While navigating a loaded class 8 combination unit up a 6% highway grade, traffic congestion brings all lanes to a halt. To prevent severe drivetrain strain and avoid dangerous backward roll, place the required driver actions for coming to a complete stop, holding the vehicle, and restarting up the incline into the correct sequential order.
- 1Apply steady service foot brake pressure until the combination unit comes to a complete, balanced stop.
- 2Engage the parking brake control valve before removing foot pressure from the service brake pedal.
- 3Select the lowest forward starting gear while maintaining vehicle hold with the parking brake.
- 4Release the clutch pedal gradually until the engine begins to pull against the hold of the parking brake.
- 5Release the parking brake valve smoothly as engine power transfers to drive the vehicle forward without rolling backward.
Answer
The correct sequence begins with bringing the vehicle to a complete stop with the service brake, setting the parking brake before releasing foot pressure, shifting into a low forward starting gear, engaging the clutch until engine torque is felt pulling against the brake, and finally releasing the parking brake as power transfers to propel the vehicle forward without rollback.
On an upgrade stop and restart, safety requires continuous positive vehicle hold. The sequence must progress from service braking to spring parking brake engagement, selecting low gear, finding the clutch friction point to generate forward torque, and releasing the parking brake only after power transfer is established.
Step-by-Step Solution
Key Concept
Upgrade stopping, holding, and anti-rollback restart procedures
Estimated Time:1m 30s