Use of the 4C6534 Speed Switch Calibration Harness{0781, 0785} Caterpillar

Introduction

The 4C6534 Speed Switch Calibration Harness (1) is now available, and is a replacement for the former 9W6370 Harness. This new harness is for use with the 8T5200 Signal Generator/Counter Group to perform a functional check, and a calibrated check, for an engine electronic speed switch that has two, three, or four elements.

NOTE: The former 9W6370 Harness can still be used with two and three element speed switches, but, it does not provide enough voltage to operate four element speed switches. When using the 9W6370 Harness, it may be necessary to also use the 8T5197 Calibrator Cable.

The calibration check and the functional check can not be used on electronic speed switches that provide reverse protection. They require the use of a tachometer drive low mounted speed sensor.

Do not perform any procedure, outlined in this publication, or order any parts until you read and understand the information contained within.

Reference: Special Instruction form SEHS8579.

Using the 4C6534 Speed Switch Calibration Harness to Connect the 8T5201 Signal Generator/Counter to an Electronic Speed Switch

1. Connect 4C6534 Speed Switch Calibration Harness (1) to the OUTPUT connection (2) on 8T5201 Signal Generator/Counter (3).

2. Disconnect magnetic speed sensor wires (4) and (5) at the COM and SIG terminals on electronic speed switch (6). (COM and SIG are terminals 3 and 4 on the electronic speed switch.)

Disconnect any other wires that are connected to terminals 3 and 4.

NOTE: The above procedure includes disconnection of electrical wires. Always identify each wire in some manner before it is disconnected. This will aid in the correct connection of all wires after the checks and calibrations are completed.

3. Connect 4C6534 Speed Switch Calibration Harness (1) to the COM and SIG terminals on electronic speed switch (6).

One connecting terminal of harness (1) has a (+) symbol. This terminal must be connected to the SIG terminal.

4. If the engine is equipped with an electrical fuel shutoff solenoid, disconnect the positive (power) wire at fuel shutoff solenoid (7). Use electrical tape, or some other type of insulation, to cover the terminal of the disconnected wire. This will insulate it from the engine so it will not cause an electrical short.

5. Use a voltmeter to measure the DC Voltage supplied to terminals 5 and 6 (8) on electronic speed switch (6). With correct polarity, voltage for all electronic speed switches should be 8 Volts DC minimum, and 40 Volts DC maximum.

NOTE: The engine should NOT be running during the functional check or the calibration check. Take the necessary precautions to make sure the engine will not start.

Conversion of Set Point rpm to Hz

1. Before doing any of the checking procedures given in this instruction, refer to the SPEED SPECIFICATION CHART in this instruction for the specified rpm setting for each function of the electronic speed switch.

NOTE: The SPEED SPECIFICATION CHART will give conversion values between rpm and Hz. For engine ratings not shown in the chart, use the following formulas to convert rpm to Hz, or Hz to rpm.

* rpm to Hz

Hz = number of teeth on flywheel ring gear × rpm ÷ 60

Example: (converting rpm to Hz) number of teeth on flywheel ring gear = 150 engine (rated) rpm = 800

Conversion:

Hz = 150 × 800 = 120,000

120,000 ÷ 60 = 2,000 Hz

* Hz to rpm

rpm = Hz value (shown on signal generator/counter) × 60 ÷ number of teeth on the flywheel ring gear.

Example = (converting Hz to rpm)

Hz value (shown on signal generator/counter) = 4000 number of teeth on flywheel ring gear = 200

Conversion:

rpm = 4000 × 60 = 240,000

240,000 ÷ 200 = 1200 rpm

2. Release brake (9) for Hz adjustment knob (10). Turn knob (10) counterclockwise (CCW) (as seen from the top as shown) until it stops. This will ensure that the signal generator/counter is at the low end of its range.

Check of rpm Settings (Set Point) for Electronic Speed Switch

1. Use 4C6534 Speed Switch Calibration Harness (1) to connect 8T5201 Signal Generator/Counter (3) to the electronic speed switch (6) that is to be checked and or calibrated.

Refer to the topic entitled Using the 4C6534 Speed Switch Calibration Harness to Connect 8T5201 Signal Generator/Counter to an Electronic Speed Switch in this instruction.

2. Push ON switch (12) to turn on power to signal generator/counter (3), then push HI switch (13). Approximately 7 Hz will appear on LCD display (14).

NOTE: If the overspeed switch activates, push reset button (15) to reset the switch.

3. Remove sealing screw (16) from the hole for the oil step switch.

4. Connect a Caterpillar® Digital Multimeter (DMM) to crank termination (CRANK TERM) terminals 10 and 11 (17) on the electronic speed switch. Set the DMM at the 200 Volt DC range.

NOTE: When getting near the desired set point, turn the Hz adjustment slowly. This is because it is quite easy to overshoot (go past) the specified set point frequency.

5. Using the Hz adjustment knob on the signal generator/counter, slowly increase the frequency until the DMM display switches to 0 Volts.

Stop increasing the Hz frequency and record the reading shown on the signal generator/counter LCD display. This will be the crank termination set point in Hz.

6. Turn the Hz adjustment knob to increase the the Hz reading until the oil step relay activates. Look into the hole where sealing screw (16) was removed, and watch to see when the red LED comes on.

When the red LED comes on, stop turning the Hz adjustment knob and record the reading that appears on the signal generator/counter LED display. This is the oil step set point, in Hz.

NOTE: To reset either an oil step relay or crank termination relay, turn the Hz adjustment knob counterclockwise (CCW) far enough, so the Hz reading on the signal generator/counter LCD display is lower than the set point value required to activate them.

Now push OUTPUT OFF switch, on the signal generator/counter, wait three seconds and then push the OUTPUT ON switch. This will reset the relay.

7. Now turn the Hz adjustment knob further, to increase the Hz reading on the signal generator/counter LCD display, until the calculated Hz reading for overspeed set point is reached, and the relay is activated.

A red LED (18) (on the front of the electronic switch) will turn on, when the overspeed set point is reached. When the light turns on, immediately stop turning the Hz adjustment knob and record the Hz reading that appears on the signal generator/counter LCD display.

8. To check the set point for 75 percent overspeed, first reset the relays as follows:

* Turn the Hz adjustment knob counterclockwise (CCW) far enough, so the Hz reading on the signal generator/counter LCD display, is lower than 75 percent of the set point value required to activate the relay.

* Now push the OUTPUT OFF switch, wait three seconds, and then push the OUTPUT ON switch. Push reset button (15). This should reset the relay.

9. Push in and hold 75 percent verify button (19) on electronic speed switch (6). Turn the Hz adjustment knob to increase the Hz reading on the signal generator/counter LED display.

The overspeed switch relay should activate at 75 percent of the overspeed set point.

10. Push OFF switch (20) to turn off the signal generator/counter. Push reset button (15) to reset the electronic speed switch.

11. If any Hz readings are in error by more than ± 25 Hz of the value calculated, it is an indication that the electronic speed switch needs to be calibrated. Keep the signal/generator counter connected to the electronic speed switch, and refer to the topic entitled Calibration of Electronic Speed Switch in this publication.

12. If the Hz readings were within ± 25 Hz of the values calculated in the topic entitled Conversion of Set Point rpm to Hz in this publication, disconnect the signal/generator counter from the electronic speed switch.

Connect all wires to the electronic speed switch that had been disconnected for the rpm setting check. Install sealing screw (16) (removed in Step 3) in the hole for the oil step switch.

Calibration of Electronic Speed Switch

1. Remove appropriate sealing screw (21) for each operational function of the electronic speed switch that is to have a set point adjustment.

2. For the operational function that is to be adjusted, use the 4C4029 Trimmer Adjustment Tool to turn the adjustment screw twenty turns clockwise (CW) to the maximum setting.

3. Release the brake for Hz adjustment knob (10). Turn the knob counterclockwise (CCW) (as seen from the top of the signal generator/counter). This will ensure that the signal generator/counter is at the low end of its range.

4. Push ON switch (12) to turn on power to signal generator/counter (3), then push HI switch (13). Approximately 7 Hz will appear on LCD display (14).

NOTE: If the overspeed switch activates, push reset button (15) to reset the overspeed switch.

5. Release the brake and turn Hz adjustment knob (10) on the signal generator/counter to get the calculated Hz reading on the LCD display, for the set point that is being calculated.

NOTE: When making a set point adjustment, always make sure the final turn of the adjustment screw is in a counterclockwise (CCW) direction.

6. To adjust the oil step function, turn adjustment screw (22) counterclockwise (CCW - toward minimum setting) until the relay activates. When the OIL STEP relay activates (calculated set point has been reached) a red LED in the adjustment screw hole, will turn on.

7. For adjustment of the crank termination (CRANK TERM) function, connect a Caterpillar Digital Multimeter (DMM) to terminals 10 and 11 (17) on the electronic speed switch. Set the DMM to the 200 Volt DC range.

With the correct calculated Hz on the signal generator/counter display, turn CRANK TERM adjustment screw (23), until the display on the DMM (connected to terminals 10 and 11) turns to 0 Volts. This is the crank termination set point.

8. To adjust the overspeed function, with the correct calculated Hz on the signal generator/counter display, turn overspeed adjustment screw (24) until the set point is reached.

When the set point is reached and the overspeed relay activates, red LED (25) on the front of the electronic speed switch will turn on. Use manual reset button (26) to reset the overspeed relay.

9. To reset either an oil step relay or crank termination relay, turn the Hz adjustment knob counterclockwise (CCW) far enough, so the Hz reading on the signal generator/counter LCD display is lower than the set point value required to activate them.

Now push the OUTPUT OFF switch, on the signal generator/counter, wait three seconds, and then push the OUTPUT ON switch. This will reset the relay.

10. Use the procedure beginning with Step 2 in the topic entitled Check of rpm Settings (Set Point) for Electronic Speed Switch, and again check the adjustment of each set point. Make further adjustments as necessary.

11. When all set point checks and adjustments are complete, disconnect the test equipment and connect all wires that were disconnected. Install the sealing screws to a torque of 0.20 ± 0.03 N·m (2 ± 0.3 lb in). Install the lockwire and seal.

Speed Specification Chart

NOTE: An explanation of the column heading letters A and B in both charts that follow, and the letter C that appears in the Engine Family column in second chart is as follows:

A - Typical rated engine speeds.

B - Electronic speed switch functions.

C - 3500 Family PEEC Locomotive Engine.

Additional footnotes are at the bottom of each chart.