How to Maintain Hydraulic Breaker for Mini Excavator

Excavator hydraulic breakers are usually used to break rock, concrete, asphalt and other construction and aggregate materials. However, Wear and tear is an outright certainty, so maintaining the breaker is vital to keeping it running at peak efficiency.

precautions during use of hydraulic Breaker

Before Operation

• Check the oil level in the tank
• Grease up Chisel
• Check bolts of looseness
• Charge Nitrogen (N2) Gas in Back Head and Accumulator to meet standard pressure required

During Operation

• Avoid blank hitting
• Must place chisel vertically to surface
• Do not blow more than one minute on same spot
• Must replace new front cover once the gap between front cover and chisel is over the maximum wear allowance
• Do not operate the breaker when the cylinder on the excavator is fully extended.

Storage

• When dismounting breaker, be sure to put plugs in
• Foreign matters in piping will be the cause of trouble
• Discharging Nitrogen (N2)
• Be sure to keep piston in the position of back head side

Moving and Lifting Breaker

• Always use eye-bolts when lifting & moving the hydraulic breaker, after fasten up to bracket.
• Fasten the ropes to the shackles (four pieces) and lift the hydraulic breaker up
• Remove the eye-bolts before hydraulic breaker operation

Model	Eye bolt size (mm)	Wire Rope Size (mm)
135/140/150/155/165	M24	∮16
175	M30	∮20

Maintenance intervals

Before hydraulic breaker operation, be sure to check the following points.

Hydraulic oil standard

Normally, any hydraulic oil originally intended for base machine can be used in the hydraulic breaker. However, oil viscosity must be checked timely, because the oil may be heated much more in the hydraulic breaker works than in normal excavator works.

When hydraulic breaker is used continuously the oil temperature normalizes at certain levels, depending on conditions and carrier. At such temperatures, hydraulic oil viscosity should be 20-40 cST.

Recommended hydraulic oil

Maker	ISO VG68(For hat weather use)	ISOVG46(For cold weather use)
ESSO	Nuto H68	Univis N46
SHELL	Tellus oil 68	Tellus oil 46
MOBILE	DTE 16	DTE 15
GULF	Harmony68	Harmony 46

Usually, the hydraulic oil temperature of hydraulic breaker and base machine must be controlled between 40℃ and 60℃. When you operate the hydraulic breaker while the oil temperature exceeds 80℃, you must check the seals.

Replacement of hydraulic oil & filter

Contamination of hydraulic oil may result in part damage, not only in hydraulic breaker but also in carrier main components. We recommend hydraulic oil and oil filter replacement as shown in the following table, which is based on 100% hydraulic breaker operation.

Hydraulic oil	First 250 hours Every 600 hours
Oil filters	First 50 hours Every 100 hours

Hydraulic oil viscosity

The hydraulic breaker must not be started if hydraulic oil viscosity exceeds 1000 cST, not operated when hydraulic oil viscosity falls 15 cST.

Cooling

Maximum permitted hydraulic oil temperature range in continuous hydraulic breaker use in 50-80 oC (120-175 oF), depending on viscosity of oil in the system. Therefore, a reliable hydraulic oil thermometer is necessary. If there is no thermometer on the carrier, one must be installed. Hydraulic oil temperature depends on ambient conditions, carrier cooling system efficiency, and on hydraulic breaker use.

When hydraulic breaker is used continuously, it is necessary to have a cooling system with extra cooling capacity, as compared with normal excavation work.

Apply Grease

Inspection and Charging of Nitrogen (N2) gas

Back head

Accumulator

Inspection of charging pressure

1. Turn the handle of charging gauge counterclockwise.
2. Remove the A plug on the accumulator and charging gauge completely.
3. Remove the cap of adjuster from accumulator.
4. Turn the adjuster counterclockwise slowly to indicate accumulator charging pressure.
5. Remove charging gauge and tighten plug an cap. (Ensure O-rings must be installed in plug and cap).

Charging accumulator with nitrogen gas.

