Caterpillar Diesel Electric Set (Earlier Type)

Remote Start And Stop Control System Operation

COMPONENT LOCATION

1. Water temperature gauge W

2. Oil pressure gauge O

3. Governor Control

4. Hourmeter H

5. Water temperature switch WT

6. Alternator

7. Starting motor SM

8. Cranking solenoid CR

9. Start slave relay SS

10. Frequency sensing relay FS

11. Circuit breaker CB

12. Alternator regulator

COMPONENT LOCATION

13. Water temperature sender WTS

14. Fuel solenoid F

15. Oil pressure switch OP

16. Ammeter A

17. Safety light

18. Remote, Off, Run switch

19. Oil pressure sender OPS

20. Oil pressure switch OP2

21. External connections EC

The following generator mounted control panel components are illustrated in the topic ELECTRICAL COMPONENTS

The following illustrations are intended as diagrammatic representations for the operation of the 12 volt starting, charging and stopping system. They are NOT intended to be used as complete wiring diagrams.

NORMAL "OFF" CONDITIONS
Remote, Off, Run switch is in "OFF" position so no circuits are energized.

Cranking

SWITCH IN "RUN" POSITION

1. The fuel solenoid (F) is energized which turns on fuel to fuel pump.

2. Start slave relay (SS) is energized which closes the (SS) contacts and energizes cranking solenoid (CR) (cranking motor solenoid). The (CR) pulls the starter pinion into engagement with the flywheel ring gear and cranks the engine NOTE: In the event of a "butt engagement," circuit breaker (CB) opens to de-energize the cranking circuit because of the high pull-in current draw of the solenoid. The circuit breaker is self-resetting and closes again in about about 5 seconds. This allows the starter pinion to move to a new position and clears the butt engagement.

3. The oil pressure gauge (0) and water temperature gauge (W) are energized through their sender units as temperature or pressure increase.

4. Cranking the engine causes the oil pressure to close oil pressure switch (OP2) and energizes the hour meter (H) and also energizes the charging alternator field circuit.

5. Cranking time limiter (CRT) is energized. This is a time delay relay with the (CRT) contacts closing about 30 seconds after energizing to limit the cranking of the engine if start fails.

Engine Running

ENGINE RUNNING

1. When the engine starts, the frequency sensing relay (FS) operates at an engine speed of about 450 rpm. The (FS) contacts open and de-energize the cranking circuit by de-energizing (SS) and (CRT).

2. As oil pressure rises to 30 psi (2,1 kg/cm²), the oil pressure switch (OP) has one contact which closes and another which opens. When the normally open contacts close, arming relay (AR) is energized which places (AR) contacts in parallel with the closed oil pressure switch.

The set should now be running normally with (AR) energized, (F) energized, gauges energized, hour meter (H) energized and charging alternator functioning.

Automatic Stopping

LOW OIL PRESSURE

1. Automatic stopping in these examples are for protection of the engine in case of high water temperature or low oil pressure. The action or these two conditions is on the safety relay (SR) discussed in Step 2 below.

a. In the event of low oil pressure (OP), contacts will change position (one set of contacts closing and the other set opening). Safety relay (SR) will be energized through the (AR) contacts, then energizing the (OP) contacts the locking relay (LR) and the safety indicator light.

CONTROL PANEL EXTERNAL VIEW

1. Water temperature gauge W

2. Oil pressure gauge O

3. Ammeter A

4. Safety Light.

5. Remote, Off, Run switch.

b. In the event of high water temperature, relays (SR), (LR) and the safety indicator light are energized.

2. Energizing (SR) opens the fuel valve circuit thus closing the fuel solenoid (F) and shuts down the engine. Relay (SR) also has a set of contacts which lock-in (SR) so if the engine cools and (WT) opens, the engine will not restart. Relay (LR) serves to lock-in the remote starting circuit if it is being used so that the safety circuit will remain energized, even if the remote control switch is opened. To reset the safety circuit, the Remote, Off, Run control switch must be turned to "OFF" position.

HIGH WATER TEMPERATURE

INTERNAL VIEW OF THE CONTROL PANEL

6. Cranking time limiter CRT

7. Locking relay LR

8. Arming relay AR

9. Safety relay SR

Electrical System

Starting And Charging Components

Starting and charging components are covered in the BASIC ENGINE SECTION of this manual. Some of the components are covered in two places, as an attachment and as standard engine components, because of their close relationship with the electrical control components which are attachments.

Solenoid

A solenoid is a magnetic switch that utilizes low current to close a high current circuit. The solenoid has an electromagnet with a movable core. There are contacts on the end of the core. The contacts are held open by a spring that pushes the core away from the magnetic center of the coil. Low current will energize the coil and form a magnetic field. The magnetic field draws the core to the center of the coil and the contacts close.

SOLENOID SCHEMATIC

Electrical Control Components

Fuel Solenoid

FUEL TRANSFER PUMP AND SOLENOID
1. Fuel transfer pump. 2. Fuel solenoid.

Energizing the fuel solenoid, which is located in the vee of the engine, turns on the fuel to the fuel injection pumps. The fuel solenoid shuts off the fuel and stops the engine when it is de-energized.

Start Slave Relay (Earlier Electric Sets)

When the start slave relay is energized the cranking solenoid (starter solenoid) is energized and engine cranking begins. The frequency sensing relay de-energizes the cranking circuit to stop cranking when the engine starts.

RELAYS
1. Start slave relay. 2. Frequency sensing relay.

Circuit Breaker (Earlier Electric Sets)

The circuit breaker is in the cranking circuit. It opens in event of a starter pinion "butt engagement" because of the high pull in current draw of the starter solenoid. The circuit breaker is self-resetting and closes in about 5 seconds.

CIRCUIT BREAKER AND STARTER SOLENOID
1. Circuit breaker. 2. Starter solenoid.

Oil Pressure Sender

The sender energizes the oil pressure gauge as soon as the Remote, Off, Run switch is in "RUN" position.

OIL PRESSURE SENDER
1. Oil pressure sender. 2. Oil pressure switch (OP2).

Frequency Sensing Relay

The frequency sensing relay is energized by the alternator output. The points open to stop engine cranking.

FREQUENCY SENSING RELAY

Water Temperature Switch

A water temperature switch is located in the front cover. The unit is nonadjustable. Thermal expansion of the element operates a micro-switch that signals the arming relay (AR) and safety relay (SR) and they in turn act upon the fuel solenoid circuit and close the fuel valve which causes engine shutdown. If overheating occurs due to low coolant level or no coolant, the unit will not function. The water temperature element must be in contact with the coolant.

WATER TEMPERATURE SWITCH

The water temperature switch can also be wired into an alarm or light to signal high water temperature. After an overheated engine is allowed to cool, the contactor automatically resets itself.

Oil Pressure Switches

The oil pressure switch (OP2) is in the battery charging circuit to close the circuit between the alternator regulator and battery when oil pressure rises after the engine has started. This switch is located on the left side of the engine near the oil filters. The switch opens to prevent battery current flow from battery to alternator and hourmeter when the engine is stopped.

OIL PRESSURE SWITCH (OP2)
1. Oil pressure sender. 2. Oil pressure switch (OP2).

The oil pressure switch (OP) on the top of the engine has three connectors, common "C", normally open "NO" and normally closed "NC." One set of points open, the other closes as normal operating oil pressure is reached. The opening points prevent activation of the safety relay (SR) and locking relay (LR). The closing points activate the arming relay (AR).

Pressure switches are for other uses such as; alarm system switches, disconnect device to prevent motoring, and alarm lights.

OIL PRESSURE SWITCH (OP)
3. Oil pressure switch (OP). 4. Hourmeter.

Safety Instrument Panel

SAFETY INSTRUMENT PANEL
1. Oil pressure gauge. 2. Ammeter. 3. Water temperature gauge. 4. Reset button. 5. Magnetic control switch. 6. Fuse.

The safety instrument panel has a magnetic control switch (5) in the panel. Pushing in and holding the reset button (4) while cranking the engine, allows the engine to start. When the oil pressure is above 15 psi (1,0 kg/cm²) the engine will continue to run after the button is released.

WATER TEMPERATURE SWITCH

The normally open water temperature switch closes when the coolant temperature exceeds the setting of the switch. The engine mounted oil pressure switch closes when low oil pressure drops below the setting of the switch. In either event, the magnetic control switch is tripped and opens the circuit between the fuel solenoid valve and battery. Thus, closing of the fuel valve stops the engine. A 14 ampere fuse located at (6), protects the switch from overload.

OIL PRESSURE SWITCH

Wiring Diagrams

Only the 12 volt control system information is covered in these diagrams. The engine mounted components are covered in one diagram and the generator mounted control panel components are covered in the second diagram.

TACHOMETER WIRING DIAGRAM
1. Socket. 2. Plug. 3. Connect to key switch "ON" terminal. 4. Tachometer. 5. Tachometer sending unit.

REMOTE MOUNTED INSTRUMENT PANEL
1. Ammeter. 2. Lead to key switch "ON" terminal. 3. Oil pressure gauge. 4. Water temperature gauge. 5. Ammeter shunt. Resistance of shunt to ammeter lead to be .10 ohms. 6. Oil pressure sender. 7. Water temperature sender. 8. Terminal strip. 9. Lead connected to solenoid terminal (battery positive). 10. Lead connected to alternator output terminal.

ENGINE MOUNTED 12 VOLT COMPONENT WIRING DIAGRAM (Earlier Electric Set)

GENERATOR MOUNTED CONTROL CABINET 12 VOLT COMPONENT WIRING DIAGRAM (Earlier Electric Set)

12 VOLT STARTING AND CHARGING SYSTEM WITH ELECTRICAL SAFETY INSTRUMENT PANEL
1. Off, Start Switch. 2. Control panel magnetic switch. 3. Water temperature sending unit. 4. Oil pressure sending unit. 5. Starter solenoid. 6. Starting motor (12V). 7. Hourmeter. 8. Water temperature gauge. 9. Oil pressure gauge. 10. Battery (12V). 11. Ammeter. 12. Fuel solenoid. 13. Alternator regulator. 14. Water temperature shutoff switch (normally open). 15. Oil pressure shutoff switch (normally closed). 16. Alternator stator terminal. 17. Alternator field terminals. 18. Alternator output terminal. 19. Alternator negative (ground) terminal.

12 VOLT STARTING AND CHARGING SYSTEM
1. Off, Start Switch. 2. Ammeter. 3. Fuel solenoid. 4. Starter solenoid. 5. Alternator regulator. 6. Starting motor (12V). 7. Pressure switch (normally open). 8. Alternator field terminals. 9. Battery (12V). 10. Hourmeter. 11. Alternator stator terminal. 12. Alternator output terminal. 13. Alternator negative (ground) terminal.

HIGH WATER TEMPERATURE AND LOW OIL PRESSURE ALARM SYSTEM
1. Water temperature contactor. 2. Oil pressure switch (normally closed). 3. Battery. 4. Toggle switch. 5. Signal light. 6. Horn.