Hydraulic Breaker Chisel Replacement — When and How
The chisel (also called the tool or moil) is the wear component of a hydraulic breaker — it is designed to be replaced when worn. Using a worn chisel reduces breaking efficiency, increases stress on the front head bushing, and can cause chisel breakage. This guide explains how to identify when a chisel needs replacement, how to remove and install it correctly, and how to select the right chisel type for your application.
Safety Precautions
- Never remove a chisel while the breaker is pressurized or the excavator is running.
- The chisel is heavy — use appropriate lifting assistance for large breakers.
- Wear safety glasses when driving out the chisel retaining pin.
- Inspect the front head bore for damage before installing a new chisel.
Chisel Wear Indicators
Chisels wear in two ways: diameter reduction (the shank wears thinner) and tip wear (the working end wears blunt or deforms). Both types of wear affect performance and must be monitored.
Diameter wear check
Measure the chisel shank diameter with calipers at the point of maximum wear (typically in the bushing contact zone). Compare to the minimum diameter marked on the chisel or specified in the service manual. Replace when the shank diameter reaches the minimum.
A worn shank diameter allows the chisel to develop lateral play in the bushing. Even 1–2mm of excess clearance significantly increases impact loads on the front head.
Tip wear check
Inspect the working tip of the chisel. A moil point should maintain a sharp, conical profile. A blunt chisel tip reduces penetration efficiency and increases the energy required per blow. Reshape or replace when the tip is visibly rounded or deformed.
Some operators have worn chisel tips re-ground or re-hardened by a specialist. This is cost-effective for large chisels (SB50, SB81) but rarely economical for smaller models.
Retaining pin groove wear
Inspect the retaining pin groove on the chisel shank. If the groove is worn or deformed, the retaining pin may not hold the chisel securely, creating a safety hazard. Replace the chisel if the groove is damaged.
Chisel body cracks
Inspect the chisel body for cracks, especially near the retaining pin groove and at the transition between the shank and the working section. Any visible crack is grounds for immediate replacement.
A cracked chisel can break during operation, sending fragments at high velocity. Never operate with a cracked chisel.
Chisel Removal Procedure
Lower the breaker and shut down
Lower the breaker to the ground. Shut down the excavator completely and relieve any residual hydraulic pressure.
Remove the retaining pins
Locate the retaining pins on the front head (typically two pins, one on each side). Use the chisel removal tool or a drift punch and hammer to drive out the retaining pins. Keep the pins in a safe place — they will be reused if in good condition.
Remove the chisel
With the retaining pins removed, the chisel can be pulled or driven out of the front head. For large chisels, use a lifting strap or the excavator's bucket to support the weight. Some chisels are tight in the bushing — use the chisel removal tool to drive them out from the top.
If the chisel is stuck, apply penetrating oil to the bushing area and allow 15–30 minutes before attempting removal again.
Inspect the front head
With the chisel removed, inspect the front head bore and bushing for wear, scoring, or damage. Measure the bushing inner diameter and compare to the specification. If the bushing clearance exceeds the maximum, replace the bushing before installing the new chisel.
Chisel Installation Procedure
Clean and inspect
Clean the front head bore and the new chisel shank. Remove any debris, old grease, or corrosion. Inspect the new chisel for any defects before installation.
Apply chisel paste grease
Apply a generous coat of chisel paste grease to the shank of the new chisel, covering the full length of the bushing contact zone.
Insert the chisel
Insert the chisel into the front head bore. Align the retaining pin groove with the pin holes in the front head. Push the chisel in until the groove is aligned.
Install the retaining pins
Drive the retaining pins into place using the installation tool or a drift punch. Ensure both pins are fully seated and secure.
Grease and test
Apply 3–5 pumps of chisel paste through the grease fitting. Start the excavator and operate the breaker for 2–3 minutes on a test surface to bed in the new chisel.
Chisel Type Selection
Choosing the correct chisel type for the application significantly affects productivity and chisel life:
Moil point (conical): The most versatile chisel type. Suitable for rock breaking, concrete demolition, and general work. The pointed tip concentrates impact energy for maximum penetration.
Blunt (flat) chisel: Best for breaking concrete slabs, asphalt, and materials where a wide fracture is needed. Less effective in hard rock.
Wedge chisel: Used for splitting rock along natural fracture lines. Effective in layered rock formations.
Chisel (flat with edge): Used for cutting concrete, asphalt, and soft rock. Provides a clean cut rather than a fracture.
For most applications, the moil point is the default choice. Use a blunt chisel when breaking flat concrete slabs where the moil point tends to deflect rather than penetrate.
Frequently Asked Questions
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Applies to These Models
This guide is especially relevant for the following hydraulic breaker models.
1–4 ton excavators
The SB10 is a compact mini hydraulic breaker designed for 1–4 ton excavators. Ideal for light demolition, trenching, and confined-space work.
View All8–14 ton excavators
The SB43 is a heavy-duty medium-class hydraulic breaker for 8–14 ton excavators, delivering superior impact energy for hard rock, reinforced concrete, and demanding demolition work.
View All20–35 ton excavators
The SB81 is an extra-heavy hydraulic breaker for 20–35 ton excavators, delivering 2000–3000 J of impact energy for quarrying, mining, and major demolition projects.
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