304C CR and 305C CR Mini Hydraulic Excavators Hydraulic System Caterpillar

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. 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".

Table 1

Required Tools
Description	Qty
Stopwatch	1

Boom Cylinder

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Illustration 1	g01187151
(A) Extension test (B) Retraction test

1. Start the engine.

2. Place the machine on level ground.

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

4. Empty the bucket.

5. Fully retract the bucket cylinder and fully retract the stick cylinder. Refer to Illustration 1.

6. Position the bucket on the ground. With a stopwatch, measure the time that is required to extend the boom cylinder to full extension.

   Note: Do not include the time of the snubber operation of the boom cylinder.

7. 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.

8. Refer to the specifications in Table 2 for the operating speed of the boom cylinders.

Stick Cylinder

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Illustration 2	g01187149
(A) Extension test (B) Retraction test

1. Start the engine.

2. Place the machine on level ground.

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

4. Empty the bucket.

5. Position the upper surface of the boom parallel to the ground.

6. Fully extend the bucket cylinder. Refer to Illustration 2.

7. Fully retract the stick cylinder. With a stopwatch, measure the time that is required to extend the stick cylinder to full extension.

8. Fully extend the stick cylinder. With a stopwatch, measure the time that is required to retract the stick cylinder to full retraction.

   Note: Do not include the time of the snubber operation of the stick cylinders.

9. Refer to the specifications in Table 2 for the operating speed of the stick cylinder.

Bucket Cylinder

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Illustration 3	g01187147
(A) Extension test (B) Retraction test

1. Start the engine.

2. Place the machine on level ground.

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

4. Empty the bucket.

5. Position the upper surface of the boom parallel to the ground.

6. Position the stick so that the stick is perpendicular to the ground. Refer to Illustration 3.

7. Fully retract the bucket cylinder. With a stopwatch, measure the time that is required to extend the bucket cylinder to full extension.

8. Fully extend the bucket cylinder. With a stopwatch, measure the time that is required to retract the bucket cylinder to full retraction.

9. Refer to the specifications in Table 2 for the operating speed of the bucket cylinder.

Blade Cylinder

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Illustration 4	g01187145
(A) Extension test (B) Retraction test

1. Start the engine.

2. Place the machine on level ground.

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

4. Position the stick so that the stick is perpendicular to the ground.

5. Lower the stick to the ground. Refer to Illustration 4.

6. Fully retract the blade cylinder. With a stopwatch, measure the time that is required to lower the blade to the ground.

7. Position the blade on the ground. With a stopwatch, measure the time that is required to retract the blade cylinder to full retraction.

8. Refer to the specifications in Table 2 for the operating speed of the blade cylinder.

Boom Swing Cylinder

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Illustration 5	g01187054
View from top of machine (A) Extension test (B) Retraction test

1. Start the engine.

2. Place the machine on level ground.

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

4. Position the stick so that the stick is perpendicular to the ground.

5. Fully retract the boom swing cylinder. With a stopwatch, measure the time that is required to extend the boom swing cylinder to full extension.

6. Position the boom swing against the swing stop. With a stopwatch, measure the time that is required to retract the boom swing cylinder to full retraction.

7. Refer to the specifications in Table 2 for the operating speed of the boom swing cylinder.

Specifications

Table 2

Cylinder Operating Speed
Item		Specification
		304C CR	305C CR
Boom	Extension	2.6 ± 0.4 sec	2.8 ± 0.4 sec
	Retraction	2.7 ± 0.4 sec	2.5 ± 0.4 sec
Stick	Extension	3.2 ± 0.4 sec	3.4 ± 0.4 sec
	Retraction	2.6 ± 0.4 sec	2.9 ± 0.4 sec
Bucket	Extension	3.1 ± 0.4 sec	3.1 ± 0.4 sec
	Retraction	2.0 ± 0.4 sec	2.0 ± 0.4 sec
Blade	Extension	1.1 ± 0.2 sec	1.0 ± 0.2 sec
	Retraction	1.0 ± 0.2 sec	1.0 ± 0.2 sec
Boom Swing (with stop)	Extension	5.3 ± 0.4 sec	5.5 ± 0.4 sec
	Retraction	5.4 ± 0.4 sec	5.5 ± 0.4 sec
Boom Swing (without stop)	Extension	5.8 ± 0.4 sec	6.0 ± 0.4 sec
	Retraction	5.9 ± 0.4 sec	6.0 ± 0.4 sec