311B and 312B Excavators Hydraulic System Caterpillar

The checks during operation can be used to find leakage in the system and components that are not functioning correctly. The speed of rod movement or the torque on a motor can be used to check the condition of the cylinders, motors and the pumps.

Specifications are listed in tables for the following operational checks. These specifications are calculated average values. The values will vary due to the configuration of the machine.

A machine with the following equipment was used to achieve these specifications: 4650 mm (15.0 feet 3 inches) boom, 2500 mm (8.0 feet 2 inches) stick and .52 m³ (.68 yd³) bucket.

Table 1

Required Tools
Part Number	Description	Qty
6V-3121	Multitach group	1

Engine speed for an excavator with no load at high idle is 1980 ± 50 rpm.

Table 2

Item		312B Specifications
		New	Rebuild	Service Limit
No load high idle(1)		1980 ± 50 rpm(2)		1780 to 2030 rpm(2)
		2080 ± 50 rpm(3)		1880 to 2130 rpm(3)
No load low idle		850 ± 50 rpm		850 ± 100 rpm
Maximum speed with load(4)		1840 rpm(5)	1790 rpm(5)	1740 rpm(5)
No load speed(6)		1300 ± 80 rpm		1300 ± 100 rpm

(1)	AEC switch in the OFF position
(2)	Three seconds after the engine speed dial was placed at position "10"
(3)	Engine rpm within three seconds after the engine speed dial was placed at position "10"
(4)	Pressure is relieved from both pumps.
(5)	Minimum rpm
(6)	AEC switch in the ON position

Note: A New specification is the performance that can be expected for a new machine. A Rebuild specification is the performance that can be expected after rebuilding the components of a system. Performance beyond the Service Limit is an indication of these problems: improper maintenance or adjustment, component wear and failure.

Preparation For Operational Checks

Perform Steps 1 through 3 prior to performing any of the following operational checks.

1. Place the machine controls at the following settings: Power Mode, Boom Priority Mode, Engine speed dial "10" and AEC switch OFF.

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

3. Set the relief valve pressure settings to the proper specification.

   Note: Refer to Testing and Adjusting, "Pressure Specifications".

Travel Test On Level Ground

Table 3

Required Tools
Part Number	Description	Qty
5P-3277	Measuring Tape	1
	Stopwatch	1

Preparation

Illustration 1	g00296317
(A) Preliminary run 5 m (16.4 ft) (B) Travel distance 20 m (65.6 ft) (C) Bucket height 0.5 to 1 m (1.6 to 3.3 ft)

1. Travel distance must be at least 25 m (82 ft) long. Travel test ground must be hard and as level as possible.

2. Draw a 25 m (82 ft) straight line on travel test ground as a reference line.

3. Position the machine so that one track is parallel with the reference line. Position the machine for the travel test. Refer to Illustration 1.

4. The bucket should be empty.

Test

Reference: Make reference to "Preparation For Operational Checks".

1. Place the travel speed control switch in HIGH position.

2. Move the machine by operating both travel levers at the same time.

3. The first 5 m (16.4 ft) are for a preliminary run. Measure the travel time that is required to travel the remaining 20 m (65.6 ft). Measure the time that is required in each direction.

4. Measure the travel deviation from the reference line.

5. Place the travel speed control switch on the LOW position and repeat Steps 2 through 4.

Table 4

Travel Time (time in seconds)
Travel Speed		New	Rebuild	Service Limit
HIGH	Forward	14.0 or less	16.1 or less	18.2 or less
	Reverse
LOW	Forward	20.3 or less	23.3 or less	26.4 or less
	Reverse

Note: The following table represents the travel deviation (distance) from the reference line.

Table 5

Travel Deviation mm (inch)
Travel Speed		New	Rebuild	Service Limit
HIGH	Forward	800 (31.5) or less	1200 (47.2) or less	1500 (59.1) or less
	Reverse
LOW	Forward	800 (31.5) or less	1200 (47.2) or less	1500 (59.1) or less
	Reverse

Travel Test On Level Ground (Optional Test)

Note: When "Travel Test On Level Ground" cannot be performed, this test may be used as a substitute.

Table 6

Required Tools
Part Number	Description	Qty
	Stopwatch	1

Preparation

Illustration 2	g00297292

1. Position the machine on level ground.

2. Raise a track off the ground. Refer to Illustration 2.

3. Put a mark on a shoe of the raised track.

Test

Reference: Make reference to "Preparation For Operational Checks".

1. Place the travel speed control switch in HIGH position.

2. Move the control lever of the raised track to full travel position.

3. Measure the time that is required for the raised track to make three complete revolutions. Measure the time that is required in each direction.

