the separation is being
maintained within the applicable specification. This is different from a
continuity test, which primarily establishes whether an intended conductive
path exists. The test must be performed using the equipment manufacturer's
prescribed procedure and appropriate safety precautions.
9. During scheduled maintenance, a
technician finds a filter heavily contaminated with dust and debris. The
associated equipment has also been operating at a higher temperature than
usual. What is the MOST appropriate interpretation?
A. Restricted
airflow may be reducing cooling effectiveness B. The contamination necessarily
proves the motor winding is open C. The filter condition automatically
confirms excessive battery voltage D. The debris necessarily indicates a
refrigerant overcharge
Answer: A
Rationale: A heavily contaminated filter can
restrict airflow and reduce the ability of the associated cooling system to
remove heat. Reduced airflow may cause equipment temperatures to rise,
particularly where fans and filters are part of the cooling arrangement. However,
the technician should not assume that the filter is the only fault; after
servicing or replacing it according to procedure, the equipment should be
inspected and tested to determine whether the temperature returns to the
expected range. The other alternatives do not logically follow from the
observed filter condition.
10. An electric motor draws
higher-than-normal current while producing less useful mechanical output. The
shaft is difficult to rotate manually when the equipment is safely isolated.
Which combination of findings would MOST strongly support a mechanical overload?
A. Low
refrigerant pressure and clean electrical terminals B. High insulation
resistance and normal bearing temperature C. Increased mechanical resistance
together with elevated motor current D. Normal shaft movement together with
reduced battery terminal voltage
Answer: C
Rationale: Mechanical resistance at the shaft
combined with elevated motor current provides strong evidence that the motor is
working against an abnormal mechanical load. A seized or deteriorating bearing,
excessive friction, misalignment, or another mechanical restriction can require
the motor to draw more current to maintain operation. The technician should
investigate the driven equipment and rotating assembly while also checking
electrical parameters. The combination is more informative than considering
elevated current alone because excessive current can have several possible
causes.
11. A refrigeration compressor is operating,
but the conditioned space remains warmer than expected. The condenser is
visibly dirty and airflow through it is restricted. What is the MOST
appropriate first maintenance consideration?
A. Replace the
locomotive battery immediately B. Clean the condenser and restore the required
airflow C. Increase compressor voltage without further inspection D.
Disconnect the evaporator fan from the control circuit
Answer: B
Rationale: The condenser must reject heat from the
refrigeration system, and adequate airflow is essential for effective heat
transfer. Dirt and restricted airflow can increase condensing temperature and
pressure and reduce overall cooling performance. Restoring airflow by cleaning
the condenser according to the applicable maintenance procedure is therefore an
appropriate first consideration. Increasing electrical voltage or disconnecting
other components without diagnosis could create additional faults or unsafe operating
conditions. After servicing, system performance should be verified against the
required operating parameters.
12. During replacement of a locomotive cable,
the technician finds that the replacement conductor has the correct
cross-sectional area but is routed through a location where it can rub
repeatedly against a sharp metal edge. What is the MOST important concern?
A. Progressive
damage to the cable insulation and possible conductor exposure B. Automatic
increase in the cable's current-carrying capacity C. Reduced rotational speed
of nearby auxiliary equipment D. Improved electrical isolation caused by
mechanical contact
Answer: A
Rationale: Repeated mechanical abrasion can damage
cable insulation and eventually expose the conductor. In a locomotive,
vibration and movement can accelerate this deterioration, potentially creating
an earth fault, short circuit, or intermittent failure. Correct conductor size
alone does not make a cable installation acceptable; routing, support,
protection against abrasion, bend radius, and clearance from moving or hot
components must also comply with the applicable maintenance requirements.
13. During a continuity test, a technician
obtains no continuity through a cable that should provide a continuous
electrical path. Which fault is MOST directly indicated?
A. Excessive
refrigerant concentration in the cooling system B. A possible open circuit in
the conductor or connection C. Excessive mechanical alignment of the drive
shaft D. Increased cooling efficiency of the traction motor
Answer: B
Rationale: Lack of continuity through a conductor
that should form a complete circuit indicates that the expected electrical path
is interrupted. The interruption may result from a broken conductor,
disconnected terminal, failed connector, or another open-circuit condition. The
technician should isolate the location of the interruption rather than
immediately replacing unrelated components. Continuity testing is particularly
useful for identifying breaks in wiring, although the test should always be
performed using the correct procedure and with the circuit in an appropriate
safe state.
14. A diesel locomotive develops an unusually
high operating temperature while the engine is under a normal load. The coolant
level is correct, but inspection shows that the cooling fan is not operating at
its expected speed. Which area should receive PRIORITY investigation?
A. The
locomotive's passenger communication system B. The traction gearbox lubricant
specification C. The fan drive, control circuit, and associated components D.
