How to Replace a SOOSAN Hydraulic Breaker Chisel

The chisel (also called the breaker tool or moil point) is the most frequently replaced wear part on any hydraulic breaker. On SOOSAN SB and SQ series breakers, chisel replacement is a straightforward procedure that can be completed in the field without specialized equipment.

This guide walks you through the complete chisel replacement process, from identifying when replacement is needed to installing the new tool correctly.

Knowing when to replace the chisel is as important as knowing how. Operating with a worn chisel reduces breaking efficiency and can damage the front head and bushing.

Replace the chisel when:

• The chisel tip diameter has worn down by more than 10% of the original specification
• Visible cracks appear anywhere on the chisel body
• The chisel shows bending or deformation — even slight bending causes uneven loading
• The chisel surface shows deep scoring or pitting that cannot be cleaned
• The chisel sticks in the front head and does not slide freely

Refer to your model's service manual for exact specifications.

Before starting, gather the following:

• Chisel pin punch (brass or copper — never steel, to avoid damaging pin holes)
• Hammer (1–2 kg)
• Retaining clip pliers or flat-head screwdriver
• Clean cloth or rag
• EP2 grease and grease gun
• New chisel (genuine SOOSAN part for your model)
• New retaining pins (recommended to replace with chisel)
• Safety glasses and gloves

Before beginning any chisel replacement:

1. Shut down the excavator and remove the key from the ignition
2. Release hydraulic pressure — cycle the breaker control lever several times with the engine off
3. Lower the breaker to the ground — never work under a suspended breaker
4. Allow the breaker to cool — the front head can reach high temperatures during operation
5. Wear safety glasses — retaining pins can spring out unexpectedly

Lower the breaker to the ground with the chisel pointing downward. This is the safest working position and allows gravity to assist with chisel removal.

If working on a workbench, secure the breaker in a stable position with the front head accessible.

Locate the two retaining clips (also called snap rings or lock pins) on either side of the front head. These small spring clips prevent the chisel pin from sliding out during operation.

• Use retaining clip pliers or a flat-head screwdriver to carefully pry out each retaining clip
• Set the clips aside — inspect them for deformation and replace if bent or worn
• Caution: Retaining clips are under spring tension and can fly out. Keep your face away from the front head.

The chisel pin passes through the front head and through the hole in the chisel, locking it in place.

• Position the brass or copper punch against one end of the chisel pin
• Strike the punch firmly with the hammer to drive the pin out from one side
• Never use a steel punch — it will damage the pin hole in the front head
• If the pin is stuck, apply penetrating oil and allow 10–15 minutes before trying again
• Collect the chisel pin and inspect it for wear, bending, or cracking

With the chisel pin removed, the chisel should slide downward out of the front head.

• If the chisel does not slide freely, it may be seized due to lack of lubrication
• Tap the chisel gently with a hammer to break it free — do not use excessive force
• If severely seized, apply penetrating oil around the chisel-to-bushing interface and allow time to penetrate

Before installing the new chisel, inspect the front head components:

Chisel bushing inspection:

• Check the inner diameter of the bushing for wear
• Measure the bushing ID and compare to the new chisel OD — clearance should be within specification
• If the bushing is worn beyond specification, replace it before installing the new chisel

Front head inspection:

• Check for cracks, especially around the chisel pin holes
• Inspect the pin hole for elongation or damage
• Clean out any debris, old grease, and metal particles

When to replace the bushing: Replace the chisel bushing whenever the clearance between chisel and bushing exceeds the manufacturer's specification. Operating with an oversized clearance causes the chisel to rock, accelerating wear on both the chisel and the front head.

• Clean the front head bore thoroughly with a clean cloth
• Remove all old grease, metal particles, and debris
• Apply a light coat of fresh EP2 grease to the inside of the front head bore
• Apply grease to the new chisel's upper shank (the area that contacts the bushing)

• Insert the new chisel into the front head from below, sliding it upward
• Align the chisel pin hole in the chisel with the pin holes in the front head
• The chisel should slide smoothly — if it binds, check alignment and grease application

• Insert the new (or inspected) chisel pin through the front head and chisel pin hole
• Drive the pin fully home using the brass punch and hammer
• The pin should be flush with or slightly recessed from the front head surface on both sides

• Install the retaining clips into their grooves on both sides of the chisel pin
• Ensure each clip is fully seated in its groove — a partially seated clip can work loose during operation
• Tug the chisel pin to confirm it is locked in place

• Apply 3 pumps of grease through the grease nipple
• Manually move the chisel up and down — it should slide freely with no binding
• Visually confirm both retaining clips are in place
• Check that the chisel pin is fully seated

For the first 30 minutes of operation with a new chisel:

• Work at reduced hydraulic pressure if your excavator allows adjustment
• Avoid maximum-force applications — allow the chisel and bushing to seat properly
• Apply grease after the first 30 minutes of operation

SOOSAN offers multiple chisel types for different applications:

Always specify your breaker model when ordering chisels to ensure correct dimensions and material specification.

Genuine SOOSAN chisels are manufactured from alloy steel with precise heat treatment to match the impact energy and operating conditions of each breaker model. Third-party chisels with incorrect hardness can cause premature bushing wear or front head damage.

Contact us at [email protected] to order genuine SOOSAN chisels and wear parts for your SB or SQ series breaker.