SECTION 6

TROUBLE-SHOOTING

600 General It is often stated that on a steam locomotive it takes 5 minutes to find the trouble and an hour to fix it; while on a diesel locomotive it takes an hour to find the trouble but only 5 minutes to correctit. However true the foregoing statement maybe is of no concern, other than to pont out the fact that a logical approach to finding trouble on a diesel, should it happen, is absolutely necessary. By use of this trouble shooting section it is hoped that the afforementioned "hour to find the trouble" will be considerably reduced.

To obtain the full benefit of this section one must THINK and analyze any difficulty encountered before haphazardly pushing buttons, testing fuses, etc. For example, if the locomotive suddenly loses power, a person should stop and think of those fundamental items necessary for the development of power. With a loss of power, the engine will be doing one of two things: RUNNING or STOPPED. If the engine is stopped, obviously, no power can be developed until a check is made of a few items, locating the trouble, and the engine restarted. If the engine is running, then, Of course, items separate from those that would cause the engine to stop must be checked.

As the lack of the usual functioning of but one item will prevent the normal operation of all or a portion of the locomotive, it is strongly suggested that in the event of trouble an attempt be made to first determine, in general, the type of trouble. After making a general diagnosis based on the way the equipment acts, a check should then be made of those items that are known to cause that type of trouble. If it is not known which items to check, following this diagnosis, they will usually be found listed in Articles 601-605.

TROUBLE SHOOTING CHART FOR SW8 AND SW9 LOCOMOTIVES

In using this table one must be sure that the control, generator field and fuel pump
switches are closed ON), and the isolation switch (if used) in RUN.  The contactors and relays
followed by an "X" are closed, with the throttle and reverse levers in the positions shown.

  Throttle Lever                       Above Or At IDLE        IDLE     Above IDLE       STOP FULL
  Reverse Lever                              Neutral         Forward      Forward      Forward Forward
  Transition Forestalling Switch             Series            Series      Series        Series     Auto

  Reverser Drum (FOR)                                                        x             x          x
  Reverser Drum (REV)
  Shunt Field Contactor (SH)                                                 x                        x
  Battery Field Contactor (BF)                                               x                        x
  Series Contactor (S)                                          x            x             x
  Parallel Contactor (Pl)                                                                             x
  Parallel Contactor (P2)                                                                             x
  Battery Charging Contactor (BC)              x                 x           x                        x
  Reverse Current Relay (ETCR)                 x                 x           x                        x
  Parallel Relay (PR)                                                                                 x
  Starting Contactors (ST+ ST-)

    Assuming locomotive speed to be above forward transition speed.
                                                  Fig. 6-1

Approximately 90% of the troubles on the road are caused by only 5 items that anyone should be able to correct. For reference these items are listed below:

• 1. Ground Relay
• 2. Starting Contactor Interlocks
• 3. Engine Overspeed Trip
• 4. Lube Oil Button On The Governor
• 5. Emergency Fuel Cutoff Valve

The lack of knowledge as to which contactors, relays, etc. are supposed to be closed at a particular time is probably the greatest obstacle in trouble shooting. Therefore, in order to attempt to clarify this situation the Trouble Shooting Chart shown in Fig. 6-1 is included. A study of this chart will aid in narrowing down the search for the location of trouble.

601 Engine Does Not Rotate When "Engine Start" Button Is Pressed

• 1. Check starting contactors (ST+ and ST-). If the contactors fail to close, the cause may be
  • a. Reverse lever not in the neutral position.
  • b. Control switch not IN at push-button switch box.
  • c. Main battery switch not closed in electrical cabinet.
  • d. Positive fuse (60-ampere) blown in electrical cabinet.
  • e. Control fuse (30-ampere) blown in pushbutton switch box.
  • f. Engine start fuse (15-ampere) blown in pushbutton switch box.
  • g. Defective ENGINE START switch.
• 2. If the starting contactors close, the cause of failure to rotate may be:
  • a. Weak battery - indicated by the cab lights going out when START button is pressed.
  • b. 400-ampere starting fuse blown in electrical cabinet.
  • c. Starting contactors failing to make contact.

602 Engine Rotates But Does Not Fire

• 1. Check to see that the throttle is in IDLE.
• 2. Check to see that overspeed trip lever is in RUN position.
• 3. Check proper fuel supply. Fuel pump fuse (10-ampere) in control switch box may be blown. Check emergency fuel cutoff valve.
• 4. Layshaft may be stuck in shutdown position.
• 5. Check oil level in governor.

603 Locomotive Does Not Move When Throttle Is Opened

• 1. If the engine does not speed up when the throttle is opened, the cause may be:
  • a. No control air pressure.
  • b. Defective governor.
• 2. If the engine.speeds up but locomotive does not move, when the throttle is opened, the cause may be:
  • a. Reverse lever in neutral position.
  • b. Generator field switch not IN, or its 15 ampere fuse blown in push-button switch box.
  • c. Control switch not IN, or its 30-ampere fuse blown in push-button switch box.
  • d. Starting contactor interlocks not making good contact. e. Control air pressure low.
  • f. Battery field fuse (70-ampere) blown in electrical cabinet.
  • g. Reverser interlocks not making good contact.
  • h. Ground relay tripped (close throttle to idle before resetting).
  • i. Hand or air brake applied.
  • j. Throttle switch not making good contact.

604 Engine Stops If the engine stops after previously being in operation, the cause may be:

• 1. Throttle may have been placed in the STOP position.
• 2. Low oil pressure button on the governor might have tripped.
• 3. Engine overspeed lever may be tripped.
• 4. Fuel supply may have stopped because of:
  • a. Fuel tank empty.
  • b. Fuel pump fuse blown or switch OUT.
  • c. Emergency fuel cutoff tripped.

605 Battery Ammeter Shows Continual Discharge

• 1. The battery charging (auxiliary generator output) fuse (150-ampere) may be blown.
• 2. The battery charging contactor may not be closing completely.
• 3. The auxiliary generator field fuse (30-ampere) may be blown in electrical cabinet.

606 Ground Relay If the ground relay is tripped the locomotive will not be able to develop power. Therelay is reset by pressing in on the push-button when the engine is at idle speed.

607 Starting Contactors Starting contactors sometimes weld together when an engine is started, especially if the START button is not held in firmly. If one welds, the locomotive will not move even though the engine will speed up. The contacts may be separated by prying the contacts apart with a piece of wood or other non-conductive material. When the contacts are open the interlocks are closed, and vice versa.

608 Engine Overspeed Trip If the engine speed should exceed approximately 910 RPM an overspeed device will TRIP land stop the engine by preventing the injectors from injecting fuel into cylinders. The overspeed trip must be latched in the SET position before engine can be started.

609 Lube Oil Button On The Governor In case of low oil pressure or high suction the governor will shut the engine down. A push-button on the front of the governor will move out an approximate 1/2", exposing a red band on the button. The engine cannot be restarted until the button has been re- set by being pushed back into the governor housing.

610 Emergency Fuel Cutoff Valve If this valve has been tripped, either accidentally or by pulling one of the emergency pull cords the supply of fuel to the engine will be stopped. The valve is located in the fuel suction line just ahead of the right side of the fuel and immediately below the frame of the locomotive. To reset: Reach in and pull valve stem out enough so the yoke will slide into place, thereby holding valve open, Fig. 4-4.

Ground Relay (Set Position) Fig. 6-2	Starting Contactors Fig. 6-3
Overspeed Trip Fig. 6-4	PG Governor Fig.6-5