Using The 6V4060 Engine Set Point Indicator Group{0781} Caterpillar

NOTE: In this instruction, R/MIN and rpm are abbreviations for revolutions per minute.

The 6V4060 Engine Set Point Indicator Group can be used for measurements of the set point R/MIN (revolutions per minute) of Caterpillar diesel engines. The set point [formerly called the balance point] is 20 R/MIN more than the full load R/MIN of the engine. Because of this, 20 R/MIN must always be subtracted from the measured set point to find full load R/MIN. This is a new, more accurate method of measuring full load R/MIN on Caterpillar engines.

The LUG and OVERRUN indicators on the front panel of the set point indicator are controlled by sensitive electronic circuits, and are used to accurately locate the set point of the engine. The set point R/MIN is then read directly on a tachometer. If the 6V2100 Multitach is used, it can be installed on the set point indicator as shown above. This permits the digital readout to hold constant for a short time at the set point R/MIN allowing the set point R/MIN to be more accurately read. All connections necessary for operation of the multitach are provided for by the set point indicator.

The 6V4060 Set Point Indicator, with the 6V2100 Multitach installed, can be easily stored in the space provided in the 6V3150 Engine Pressure Group as shown. With this arrangement, the engine pressure group can be used to measure engine speed, set point and pressures. Because all of the multitach input connections are easily accessible on the front panel of the set point indicator, the multitach and set point indicator can be used while installed in the case as shown.

The set point indicator has two independent input channels. This permits power balancing of twin engine installations. The set point for either channel can be held for three seconds on the multitach digital display to allow easier reading. A selector switch determines which engine speed reading will be held.

Each channel has two indicator lights to show where the engine is operating on the load curve, and to show when the set point has been reached. The OVERRUN indicator light (1) is on when the engine is not fully loaded and the rack contact is open or is making contact less than 10% of the time. When the engine is fully loaded and the rack contact is closed or is making contact for more than 75% of the time, LUG light (2) will be on. The set point of the engine is indicated by OVERRUN light (1) going off as an increasing load is slowly applied to the engine and the rack contact makes contact just over 10% of the time, but not more than 75% of the time.

After both lights have been off for 3/4 of a second, both the OVERRUN and the LUG lights will come on together if MULTITACH HOLD SOURCE switch (3) is not in the OFF position. If a 6V2100 Multitach is installed, NO INPUT SIGNAL light (4) will come on bright and the digital display reading of the set point will be held for three seconds; then all three lights will go off. The set point is read during the three seconds that the multitach reading is held. After the three second hold period, the multitach reading may decrease for several seconds, then return to actual engine speed.

Components Of The 6V4060 Engine Set Point Indicator Group

1. Engine Set Point Indicator

2. 1P7446 Rack Contact Cable

3. 6V4949 Fastener Strips (for securing 6V2100 Multitach)

Optional Items For Use With The Engine Set Point Indicator Group

Features And Specifications Of The Engine Set Point Indicator

HIGH ACCURACY MEASUREMENTS: High accuracy set point R/min measurements are possible using the engine set point indicator. Electronic circuitry eliminates errors caused by operator interpretation of test light brightness, low batteries, or high rack contact resistance.

REPEATABLE MEASUREMENTS: Set point measurements of the same engine are usually repeatable within ± 5 R/min, depending on how accurately the load can be controlled and repeated. Stable, regulated voltages and electronics makes this possible.

DIRECT SPEED READOUT: By mounting a 6V2100 Multitach on the set point indicator, direct readout of set point speed is possible. At the set point, the speed reading is held constant for three seconds, allowing it to be easily read.

TWIN ENGINE BALANCING: Dual channels with separate indicators allow twin engine installations to be easily balanced. Applications include marine installations, compound mechanical drives and generator sets.

LED INDICATORS: All indicators are light emitting diodes (LED's) for long life.

INPUT POWER REQUIRED: External power source of 11 to 40 Volts DC at a maximum of 1 Ampere. The engine battery or other external power source can be used.

