Payload Control System (PCS) 2.X Calibration Caterpillar

This mode allows you to calibrate the sensor for the lift position. This mode allows you to calibrate the system for weighing. This mode is protected by the password of the owner. Press the "CAL" key in order to show the number of times that the system has been calibrated. The display will also show the date of the last calibration. This information will be shown on the display for three seconds. The system will then request the password of the owner.

Press the "SCROLL" key in order to view the dates of previous calibration. This must be done while the total count and the date of the last calibration is shown.

Recalibration is required when one of the following events occur.

• Replacement of the display unit

• Adjusting the position sensor

• Replacing the position sensor

• The oil pressure sensor for the head end of the lift cylinder is replaced.

• The optional oil pressure sensor for the rod end of the lift cylinder is replaced.

• The bucket is changed.

• Any changes to the lift linkage

• The start of each season

• The average ambient air temperature has changed by 10 °C (18 °F).

When a new payload control system (PCS) is being installed, it is advisable to check for any faults that may exist. Enter the Service mode in order to check for any faults. Check the position sensor and the pressure sensor. Make sure that the sensors are operating properly.

Note: Calibration requires the use of a known weight. The known weight should be as close to the rated bucket load as possible.

Note: The message "***MAX***" may be displayed if you are using software version 2.06 or a later version. This will show when you are attempting to weigh a bucket of material. The load has exceeded 150% of the weight that was used for calibration. The PCS is not accurate at this range. Recalibration is required in order to weigh this amount of material.

Use one of the following methods in order to obtain a known weight for calibration.

Solid Calibration Weight - Use a solid calibration weight. Fill a concrete tube with concrete or fill a steel tube with concrete. Use the following chart in order to construct this weight. The tube must then be weighed in order to determine the exact weight.

Bucket Load of Material - The material is weighed in the bucket of the loader. The loader is weighed on scales for the truck.

Bucket Load of Material - The material is loaded into an empty truck. The truck should have a known weight. The truck is then weighed on a scale.

Note: An empty truck can be used in order to obtain the weight if a loader cannot fit onto the scales.

Illustration 1	g00584739
Weight for Calibration (A) Outside diameter. (B) Length.

Pre-Calibration Steps

Note: Do not shut off the electrical system until the calibration is complete. Otherwise, the system will store any calibration information and the PCS will not work properly.

All steps should be followed when you are calibrating the PCS. Omitting steps may result in incorrect operation. Performing steps out of order may result in incorrect operation.

Ride Control

If your machine is equipped with ride control, calibrate the PCS with the ride control in the AUTO position or the OFF position.

Note: If the ride control is turned on, the PCS will be adversely affected.

Kickout

Adjust the lift kickout so that weighing is completed prior to the start of kickout.

Note: During calibration, the kickout must be set above 81% of the lift height.

Oil Temperature Compensation

The oil temperature compensation is set to the default of “0”. This is the OFF position.

If the oil temperature compensation is desired, turn the oil temperature compensation to the ON position prior to calibration.

• For machine models 980 and larger machine models, start with a setting of “12”.

• For machine models 972 and smaller machine models, start with a setting of “15”.

• Further adjustment may be needed to fine tune the oil temperature compensation.

Note: The temperature compensation must be turned on prior to calibration for the temperature compensation to work properly.

Reference: For more information on fine tuning the oil temperature compensation, refer to System Operation, Troubleshooting, Testing and Adjusting Payload Control System, "System Setup Procedure, Setting the Temperature Compensation".

Illustration 2	g00984424

Warm Up

1. Warm the hydraulic oil of the machine prior to starting calibration. This should be done with a load that is similar to the calibration weight. With a loaded bucket , lift the bucket at least ten times. The hydraulic oil should be at normal operating temperature. This should be completed before you begin calibration. The PCS will be inaccurate if these steps are not followed.

   Note: The normal operating temperature is dependent on seasonal temperatures. The machine should be recalibrated for each season or the machine should be calibrated when the average ambient air temperature has changed by 10 °C (18 °F).

   During calibration, the following operating techniques must be observed.

   • The bucket must be fully tilted back.

   • The lift control lever should be in the detent position.

The 988G has an automatic tilt feature. This tilts the bucket forward slightly at the top of the lift range. This feature can interfere with the calibration. Use the following procedure in order to place the bucket in the proper position for calibration on the 988G only. This procedure can be used for a full bucket or for an empty bucket. These instructions are not for setting the zero offset. For all other machines, proceed directly to the calibration procedure.

