Know your breaker: Pins, bushings and wear parts explained

Why wear parts matter more than most operators think

Pins and bushings carry the full impact load between the breaker and the chisel. Every blow runs through them. When tolerances open up, even by a few millimetres, the chisel starts to move sideways inside the holder. That lateral movement costs energy, accelerates wear, and shortens tool life across the entire system.

A properly maintained set of wear parts delivers three things at once:

• Full transfer of impact energy from piston to chisel
• Protection of the breaker housing from uneven loads
• Predictable service intervals, so downtime stays planned instead of unexpected

The core wear parts on an ESTM breaker

Every ESTM breaker is built around a simple, robust design with only three moving parts: the piston, control valve and pilot valve. The wear parts that sit around them are equally straightforward, and equally critical:

• Chisel pins: lock the chisel in place and absorb the recoil of every strike
• Bushings (upper and lower): guide the chisel and protect the housing from wear
• Retainer pins and locking systems: prevent pins from walking out under vibration
• Thrust rings and wear plates: absorb axial forces and protect internal surfaces

All ESTM wear parts are manufactured from hardened, wear-resistant steel to match the HARDOX housing of the breaker itself. This keeps wear uniform across the breaker, so no single component fails prematurely.

How to spot worn pins and bushings

Operators don't need a workshop to catch early wear. A quick daily check is usually enough:

• Visible play between the chisel and the lower bushing
• Flattened or mushroomed ends on the chisel pins
• Oval wear patterns inside the bushing bore
• Fine metal dust around the chisel holder
• Noticeable drop in breaking performance on familiar material

If one of these signs appears, the parts should be replaced before the next shift. Running a breaker on worn pins or bushings almost always leads to damage further up the tool, and that's where repair costs climb quickly.

Choosing the right wear parts

Not every pin or bushing on the market fits an ESTM breaker, and aftermarket parts that look identical rarely match the original hardness or tolerances. Using the correct ESTM wear parts keeps the breaker inside its designed operating window, protects the warranty, and ensures the dealer network can support the tool throughout its life.

The ESTM dealer network stocks matched sets of pins, bushings and retainers for every model, so operators get the right part the first time, without guesswork.

Preparation is the job

Pins and bushings are small parts with a big impact on productivity. Checking them daily, replacing them on time, and using genuine ESTM wear parts is the easiest way to protect your investment and keep breaking performance consistent from the first blow to the last.

From hydraulic breakers to chisels, pins and bushings, there's always the right solution for your project. Thanks to the STM dealer network, robust design, and extended warranty, you benefit from maximum productivity, minimal downtime, and the highest quality.