OVERRUN INDICATION: The OVERRUN indicator will light whenever the engine rack contact is open and/or has contact less than 10% of the time.

LUG INDICATION: The LUG indicator will light whenever the engine rack contact is closed and/or has contact more than 75% of the time.

SET POINT INDICATION: Engine set point is indicated by the OVERRUN light going off, and both the OVERRUN and LUG lights staying off. After both lights have been off 3/4 of a second, both lights will come on together for three seconds to indicate set point has been reached.

RACK CONTACT TEST CURRENT: A direct current of 0.1 Ampere at 5 Volts is applied to rack contact during the test.

R/MIN READOUT: A 6V2100 Multitach can be mounted on the engine set point indicator to directly display the engine R/MIN.

MULTITACH HOLD FEATURE: The set point R/MIN will be held on the multitach for approximately three seconds to allow it to be easily read. This is done automatically by removing the multitach input signal for three seconds. This causes the last speed reading to be held on the digital display.

DUAL CHANNEL: Two identical separate channels are provided on the set point indicator. This allows twin engine installations to be easily balanced.

SELECTABLE HOLD SOURCE: Since only one multitach is used, a switch is provided to allow the set point of either engine on twin engine tests to hold the reading on the multitach.

ELECTRICAL ISOLATION: Both set point indicator channels are electrically isolated so the voltage differences between battery and rack contact or from engine to engine will not affect accuracy or cause damage to the indicator.

INDICATOR ACCURACY: Overrun indication 0% to 10% ± 3% rack contact Lug indication 75% ± 5% to 100% rack contact

OPERATING TEMPERATURE: ... -18°C to +60°C (0°F to +140°F)

STORAGE TEMPERATURE: ... -40°C to +100°C (-40°F to +212°F)

SIZE: ... 264 mm x 112 mm x 67 mm (10.4" x 4.4" x 2.6")

WEIGHT: Indicator only - ... .45 kilograms (1 lb.)

Connections And Controls

Installation Of The 6V2100 Multitach On The Set Point Indicator

NOTE: The 6V4060 Set Point Indicator has been designed to be used with the 6V2100 Multitach. If necessary, the set point indicator can be used with an external tachometer. However, the hold feature of the set point indicator can only be used when the multitach is installed.

(1) Obtain a 6V2100 Multitach (with or without the 6V4190 Auto Programmer). Look at the lower rear side of the multitach to see if fastener strip (1) has been installed. If it has been installed, go to step 5. If the strip has not been installed, install a new 6V4949 Fastener Strip as follows.

(2) Use a mild detergent and water solution to remove all dirt and oil film from the lower rear side of the multitach. Make sure the case is completely dry before installation of the fastener strip.

(3) Without removing the protective backing from either piece of the new fastener strip, pull the two pieces apart. Look at the surface texture of both pieces (one piece has hooks, the other has loops), and compare them to strip (2) already installed on the set point indicator. Use the piece of fastener strip that is different from strip (2). Press this piece onto strip (2). Make sure the piece is straight. If this piece will not stick to strip (2), use the other half of the fastener strip. After the fastener strip has been installed, carefully remove protective backing (3). Do not touch the adhesive on the fastener strip or allow it to become contaminated.

(4) Put multitach (4) in position on the set point indicator with connectors (5) in alignment as shown. Keep end (A) of the multitach up when aligning the connectors so the fastener strip will not touch the multitach. Once the connectors have been aligned, lower end (A) just enough to push the multitach forward to fully engage the connectors. Do not force the multitach into the set point indicator if the connectors are not properly mated or damage to the connectors will result. Press down on end (A) of the multitach to fasten the top piece of the fastener to the multitach.

(5) If the multitach already has a fastener strip installed, put the multitach in position on the set point indicator with connectors (5) in alignment as shown. Keep end (A) of the multitach up when aligning the connectors so the fastener strips will not touch each other. After connectors (5) have been aligned, lower end (A) just enough to push the multitach forward to fully engage the connectors. Do not force the connectors together if they are not properly aligned or damage to the connectors will result. Push down on end (A) to fasten the two pieces of fastener together. If the two pieces do not attach to each other, remove the piece from the multitach and install a new piece as shown in steps 2 through 4.

