Fault Phenomenon: Caterpillar 785 mining truck brake pedal travel becomes longer; after multiple brake applications, braking effect deteriorates.

Troubleshooting Process:
– Checked accumulator: bladder ruptured or valve core leaking.
– Checked pre-charge pressure: nitrogen pressure zero.
– Checked brake pump: brake pump output pressure normal.
– Checked leakage: brake valve internal leakage.

Root Cause: The brake system accumulator bladder ruptured, causing nitrogen to leak and losing the function of storing high-pressure oil and buffering pulsation.

Required Parts: Replace brake accumulator bladder or assembly, recharge with nitrogen.