Assembly and Calibration Procedures for Rack Position Sensors{1911, 1911} Caterpillar

Engine:

3606 (S/N: 8RB1-UP)

3608 (S/N: 6MC1-UP)

3612 (S/N: 9FR1-UP; 9RC1-UP)

3616 (S/N: 1FN1-UP; 1PD1-UP)

Introduction

The rack position sensor works with the fuel injection control in order to interpret the position of the fuel rack. The rack position sensor produces a signal that represents the engine load. The signal can be used for different purposes. The signal may activate an indicator in order to display the percent of engine load to the operator. The signal can be routed to a controller in order to limit the load.

The signal of the rack position sensor is delivered via a remote mounted amplifier. The wiring of the amplifier determines the type of signal that is produced. The amplifier can be wired in order to provide a signal of voltage or a signal of milliamperes.

This Special Instruction describes assembly of the 4P-6989 Position Sensor and the 127-1020 Position Sensor . Instructions for wiring of the 132-7523 Rotary Amplifier are provided. The procedure for calibration of the amplifier and the rack position sensor is also included.

Do not perform any procedure in this Special Instruction until you read this information and you understand this information.

Assembly Procedure

Your governor actuator may be different from the illustrations. However, this procedure is suitable for use with any governor actuator that is supplied by Caterpillar.

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Illustration 1	g00743716
Typical example for in-line engines (1) Lever for the fuel injection control (2) Fuel control rod

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Illustration 2	g00755991
Typical example for vee engines (1) Lever for the fuel injection control (2) Fuel control rod

1. Install lever (1) onto the fuel injection control. Adjust fuel control rod (2) according to the Service Manual for the particular equipment.

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Illustration 3	g00756327
Typical example for in-line engines The fuel control rod is not shown. (3) Lever for the rack position sensor (4) Bolt (5) Shaft of the rack position sensor

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Illustration 4	g00756002
Typical example for vee engines (3) Lever for the rack position sensor (4) Bolt (5) Shaft of the rack position sensor

2. Install lever (3) and bolt (4) loosely onto shaft (5) of the rack position sensor. Do not tighten the bolt yet.

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Illustration 5	g00756028
(D) Distance between the centers of the rod ends (6) Rod assembly for the rack position sensor

3. Adjust the length of rod assembly (6) for the rack position sensor.

   For in-line engines, ensure that distance (D) between the centers of the rod ends is 137 mm (5.39 inch).

   For vee engines, ensure that distance (D) between the centers of the rod ends is 92 mm (3.62 inch).

   Tighten the locknuts on the rod assembly.

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Illustration 6	g00756048
Typical information plate

4. Determine the engine's full load static fuel setting.

   The setting is stamped on the engine's information plate. The information plate is on the side of the cylinder block above one of the crankshaft inspection covers.

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Illustration 7	g00756332
Typical example for in-line engines The fuel control rod is not shown. (1) Lever of the fuel injection control (3) Lever of the rack position sensor (6) Rod assembly

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Illustration 8	g00743918
Typical example for vee engines (1) Lever of the fuel injection control (3) Lever of the rack position sensor (6) Rod assembly

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Illustration 9	g00745147
Holes in lever (3) of the rack position sensor

5. Install rod assembly (6) onto lever (1) of the fuel injection control and lever (3) of the rack position sensor. Make sure that you install the rod assembly into the correct hole of lever (3) . The correct installation depends on the full load static fuel setting. Refer to Table 1.
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   Table 1

   Installation of the Rod Assembly
   Full Load Static Fuel Setting	Hole in the Lever for the Rack Position Sensor
   In-Line Engines
   Greater than 8.2 mm (0.32 inch)	(A)
   (4.71 to 8.2 mm)(0.185 to 0.32 inch)	(B)
   Less than 4.71 mm (0.185 inch)	(C)
   Vee Engines
   Greater than 6.7 mm (0.26 inch)	(A)
   (2.98 to 6.7 mm)(0.117 to 0.26 inch)	(B)
   Less than 2.98 mm (0.117 inch)	(C)

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Illustration 10	g00756336
Typical example for in-line engines The fuel control rod is not shown. (1) Lever of the fuel injection control (4) Bolt (5) Shaft

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Illustration 11	g00756085
Typical example for vee engines (1) Lever of the fuel injection control (4) Bolt (5) Shaft

6. Hold lever (1) at the minimum rack position. Rotate shaft (5) to the fully counterclockwise position and tighten bolt (4) .