(6) To remove the multitach, carefully lift up on end (A) to separate the fastener strips; then pull the multitach out of the connectors. Do not lift end (A) too much or damage to the connectors will result.

Connection Of Power To The Set Point Indicator

(1) An external power source must be used to supply power to the set point indicator [if the multitach is installed, it will automatically receive power from the set point indicator]. This power source can be a battery or a DC power supply capable of supplying between 11 and 40 Volts at one Ampere. For portable use, two 6 Volt lantern batteries connected in series can be used. Use the following procedure to connect the power source to the set point indicator.

(2) Obtain a 5P7366 Power Cable. This is the same cable used to supply power for the 6V2100 Multitach. If the power source or battery is on a machine or engine, connect one of the clips on the power cable to the frame of the machine or engine. Make sure the clip is in contact with bare metal. Connect the other clip of the power cable to the power source or terminal of the battery which is not connected to the frame. On machines, this clip can be connected to any wire or terminal capable of supplying 11 to 40 Volts DC at one Ampere.

(3) Fasten the power cable connector to the 11 TO 40 VDC connector (1) on the set point indicator. Put the disconnect switch or the power source switch in the on position. If the multitach is installed, either MAG light (2) or PHOTO light (3) should be on to indicate power has been applied. To provide an indication of power being supplied on the set point indicator, plug 1P7446 Rack Contact Cable (4) into ENGINE 1 connector (5). Either OVERRUN light (6) or LUG light (7) must come on and be flashing.

Explanation Of Engine High Idle And Correct Adjustment Of Set Point

By measuring the set point of a Caterpillar diesel engine, the actual full load R/MIN can be determined within ± 10 R/MIN. The set point of an engine is:

a) Full load R/MIN + 20 R/MIN [except those applications that have a hp spread; then set point is full load speed + hp spread R/MIN + 20 R/MIN].

b) When the engine is just leaving the overrun (governed) condition, but has not yet reached the lug (non-governed) condition.

c) When the load stop pin or rack stop collar just starts to touch the torque spring or stop bar (makes contact approximately 10% of the time).

High Idle R/MIN

The high idle R/MIN of an engine is not an adjusted specification, but is the result of three factors:

1. Engine set point R/MIN (adjusted with the high idle screw).

2. The differences in governor springs and governor weights.

3. Parasitic (accessory) loads on the engine (fan, alternator, air compressors, pumps, BrakeSaver, etc.).

The high idle R/MIN is shown on the engine information plate or listed in the fuel setting information. The engine information plate must be used for all references if it is available.

Full Load Speed

The speed at which the engine will develop the rated and advertised horsepower. If the engine is equipped with a torque spring, full load speed may or may not be the R/MIN where the engine develops maximum horsepower.

Set Point

The engine set point is the speed at which the fuel control adjustment screw just begins to come into contact with the stop bar or torque spring [first torque spring in dual (two) torque spring applications]. Use the 6V4060 Engine Set Point Indicator to measure the engine set point. When the LUG and OVERRUN lights are both off (out) the engine speed is in the set point speed range. (The fuel control is still dynamic at this engine speed, moving back and forth several thousandths of an inch.) When additional load is applied to the engine, the fuel control will advance and become stable (steady) against the torque spring or stop bar.

Current Procedure For Full Load Speed (Set Point) Adjustment

The current procedure reduces the horsepower variation in the full load speed zone. This was done by increasing the former balance point speed Point (A), to a point approximately 20 rpm higher. This new balance point, now called "set point" speed, makes sure the engine will develop the specified power within the (±) power tolerance at the specified full load speed.

A-Original Balance Point rpm. B-Bare Engine High Idle rpm. C-Horsepower. D-Engine Speed. E-Set Point. F-Specified Full Load Speed. G-Horsepower Difference (caused by speed setting tolerance).

NOTE: In the procedure that follows, test points, specified full load speed and rpm spread are used and explained. Some of these test points can be found only if the engine is tested on a dynamometer under controlled conditions.

The set point zone is usually 20 rpm above Specified Full Load Speed (F) on governors that have 10% or more droop. The fuel control (rack stop collar or load stop pin) makes fuel contact at Specified Full Load Speed (F). The fuel rack oscillates (moves back and forth) slightly at set point speed, but the rack stop collar makes contact with the rack stop between 10 and 70% of the time. Set Point (E) must be 20 rpm faster than Full Load Speed (F), to allow a stable full contact of the rack stop collar at Rated Full Load Speed.

Dynamometer Test Procedure

A-Original High Idle rpm. B-Bare Engine High Idle rpm. C-Horsepower. D-Engine Speed. E-Set Point. F-Specified Full Load Speed. G-Horsepower Difference (caused by speed setting tolerances).

The first speed is stabilization speed (H). The throttle is moved to the high idle stop, and then load is applied until the engine runs at a stabilized speed to obtain operating temperature.

For the second test point, increase engine load so the engine will run at Set Point Speed. While the engine is running at Set Point Speed, the high idle adjustment screw can be used to adjust set point. Begin at a higher speed, and adjust the high idle screw down until set point is reached. (The next check for horsepower would occur at Full Load speed.) Again, check Set Point before finishing the test. Temperatures may cause a minor change, but this is usually acceptable. After this set point check, operate the engine at high idle and record this speed.

The procedures given here are used to find the actual high idle speed, the fuel setting and the torque control group needed for a specific engine rating. Usually during this procedure, adjustments to the fuel setting and torque control group are not necessary. If adjustment is necessary, it is only minor to allow for parts tolerances.

In-Chassis Full Load Speed Setting

A-Specified Full Load Speed. B-Bare Engine - No Load. C-Set Point Tolerance ± 10 rpm. E-Horsepower. F-Engine Speed. H-Set Point - All Engines. R-Accessory Load Horsepower. S-High Idle With Accessory Load.

To find Set Point (H) for all engines (except those that have a specified horsepower spread), add 20 rpm to Specified Full Load Speed (A).

Horsepower spread engines are generally found in off-highway hauling units. This is accomplished with a light first torque spring and large spacer block. These engines have a specified horsepower spread (M). There is also a specified rpm spread (L). To find Set Point rpm (H) for these engines, add 20 rpm and specified rpm spread (L), to specified full load speed (A). H = A + L + 20 rpm.

Use the high idle adjustment screw to adjust Set Point (H) rpm.

After engine Set Point has been adjusted, do not change the high idle adjustment. The high idle speed for that engine will depend on the Set Point adjustment, the governor flyweights, the governor spring, and the parasitic loads for the specific engine application.

The high idle R/MIN for an installed engine, with accessories, will be less than the high idle R/MIN of an engine that is not installed (out of chassis) and does not have accessories. In a typical vehicle engine installation, high idle R/MIN will be approximately 20 R/MIN less than the same engine when it is not installed in a vehicle. Therefore, high idle R/MIN must not be used as a reference R/MIN to adjust the governor speed setting. Use the actual high idle R/MIN only to check for governor linkage binding, or to calculate governor speed regulation, to determine if the correct governor spring and flyweights are installed in the governor.

For engine speed tolerances according to engine model, see the chart that follows.

Measuring Engine Set Point With 6V2100 Multitach

(1) Install the multitach on the set point indicator as shown on page 7. Connect power to the indicator as shown on page 8. Refer to Special Instruction Form SEHS7807, "USING THE 6V2100 MULTITACH AND 6V3121 MULTITACH GROUP". Use the multitach inputs MAG (1) or PHOTO (2) to connect the engine speed sensors to the multitach. Program the multitach to display engine R/MIN.

(2) Plug 1P7446 Rack Contact Cable (3) into ENGINE 1 connector (4). OVERRUN light (5) should be flashing if clips (7) and (9) on cable (3) are not touching each other; and LUG light (6) should flash when clips (7) and (9) are touching each other. This shows that the set point indicator is ready for use.

(3) Connect insulated clip (7) of the rack contact cable to rack contact screw (8). Connect bare metal clip (9) of the cable to a bare metal ground.

IMPORTANT: When using the set point indicator, there must be no other wires connected to the rack contact screw except rack contact cable clip (7). The rack contact screw is an insulated screw located on the governor housing of the engine. Refer to the Engine Maintenance Manual for the location of this screw. The rack contact screw may have a cap on it. If it does, remove the cap. If necessary, remove any paint from the screw so the bare metal is exposed.

(4) Start the engine and let it run until it is at normal operating temperature. Make sure the multitach is correctly indicating the engine speed. If it is desirable to have the set point R/MIN reading held on the multitach display, put MULTITACH HOLD SOURCE switch (10) in position 1. Refer to the instructions for the particular application (pages 16 through 18) to determine if the set point should be held.

(5) Run the engine at high idle. With no load (or a very small load) on the engine, ENGINE 1 OVERRUN light (5) should be on. Keep the throttle against the high idle stop, and smoothly increase the load on the engine until the OVERRUN light goes off. This is the set point. For various methods of applying loads to different engine applications, see pages 16 through 18.

(6) When the OVERRUN light goes off, the set point has been reached and the load should be held constant, so the engine speed can be read accurately. At the set point, both the OVERRUN and the LUG lights should be off, if the MULTITACH HOLD SOURCE switch is in the OFF position. If the LUG light comes on, too much load has been applied to the engine. If this happens, reduce the load until the OVERRUN light comes back on; then increase the load until both lights are off again and read the R/MIN.

(7) If MULTITACH HOLD SOURCE switch (10) is in position 1 and OVERRUN light (5) and LUG light (6) are both off, after 3/4 of a second both lights will come on together and flash for 3 seconds. Read the set point R/MIN on the multitach during this time. The NO INPUT SIGNAL light (11) on the multitach will also come on during this 3 second period, and the engine set point R/MIN will be held on the digital display. The set point R/MIN must be read during this 3 second period. After the 3 second hold period, the multitach reading may decrease for several seconds, then return to actual engine speed. Do not take another set point measurement until the multitach is again reading correct engine speed. To find the full load speed, subtract 20 R/MIN from the set point R/MIN reading.

(8) For maximum accuracy, the set point of the engine should be measured a minimum of five times to determine an average reading. Due to fluctuations in load and speed, there will be some difference between the readings. To find the average set point R/MIN, add the R/MIN readings together and divide the total by the number of readings taken. Subtract 20 R/MIN from the average reading to find full load R/MIN setting of the engine. An example of determining average set point R/MIN follows.

Measuring Engine Set Point With External Tachometer

An external tachometer can be used with the set point indicator to determine set point R/MIN. After the tachometer has been connected to the engine, use the same procedure as shown on pages 14 and 15. If an external tachometer is used, the multitach hold feature can be used only as an indicator; it will not hold the reading of an external tachometer. When both lights on the set point indicator come on together, read the R/MIN on the tachometer. To find full load R/MIN, subtract 20 R/MIN from the average set point R/MIN. The accuracy of these readings will depend on the accuracy of the tachometer being used.

Power Balancing Twin Engine Installations

(1) Because the set point indicator has two identical channels, it can be used to balance twin engine installations. Connect the power to the set point indicator as shown on page 8. Connect the indicator to the engines as shown on page 14, except use two 1P7446 Rack Contact Cables instead of one. Connect one cable to the rack contact screw of one engine and to the ENGINE 1 connection on the indicator. Connect the other cable to the rack contact screw of the other engine and to the ENGINE 2 connection on the indicator.

(2) If the multitach is being used, read the speed of one engine on the MAG input and the speed of the other engine on the PHOTO input of the indicator. If the multitach is not being used, an external tachometer must be used for each engine.

(3) Measure the set point of engine 1 as shown on pages 14 and 15. Move the MULTITACH HOLD SOURCE switch to position 2 if the multitach is being used. Measure the speed of engine 2 on the multitach or external tachometer; then repeat the procedure shown on pages 14 and 15 to determine set point of engine 2. If the set points of the two engines are not within 10 R/MIN of each other, refer to the appropriate engine Service Manual to adjust the high idle on one engine until the set points are within 10 R/MIN.

