Brake Pedal Creep on the Pre-Start Check
During the pre-start check on a 25-tonne articulated dumper, you find the engine oil and coolant at the correct levels and no visible leaks. On the level concrete pad, however, the service brake pedal slowly creeps toward the floor when you hold firm pressure, and the red brake warning lamp flickers when the engine idles. The machine also pulls to the left under braking. The air pressure gauge reads 8 bar at start-up but drops to 6.5 bar within four minutes after shutdown. The tyres and steering look normal. The supervisor says the warning is ‘just a sensor’ and asks you to drive the machine 300 m to the workshop at lunchtime so the fitter can look at it. The dumper is needed on the haul road within the hour.
1. What is your assessment and immediate action?
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Treat this as a safety-critical brake defect, not a sensor problem. Pedal creep under constant pressure means the hydraulic or air system may not be holding pressure; the flickering red warning and the pressure drop from 8 bar to 6.5 bar in four minutes support a leak or faulty valve. Pulling left under braking also indicates an imbalance. Do not drive the machine, even 300 m. Park on the level pad, apply the parking brake, lower the body, put the controls in neutral, stop the engine, remove the key and fit a ‘do not operate’ tag. Report the defect immediately.
2. What would you record and who should decide whether it moves?
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Record the machine number, hour meter, date and time, the exact symptoms, the pressure readings, the warning lamp behaviour and the pull to the left. Enter it in the site defect book and tell the supervisor and the maintenance provider. The machine should be quarantined until a competent fitter inspects it. Moving it to the workshop is a maintenance recovery operation, not a normal haul; it needs a risk assessment, a competent driver and a controlled route, and the fitter should decide whether it can be moved at all. You should not make that decision under production pressure.
3. If the supervisor says ‘just test it on the haul road’, how do you respond?
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Refuse. A haul-road ‘test’ would expose you and others to a brake failure at speed, and the defect has already shown up in a stationary test. The correct test is a controlled inspection by a competent person, not a production run. Explain the specific evidence and ask the supervisor to record the instruction if they persist. If the machine is needed, the supervisor should arrange another machine or bring the fitter to the pad. Escalate to the site manager if you are pressured.