Installation and Calibration of the 144-0441 Tachometer {7462} Caterpillar

Engine:

3606 (S/N: 8RB1-UP)

3608 (S/N: 6MC1-UP)

3612 (S/N: 9RC1-UP; 2NZ1-UP; 9FR1-UP)

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

Introduction

The tachometer is used to monitor the rpm of the turbocharger shaft, the turbine wheel, and the compressor wheel.

If the turbocharger is rotating too fast, the service life of the bearings will be reduced. Monitoring the rpm of the turbocharger can help prevent damage.

A new turbocharger operates with optimum efficiency. As the turbine and the compressor become fouled and/or worn, the efficiency of the turbocharger changes. A record of the turbocharger's rpm and corresponding factors such as boost pressure can help determine the efficiency of the turbocharger.

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

System Operation

The basic components that are needed for operation of the tachometer are a speed sensor, a frequency transmitter, a power source, and wiring.

Illustration 1	g00779286
Block diagram of the tachometer's system (1) Speed sensor (2) Frequency transmitter (3) Power supply (4) Tachometer

Speed sensor (1) is installed in the adapter of the turbocharger air inlet. The speed sensor monitors the rotation of the turbocharger's compressor wheel. The rotation is sensed as a frequency.

Note: Three different speed sensors are available for use with different types of adapters. Two of the sensors monitor rotation of the compressor wheel's shaft. The third sensor monitors the rotation of the impeller vanes.

The speed sensor sends a signal to frequency transmitter (2). Positive DC voltage is provided to the transmitter by power supply (3) .

The transmitter converts the signal from the speed sensor into output of 4 to 20 mA. The output is sent to tachometer (4). The digital display of the tachometer indicates the rpm of the turbocharger.

Illustration 2	g00782274
Typical display

A label of "RPM X10" is on the front of the tachometer beneath the display. The label indicates that the display represents one-tenth of the actual rpm. Therefore, the displayed value must be multiplied by ten in order to determine the actual rpm. For example, a display of "2500" represents an actual rpm of 25,000.

Required Parts

Installation

Installing the Speed Sensor

Installation of the speed sensor depends on the type of turbocharger and the type of adapter for the inlet air. For the installation instructions, refer to the following procedures for the specific speed sensors.

141-9884 Speed Sensor

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Illustration 3	g00780377
(1) Clamp (2) Adapter (3) 129-8228 Cap (4) Bolt

1. Remove clamps (1) in order to remove the hose from adapter (2) .

Note: Cap (3) is threaded onto the turbocharger shaft. A strong magnet should be inside the cap.

2. Reach into the adapter with a ferrous object and check cap (3) for a magnet. Be sure to remove the ferrous object from the adapter. If the cap does not have a magnet, install a new cap. Screw the new cap onto the turbocharger shaft. After the cap is fully threaded, turn the cap for an additional 10 mm (0.4 inch).

3. Remove three bolts (4) and washers.

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Illustration 4	g00781751

4. Use bolts (4) and washers to install speed sensor (5) outside the flange of insert (6) .

   Note: The speed sensor's connector can be adjusted by turns of 90 degrees in order to obtain a convenient position for the cable.

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Illustration 5	g00780379

5. Adjust the position of speed sensor (5) in order to achieve a clearance of 0.5 mm (0.02 inch) between the sensor and the flange of insert (6) .

6. Install the hose and clamps (1) onto adapter (2). Tighten the clamp bolts to a torque of 10 N·m (7 lb ft).

168-3630 Speed Sensor

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Illustration 6	g00780416
Front view and side view of the elbow at the air inlet for the turbocharger (1) Plug (2) Elbow (AA) See Illustration 7 for the section view.

1. Remove plug (1) from elbow (2) .

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Illustration 7	g00780417
View (AA) (3) Speed sensor (4) Shaft for the compressor wheel (5) Locknut

2. Install speed sensor (3) into the hole for plug (1). Screw in the sensor until the tip of the sensor contacts shaft (4). Then unscrew the sensor for one turn (360 degrees) in order to obtain a clearance of approximately 1 mm (0.04 inch) between the sensor and the shaft. Tighten locknut (5) to a torque of 18 ± 7 N·m (13 ± 5 lb ft).

164-5336 Speed Sensor

Perform the following work according to Special Instruction, REHS0285, "Disassembly And Assembly Of The Napier NA 297 Turbocharger":

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Illustration 8	g00780497
Typical section view of a Napier turbocharger (1) Compressor insert (2) Speed sensor (3) Locknut

1. Remove insert (1) .

2. Install speed sensor (2) .

3. Reassemble the turbocharger.

   When the turbocharger is reassembled, tighten locknut (3) to a torque of 10 N·m (7 lb ft).

Configuring the Transmitter

Before you install the transmitter, configure the range of the transmitter's span for the turbocharger.

The range of the transmitter's span is 12,800 to 25,600 Hz. The range is determined by the position of an internal jumper block. For access to the jumper block, the case must be opened. The case does not have removable fasteners. The plastic case is held together with locking tabs.

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NOTICE
The electronic circuit boards can be damaged by static electricity. Only open the case in an environment that is free of static electricity.

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NOTICE
If the screwdriver is inserted too far into the case, the circuit boards can be damaged. Be careful when you pry the halves of the case. Do not insert the screwdriver for more than approximately 2.5 mm (0.10 inch).

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Illustration 9	g00779695

1. Use a screwdriver with a thin blade to carefully separate the two halves of the case. Press the tip of the blade into the seams that are indicated by the arrows in Illustration 9. Slightly twist the screwdriver and work evenly around the seams until the plastic pins that hold the pieces together can be easily separated.

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Illustration 10	g00780216
Opened transmitter (1) "INPUT" board (2) "OUTPUT" board (3) Connector pins (4) Location of the pins for the jumper block

2. Carefully pull "INPUT" board (1) away from "OUTPUT" board (2). Use caution not to damage connector pins (3) on the "INPUT" board when the pins are removed from the sockets in the "OUTPUT" board.

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Illustration 11	g00779692
Magnified view of location (4) (5) Jumper block

3. Look in location (4) and find jumper block (5). Pull the block straight away from the pins. Move the block to the appropriate pin location according to the model of the turbocharger.

   The pin locations are identified in Illustration 11 with "A" through "J". The different models of turbochargers and the corresponding locations for the jumper block are listed in Table 2.

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   Table 2

   Turbochargers and Corresponding Locations for the Jumper Block
   Turbocharger	Location
   ABB VTC254 (1)	F
   ABB VTC254 (2)	G
   Napier NA297 G (3) (4)	I
   Napier NA297 GS (3) (4)	J

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   ( 1 )	This turbocharger uses the 141-9884 Speed Sensor with an adapter for the inlet air that is straight.
   ( 2 )	This turbocharger uses the 168-3630 Speed Sensor with an adapter for the inlet air that is at 90 degrees or with a silencer.
   ( 3 )	This turbocharger uses the 164-5336 Speed Sensor .
   ( 4 )	The "G" and the "GS" designate the compressor wheel.

4. After the jumper block is installed, reconnect "INPUT" board (1) to "OUTPUT" board (2). Make sure that connector pins (3) on the "INPUT" board fit correctly into the sockets on the "OUTPUT" board. Press the boards together until the connections are fully seated.

5. Install the circuit boards into the side of the case that has the label of the transmitter's model.

6. Reassemble the halves of the transmitter's case. Use care to press the halves of the case firmly together.

Installing the Tachometer and Transmitter

Install the tachometer in the front of the instrument panel. Install the transmitter into the same panel.

Alternatively, install a new panel that is dedicated to the tachometer's system.

Illustration 12	g00779469
Dimensions of the tachometer (side view)

1. Cut an opening with a diameter of 85.7 mm (3.375 inch) into the front of the instrument panel.

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Illustration 13	g00779493
Rear view and side view of the tachometer (1) Bracket (2) Nut

2. Remove bracket (1) from the rear of the tachometer by removing two nuts (2) .

3. Fit the rear of the tachometer through the hole in the front of the panel. Secure the tachometer onto the panel with bracket (1) and two nuts (2) .

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Illustration 14	g00780157
Rear of the tachometer and magnified view of the adjustment controls (3) Plug over the adjustment controls (4) Switch

Note: The adjustment controls for the tachometer are under plug (3). The adjusting screws are used to calibrate the tachometer's zero point and the range of the span for the display. Switches "1", "2", and "3" are for setting the position of a decimal point. No decimal will be used. Switch number "4" adds a dummy "0" as a last digit for the display.

4. Remove plug (3) from the rear of the tachometer. Turn ON switch (4). Then reinstall the plug.

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Illustration 15	g00779846
Dimensions of the transmitter and installation on a rail (5) G rail (6) T rail (7) Slot for a screwdriver for removal of the transmitter from the T rail

5. Use suitable hardware to fasten a rail to the inside of the panel. A T rail (5) or a G rail (6) may be used. Attach the transmitter to the rail.

   If more than one transmitter is used, adjacent transmitters may be installed on 25 mm (1 inch) centers.

Wiring

1. Turn OFF the power to the instrument panel.

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Illustration 16	g00780603
Typical wiring diagram (1) Speed sensor (2) Transmitter (3) Power source (4) Tachometer (5) Circuit breaker (6) Ground

2. Use a shielded two-wire cable to connect speed sensor (1) to the positive "+" and negative "-" terminals on the "INPUT" end of transmitter (2). Connect the shield only from one end of the cable. Connect the shield to ground (6) for the instrument panel.

Note: The nominal power supply for the transmitter is 24 VDC. The transmitter can operate with a minimum of 12 VDC to a maximum of 50 VDC. The power supply must never exceed an instantaneous peak voltage of 75 volts.

Note: A wire size of 16 AWG is recommended.

3. Connect a wire between the positive "+" terminal on the "OUTPUT" end of transmitter (2) to the positive "+" terminal of the power source (3) .

   If the instrument panel does not have a source of 24 VDC, the power source must be provided. If another panel with 24 VDC is available, that panel may be used as the source.

   If the instrument panel already has 24 VDC, identify the positive "+" and negative "-" terminals in the panel.

   Usually, panels for 3600 Engines use a terminal that is designated "1" if the terminal is directly connected to the positive "+" power supply. A designation of "1A" indicates that the terminal is connected to the positive "+" power supply via a circuit breaker or a fuse. The 24 VDC negative "-" is designated by "2".

   Make sure that circuit breaker (5) or a fuse with a rating of one ampere is installed for the wiring between the transmitter and the positive "+" power source.

4. Connect a wire between the negative "-" terminal of power source (3) to the negative "-" terminal of tachometer (4) .

   On the tachometer, the negative "-" terminal is identified with a "2".

5. Connect a wire between the negative "-" terminal on the "OUTPUT" end of transmitter (2) to the positive "+" terminal of tachometer (4) .

   On the tachometer, the positive "+" terminal is identified with a "1".

Calibration

1. Turn OFF the power supply for the tachometer's system.

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Illustration 17	g00779954

2. Disconnect one end of wire (1) that is between the negative terminal "-" on the "OUTPUT" end of the transmitter and the positive terminal "+" on the tachometer. Either end of the wire may be disconnected.

3. Connect a digital ammeter between the disconnected end of wire (1) and the terminal that was disconnected in Step 2. Adjust the ammeter to a scale that will display 4 to 20 mA.

4. Disconnect leads (2) and (3) from the positive "+" and negative "-" terminals on the "INPUT" end of the transmitter.

5. Connect the leads of a signal generator to the positive "+" and negative "-" terminals on the "INPUT" end of the transmitter. Make sure that the polarity is correct. Make sure that the signal generator is OFF.

6. Turn ON the power to the tachometer's system.

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Illustration 18	g00780053
(4) "ZERO" adjusting screw on the transmitter (5) "ZERO" adjusting screw on the tachometer

7. Turn the transmitter's "ZERO" adjusting screw (4) until the display on the ammeter is 4 mA. Remove the plug from the rear of the tachometer and turn the tachometer's "ZERO" adjusting screw (5) until the display on the tachometer is "0000".

   The transmitter's output of 4 mA corresponds to a display of "0000" rpm on the tachometer.

8. Turn ON the signal generator. Adjust the frequency of the signal generator according to the model of the turbocharger.

   The different models of turbochargers and the corresponding frequencies are listed in Table 3.

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   Table 3

   Turbochargers and Corresponding Frequencies
   Turbocharger	Pulses per Revolution	Frequency in Hz
   ABB VTC254 (1)	1	833
   ABB VTC254 (2)	2	1667
   Napier NA297 G (3) (4)	9	7500
   Napier NA297 GS (3) (4)	13	10,833

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   ( 1 )	This turbocharger uses the 141-9884 Speed Sensor with an adapter for the inlet air that is straight.
   ( 2 )	This turbocharger uses the 168-3630 Speed Sensor with an adapter for the inlet air that is at 90 degrees or with a silencer.
   ( 3 )	This turbocharger uses the 164-5336 Speed Sensor .
   ( 4 )	The "G" and the "GS" designate the compressor wheel.

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Illustration 19	g00780064
(6) "SPAN" adjusting screw on the transmitter (7) "SPAN" adjusting screw on the tachometer

9. Turn the transmitter's "SPAN" adjusting screw (6) until the display on the ammeter is 20 mA. Turn the tachometer's "SPAN" adjusting screw (7) until the display on the tachometer is "5000".

   The transmitter's output of 20 mA corresponds to a display of "5000" rpm on the tachometer.

   Note: Remember that the display represents one-tenth of the actual rpm. To determine the actual rpm, multiply the tachometer's display by ten. A display of "5000" that is multiplied by ten indicates 50,000 rpm. This is the maximum reading.

   Note: If you are using the tachometer for an ABB turbocharger with the 168-3630 Speed Sensor , the transmitter's "SPAN" may not have the correct range. This will be due to the position of the jumper block in the transmitter. For this situation, turn OFF the power to the tachometer's system. Remove the transmitter from the instrument panel. Move the jumper block to pin location "F". See ""Configuring the Transmitter" ". Then reinstall the transmitter and perform the calibration procedure.

10. Verify that the transmitter's output of 4 mA produces a display of "0000" on the tachometer and that an output of 20 mA produces a display of "5000".

11. When the calibration is complete, turn OFF the power to the tachometer's system. Turn OFF the signal generator.

12. Remove the signal generator and the ammeter.

13. Install the plug over the adjustment controls on the rear of the tachometer. Reconnect wire (1) between the negative terminal "-" on the "OUTPUT" end of the transmitter and the positive terminal "+" on the tachometer.

14. Reconnect leads (2) and (3) from the speed sensor to the positive "+" and negative "-" terminals on the "INPUT" end of the transmitter.

    Proceed with normal operation.

Performance Data

Records of performance are an important element of a maintenance program. You are encouraged to monitor the trends of performance over time.

Obtain data for use as a baseline when the installation is new. Frequently record new data over time during engine operation. Review the data in a graphic form at regular intervals. The trend information can help predict problems with operation.

Table 4 is an example of a log for recording performance data for operation of the turbocharger. This is not a complete list of all the factors that can affect the turbocharger. However, the data for the parameters can be obtained with common devices such as equipment for measuring temperature and pressure.