The insulation resistance of an unrelated lighting circuit
Answer: C
Rationale: If engine temperature is rising under
normal load while the cooling fan is operating below its expected speed, the
fan system becomes a primary diagnostic area. Depending on the locomotive
design, the technician should investigate the fan motor or drive mechanism,
electrical supply and control, mechanical transmission, and associated
protection or control components. Correct coolant level does not eliminate a
cooling-system fault because inadequate airflow can still cause overheating.
Unrelated lighting or communication circuits would not be the logical starting
point.
15. After replacing a locomotive electrical
component, which action provides the MOST reliable confirmation that the
maintenance work has been completed correctly?
A. Visually
closing the equipment compartment without testing B. Confirming only that the
replacement component is physically present C. Returning the locomotive to
service immediately after installation D. Performing the prescribed
inspection, testing, and functional verification
Answer: D
Rationale: Correct maintenance does not end when a
replacement component is physically installed. The technician must verify that
connections are correct, fasteners and terminals are secure, protective
measures are restored, and the equipment performs according to the applicable
maintenance procedure. Functional testing is particularly important because an
incorrectly connected component can appear physically satisfactory while
causing a further fault. The prescribed inspection and testing sequence
provides objective evidence that the work has restored the intended function
before the equipment is returned to service.
16. A locomotive repeatedly reports an
overheating alarm, but visual inspection shows no obvious damage. The
technician immediately replaces the temperature sensor, yet the alarm returns.
What is the MOST appropriate next approach?
A. Continue
replacing sensors until the alarm disappears B. Diagnose the complete alarm
circuit and verify the actual temperature condition C. Disable the alarm
because the locomotive remains operational D. Replace the traction motor
without checking the alarm circuit
Answer: B
Rationale: Replacing a component without
establishing whether it is actually responsible for the fault can lead to
repeated unsuccessful repairs. When an overheating alarm returns after sensor
replacement, the technician should verify the actual equipment temperature and
systematically inspect the sensor circuit, wiring, connectors, signal path,
control system, and possible genuine overheating sources. The alarm itself may
be caused by a real thermal condition or by an erroneous signal. Disabling the
protection or replacing unrelated major equipment would not constitute sound
fault diagnosis.
17. During inspection of a locomotive wiring
harness, a technician finds that a cable is supported by a damaged clamp and is
hanging close to a moving mechanical linkage. Which risk should receive the
greatest attention?
A. The cable may
suffer mechanical damage or become caught in the moving linkage B. The cable
will necessarily develop higher insulation resistance C. The battery will
automatically receive excessive charging current D. The refrigeration system
will experience reduced condenser pressure
Answer: A
Rationale: A damaged cable support near moving
mechanical equipment creates a direct risk of abrasion, stretching, crushing,
or entanglement. Continued vibration and movement can progressively damage the
insulation or conductor and may eventually produce an electrical fault. The
technician should restore the cable support and required clearance according to
the maintenance procedure before returning the equipment to service. This is
primarily an installation and mechanical-protection issue rather than a
refrigeration or battery problem.
18. A technician is asked to determine
whether a suspected cable fault is an open circuit or a short circuit. Which
approach provides the MOST useful initial distinction?
A. Inspect the
cable colour without performing an electrical test B. Check continuity through
the intended conductor and test for unintended conductive paths C. Measure
only the temperature of the nearest motor bearing D. Check the refrigeration
compressor before examining the cable
Answer: B
Rationale: An open circuit means the intended
electrical path is interrupted, whereas a short circuit involves an unintended
low-resistance path between conductors or between a conductor and another
reference such as earth. Continuity testing helps establish whether the
intended path exists, while appropriate resistance or insulation testing can
identify unintended conductive paths. The exact procedure must follow the
equipment's maintenance and safety requirements. Cable colour and unrelated
mechanical or refrigeration measurements cannot establish the electrical fault
type reliably.
19. During maintenance of a rotating machine,
a technician notices that the bearing is producing abnormal noise and has
become hotter than its normal operating condition. Which action is MOST
appropriate?
A. Ignore the
condition because the machine is still rotating B. Increase electrical supply
voltage to compensate for the bearing condition C. Investigate bearing
lubrication, wear, alignment, and mechanical loading D. Replace the machine's
electrical protection device without testing
Answer: C
Rationale: Abnormal bearing noise accompanied by
elevated temperature is a significant indication of possible inadequate
lubrication, bearing wear, misalignment, excessive loading, contamination, or
another mechanical problem. Continuing operation without investigating the
cause may allow the condition to progress to bearing failure or damage to
associated components. The technician should follow the maintenance procedure
to inspect lubrication, bearing condition, alignment, and loading and determine
whether repair or replacement is required. Increasing voltage or changing
unrelated protection devices would not address the observed mechanical
symptoms.
