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Suspension Systems

The suspension system holds up the vehicle and its load and keeps the axles in place. Therefore, broken suspension parts can be extremely dangerous. Look for the following:

  • Spring hangers (Figure 2-2) that allow movement of axle from proper position.
  • Cracked or broken spring hangers.
  • Missing or broken leaves in any leaf spring. If 1/4 or more are missing, it will put the vehicle “out of service,” but any defect can be dangerous (Figure 2-3).
  • Broken leaves in a multi-leaf spring, or leaves that have shifted so they might hit a tire or other part.
  • Leaking shock absorbers (Figure 2-4).
  • Torque rod or arm, U-bolts, spring hangers, or other axle positioning parts that are cracked, damaged or missing (Figure 2-2).
  • Air suspension systems that are damaged and/or leaking (Figure 2-4).
  • Any loose, cracked, broken or missing frame members.

Figure 2-2
Key Suspension Parts

Figure 2-3
Safety Defect Broken Leaf in Leaf Spring

Figure 2-4
Air Suspension Parts

Exhaust System

A broken exhaust system can let poisonous fumes into the cab or sleeper berth. Look for the following:

  • Loose, broken or missing exhaust pipes, mufflers, tailpipes or vertical stacks.
  • Loose, broken or missing mounting brackets, clamps, bolts or nuts.
  • Exhaust system parts rubbing against fuel system parts, tires or other moving parts of vehicle.
  • Exhaust system parts that are leaking.

Emergency Equipment

Vehicles should be equipped with the following emergency equipment:

  • Fire extinguisher(s).
  • Spare electrical fuses (unless equipped with circuit breakers).
  • Warning devices for parked vehicles (e.g., three reflective warning triangles).

Cargo (trucks)

Make sure the truck is not overloaded and the cargo is balanced and secured before each trip. If the cargo contains hazardous materials, you must inspect for proper papers and placarding.

CDL Pre-Trip Inspection Test

To obtain a CDL you must pass a pre-trip vehicle inspection test. You will be tested to see if you know whether your vehicle is safe to drive. You may be asked to do a pre-trip inspection of your vehicle and explain to the examiner what you would inspect and why. Section 10 describes what to inspect and how to inspect it.

Remember: If 1/4 or more of the leaf springs are broken or missing, the vehicle must be placed out of service. You may see this on the written exam and will absolutely need to know that for the pre-trip inspection.
It is very important to memorize the three required emergency equipment items that every commercial vehicle must have. You will most likely get a question on this on the written exam and will need to know it for the pre-trip exam as well. This must be memorized!

Pre-trip Inspection:

A pre-trip inspection is a thorough inspection of the truck completed before driving for the first time each day.

Federal and state laws require that drivers inspect their vehicles. Federal and state inspectors also may inspect your vehicles. If they judge a vehicle to be unsafe, they will put it “out of service” until it is repaired.

CDL:

Commercial Driver's License (CDL)

A CDL is required to drive any of the following vehicles:

  • Any combination of vehicles with a gross combined weight rating (GCWR) of 26,001 or more pounds, providing the gross vehicle weight rating (GVWR) of the vehicle being towed is in excess of 10,000 pounds.
  • Any single vehicle with a GVWR of 26,001 or more pounds, or any such vehicle towing another not in excess of 10,000 pounds.
  • Any vehicle, regardless of size, designed to transport 16 or more persons, including the driver.
  • Any vehicle required by federal regulations to be placarded while transporting hazardous materials.

Sleeper Berth:

The portion of the tractor behind the seats which acts as the "living space" for the driver. It generally contains a bed (or bunk beds), cabinets, lights, temperature control knobs, and 12 volt plugs for power.

OWI:

Operating While Intoxicated

OOS:

When a violation by either a driver or company is confirmed, an out-of-service order removes either the driver or the vehicle from the roadway until the violation is corrected.

Review Questions - Click On The Picture To Begin...

The following are common suspension system defects except:
  • Leaking shock absorbers
  • Cracked or broken spring hangers
  • Missing or broken leaf springs
  • Bent side rails

Quote From The CDL Manual:

The suspension system holds up the vehicle and its load and keeps the axles in place. Therefore, broken suspension parts can be extremely dangerous. Look for the following:

  • Spring hangers that allow movement of axle from proper position.
  • Cracked or broken spring hangers.
  • Missing or broken leaves in any leaf spring. If 1/4 or more are missing, it will put the vehicle "out of service," but any defect can be dangerous.
  • Broken leaves in a multi-leaf spring, or leaves that have shifted so they might hit a tire or other part.
  • Leaking shock absorbers.
  • Torque rod or arm, U-bolts, spring hangers, or other axle positioning parts that are cracked, damaged or missing.
  • Air suspension systems that are damaged and/or leaking.
  • Any loose, cracked, broken or missing frame members.
Next
The following emergency equipment is required on all commercial motor vehicles except:
  • Fire Extinguisher
  • Three red reflective triangles
  • First Aid Kit
  • All of these are required

Quote From The CDL Manual:

Emergency Equipment: Vehicles should be equipped with the following emergency equipment:

  • Fire extinguisher(s)
  • Spare electrical fuses (unless equipped with circuit breakers)
  • Warning devices for parked vehicles (e.g., three reflective warning triangles)

TruckingTruth's Advice:

It is almost guaranteed that this type of question will show up on both your written exam as well as the pre-trip exam. The 3 required emergency equipment items absolutely must be memorized!

Prev
Next
The following emergency equipment must be carried on all commercial motor vehicles:
  • First aid kit, fire extinguisher, and three red reflective warning triangles
  • Fire extinguisher, spare electrical fuses (unless equipped with circuit breakers), and three red reflective warning triangles
  • Spare electrical fuses (unless equipped with circuit breakers), road flares, and a fire extinguisher
  • Fire extinguisher, first aid kit, and road flares

Quote From The CDL Manual:

Emergency Equipment Vehicles should be equipped with the following emergency equipment:

  • Fire extinguisher(s)
  • Spare electrical fuses (unless equipped with circuit breakers)
  • Warning devices for parked vehicles (e.g., three reflective warning triangles)

TruckingTruth's Advice:

It is almost a guarantee that a question like this will show up on your written exam. You will certainly be asked about emergency equipment during your pre-trip exam as well. The three required pieces of emergency equipment that must be carried with you has to be memorized. This one is very important!

Prev
Next
In a commercial vehicle suspension system, how many leaf springs may be missing?
  • No more than 1/4 of the leaf springs can be missing
  • None can be missing
  • No more than 1 leaf spring can be missing
  • No more than 1/2 of the leaf springs can be missing

Quote From The CDL Manual:

Suspension systems: The suspension system holds up the vehicle and its load and keeps the axles in place. Therefore, broken suspension parts can be extremely dangerous. Look for the following:

  • Spring hangers that allow movement of axle from proper position.
  • Cracked or broken spring hangers.
  • Missing or broken leaves in any leaf spring. If 1/4 or more are missing, it will put the vehicle "out of service," but any defect can be dangerous.
  • Broken leaves in a multi-leaf spring, or leaves that have shifted so they might hit a tire or other part.
  • Leaking shock absorbers.
  • Torque rod or arm, U-bolts, spring hangers, or other axle positioning parts that are cracked, damaged or missing.
  • Air suspension systems that are damaged and/or leaking.
  • Any loose, cracked, broken or missing frame members.

TruckingTruth's Advice:

Be sure to memorize that 1/4 or more leaf springs missing is unacceptable and will put the vehicle out of service. This may be included on the written exam and will need to be memorized for the pre-trip exam.

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