1. After performing steps same inspection of charging pressure.
2. Connect gas hose charging gauge and N₂ gas cylinder.
3. Turn the adjuster counterclockwise after remove the cap from adjuster.
4. Slowly turn handle of N₂ gas counterclockwise to charge accumulator with N₂ gas charging pressure.(refer in Fig.5-7-4)
5. When accumulator is charged with N₂ gas completely, close the adjuster fully.
6. Turn the handle of N₂ gas cylinder clockwise to close.
7. Loosen adjuster of charging gauge to discharge N₂ gas remaining in gas hose.
8. Remove the gas hose from charging gauge to N₂ gas cylinder.
9. After removing gas hose, adjuster the pressure referring A) Inspection of charging pressure
10. After charged accumulator with N₂ gas, check gas leakage from adjuster, plug hole of accumulator.

Pressure Setting

The pressure setting for hydraulic breaker must be lower than the base machine pressure setting in order to protect the pump of base machine.

Normally, set the pressure for hydraulic breaker about 5-10kg/cm2 lower than base machine pressure setting, when the main pressure of base machine is lower than below table.

If hydraulic breaker setting pressure higher than below table: That will be shorten durable of main pump and shorten service life of seals & tool in hydraulic breaker.

If hydraulic breaker setting pressure higher than below table: Hydraulic breaker performance will be downed.

Recommended setting pressure for hydraulic breaker (bar)

45/53/68/75	160-180
85/100	160-180
140/140A	180-200
155/165/175	200-210
135/150	200-210

Seal Inspection

If any hydraulic oil leakage from hydraulic breaker is discovered, faulty seals should be replaced. To figure where seals are bad, refer to following drawings:

Replace seals every 2000 hours of actual operation.

When bad seal is found, the cause of the damage must be determined and rectified.
When seal is changed, apply grease to seal and seal seat, and hold seal firmly with thumb, index and middle fingers, as per marking.
Be careful not to break seal through excessive deformation.

Wear Inspection

Front cover

If the clearance between tool and front cover is too big, this could cause of damage, or breakage of tool through piston irregular contact.

Item	Model	Measureat B	Measureat A	RejectInside Dia.
1	45	10	45	48
2	53	10	53	56
3	68	10	68	72
4	75	10	75	80
5	85	10	85	85
6	100	10	100	105
7	135	10	134.5	140.5
8	140(A)	10	140(A)	146
9	150	10	150	156
10	155	10	155	161
11	165(F)	10	165	172
12	175	10	175	182

If the clearance between tool and front cover is too big, it could cause following problems:

1. It could cause irregular impact and this may shorten the life of piston.
2. It could cause angle of inclination and this may lead to the breakage of the tool.

Tool Pin

When each tool pin is excessively deformed, it is difficult to replace the tool, therefore, after operating the hydraulic breaker every 100 to 150 hours, change the face of each pin that comes in contact with the tool (The faces of each pin can be used).

When replacing each tool pin, check each part for wear, breakage, scores, etc., especially. And remove burrs and swelling on tool pins.

Replace the tool after grinding the worn parts of front cover and tool pins.

• Change the face of tool pins every 100 to 150 hours of actual operation.
• Replace tool pins every 500 hours of actual operation.

Inspection and Replacement of Through Bolt

Torque Table

Before starting the hydraulic breaker operation, check all kind of bolts and nuts for tightness including the through bolts, socket bolts for accumulator, valve housing socket bolts, valve cover socket bolts and bracket bolts.

Also be sure tighten again any loosen bolts and nuts according to the specified torque.
Using the hydraulic breaker with loose bolts and nuts will cause not only oil leakages but also damages to the screw threads and breakage to the bolts. These can lead also defective operation.

After first 10 hours of operating, retighten the bolts and nuts of all components and sections.

At first, lightly tighten the bolts and nuts by referring to the following torque force.
The bolts and nuts should be screwed down alternately and diagonally until the bolts and nuts are tightened to the uniform torque.

Storage

When operation is interrupted or finished

When operation is interrupted or after finished move the base machine on level ground. Remove mud from the hydraulic breaker and set the hydraulic breaker on wood blocks.

• Check whether oil leaks from hydraulic system and whether the tool oil is damaged.
• If the hydraulic breaker is operated in river, dry the hydraulic breaker body and apply the grease to the front head.

Do not touch the tool when hydraulic breaker just stop to work, because it’s very hot.

When hydraulic breaker is not used for a long time-3 weeks or more

• Discharge the nitrogen gas with the back head and accumulator, and then push the piston to avoid rust cylinder.
• Assemble the tool and store the hydraulic breaker indoors after applying the grease to every part, especially internal parts of front head.

If the following procedures are neglected, the rust is generated in the main body to cause serioustroubles.