Comprehensive Commercial Vehicle In-Cab Inspection and Air Brake Procedures

Pre-Trip Wheel Chocking Procedures

• Wheel chock deployment:
  • Retrieve wheel chocks before mounting the vehicle cab.
  • Place exactly $1$ wheel chock on the inside of each tire.
  • Purpose: Prevent the truck from rolling forwards or backwards during mechanical testing and brake system disengagement.

Four-Stage Air Brake Inspection

• Overview of the four-stage brake test protocol:

  • Stage $1$: Safe Start.
  • Stage $2$: Applied Pressure Test.
  • Stage $3$: Low Air Warning Light and Buzzer Test.
  • Stage $4$: Tractor and Trailer Protection Valve Pop-Out Test.

• Stage $1$: Safe Start:

  • Pre-ignition checklist and mandatory verbal declaration:
  • Verbalize clearly: "My wheels are chocked, my brakes are set, and my truck is at neutral."
  • Ignition and air pressure buildup:
  • Turn the truck ignition on and start the engine.
  • Closely monitor the dashboard air pressure gauge as pressure builds toward the governor cutoff range of $120\text{--}140\,\text{psi}$.
  • Audible cutoff confirmation: Listen for the air system to "sneeze" (governor air discharge), which alerts that air pressure has built up to the proper pressure of $120\text{--}140\,\text{psi}$ governor cutoff.

• Stage $2$: Applied Pressure Test:

  • System configuration:
  • Turn the vehicle engine completely off.
  • Turn the ignition key back to the "on" electrical position.
  • Release both the tractor and trailer parking brakes (push both valves in).
  • Brake application:
  • Step firmly on the service brake pedal with foot pressure.
  • Allow the air pressure gauge to stabilize.
  • Timing and leakage rate parameters:
  • Request to be timed for an exact duration of $1\,\text{minute}$.
  • Hold firm foot pressure on the service brake pedal continuously for $1\,\text{minute}$.
  • Leakage threshold: Air pressure must not drop by more than $4\,\text{psi}$ within that $1\,\text{minute}$ period while actively listening for audible air leaks.
  • Verbalize confirmation that no more than $4\,\text{psi}$ was lost in $1\,\text{minute}$ and no audible leaks were detected.

• Stage $3$: Low Air Warning Light and Buzzer Test:

  • System depressurization procedure:
  • Repeatedly pump (fan) down the service brake pedal to deplete reservoir air pressure.
  • Threshold of activation:
  • Pump the brakes until the low air warning light illuminates and the warning buzzer activates.
  • The warning light and buzzer must activate at $55\,\text{psi}$ or above.
  • Verbalize confirmation that the warning light and buzzer activated at $55\,\text{psi}$ or above.

• Stage $4$: Protection Valve Pop-Out Test:

  • Continuous air depletion procedure:
  • Continue pumping down the service brake pedal to further drop the remaining air pressure.
  • Valve ejection parameters:
  • Observe the tractor and trailer protection valves on the dashboard.
  • Deplete air until both protection valves automatically pop out.
  • Required activation threshold: Both valves must pop out between $20\,\text{psi}$ and $45\,\text{psi}$.
  • Verbalize confirmation that both protection valves popped out between $20\,\text{psi}$ and $45\,\text{psi}$.

• Post-test air recharge:

  • Restart the vehicle engine immediately after the protection valves pop out.
  • Allow the air pressure to rebuild completely to $120\text{--}140\,\text{psi}$ governor cutoff before initiating any vehicle movement or subsequent brake checks.

Parking, Trailer, and Service Brake Functional Checks

• Wheel chock removal:

  • Exit the vehicle cab once air pressure returns to $120\text{--}140\,\text{psi}$ governor cutoff.
  • Remove all wheel chocks from the tires prior to testing brake hold capacity.

• Valve identification and color coding:

  • Red octagonal valve: Trailer emergency/parking brake.
  • Yellow diamond valve: Tractor parking brake.

