If your hydraulic hammer has started “tapping” instead of striking, or the impact cycle feels slower and weaker than usual, the good news is that in most cases the cause is identifiable and fixable without a full teardown. Before assuming the breaker itself has failed, it helps to run through the most common causes in order, starting with the easiest to check.
Below are the six most frequent reasons a hydraulic hammer loses power, what each one looks like in the field, and which component is usually responsible.
1. Insufficient Hydraulic Flow or Pressure from the Carrier
This is the single most common cause of a weak-hitting breaker, and it isn’t a fault of the hammer itself. Every hydraulic hammer is designed to operate within a specific flow and pressure range. If the excavator’s auxiliary hydraulic circuit is undersized, misconfigured, or the carrier is simply the wrong weight class for the breaker, the piston never receives enough energy to build full impact force.
How to check: Compare the excavator’s actual auxiliary flow and pressure output (from the machine’s display or manual) against the breaker’s rated specifications. A mismatch here means no internal part is failing yet, but continuing to operate under-supplied can accelerate wear on the valve and piston over time.
As a general reference, typical operating ranges across common excavator weight classes look roughly like this:
| Excavator Class | Typical Oil Flow | Typical Working Pressure |
| Mini (1-3 ton) | 15-40 L/min | 100-160 bar (1,450-2,320 psi) |
| Medium (5-20 ton) | 60-160 L/min | 140-180 bar (2,030-2,610 psi) |
| Large (20-45 ton) | 160-350 L/min | 160-200 bar (2,320-2,900 psi) |
These are general industry ranges, not a substitute for the exact specification of your specific breaker model, always confirm against the rating plate or spec sheet before adjusting anything.
View SWT Hydraulic Breakers to check detailed specifications and weight class matches]
2. Low Nitrogen (Accumulator) Pressure
The nitrogen chamber acts like a spring that stores energy during the piston’s upward stroke and releases it on the downward strike. When nitrogen pressure drops, usually from a slow leak, the breaker will still cycle but each blow feels soft, and in worse cases the tool just “taps” the material without breaking it.
Field signs: hydraulic hoses bouncing or jumping more than normal, inconsistent strike rhythm, breaking performance that degrades gradually rather than stopping all at once.
Fix: Nitrogen pressure should be checked periodically with a charging regulator and topped up to the manufacturer’s specified value, not by guesswork. Pre-charge pressure varies by breaker size, but commonly falls somewhere in the 10-25 bar (145-360 psi) range, the exact figure is always stamped on the breaker’s rating plate or listed in its manual, and that’s the number to charge to, not a generic industry average.
Browse SWT Hydraulic Breaker Spare Parts for accumulator components, nitrogen charging tools, and replacement kits.
3. Worn Piston or Cylinder
Because the piston is in constant high-speed contact with the cylinder wall, wear here is gradual rather than sudden. As clearances increase, internal pressure leaks past the piston instead of being converted into strike force, so power loss tends to show up as a slow decline over weeks or months of use rather than a sudden stoppage.
Field signs: breaker still cycles normally but impact energy keeps dropping even after nitrogen and hydraulic supply have been confirmed correct.
Browse SWT Hydraulic Breaker Spare Parts for replacement pistons, cylinders, and internal components, or Request a Quote for your specific hammer model.
4. Control Valve Stuck or Worn
The control valve is what redirects oil flow to switch the piston between upward and downward strokes. If it sticks or wears out of tolerance, the cycle becomes irregular or stops completely, contamination in the hydraulic oil is a common contributing factor here.
Field signs: breaker doesn’t fire at all, or cycles inconsistently even though flow and pressure at the inlet are correct.
5. Seal Leak or Oil Ingress into the Back Head
This is a less obvious cause but a fairly common one in the field: if seals fail and hydraulic oil migrates into the back head (the nitrogen chamber area), the piston can no longer compress properly on the return stroke. A telltale pattern is a breaker that seems to recover briefly after nitrogen is bled off, then loses power again shortly after as pressure builds back up from the trapped oil.
Fix: This requires disassembly and replacement of the seal kit, it isn’t something that can be resolved by adjusting nitrogen pressure alone.
6. Worn Bushing or Chisel
Not a power loss in the strict sense, but worn bushings or a dull/mismatched chisel reduce how much of the piston’s energy actually transfers into the material, so the breaker can feel underpowered even when every internal component is working correctly.
Field signs: excessive play between the tool and the front head, or noticeably slower demolition progress despite normal cycling.
Find replacement chisels, front bushings, and lock pins on the SWT Hydraulic Breaker Spare Parts Catalog.
Quick Diagnostic Checklist
| Symptom | Likely Cause | Part to Check |
| Weak hits from the start, never worked at full power | Flow/pressure mismatch with carrier | Carrier hydraulic settings |
| Tapping without real force, hoses bouncing | Low nitrogen pressure | Accumulator / nitrogen kit |
| Gradual decline in power over weeks | Piston/cylinder wear | Piston / cylinder |
| No firing, or inconsistent cycling | Valve stuck or worn | Control valve |
| Power returns briefly then fades again | Oil in back head | Seal kit |
| Normal cycling, slow demolition progress | Worn bushing/chisel | Bushing / tool |
(Note: this table is meant to be scanned quickly on-site, worth keeping as a simple table rather than prose if the CMS supports it.)
Frequently Asked Questions
How often should nitrogen pressure be checked? As part of routine maintenance, ideally at scheduled service intervals rather than only after a problem appears, since gradual leaks are easy to miss until performance has already dropped.
Can I keep operating a hammer that’s losing power? Not recommended. Running an underpowered breaker to compensate for low pressure or worn components usually accelerates wear on the parts that are already stressed, turning a simple fix into a more expensive repair.
Does a weak-hitting hammer always mean a broken part? No. The most common cause is a mismatch between the excavator’s hydraulic output and the breaker’s requirements, not a failed component. It’s worth checking the carrier’s settings before assuming the hammer itself needs repair.
Need a Replacement Part?
If your diagnosis points to a worn or failed component, SWT supplies spare parts individually, including accumulators, pistons, cylinders, valves, seal kits, and bushings, so you can replace only what’s needed instead of the whole unit. Contact the SWT Team to request a quote or confirm the exact replacement parts for your breaker model.