1. Lower the bucket to ground level.

2. Fully rack back the bucket.

3. Lift the bucket to the maximum height. Hold the lift lever for approximately five to ten seconds. This will allow the automatic tilt feature to tilt the bucket forward slightly to the desired position.

4. Lower the bucket to the ground without changing the position of the bucket. The bucket is now in the correct position for calibration.

   Note: Do not change the tilt position of the bucket for the remainder of the calibration.

5. Proceed with the calibration.

Calibration Steps

Calibrate the system with the display and with the keypad. Cat ET is not recommended.

1. Empty the bucket. Place the machine on flat ground. Press the "CAL" key. The system will request the password of the owner. Enter the password. The factory set password is 12345.

   The correct password must be entered. If an incorrect password is entered, the display will revert to the weighing operation. If an incorrect password is entered, no warning will be given.

   Note: You should not move the machine during calibration.

2. Calibrate the Lift Position Sensor.

   The display will show the message "SHOW LOWEST-PRESS STORE". Lower the lift arms to the lowest possible position. Press the "STORE" key. The display must show between 6500 and 22000. The display will now show the message "SHOW HIGHEST-PRESS STORE". Raise the lift arms to the highest possible position beyond the kickout position. Press the "STORE" key. The display must show between 44500 and 61600. The position sensor needs adjustment if the number is not within these ranges.

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   Illustration 3	g00585117

3. Calibrate while you are lifting an empty bucket. During this step, the message "LIFT EMPTY BUCKET-2000 RPM" will be shown. With the bucket near the ground, maintain a constant engine speed. The engine speed should be approximately 2000 rpm or a comfortable operating speed for the primary operator. The bucket should be lifted by placing the lift control lever into the detent position. Lift the bucket smoothly. Both lines of the display will change to dashes"--" when the lift arms are within the range of calibration. Maintain a constant engine rpm while the lift arms are in the range of calibration.

   Note: It is important to keep the lift control lever in the detent position during all weighing and calibration procedures. If you do not use the detent, the accuracy of the weighing process will be affected. The bucket must also be in the fully tilted back position.

   The display will now show the message "LIFT EMPTY AGAIN-2000 RPM". The operator should repeat Step 3. The message "GOOD CAL" will then be shown on the display. The bucket should be consistently lifted for two times. The process will then proceed to Step 4. If the bucket is not lifted consistently for two times, Step 3 will be repeated until two consecutive lifts are equal.

   Possible reasons for two inconsistent lifts

   • The machine is not warm.

   • The pins are sticking.

   • The engine speed is not maintained at a constant RPM.

   • The detent is not used properly.

   Note: If the message "USE HEAVIER WEIGHT" is displayed, check the following:

   1. Make sure that the wires of the Head Pressure sensor and the wires of the Rod End Pressure sensor have not been interchanged.

   2. Set the detent to 95% or higher.
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   Illustration 4	g00585162

4. Calibrate an empty bucket in the Stationary position. The top line of the display will show the message "STATIONARY CAL". If the lift arms are above the first position for stationary calibration, the top line of the display will show the message "LOWER BUCKET". If the lift arms are below the first position for calibration, the message "RAISE SLOWLY-POINT 10" will be shown. The bottom line of the display will show the distance to the next point of calibration. This distance is shown as a percent of the total lift height. When the remaining distance reaches zero, the top line of the display will show "STOP". The bottom line will show dashes until the pressure in the lift cylinder stabilizes. The system will then take a reading of the weight. This process is repeated ten times at different positions. The system counts down from "POINT 10" to "POINT 1".

   Note: If the waiting period is longer than 5 seconds there is a problem with the pressure or there is a problem with a sensor.

5. Calibrate while you are lifting a full bucket. Load the bucket with a calibration weight or a full bucket of material. The material will need to be weighed on an accurate scale. The display will show the message "LIFT FULL BUCKET-2000 RPM". With the bucket near the ground, maintain a constant engine speed. The engine speed should be approximately 2000 rpm or a comfortable operating speed for the primary operator. The bucket should be lifted by placing the lift control lever into the detent position. Lift the bucket smoothly. Both lines of the display will change to dashes "--" when the lift arms are in the range for calibration. Maintain a constant engine speed through this range.

   It is very important to calibrate the system with a load that is close to the rated load. Do not use a load that is too small or a load that is too large. When the PCS is in the normal weigh mode and a heavy load is weighed, the operator may receive the message "***MAX***". If this message appears, dump some material from the bucket and try again. If the message "***MAX***"repeatedly appears, recalibration is required. See Operation Manual, "System Calibration".

   The display will now show the message "LIFT FULL AGAIN-2000 RPM". The operator should repeat Step 5. The message "GOOD CAL" will then be shown on the display. The bucket should be consistently lifted for two times. The process will then proceed to Step 6. If the bucket is not lifted consistently for two times, Step 5 will be repeated until two consecutive lifts are equal.

   Possible reasons for two inconsistent lifts

   • The machine is not warm.

   • The pins are sticking.

   • The engine speed is not maintained at a constant RPM.

   • The detent is not used properly.

6. Calibrate a full bucket in the Stationary position. The top line of the display will show the message "STATIONARY CAL". If the lift arms are above the first position for stationary calibration, the top line of the display will show "LOWER". When the lift arms are below the first position for calibration, the top line of the display will show the message "RAISE SLOWLY-POINT 10". The bottom line of the display will show the distance to the next point of calibration. This distance is shown in a percent of the total lift height. When the remaining distance reaches zero, the top line of the display will show "STOP" until the pressure in the lift cylinder stabilizes. The system will then measure the weight. This process is repeated ten times at different positions. The system counts down from "POINT 10" to "POINT 1".

7. Calibrate the full bucket by using the Full Bucket Velocity Compensation. This step requires lifting the calibration weight eight times with an engine speed of 1000 rpm to 2400 rpm. Software version 2.07 requires the calibration weight to be lifted fourteen times with an engine speed of 1000 rpm to 2300 rpm. Software version 2.09 or later software versions requires the calibration weight to be lifted seven times with an engine speed of 1000 rpm to 2200 rpm. It is not critical that the engine speed is exactly within this range. However, the engine speed should be as consistent as possible.

   When this step is started, the top line of the display will show the message "VELOCITY CAL". The message "LIFT AT ****RPM" is shown. The engine speed "****" will be incremented from 1000 to 2300 in intervals of 100 rpm for software version 2.07. The engine speed "****" will be incremented from 1000 to 2200 in intervals of 200 rpm for software version 2.09 or later software versions. The PCS may ask you to lift the bucket again if the data seems inconsistent. The message "LIFT SLOWER" indicates that you should lift the bucket again at a reduced speed.

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   Illustration 5	g00585333

8. Enter the full weight of the bucket. The top line of the display will show the message "ENTER WEIGHT". The bottom line will show "0.00" or the previous calibrated weight. The operator should enter the weight in the currently selected units. The "SERV/." should be used in order to enter the decimal portion of the known weight. If you are operating in "lbs x 1000" mode, the weight that is entered is the actual weight. This weight is then divided by 1000. The system will wait at this point while the weight of the payload is entered and the "STORE" button is pressed. The electrical system must not be shut off before you enter the actual weight or the calibration information will be lost.

   Note: A method for setting the precision level is provided by PCS. The default setting for this feature is Auto. The same rules of precision are used in this version of PCS that was used in the previous versions of PCS. Setting this menu item to a value of 1 will force PCS to display 1 digit of precision (30.2 tons). Setting this menu item to a value of 2 will force PCS to display 2 digits of precision (30.23 tons).

9. Perform the following steps.

   • Empty the bucket.

   • Tilt the bucket fully backward.

   • Lift the bucket at 2000 rpm or at normal operating RPM range.

   • Press the ZERO key. "ZERO ACCEPTED" will be displayed.

Post Calibration Steps

1. Check the weigh range. Make sure that the weigh range is correct.

   Reference: Refer to Systems Operation, "Weighing Range Setting" for information.

2. Lift a known calibrated weight 5 times and record the weights.

3. Compare the known calibrated weight to the displayed value on the PCS. Record the difference.

   • "CAL weight" equals 8.38.

   • Displayed weight (PCS) equals 7.88.

   • The Difference equals 0.5.

4. Re-enter the calibration mode and next function until the "CAL weight" is displayed.

5. Adjust the number in the "CAL weight" by the difference in Step 3.

   • "CAL weight" equals 8.38.

   • The Difference equals 0.5.

   • New "CAL weight" equals 8.88.

6. Press the "Store" key.

7. Press the "Clear" key.

8. Lift the "CAL weight".

   The displayed value should be slightly higher than the actual "CAL weight". The truck weight will be slightly less than the weight in the PCS.

9. This completes the calibration.