• Trailer brake check:

  • Release the tractor parking brake (push yellow valve in) while keeping the trailer brake set (red valve out).
  • Apply foot to the brake pedal, shift transmission into drive, and apply gentle acceleration.
  • Verify that the trailer brake holds the vehicle stationary against the engine power.

• Tractor parking brake check:

  • Release the trailer brake (push red valve in) while keeping the tractor brake set (yellow valve out).
  • Shift the vehicle into drive and apply gentle acceleration.
  • Verify that the tractor parking brake holds the vehicle stationary against the engine power.

• Service brake check:

  • Release both the tractor and trailer protection valves simultaneously by pushing both the red and yellow knobs in.
  • Place the truck transmission into drive.
  • Accelerate the vehicle forward to approximately $5\,\text{mph}$.
  • Depress the service brake pedal firmly while completely removing hands from the steering wheel.
  • Assessment standard: Ensure the vehicle comes to a complete stop smoothly without pulling or drifting to the left or right.
  • Verbalize confirmation: State that the truck did not pull left or right.

Cab Lighting Indicators and Dashboard System Checks

• Dash lighting indicator checks:

  • Left turn signal indicator: Engage left signal; verify indicator flashes on dashboard.
  • Right turn signal indicator: Engage right signal; verify indicator flashes on dashboard.
  • Four-way emergency flashers: Engage hazard switch; verify both dash indicator arrows flash simultaneously.
  • Headlights: Turn on low-beam headlights; verify the green dash indicator illuminates.
  • High beams: Engage high-beam switch; verify the blue dash indicator illuminates.

• Electronic dashboard safety systems check:

  • Turn the engine off and turn the ignition key back to the "on" position.
  • Observe dash display and trailer:
  • Point out that the Anti-lock Braking System (ABS) and Diesel Exhaust Fluid (DEF) warning lights illuminate (come on) and then extinguish (go off) on the dashboard and on the trailer.

Emergency Equipment Inspection

• Cab under-bunk storage area:

  • Fire extinguisher:
  • Inspect mounting: Verify it is properly mounted and secured.
  • Inspect charge status: Check pressure gauge to verify it is fully charged.
  • Reflective warning devices:
  • Verify presence of exactly $3$ red reflective triangles.
  • Verify that the triangles are properly mounted and secured.

• Glove compartment storage:

  • Spare electrical fuses:
  • Open glove box and verify presence of spare fuses for vehicle electrical circuits.

Windshield, Mirrors, and Visibility Equipment

• Windshield:

  • Mounting status: Properly mounted and secured.
  • Structural condition: Not cracked, bent, or broken.
  • Clarity: Clean and completely free of any obstruction.

• Mirrors (traffic monitoring devices):

  • Mounting status: Properly mounted and secured.
  • Structural condition: Not cracked, bent, or broken.
  • Cleanliness: Clean and completely free of obstruction.
  • Driver alignment: Properly adjusted to the individual driver.

• Windshield wipers and washer system:

  • Wiper arms and blades: Properly mounted and secured, not cracked, bent, or broken.
  • Wiper motor operation: Turn wipers on and verify that they operate smoothly across the windshield.
  • Washer fluid: Depress washer fluid control button and verify that fluid sprays and operates smoothly.

Climate Control and Warning Devices

• Heater and defroster systems:

  • Setting selection: Switch climate control mode to defroster and heater.
  • Temperature adjustment: Switch temperature to maximum heat and increase fan speed fully ("crank it up").
  • Airflow verification:
  • Feel upper dash vents to verify that the defroster is working correctly.
  • Feel floor vents to verify that the cab heater is working correctly.

• Vehicle warning horns:

  • City horn (electric horn): Depress horn control on steering wheel; verify city horn operates correctly.
  • Air horn: Pull lanyard/control; verify air horn operates correctly.
  • Completion: These operational checks conclude the in-cab safety and functional inspection.