4. Place the travel speed control switch in the LOW position and repeat Steps 2 through 3.

Table 7

312B Specifications (time in seconds)
Travel Speed		New	Rebuild	Service Limit
HIGH	Forward	15.4 or less	17.7 or less	20.0 or less
	Reverse
LOW	Forward	22.5 or less	25.9 or less	29.3 or less
	Reverse

Table 8

312B L Specifications (time in seconds)
Travel Speed		New	Rebuild	Service Limit
HIGH	Forward	16.0 or less	18.4 or less	20.8 or less
	Reverse
LOW	Forward	23.3 or less	26.8 or less	30.3 or less
	Reverse

Drift On Slope

Note: Measuring the amount of drift of the machine on a slope will determine if there is a need to check the travel brake.

Preparation

Table 9

Required Tools
Part Number	Description	Qty
	Stopwatch	1
	Scale 150 mm (6 inch)	1

Illustration 3	g00297342

1. Place the machine on a slope of 12 degrees. The surface of the slope must be hard and smooth.

2. Position the implements, as shown. Refer to Illustration 3.

3. The bucket should be empty.

Test

Illustration 4	g00297498

1. To indicate the machine's relative position to the slope, put a mark on both the track and the ground. Refer to Illustration 4.

2. Stop the engine.

3. Measure the machine movement on the slope after three minutes.

Table 10

Drift mm (inch)
New	Rebuild	Service Limit
0	0	0

Swing Speed And Overswing (On Level Ground)

Note: Measuring the swing speed and the overswing of the machine will determine if there is a need to check the swing motor or the anti-reaction valve. The fine swing control switch (if equipped) must be in the OFF position.

Table 11

Required Tools
Part Number	Description	Qty
5P-3277	Measuring Tape	1
	Stopwatch	1

Preparation

Illustration 5	g00297618

1. Position the machine on level ground. Refer to Illustration 5.

2. Stop the engine.
   Show/hide table

   Illustration 6	g00293972
   (A) Upper frame (B) Undercarriage frame (C) Marking

3. To indicate the relationship of the two positions, put a mark (C) on the inner race and the outer race of the swing bearing. The mark will be used as a target to stop the swing operation. Refer to Illustration 6.

4. The bucket should be empty.

Test (Overswing)

Reference: Make reference to "Preparation For Operational Checks".

1. Move the swing control lever in either direction until the machine completes a 180 degree swing operation away from the target.

2. Move the swing control lever in either direction until the machine completes a 180 degree swing operation toward the target. Return the swing control lever to the NEUTRAL position at the target.

3. Measure the amount of overswing by measuring the distance between the marks on the swing bearing. Refer to Illustration 6.

Note: Use a point that is visible from the operator seat as a reference point for the target.

Table 12

Specification for Overswing
Item	New	Rebuild	Service Limit
Right Swing	1050 mm (41.3 inch) or less	1210 mm (47.6 inch) or less	1365 mm (53.7 inch) or less
Left Swing

Test (Speed)

1. Move the swing control lever in each direction and measure the time that is required to complete a 180 degree swing operation.

Table 13

Swing Time
Item	New	Rebuild	Service Limit
Right Swing	4.4 seconds or less	5.1 seconds or less	5.7 seconds or less
Left Swing

Swing Speed And Swing Drift (On A Slope)

Note: Measuring the swing speed on a slope will determine if there is a need to check the swing motor and the anti-reaction valve. Measuring the swing drift on a slope will determine if there is a need to check the swing parking brake.

Table 14

Required Tools
Part Number	Description	Qty
5P-3277	Measuring Tape	1
	Stopwatch	1

Preparation

Illustration 7	g00298078

1. The bucket should be empty.

2. Position the machine on a slope of 12 degrees. Refer to Illustration 7.

3. Position the implements at maximum reach. Position the bucket above the ground so that the bucket will not come in contact with any obstacles.

Test (Speed)

Illustration 8	g00298079

1. Position the upper structure at position (A). The upper structure should be at a 90 degree angle to the lower structure. Refer to Illustration 8.

2. Measure the time that is required to swing the upper structure from position (A) to position (B).

3. Position the upper structure at position (C). The upper structure should be at a 90 degree angle to the lower structure.

4. Measure the time that is required to swing the upper structure from position (C) to position (B).

Table 15

Swing Time (seconds)
Item	New	Rebuild	Service Limit
Right Swing	4.0 or less	4.6 or less	5.2 or less
Left Swing

Test (Drift)

Illustration 9	g00298079

1. Position the upper structure at position (A). The upper structure should be at a 90 degree angle to the lower structure. Refer to Illustration 9.
   Show/hide table

   Illustration 10	g00293972
   (A) Upper frame (B) Undercarriage frame (C) Marking

2. To indicate the relationship of the two positions, put a mark (C) on the inner race and the outer race of the swing bearing. Refer to Illustration 10.