20. A locomotive control circuit repeatedly
blows its protective fuse shortly after a particular component is energized.
The replacement fuse is of the correct rating. Which diagnostic approach is
MOST appropriate?
A. Fit a larger
fuse to prevent further fuse operation B. Investigate the component and
circuit for excessive current or a short circuit C. Remove the fuse
permanently while monitoring the component D. Replace all locomotive cables
without isolating the affected circuit
Answer: B
Rationale: A correctly rated protective fuse opening
repeatedly indicates that the circuit is experiencing a condition that causes
current to exceed the fuse's permissible level, such as a short circuit, faulty
component, damaged insulation, or another abnormal load. The fuse is performing
its protective function and should not simply be replaced with a larger rating
or bypassed. The technician should isolate the circuit and systematically
determine where the excessive current originates. Replacing all cables without diagnosis
is unnecessarily broad and may not correct the actual fault.
21. During inspection of a locomotive
air-conditioning system, the compressor cycles on and off at unusually short
intervals even though the cabin temperature has not reached the normal set
point. Which area should be investigated as part of the initial diagnosis?
A. The thermostat
or temperature-sensing and control circuit B. The traction gearbox bearing
clearance C. The diesel fuel injector nozzle specification D. The locomotive
pantograph contact pressure
Answer: A
Rationale: Repeated short compressor cycling without
the conditioned space reaching its required temperature can indicate an
abnormal control or sensing condition, including an incorrectly responding
thermostat or temperature sensor. Refrigeration-system pressures, airflow, and
other operating parameters should also be checked according to the applicable
procedure before concluding that the compressor itself is defective. The other
alternatives concern unrelated locomotive systems and would not be an
appropriate initial diagnostic focus for the reported symptom.
22. A supervisor asks a technician to record
the results of routine locomotive maintenance. Which information is MOST
valuable for future fault diagnosis and maintenance planning?
A. Only the
technician's name and date of attendance B. Only the total number of
locomotive components inspected C. Inspection findings, measurements, work
performed, and abnormal conditions D. Only the amount of time spent inside the
maintenance workshop
Answer: C
Rationale: Useful maintenance records should provide
sufficient technical information to establish what was inspected, what was
measured, what work was performed, and what abnormal conditions were
identified. Such records create a history that can help technicians recognize
recurring faults, assess component condition, plan future maintenance, and
communicate accurately with supervisors. Merely recording attendance, component
counts, or time spent in the workshop provides limited technical value.
Accurate records are therefore part of effective maintenance rather than an
administrative activity separate from engineering work.
23. During preventive maintenance, a
technician discovers that a flexible electrical cable has insulation that is
cracked at several locations, although continuity through the conductor remains
satisfactory. What is the MOST appropriate assessment?
A. The cable may
require replacement because insulation integrity has been compromised B. The
cable is fully serviceable because continuity is satisfactory C. The cracks
will necessarily reduce mechanical load on the conductor D. The cable should
be retained until the conductor becomes electrically open
Answer: A
Rationale: Satisfactory conductor continuity does
not establish that the cable is safe or suitable for continued service when its
insulation is visibly cracked. Damaged insulation can permit leakage, contact
with earth or adjacent conductors, moisture ingress, and eventual electrical
failure. The technician should assess the damage against the applicable
maintenance criteria and replace or repair the cable using the prescribed
method rather than waiting for the conductor itself to become open.
24. A locomotive develops reduced traction
immediately after maintenance on a high-current electrical connection. The
technician confirms that the correct component was installed, but a voltage
measurement across the connection is higher than expected while the system is
carrying load. What does this finding MOST strongly suggest?
A. The
refrigeration system must necessarily be operating above capacity B. The
traction motor must necessarily have excessive insulation resistance C. The
locomotive battery must necessarily be fully discharged D. The connection may
have excessive resistance under load
Answer: D
Rationale: A measurable voltage drop across a
connection while current is flowing can indicate excessive resistance at that
connection. In a healthy high-current connection, the voltage drop should
normally remain within the specified limit. Excessive resistance may result
from loose terminals, contamination, corrosion, damaged conductors, or an
improper connection. Because electrical power is lost as heat when current
passes through resistance, the condition can also produce localized heating and
progressive deterioration. This makes voltage-drop testing a valuable
diagnostic method for loaded connections.
25. A locomotive has normal control-system
indications, but traction is unavailable only when the direction selector is
moved to one particular direction. The opposite direction operates normally.
Which diagnostic approach is MOST appropriate?
