Commercial Drivers License Pre-Trip Inspection Training Manual
A no nonsense approach to passing the CDL pre-trip inspection on the first try   by Robert C. Robinson   
Sneak Peak

 

 

2. FRONT SUSPENSION

 

SPRINGS
 

 

 

 

 

 

 

  

Purpose:

Leaf or coil springs for damping road vibration and supporting the weight of the truck and cargo. Torque arm assembly or an air bag may also act as a spring in place of leaf or coil springs. Damaged, missing, cracked, or shifted leaves may lead to a loss of vehicle control or possibly cause rollover. Shifted springs could strike a tire causing a blowout or possibly interfere with steering.

 

 

Principle:

Look for broken leaves, leaves that have shifted, and are in or nearly in contact with the tires, rim, brake drum, frame, or body. You should also be on the lookout for missing leaves in the leaf spring. If it's a coil spring, driver should look for broken or distorted springs. Driver should be certain that the spring assembly is properly mounted and secure.

 

Scoring Convention:

·         Looks for missing, shifted, cracked or broken leaf spring.

 

·         Check for proper and secure mount.

 

·         Looks for broken or distorted coil springs.

 

·         If vehicle is equipped with torsion bars, torque arms, or other types of suspension components, checks to see that they are not damaged and are mounted securely.

 

  


SPRING MOUNT

 

 

Purpose:

All mounting brackets, bolts, and bushings that are used for attaching the spring(s) to the axle and the vehicle frame. If components are worn or broken, it could lead to a loss of vehicle control.

 

 

Principle:

Driver should check for cracked or broken spring hangers, broken or missing bolts, missing or damaged bushings, and broken, loose, or missing axle mounting parts.

 

 

Scoring Convention: 

Checks that spring mounting brackets, bolts, and bushings are in place.

  • Checks for cracked or broken spring hangers. 
  •  
  • Checks for broken, missing, or loose bolts (including U-bolts).
  • Checks for broken, loose, or missing axle mounting parts.

 

 

 

 

 

 

 

    


  

SHOCK ABSORBER

 

Purpose:

A gas or hydraulic device that stabilizes the vehicle and dampens the ride by converting motion to heat. This is usually accomplished by forcing oil through small internal passages in a tubular housing.


By virtue of the purpose for which they were created (primarily to dampen suspension oscillations), shock absorbers respond to motion; their effects, therefore, are most obvious in transient maneuvers.

 

 

Principle:

Driver should check to see that the shock absorber is firmly attached and not leaking. It should not show any obvious sign of damage.

 

Scoring Convention:

·         Sees that shock absorbers are secure

 

·         Driver mentions that there are no leaks or signs of damage.

 

The score from section two (Front Suspension) is based on the following items:

Springs

Spring Mounts

Axle Mount

Shock Absorber


 

3. FRONT BRAKE

 

SLACK ADJUSTOR

 

 

Purpose:

A slack adjuster is a lever that connects the brake chamber's pushrod with the brake camshaft. It delivers the torque needed to rotate the brake camshaft when the brake pedal is pressed. It will also furnish a means of adjusting clearance between brake shoes and drum to compensate for lining wear. There are self- adjusting slack adjusters and by some accounts, they make up the majority in use today. This being said, by no means does self-adjusting mean non-maintenance, since they must be watched and occasionally adjusted. If the stroke (in the brake rod) is too long, it will increase the stopping distance or cause the vehicle to pull when stopping. An adjustment that is too tight may cause wheel lockup or excessive heat because of the brake lining dragging against the drum. It could also create a fire hazard.

 

Principle:

Driver should check for broken, loose, or missing parts (nuts, bolts, cotter keys/pins). When the pushrod is pulled by hand, the pushrod should not move more than approximately one inch.

 

Scoring Convention:

·         The driver checks for broken, loose, or missing parts.

 

·         When the driver pulls the brake rod by hand, it should not move more than approximately one inch.