3. Stop the engine.

4. Leave the machine in this position for three minutes. Measure the swing drift on the circumference of the swing bearing.

5. Position the upper structure at position (C). The upper structure should be at a 90 degree angle to the lower structure. Refer to Illustration 9.

6. Repeat Steps 3 and 4.

Table 16

Swing Drift mm (inch)
Item	New	Rebuild	Service Limit
Right Swing	0	0	0
Left Swing

Cylinder Drift

Table 17

Required Tools
Part Number	Description	Qty
5P-3277	Measuring Tape	1
	Stopwatch	1

Preparation

Illustration 11	g00298378

Reference: Make reference to "Preparation For Operational Checks".

1. Position the machine on level ground. Refer to Illustration 11.

2. The bucket should be empty.

Test (Boom And Stick Cylinders)

1. Raise the boom until the upper surface of the boom is parallel to the ground.

2. Fully extend the bucket cylinder.

3. Fully retract the stick cylinder.

4. Measure each cylinder's length from cylinder pin to cylinder pin.

5. Stop the engine.

6. Leave the machine in this position for five minutes. Measure each cylinder's length from cylinder pin to cylinder pin for cylinder drift.

Test (Bucket Cylinder)

Illustration 12	g00298379

1. Raise the boom high enough so that the stick can be positioned perpendicular to the ground. Refer to Illustration 12.

2. Fully extend the bucket cylinder.

3. Measure the bucket cylinder's length from cylinder pin to cylinder pin.

4. Stop the engine.

5. Leave the machine in this position for five minutes. Measure the bucket cylinder's length from cylinder pin to cylinder pin for cylinder drift.

Table 18

Cylinder Drift
Item	New	Rebuild	Service Limit
Boom Cylinder	6.0 mm (0.24 inch) or less	12.0 mm (0.47 inch) or less	24.0 mm (0.94 inch) or less
Stick Cylinder	10.0 mm (0.39 inch) or less	15.0 mm (0.59 inch) or less	25.0 mm (0.98 inch) or less
Bucket Cylinder	10.0 mm (0.39 inch) or less	15.0 mm (0.59 inch) or less	25.0 mm (0.98 inch) or less
Blade Cylinder	9.0 mm (0.35 inch) or less	14.0 mm (0.55 inch) or less	18.0 mm (0.71 inch) or less

Cylinder Operating Speed

Table 19

Required Tools
Part Number	Description	Qty
	Stopwatch	1

Preparation

Reference: Make reference to "Preparation For Operational Checks".

1. Place the machine on level ground.

2. The bucket should be empty.

Test (Boom Cylinders)

1. Fully retract the bucket cylinder and the stick cylinders.

Extension Test

Start with the bucket on the ground. Measure the time that is required for the boom cylinders to reach full extension.

Illustration 13	g00298498
(A) Extension test (B) Retraction test

Retraction Test

Start with the boom cylinders at full extension. Measure the time that is required for the bucket to come in contact with the ground.

Test (Stick Cylinder)

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

2. Fully extend the bucket cylinder.

Extension Test

Start with the stick cylinder in the full retracted position. Measure the time that is required for full extension of the stick cylinder.

Illustration 14	g00298558
(A) Extension test (B) Retraction test

Retraction Test

Start with the stick cylinder in the full extended position. Measure the time that is required to retract the stick cylinder.

Test (Bucket Cylinder)

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

2. Position the stick in a perpendicular position to the ground.

Extension Test

Start with the bucket cylinder in the full retracted position. Measure the time that is required for full extension of the bucket cylinder.

Illustration 15	g00298598
(A) Extension test (B) Retraction test

Retraction Test

Start with the bucket cylinder in the full extended position. Measure the time that is required to retract the bucket cylinder.

Table 20

Cylinder Operating Speed (seconds)
Item		New	Rebuild	Service Limit
Boom	Extension	3.0 ± 0.5	3.9 max.	4.5 max.
	Retraction	2.4 ± 0.5	3.1 max.	3.6 max.
Stick	Extension	2.7 ± 0.5	3.5 max.	4.1 max.
	Retraction	2.7 ± 0.5	3.5 max.	4.1 max.
Bucket	Extension	3.7 ± 0.5	4.8 max.	5.6 max.
	Retraction	2.2 ± 0.5	2.9 max.	3.3 max.
Blade	Extension	1.9 ± 0.3	2.5 max.	2.9 max.
	Retraction	1.9 ± 0.3	2.5 max.	2.9 max.