Limits of Intervention
The troubleshooting steps below are operator level — observation plus basic intervention. Work on the UHP internals (pistons, valves, seals) is carried out only by USEL Authorised Service. Risk of fatal injury from high pressure.
1. Pressure Does Not Reach the Required Level
The pump is running, but the gauge shows 3,000 bar instead of 4,000 bar.
- CHECK: Is the water supply adequate? Water valve open and the water softener filter not blocked
- CHECK: A leak on the UHP line? — A visible water trace or a glinting pinhole spray (at high pressure even a small leak is dangerous)
- CHECK: Pump oil temperature (above 65°C is abnormal — the pump may be going into protection mode)
- CHECK: The cutting head orifice is blocked — fit a spare head and test
- SOLUTION: If there is a leak call service; if there is a blockage change the orifice; wash the water filter
2. The Pump Makes an Abnormal Noise While Running
- "Knocking" noise — a sign of piston or valve damage. Stop the machine IMMEDIATELY and call service.
- "Whining" → motor bearing or belt tension. Check the vibration visually.
- "Water leak" noise → a leak on the low-pressure line, the water recirculation is faulty
- "Crackling" → contactor or electrical cabinet — ELECTRICAL FAULT, switch off at once
- SOLUTION: Never ignore an abnormal noise — the machine is not run until the cause has been diagnosed
3. The Pump Oil Is Overheating (Above 65°C)
- CHECK: Is the cooling water flow rate adequate? (above 15 L/min is normal)
- CHECK: Pump oil level — if it is at the low mark the temperature rises
- CHECK: Is the cooling heat exchanger blocked? — limescale build-up calls for annual cleaning
- CHECK: Is the ambient temperature high? (a fan should be added in environments of 35°C and above)
- SOLUTION: Check the oil change schedule (an oil change every 500 hours is typical on KMT) and stop the machine in extreme heat if necessary
4. The Pressure Fluctuates Continuously
- CHECK: Accumulator (pressure vessel) — the gas pre-charge pressure may have dropped, a service measurement is needed
- CHECK: The valve assembly is leaking — the pump and the UHP line surge together
- CHECK: Low water supply — the pump is starving, so the pressure falls and rises
- SYMPTOM: The cutting stream vibrates and wavy lines form on the surface
- SOLUTION: An accumulator service check is mandatory and the valve assembly must be inspected
5. The Pump Does Not Run / Does Not Start
- CHECK: Main isolator ON, emergency stop released
- CHECK: Phase balance (±5% between the three phases is normal) — an electrician is needed
- CHECK: Oil pressure switch — if the minimum oil pressure is not reached the pump will not start
- CHECK: Has the thermal overload relay tripped?
- CHECK: Water inlet switch — if there is no water flow the pump goes into protection mode
- SOLUTION: If there are fault codes on the panel, report them to USEL Service
6. Water Leak (Low-Pressure Line)
A leak has appeared outside the UHP line, on the pump inlet or on the water recirculation line.
- CHECK: A cracked hose or a loose connection
- CHECK: An aged pump seal — the leak shows as periodic drips
- SOLUTION: Low-pressure leaks can be dealt with by the operator by tightening and changing the seal; a UHP leak is for SERVICE ONLY
7. Irregular Garnet Feed
The garnet sometimes comes through and sometimes blocks — cutting performance zigzags.
- CHECK: Is the hopper lid closed? (moisture getting in causes clumping)
- CHECK: Damp or clumped garnet in the garnet line
- CHECK: Is the garnet feed valve (vibrator) working?
- CHECK: A blockage inside the line (disconnect the hose and clean it with compressed air)
- SOLUTION: Empty the hopper, clean it out, fill it with dry garnet and add a silica gel sachet
8. The Pump Shuts Itself Down Automatically
- CHECK: The alarm code on the screen — record it and report it to USEL Service
- The most common cause: excessive oil temperature (above 65°C) → a cooling system problem
- The second most common: low oil pressure → oil level or a blocked filter
- The third: motor thermal trip → an electrical fault
- SOLUTION: Do not press reset before the alarm code has been interpreted → the fault recurs and component damage increases
Preventive Maintenance Matters
70% of pump failures stem from neglected maintenance. The annual and five-yearly factory servicing is carried out by USEL Authorised Service — it covers the pump seals, valve set, accumulator gas charge and oil filter changes. The detailed list: