374F Excavator Machine Systems Overload Warning - Set - If Equipped Caterpillar


Overload Warning - Set - If Equipped
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1.1. Introduction
2.1. Calculation Of The Threshold Pressure For The Overload Warning Device
3.1. Input The Value Of The Threshold Pressure For The Overload Warning Device

Introduction



Illustration 1g03500717

The overload warning device is a system that warns the operator that the pump pressure for the boom cylinder lines has exceeded a set value. The set value for the overload warning device varies because of the machine configuration and the attachments that are installed. The alarm setting for the overload warning device on your machine should be checked for the proper adjustment. Use the information that follows in order to calculate the correct value and reset the parameter for the overload warning device.

Note: The engine speed and/or the machine configuration that is used during this test can affect the results of this test. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for the engine speed that was used for this test.

Note: The relief valve pressure settings must be set to the relief valve pressure specification before performing this operational check. Refer to Testing and Adjusting, "Specifications".

Calculation Of The Threshold Pressure For The Overload Warning Device

Use the information that follows in order to calculate the correct value of the threshold pressure for the overload warning device on your machine.



Illustration 2g01344310
Basic position of the machine
(A) Full extension of bucket cylinder
(B) Full retraction of stick cylinder
(C) Position of the pin in the boom foot
(D) Position of the track
(E) Secured position of the bucket
(F) Position of the pin in the stick nose

  1. Position the machine. Refer to Illustration 2.

  2. Stop the engine.

  3. Connect the linkage and a stationary object with a suitable lifting device (E). Make sure that the pin in stick nose (F) is the same distance from the ground as the pin for the boom foot (C).

    Note: Make sure that the boom is positioned perpendicular to the track. The machine should be configured with the boom, the stick, and the attachments that will be used.

  4. Start the engine.

  5. Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.

  6. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).


    Illustration 3g02936357

  7. Select "Performance" from the main menu in the monitor.


    Illustration 4g02936361

  8. From the "Performance" menu, scroll through the listed parameters to "Pump Outlet Pressure".


    Illustration 5g01344314
    Position of the machine for the measurement of the pump pressure
    (G) Extension of boom cylinder
    (H) Track at the rear or the machine
    (J) Free space between the track and the ground

  9. Slowly extend the boom cylinders. Extend the boom cylinders until the track that is under the rear side of the machine is above the ground. Refer to Illustration 5.

  10. Record the measured pump pressure from the display on the monitor in the cab in Table 1.

  11. Slowly retract the boom cylinder. Retract the boom cylinder until the track that is under the rear side of the machine is on the ground.

  12. The value of the threshold pressure for the overload warning device is 70% of the recorded pump pressure from Step 10. This calculation is shown in Table 1.

    Table 1
    Calculation for Overload Warning Device (OLWD) 
    Pump Pressure (PP)   
    OLWD Pressure = PP x 0.7   

Input The Value Of The Threshold Pressure For The Overload Warning Device



    Illustration 6g02936397

  1. Select "Service" from the main menu in the monitor.


    Illustration 7g02936417

  2. Input the password "9992" and select "ENTER".


    Illustration 8g02936422

  3. Select "Configurations"


    Illustration 9g02936436

  4. Select "Machine Attachments".


    Illustration 10g02936457

  5. Select "Overload Press Threshold". Set the overload pressure threshold to specification. Refer to Table 1 for the specification.

  6. Press "OK" to set the value into memory.

Information System: