Volvo VNL Operator's Manual page 345

340 Emergency Information
Install the washer and nut. Tighten the nut.
This compresses the brake chamber spring
and releases the parking brake.
Do not attempt in any way to disassem-
ble or tamper with the spring brake
chamber. If the force stored on the
spring is suddenly released, it can cause
serious personal injury or death.
W5000644