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Illustration 12	g00756341
Typical example for in-line engines (2) Fuel control rod

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Illustration 13	g00756354
Typical example for vee engines (2) Fuel control rod

7. Move fuel control rod (2) through full travel in order to ensure that the fuel control linkage does not bind and that the rack position sensor does not limit the travel of the linkage.

Note: The amplifier is mounted remotely. The amplifier is mounted to the plate assembly in the marine control group.

8. Connect the amplifier to the rack position sensor according to the instructions in ""Wiring for the Amplifier" ".

9. Calibrate the amplifier according to the instructions in ""Calibration of the Amplifier" ".

Wiring for the Amplifier

The wiring is provided by the customer. The amplifier can be wired in order to provide a signal output of voltage or milliamperes.

If output of voltage is desired, refer to ""Wiring for Output of Voltage" ". The amplifier is manufactured in order to produce a voltage signal of 1 to 10 VDC. The output of voltage can be reduced to 1 to 5 VDC.

If output of milliamperes is desired, refer to ""Wiring for Output of Milliamperes" ". The output signal is 4 to 20 mA.

Rotation of the Rack Position Sensor's Shaft

For most installations, clockwise rotation of the rack position sensor's shaft increases the output signal from the amplifier. The amplifier can be adjusted in order to accommodate counterclockwise rotation of the sensor's shaft.

Illustration 14	g00745179
Top view of the amplifier without the cover (J1) Jumper wire

The amplifier is manufactured with a jumper wire that is soldered to terminals (B) and (C) (solid line). With this wiring, clockwise rotation of the rack position sensor's shaft increases the output signal.

If an increase of the signal for counterclockwise rotation of the shaft is desired, remove the wire from terminal (B) and terminal (C). Then solder a wire with a minimum size of 18 AWG to terminal (A) and to terminal (B) .

Wiring for Output of Voltage

Illustration 15	g00745168
Wiring diagram for voltage output

Use the following guidelines for the wiring of the amplifier:

Illustration 16	g00745200
Top view of the amplifier without the cover Terminal strip and compression fittings

• Insert the wires through the holes in the compression fittings. Secure each wire to the proper terminal. Then tighten the nuts on the compression fittings in order to form a seal around the cables.

• The nominal supply voltage for the amplifier is 12 VDC or 24 VDC. The range of operational voltage for the amplifier is 10 to 35 VDC.

• For wiring of the power supply, use a 2-wire cable with a minimum wire size of 18 AWG. The wiring for the power supply does not require shielding. Attach the wire for the positive supply voltage to terminal 10 of the amplifier. Attach the wire for the negative supply voltage to terminal 9 of the amplifier.

• For wiring of the output signal, use a shielded 2-wire cable with a minimum wire size of 18 AWG. The cable must be shielded. The shield is grounded only to the amplifier. Attach the shield and the wire for the return signal to terminal 8 of the amplifier. Attach the wire for the output signal to terminal 7 of the amplifier.

• For wiring to the rack position sensor, use shielded 3-wire cable with a minimum wire size of 16 AWG. The cable must be shielded. Use a cable with an outside diameter of 4.95 to 10.72 mm (0.195 to 0.422 inch). Use a properly sized grommet for the end of the cable at the connector for the rack position sensor. Solder a socket onto the end of each wire for insertion into the connector for the rack position sensor.

Illustration 17	g00756184
Connector for the rack position sensor

• For wiring to the rack position sensor, attach the shield to terminal 4 of the amplifier. The shield is grounded only to the amplifier. Attach one of the wires to terminal 1 of the amplifier and insert the socket for the wire into terminal "A" of the connector. Attach one of the wires to terminal 2 of the amplifier and insert the socket for the wire into terminal "C" of the connector. Attach the third wire to terminal 3 of the amplifier and insert the socket for the wire into terminal "B" of the connector.

• Tighten the connector clamp onto the cable. Connect the connector to the rack position sensor.

• Tighten the compression fittings onto the cables at the amplifier.

After the wiring is installed, calibrate the amplifier. Refer to ""Calibration of the Amplifier" ".

Limiting the Output of Voltage

Illustration 18	g00756117
Top view R41 resistor

The R41 resistor is soldered into the amplifier at the factory. The resistor allows a maximum default voltage output of approximately 10 VDC. This is achieved at the maximum rotation of the rack position sensor's shaft. The maximum output of the amplifier can be reduced to approximately 5 VDC.