A. Inspect the
direction-selection circuit and its associated interlocks, wiring, and
switching devices B. Replace all traction motors because the locomotive has no
traction in one direction C. Recharge the air-conditioning system because
direction selection depends on cooling performance D. Replace the diesel fuel
filter before testing the direction-control circuit
Answer: A
Rationale: The fact that traction operates normally
in one direction but not the other provides an important comparison for fault
isolation. The technician should focus on components and circuits that are
specific to the affected direction, such as the direction selector, associated
interlocks, control wiring, relays or contactors, and relevant protection
devices. Comparing the functioning and non-functioning paths can help identify
the point where the expected control signal or switching action is lost.
Replacing major traction equipment without evidence would not be justified by
this symptom alone.
26. A traction motor operates normally when
cold, but after prolonged service its current rises while locomotive tractive
effort falls. Inspection shows that the motor cooling passages are partially
obstructed. Which explanation BEST connects the observations?
A. Restricted
cooling can raise winding temperature and alter motor performance B.
Restricted cooling necessarily increases gearbox lubrication efficiency C.
Restricted cooling directly increases the battery's available capacity D.
Restricted cooling necessarily reduces the mechanical load on the motor
Answer: A
Rationale: Obstructed cooling passages reduce the
ability of the traction motor to dissipate heat. As winding temperature rises,
electrical resistance can increase and the motor may operate outside its
intended thermal and performance conditions, potentially resulting in increased
current, reduced efficiency, protective intervention, or reduced tractive
output. The technician should restore the required cooling path and then verify
motor current, temperature, and performance. The other alternatives do not
provide a technically consistent relationship between restricted motor cooling
and the observed loss of traction.
27. During inspection of an electric
locomotive traction motor, a technician finds that the motor produces excessive
sparking at the commutator during operation. Which condition should receive
PARTICULAR attention?
A. Brush
condition, brush seating, and commutator surface B. Refrigerant charge and
condenser operating pressure C. Gearbox lubricant level and external housing
temperature D. Battery electrolyte level and charging-circuit fuse rating
Answer: A
Rationale: Excessive sparking at a commutator-type
traction motor can be associated with poor brush seating, worn or damaged
brushes, an irregular or contaminated commutator surface, incorrect brush
pressure, or other motor conditions affecting commutation. The technician
should inspect the brush gear and commutator according to the applicable
maintenance procedure and determine whether adjustment, cleaning, servicing, or
replacement is required. Refrigeration, gearbox lubrication, and battery
conditions do not directly explain excessive commutator sparking.
28. A diesel-electric locomotive has normal
engine speed, but the electrical output available for traction is substantially
below the expected level. Which area should be examined before assuming that
the diesel engine itself has lost mechanical power?
A. Cab lighting
switches and interior fittings B. Passenger communication equipment and
speakers C. Generator/alternator output and its associated electrical
connections D. Air-conditioning thermostat setting and evaporator filter
Answer: C
Rationale: In a diesel-electric locomotive, the
diesel engine provides mechanical input to the electrical generating equipment,
which then supplies electrical power for traction and other systems. If engine
speed and basic engine operation are normal but available traction electrical
output is low, the generator or alternator and its associated connections,
excitation, control, and protection systems become important diagnostic areas.
This does not prove that the generator is faulty, but it provides a logical
diagnostic path before condemning the diesel engine.
29. A technician finds that a motor coupling
has excessive play and the connected shaft shows signs of uneven wear. Which
additional condition is MOST likely to develop if the problem is left
unattended?
A. Improved
electrical insulation of the motor winding B. Reduced refrigerant pressure in
an unrelated system C. Increased battery charging efficiency D. Additional
vibration and accelerated mechanical wear
Answer: D
Rationale: Excessive coupling play can permit
abnormal movement between connected shafts and may contribute to misalignment,
vibration, impact loading, and uneven transmission of torque. Continued
operation can accelerate wear of couplings, bearings, shafts, and other
connected components. The technician should therefore inspect the coupling,
shaft alignment, mounting, and related components according to the applicable
maintenance procedure. Electrical insulation, refrigeration pressure, and
battery charging efficiency do not directly follow from excessive mechanical
coupling play.
30. During inspection of a locomotive battery
charging system, the battery voltage is consistently below the specified
charging range while the engine and charging equipment are operating. Which
investigation is MOST appropriate?
A. Inspect the
charging circuit, connections, and charging-unit output B. Replace the
traction gearbox lubricant before electrical testing C. Increase the battery
fuse rating to raise charging voltage D. Disconnect the battery from the
charging circuit during operation
Answer: A
Rationale: A low charging voltage during normal
operation can result from inadequate charger or alternator output, poor
electrical connections, wiring resistance, control faults, or a defective
charging component. The technician should measure the charging-unit output and
progressively check the circuit toward the battery, following the prescribed
testing procedure. Increasing a protective fuse rating does not increase
charging voltage and may compromise protection. Disconnecting the battery while
the charging system is operating may also create an unsafe or damaging
condition depending on the equipment design.
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