Fault Phenomenon: Komatsu 830E mining truck during downhill grades, electric braking fails, relying only on mechanical brakes.

Troubleshooting Process:
– Checked resistor strips: alloy resistor strips broke due to thermal expansion/contraction.
– Checked insulators: support insulators cracked, causing short circuit.
– Checked air cooling: uneven cooling causing localized overheating.
– Checked control: excessive braking current.

Root Cause: The braking resistor grid strips fatigued and broke due to long-term high temperature and vibration, causing an open circuit.

Required Parts: Replace braking resistor grid assembly.