To reduce the voltage output from approximately 10 VDC to approximately 5 VDC, remove the R41 resistor.

Wiring for Output of Milliamperes

Illustration 19	g00745175

Use the following guidelines for the wiring of the amplifier:

Illustration 20	g00745200
Top view of the amplifier without the cover Terminal strip and compression fittings

• Insert the wires through the holes in the compression fittings. Secure each wire to the proper terminal. Then tighten the nuts on the compression fittings in order to form a seal around the cables.

• The nominal supply voltage for the amplifier is 12 VDC or 24 VDC. The range of operational voltage for the amplifier is 10 to 35 VDC.

• For wiring of the power supply, use a 2-wire cable with a minimum wire size of 18 AWG. The wiring for the power supply does not require shielding. Attach the wire for the positive supply voltage to terminal 10 of the amplifier. Attach the wire for the negative supply voltage to terminal 9 of the amplifier.

• For wiring of the output signal, use a shielded 2-wire cable with a minimum wire size of 18 AWG. The cable must be shielded. The shield is grounded only to the amplifier. Attach the shield and the wire for the return signal to terminal 8 of the amplifier. Attach the wire for the output signal to terminal 5 of the amplifier.

• For wiring to the rack position sensor, use shielded 3-wire cable with a wire size of 16 AWG. The cable must be shielded. Use a cable with an outside diameter of 4.95 to 10.72 mm (0.195 to 0.422 inch). Use a properly sized grommet for the end of the cable at the connector for the rack position sensor. Solder a socket onto the end of each wire for insertion into the connector for the rack position sensor.

Illustration 21	g00756184
Connector for the rack position sensor

• For wiring to the rack position sensor, attach the shield to terminal 4 of the amplifier. The shield is grounded only to the amplifier. Attach one of the wires to terminal 1 of the amplifier and insert the socket for the wire into terminal "A" of the connector. Attach one of the wires to terminal 2 of the amplifier and insert the socket for the wire into terminal "C" of the connector. Attach the third wire to terminal 3 of the amplifier and insert the socket for the wire into terminal "B" of the connector.

• Tighten the connector clamp onto the cable. Attach the connector to the rack position sensor.

• Tighten the compression fittings onto the cables at the amplifier.

After the wiring is installed, calibrate the amplifier. Refer to ""Calibration of the Amplifier" ".

Calibration of the Amplifier

1. Use a multimeter for reading the strength of the output signal. Set the scale of the multimeter according to the type of signal that is desired:

   1. For output in voltage, use the scale for the voltmeter (DC). Attach the leads of the multimeter to terminal 8 and terminal 7 of the amplifier. Refer to Illustration 15.

   2. For output in milliamperes, use the scale for milliamperes (DC). Attach the leads of the multimeter to terminal 8 and terminal 5 of the amplifier. Refer to Illustration 19.

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Illustration 22	g00756218
Location of the green LED

2. Switch the power to the amplifier ON.

   When power is supplied to the amplifier, the green LED will illuminate.

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Illustration 23	g00756293
Typical example for in-line engines (1) Sensor shaft

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Illustration 24	g00756304
Typical example for vee engines (1) Sensor shaft

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Illustration 25	g00756309
Top view of the amplifier without the cover (2) Location of the yellow LED (P1) Potentiometer for the desired minimum level of output (P2) Potentiometer for the desired maximum level of output

3. Turn sensor shaft (1) clockwise to the maximum travel position. Adjust potentiometer (P2) to the desired maximum level of voltage or current.

   For an output signal in voltage, the maximum level is either 5 VDC or 10 VDC.

   For an output signal in milliamperes, the maximum level of the current is 20 mA.

4. Turn sensor shaft (1) in the counterclockwise direction to the minimum travel position. Adjust potentiometer (P1) to the desired minimum level of voltage or current.

   For an output signal in voltage, the minimum level is 1 VDC. Yellow LED (2) will illuminate when the level of 1 VDC is obtained.

   For an output signal in milliamperes, the minimum level of the current is 4 mA. Yellow LED (2) will illuminate when the level of 4 mA is obtained.

5. Rotate the sensor shaft to the maximum and minimum travel positions in order to recheck the levels of the output. If necessary, repeat Steps 3 and 4.

The calibration is correct when clockwise rotation of the sensor shaft increases the output signal to the desired level and counterclockwise rotation of the sensor shaft decreases the output signal to the desired level.

Specifications for the Amplifier