308C CR Excavator Hydraulic System – Cylinder Speed – Check – Boom, Stick and Bucket

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” for the engine speed that was used for this test. Refer to Testing and Adjusting, “Operational Checks” for the machine configurations that were 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”.

  1. Perform the following steps in order to test the operating speed of the boom cylinders.
    1. Start the engine.
    1. Place the hydraulic activation control lever in the UNLOCKED position.
    1. Place the machine on level ground.
    1. Place the machine controls at the following settings: Engine speed dial “10” and Low idle switch OFF.
    1. The bucket should be empty.

      Illustration 1 g00298498

      (A) Extension test

      (B) Retraction test

    1. Fully retract the bucket cylinder and the stick cylinder.
    1. Position the bucket on the ground. With a stopwatch, measure the time that is required to fully extend the boom cylinders.
    1. Position the boom cylinders at full extension. With a stopwatch, measure the time that is required for the bucket to come in contact with the ground.
    1. Refer to the specifications in Table 1 for the operating speed of the boom cylinders.
  1. Perform the following steps in order to test the operating speed of the stick cylinder.
    1. Start the engine.
    1. Place the hydraulic activation control lever in the UNLOCKED position.
    1. Place the machine on level ground.
    1. Place the machine controls at the following settings: Engine speed dial “10” and Low idle switch OFF.
    1. The bucket should be empty.

      Illustration 2 g00298558

      (A) Extension test

      (B) Retraction test

    1. Position the upper surface of the boom parallel to the ground.
    1. Fully extend the bucket cylinder.
    1. Retract the stick cylinder. With a stopwatch, measure the time that is required to fully extend the stick cylinder.
    1. Extend the stick cylinder. With a stopwatch, measure the time that is required to fully retract the stick cylinder.
    1. Refer to the specifications in Table 1 for the operating speed of the stick cylinder.
  1. Perform the following steps in order to test the operating speed of the bucket cylinder.
    1. Start the engine.
    1. Place the hydraulic activation control lever in the UNLOCKED position.
    1. Place the machine on level ground.
    1. Place the machine controls at the following settings: Engine speed dial “10” and Low idle switch OFF.
    1. The bucket should be empty.

      Illustration 3 g00298598

      (A) Extension test

      (B) Retraction test

    1. Position the upper surface of the boom parallel to the ground.
    1. Position the stick so that the stick is perpendicular to the ground.
    1. Fully retract the bucket cylinder.
    1. With a stopwatch, measure the time that is required to fully extend the bucket cylinder.
    1. Position the bucket cylinder at full extension. With a stopwatch, measure the time that is required to fully retract the bucket cylinder.
    1. Refer to the specifications in Table 1 for the operating speed of the bucket cylinder.
Table 1
Cylinder Operating Speed (seconds)    
Item     New     Rebuild     Service Limit    
Boom     Extension     3.6 ± 0.5     4.7 (1)     5.4 (1)    
Retraction 2.9 ± 0.5     3.8 (1)     4.4 (1)    
Stick     Extension     3.0 ± 0.5     3.9 (1)     4.5 (1)    
Retraction 2.3 ± 0.5     3.0 (1)     3.5 (1)    
Bucket     Extension     4.2 ± 0.5     5.5 (1)     6.3 (1)    
Retraction 2.8 ± 0.5     3.6 (1)     4.2 (1)    
( 1 ) Maximum