Methods Of Loading The Engine To Read The Set Point

In order to accurately measure the set point, a load which varies from no load to full load must be applied to the operating engine. The methods used to provide this load will depend on the engine application. The most common methods of loading engines follow.

(A) Dynamometer Loading

The most precise method of loading an engine is to use a dynamometer. Although this method is preferred, it can only be used on engines not installed and those installed in highway vehicles. When checking the set point of an engine installed on a dynamometer, it is not necessary to use the multitach hold feature. Because the load can be accurately controlled, engine speed can be held very steady at the set point. To read the set point, run the engine at high idle and keep the throttle against the high idle stop. Slowly increase the load until the OVERRUN light goes off. Hold the load constant at this point and read the set point R/MIN.

(B) On-Highway Trucks

There are several methods of applying a smoothly increasing load to the engine of an on-highway truck. The best method is to use a chassis dynamometer. This allows the load to be held constant when the set point is reached. Set point speed can easily be read without using the hold feature on the set point indicator. See the previous section on dynamometer testing for more information.

If a chassis dynamometer is not available, the truck engine can be properly loaded by driving the truck on the highway and applying the brakes with the transmission in gear. A long straight road is required. The proper transmission gear should be selected to allow the engine to be operated at full throttle without exceeding the speed limit. With the throttle against the high idle stop and the engine at maximum R/MIN, smoothly apply the truck brakes to load the engine until the OVERRUN light goes off. Measure the set point R/MIN as shown on pages 10 and 11. Let the brakes cool between test runs to prevent overheating. If any brake fade is observed, let the brakes cool before continuing with the test.

An alternate method of loading the engine is to place a heavy load in the truck and drive the truck on a hilly road. Select the transmission gear that will allow the engine to be operated at full throttle on the flat road before the hill. With the throttle against the high idle stop and the engine at maximum R/MIN, the load on the engine will increase to the set point as the truck starts to climb the hill. The MULTITACH HOLD SOURCE feature can be used to hold the display of the set point R/MIN. The problem with this method is that the load cannot be accurately controlled, and incorrect readings will result if the load changes too fast when the set point is reached. However, if a suitable length of road is available, this method can be successfully used.

(C) Track-Type Tractors

The best method for loading the engine of a track-type tractor is to run the tractor in gear with the throttle against the high idle stop and the engine at maximum R/MIN. The brakes should then be smoothly applied to load the engine to the set point (indicated when the OVERRUN light goes off). Measure the set point R/MIN as shown on pages 14 and 15.

An alternate method of loading the engine can only be used if the tractor can be worked in dirt or other material. With the throttle against the high idle stop, load the engine by slowly lowering the blade or other implement as the machine is moving, until the set point is reached. This method is not as smooth as the above method because it is difficult to keep the load constant. However, with practice, acceptable results can be obtained.

The multitach hold feature should be used for both of these methods.

(D) Wheel And Track-Type Loaders (Except Hydrostatic Drive)

To measure the set point on most loaders, it is possible to load the engine properly with the machine stationary. When this is done, the torque converter absorbs most of the load of the engine and the hydraulics are "bottomed" out. The hydraulic valve position is then adjusted to add just enough load to bring the engine to the set point.

To use this method, apply the parking brake and keep one foot on the brake pedal. Put the transmission in the highest gear. Apply maximum throttle. Let the engine reach maximum R/MIN. Observe the OVERRUN light on the set point indicator. It should still be on. If it is not on, the engine has been loaded too much and the alternate method should be used. If the OVERRUN light is still on, continue to apply load by holding a hydraulic lever until the cylinder it controls has traveled as far as it can go. At this time, move the lever very slowly in the same direction to load the engine until the OVERRUN light just goes off. Use the multitach hold feature to read the set point. Repeat this procedure until repeatable set point readings are obtained. It may take some practice to make the load change slow enough for the set point R/MIN to be accurately read. If the LUG light comes on during the test, decrease the load until the OVERRUN light comes back on, then slowly increase the load.

If the above method cannot be used, use this alternate method. Drive the loader on a smooth surface and use the brakes to load the engine to set point. Run the loader with the throttle control in the maximum position and the engine at maximum R/MIN. With the engine at maximum R/MIN, apply the brakes until the OVERRUN light just goes off; hold the load constant at this point. Use the multitach hold feature of the set point indicator to read the set point R/MIN.

(E) Track-Type Loaders With Hydrostatic Drive

Caterpillar machines with hydrostatic drive use a method of applying the brakes so the machine will not move against the force of the hydrostatic drive. This allows the engine to be smoothly loaded with the hydrostatic power unit without moving the machine.

To check the set point on these machines, refer to the Service Manual for instructions on changing the U-TUBE on the brake instruction panel to the TEST position. With the U-TUBE in the TEST position, run the engine at high idle with the governor control lever in the maximum throttle position. Slowly apply load to the engine by pulling the transmission lever toward the rear of the machine until the OVERRUN light just goes off. Read the set point at this time. The multitach hold feature should be used since it will be difficult to keep the load constant. Because a small movement of the transmission control lever causes a large change in load on the engine, it will take practice to get an accurate reading of the set point.

(F) Hydraulic Excavators

The set point of the engine in hydraulic excavators can be accurately measured by using the machine hydraulics to load the engine. Refer to the Service Manual for instructions on how to load the engine for testing. The method shown in the Service Manual requires a voltmeter for finding the set point. To use the set point indicator, replace the voltmeter with the indicator. Run the engine with the throttle against the high idle stop and no load on the engine. Slowly apply load to the engine until the OVERRUN light just goes off. Hold the load at this point and read the set point R/MIN. The MULTITACH HOLD SOURCE feature does not have to be used, because the load can be accurately controlled.

(G) Tractor-Scrapers, Motor Graders And Log Skidders

This group of machines has either direct drive or a torque converter which puts the engine into a lug condition when used as a stationary load. Therefore, the brakes must be applied while the machine is moving or the implements must be used to apply the load in order to measure the set point.

Operate the machine on a level surface with the throttle against the high idle stop and the engine running at maximum R/MIN. Select a transmission gear that will allow the engine to be loaded to LUG with the brakes but will still keep the travel speed to a minimum. Gradually apply the brakes until the OVERRUN light goes off and the set point is reached. Use the MULTITACH HOLD SOURCE feature to read the set point R/MIN. If the LUG light comes on during the test, release the brakes until the OVERRUN light comes on; then again apply the load.

An alternate method of loading the engine can only be used if the machine can be worked in dirt or other material. With the throttle against the high idle stop and the engine at maximum R/MIN, load the engine by slowly lowering the blade or other implement as the machine is moving, until the set point is reached. This method is not as successful as applying the brakes because it is difficult to keep the load constant. Because of these varying load conditions, it may be difficult to obtain satisfactory results. However, under acceptable conditions, satisfactory set point measurements can be obtained. Use the MULTITACH HOLD SOURCE feature to read the set point R/MIN.

(H) Single Engine Marine Propulsion Installations

To measure the set point, run the boat in open water at full throttle. With the throttle against the high idle stop, allow the boat to come up to full speed and maximum engine R/MIN. The engine should be operating in the OVERRUN condition. If it is not, attempt to remove some load from the engine by running with the wind, changing propeller pitch, or removing weight from the boat. With the engine at full throttle and in OVERRUN, load must be applied to bring the engine R/MIN out of OVERRUN to the set point. Methods of applying load are to run against the wind, make long sweeping turns, drag a load such as fish nets, or any other method of slowly applying drag to the boat. The MULTITACH HOLD SOURCE feature on the indicator should be used to read the set point. Because it is difficult to smoothly load the engine, several readings should be taken to ensure that the engine speed is not changing too fast at the set point to get an accurate reading.

(I) Multiple Engine Marine Propulsion Installations

To measure the set point, run the boat at full speed with all engines at full throttle. The engine being tested must be operating in the OVERRUN condition with the throttle against the high idle stop. Slowly lower the speed of one or more of the other propulsion engines until the load on the engine being tested increases to the point where the OVERRUN light goes off and the set point is reached. Because the load can usually be held constant enough to give a very stable reading at the set point, it is not necessary to use the MULTITACH HOLD SOURCE feature of the indicator.

Checking Operation Of The 6V4060 Engine Set Point Indicator

(A) Equipment Needed

(B) Connection Of Power

(1) Connect 5P7366 Power Cable (1) to the 11 to 40 VDC connector on the set point indicator. Connect the clips of the power cable to a DC (direct current) power source with a voltage between 11 and 40 Volts which is capable of supplying a minumum current of 1 Ampere. Either clip of the cable can be connected to either terminal of the power source since these input leads are not polarity sensitive.

(2) Plug 1P7446 Rack Contact Cable (2) into the ENGINE 1 connector on the indicator. Either OVERRUN light (3) or LUG light (4) should come on. If either one of them is on, this indicates that the set point indicator has power and is ready to use.

(C) Checking The Overrun And Lug Indicators

(1) With rack contact cable (1) in ENGINE 1 connector of the indicator, move MULTITACH HOLD SOURCE switch (2) to the OFF position.

(2) Operation of the OVERRUN and LUG indicator lights can be checked by touching together the clips on the end of the rack contact cable. When the clips are touching each other, LUG light (3) should be on. When the clips are not touching, OVERRUN light (4) should be on.

(3) Move rack contact cable (1) to the ENGINE 2 connector (5), and repeat step 2.

(D) Checking The Multitach Hold Source Feature

(1) Install a 6V2100 Multitach on the set point indicator as shown on page 7. Connect power to the set point indicator as shown on page 8. Connect 1P7446 Rack Contact Cable (1) to the ENGINE 1 connection on the set point indicator.

(2) Remove small adapter plug (2) from the 5P9698 Calibrator clip. Connect adapter plug (2) to cable (3) on the calibrator. Connect cable (3) to MAG MULTITACH INPUT (4) of the indicator.

(3) Turn calibrator knob (5) to the 400 OUTPUT Hz position. Make sure BATTERY indicator needle (6) is in the white part of the scale. Program the multitach for 10 P/REV and to read R/MIN on the MAG input. Refer to Special Instruction Form SEHS7807, "USING THE 6V2100 MULTITACH AND 6V3121 MULTITACH GROUP" if necessary.

(4) The number 2400 should appear on the multitach display, and the NO INPUT SIGNAL light should be off. With MULTITACH HOLD SOURCE switch (7) in the 1 position, rapidly touch the rack contact cable clips together to keep both the OVERRUN and the LUG lights off at the same time. After both lights have been off together for approximately 3/4 of a second, they should both come on and flash at the same time. When they both come on together, stop touching the clips together and look at the NO INPUT SIGNAL light on the multitach. It should be on when both the OVERRUN and LUG lights are on. All three lights should stay on for approximately three seconds, then go off. During the three seconds that all three lights are on, the multitach reading should remain at 2400. However, after the NO INPUT SIGNAL light goes off, the number on the multitach may become less; then return to 2400 after a few seconds.

(5) Remove the rack contact cable from ENGINE 1 connector, and connect it to ENGINE 2 connector (8). Move MULTITACH HOLD SOURCE switch (7) to the 2 position. Repeat the above procedure for the ENGINE 2 channel.

Repair Of The 6V4060 Set Point Indicator Group

If the set point indicator does not operate correctly, check the operation of the indicator using the procedures shown on pages 19 and 20. If the set point indicator is found faulty, it can be returned to the manufacturer for service. A letter should accompany the returned unit, stating the problem and the date of purchase from Caterpillar. Units less than one year old will be repaired under warranty (except for abuse). Cost of out-of-warranty repairs will be charged to the owner. Send the 6V4060 Engine Set Point Indicator to: