Steering and Suspension Inspection Checklist

Steering and Suspension

Steering- Check the following components

Steering Box & Hoses:

Consists of a container and hoses that transform steering column action into wheel turning action.

Check that the steering box:

• Is securely mounted, in good condition, and not leaking.
• Has no missing nuts or bolts. Loose bolts or cracks in the steering box could result in loss of steering if the gear box or steering wheel shaft become partially or fully disconnected.

Check the hoses coming from the steering box to make sure they are:

• Not damaged
• Securely mounted
• Not leaking

Steering Linkage:

Transmits steering action from steering box to front wheels.

Worn, loose, or broken steering parts (i.e., drag link, pitman arm, tie rod ends, etc.) can cause loss of steering action. Excessive movement in the linkage can cause the vehicle to wander or experience other serious control problems.

• Check that connecting links, arms, and rods from the steering box to the wheel are not worn or cracked.
• Check that joints and socket are not worn or loose.
• Check for loose or missing nuts, bolts, or cotter pins.

Suspension- Front Axle

Springs/Air/Torque Suspension

Your vehicle rides on leaf, coil, or torque suspension systems which reduce wheel vibrations and bumps created by the road surface.

Damaged or missing leaf spring parts may lead to a loss of control or a rollover if the vehicle falls on the frame or on a tire. Shifted springs may strike a tire, causing a blowout or interference with steering.

• Look for missing, shifted, cracked, or broken leaf springs.
• Look for broken or distorted coil springs.
• If vehicle is equipped with torsion bars, torque arms, or other types of suspension components, check that they are not damaged and are mounted securely.
• Air ride suspension should be checked for damage and leaks.

Spring Mounts

Consist of the brackets, bolts, shackles, and bushings used for attaching springs and/or air bags to vehicle frame. Loose, worn, or broken components may lead to loss of vehicle control or rollover.

• Look for cracked or broken spring hangers/mounts.
• Check for missing or damaged bushings.
• Check for broken, loose, or missing bolts, U-bolts, or other axle mounting parts.
• Mounts should be checked at each point where they are secured to the vehicle frame and axle[s].

U-Bolts & Shock Absorbers

U-bolts secure the springs to the axle. Shock absorbers are gas or hydraulic filled devices that cushion the ride and stabilize vehicle.

• Check to see that U-Bolts are securely mounted and not damaged.
• See that the shock absorbers are securely mounted and not leaking.

Note: Be prepared to perform the same suspension components inspection on every axle (power unit and trailer, if equipped).

Brake Components

Slack Adjuster and Pushrod

The slack adjuster is the link between the brake chamber or actuator and the foundation brake camshaft. It transforms and multiplies the force developed by the chamber into a torque which applies the brakes via the brake camshaft.

If the stroke is too long, it will increase stopping distance or cause vehicle to pull when stopping. Adjustment that is too tight may cause wheel lockup or excessive heat as a result of the brake lining dragging against the drum. This could create a fire hazard.

• Check that slack adjuster is securely mounted.
• Check slack adjuster and pushrod for bent, broken, loose, or missing parts.
• For manual slack adjustors: with brakes released and wheels chocked: when pulled by hand, the pushrod should not move more than approximately 1 inch.

Special Note: The following are two (2) types of slack adjusters found in most air brake systems:

Manual Slack Adjuster

Manual slack adjusters are equipped with an adjusting mechanism, providing a means of adjusting for brake lining wear. Slack adjuster models are designated by a number which represents its maximum torque rating (i.e. a type 20 unit is rated for a maximum of 20,000 inch pounds of torque). Slack adjusters are available in various arm configurations, lengths and spline types.

Automatic Slack Adjuster

Automatic slack adjusters perform the same function as the manual units, except that it automatically adjusts for lining wear. The entire slack adjuster operates as a unit, rotating as a lever with the brake cam shaft as the brakes are applied or released. The most efficient braking action is obtained when the slack adjuster arm travel is minimal; therefore, it is important that brake adjustments are made as often as necessary. The automatic slack adjuster does not require periodic manual adjustment; however, the unit does provide for manual adjustment.

Special Note: The 1 inch test for the brake adjustment is a basic “Rule of Thumb” number to assist the driver in making an educated guess on whether or not his/her brakes may need to be adjusted. The actual stroke adjustment varies for different size chambers. Know the measurements for the vehicle you are driving.

Brake Chamber

Converts air pressure to mechanical force to operate wheel brakes. Damage may reduce braking force, cause uneven braking, or extended stopping distance.

• Check to see that brake chambers are not leaking, cracked or dented, and are mounted securely.
• Make sure there are no loose or missing clamps.

Brake Hoses/Lines

Carries air or hydraulic fluid to wheel brake assembly. Failure may lead to loss of brake response, or with many brakes, a sudden brake application could result in wheel lockup and loss of control.

• Check for cracked, worn, frayed or leaking hoses.
• Check that all couplings and fittings are secure and not leaking.

Brake Drum or Rotor

Brake linings, or pads, rub on the inside of the drum or on the rotor to slow the vehicle down. Cracked drums or rotors may lead to loss of brake response. Worn drums or rotors can cause excessive heat buildup from reduced ability to absorb and dissipate heat or possible “CAM OVER” of S-cam brakes.

• Check brake drums or rotors for cracks, dents, or holes. Also check for loose or missing bolts.
• Check for contaminates such debris or oil/grease.
• Brake linings (where visible) should not be worn dangerously thin.

Brake Linings or Pads

The friction material that wears against the inside of the brake drum, to slow and stop the truck is called the lining; its effectiveness in doing this depends on the brake surface area, surface temperature and the brake lining material itself.

Worn linings or pads can cause excessive heat buildup from reduced ability to absorb and dissipate heat.

• On some brake drums, there are openings where the brake linings can be seen from outside the drum. For this type of drum, check that a visible amount of brake lining is showing.
• Check that brake lining or pads (where visible) have an adequate amount of lining remaining and are not worn dangerously thin. Learn what the minimum acceptable pad or lining thickness is for your vehicle.
• Check condition of linings or pads for cracks and damage.

Note: Be prepared to perform the same brake components inspection on every axle (power unit and trailer, if equipped).

Fluid or Grease on Brakes

When an axle hub seal or hydraulic wheel cylinder leaks, it can result in oil or brake fluid being flung over the braking surfaces.

Since the friction material is porous, it will absorb the oil, and the oil will act as a lubricant on the brake surfaces. This will put more work on the other brakes since the one soaked in oil will not perform as well. If this occurs, the friction material must be replaced.

Oil soaked linings and pads can also catch fire due to the heat generated by friction.

• Check brake drums or rotors, and linings or brake pads for contaminants such as grease, oil, etc.

Wheels

Rims

Tires are mounted on steel, aluminum, or alloy rims. Damaged rims can result in loss of a tire from the rim; loss of a wheel from an axle; loss of air pressure in a tire, or a wheel rolling off a rim due to damage to flange. A damaged wheel can result in loss of vehicle control, leading to an accident.

There are four inspection points for rims:

• Check for damaged or bent rims
• Check for a bent flange
• Rims should have no welding repairs.
• Check for rust trails that may indicate the rim is loose on the wheel.

Tires

Low inflation or lack of tread increases the effect of hydroplaning, reduces cornering ability, and increases the chance of blowout from excessive heat buildup due to increased flexing of the tire. Stopping distance is extended from poor contact with the road surface.

Over inflation increases the chance of tread separation and tire failure. Cuts and bruises may cause tire failure, blowout, and sudden loss of control.

The following three items must be inspected on every tire:

• Tire inflation: Check for proper inflation by using a tire gauge.
• Tread depth: Check for minimum tread depth (4/32 on steering axle tires, 2/32 on all other tires).
• Tire condition: Check that tread is evenly worn and look for cuts or other damage to tread or sidewalls. Ensure valve caps and stems are not missing, broken, or damaged.

Note: for the purposes of the test, tell the examiner how you would properly check inflation. You will not get credit if you simply kick the tires to check for proper inflation.

Special Note: Frequent checks of your tires will pay you dividends on the road. Finding a low tire in time might prevent a blow out in the middle of nowhere! Many drivers carry inflation hoses that can be hooked up to air compressor lines to inflate a low tire until it can be repaired. You can quickly get a good idea of a tire’s approximate level of inflation by walking around the truck and trailer and ‘bumping’ the tire treads with a “ Tire Billy ”, hammer, mallet, ratchet bar, or some other heavy impact tool.

Hub Oil Seals/Axle Seals

• See that hub oil/grease seals and axle seals are not leaking and, if wheel has a sight glass, oil level is adequate.

Lug Nuts

Lug Nuts hold wheel to axle. Loose or missing lug nuts could result in the loss of a wheel. Check that lug nuts are:

• All present- none missing
• Tightly fastened- no signs of looseness such as rust trails or shiny threads, or black streaks on aluminum wheels.
• Not damaged, cracked or distorted

Spacers or Budd Spacing

Axle collar between dual wheels to keep wheels evenly separated. If equipped, check that spacers are not bent, damaged, or rusted through.

• Spacers should be evenly centered, with the dual wheels and tires evenly separated.
• Check for debris between the tires and make sure they are not touching.

Note: Be prepared to perform the same wheel inspection on every axle (power unit and trailer, if equipped).

Side of Vehicle

Doors, Mirrors, and Steps

• Check that door(s) are not damaged and that they open and close properly from the outside.
• Hinges should be secure with seals intact.
• Check that mirror(s) and mirror brackets are not damaged and are mounted securely with no loose fittings.
• Check that steps leading to the cab entry and catwalk (if equipped) are solid, clear of objects, and securely bolted to tractor frame.

Fuel Tank(s)

• Check that tanks are securely mounted
• Check that caps are tight
• Check that there are no leaks from tanks or fuel lines.

Drive Shaft

Transmits power from transmission to drive axle. A bent shaft, loose, or worn U-joints may cause excessive vibration. Loss of drive shaft could dig into pavement causing loss of vehicle control. Also, shaft may come off, hitting other traffic.

• See that drive shaft is not bent or cracked.
• Check that U-joints appear to be secure and free of foreign objects.
• Check guards (if present) to see they are secure and in good condition (Guards are only required on buses).

Battery/Box

Supplies electric energy to a vehicle for starting, lighting and ignition. Commercial vehicles may have several batteries wired together.

• Check to see that batteries are secure.
• Check to see that battery box door is securely fastened
• Check to see that connections are tight and all cell caps (if any) are present.
• Check to see that battery connections are not excessively corroded.

Exhaust System

Piping for removing combustion gases from engine. Leaks under the cab area can cause asphyxiation of the driver and/or passengers. Check the Exhaust System:

• To ensure it is connected tightly, mounted securely and there are no loose clamps.
• From the stack / tail pipe to engine for damage. The exhaust system should have no cracks, holes, or severe dents.
• For any signs of leaking / severe rust / holes or carbon / soot.

If equipped with DEF (emissions after-treatment equipment):

• Check DEF tank to ensure the level of diesel exhaust fluid in the tank is adequate (more than 1/8th tank)
• Check that DEF indicator on the dash is working properly.

Frame

Structural members for supporting vehicle body or trailer body. Loose cross members may reduce vehicle stability and cause handling and cornering problems (i.e., wandering, possible rollover). Welds and/or the frame may develop cracks and ultimately break, resulting in total loss of vehicle control.

• Look for cracks
• Look for broken welds
• Check for illegal holes or other damage to the longitudinal frame members, cross members, box, and floor.

Rear of Vehicle

Mud Flaps

If equipped, check that mud flaps are:

• Mounted securely and not damaged.
• Cover both rear wheels
• Not more than 10” off the ground

Rear Doors/Ties/Lifts

Rear door, ties, chains, cables, ropes, cinches, or other devices used to secure cargo. Lift for loading and unloading cargo. Doors must be closed and latched to prevent cargo loss.

• Check that doors and hinges are not damaged and that they open, close, and latch properly from the outside, if equipped.
• Ties, straps, chains, and binders must also be secure.
• If equipped with a cargo lift, look for leaking, damaged or missing parts and explain how it should be checked for correct operation. Lift must be fully retracted and latched securely.

Reflectors/Reflector Tape (Rear of vehicle)

• Check to make sure the rear of the trailer is equipped with reflective DOT tape
• Make sure the tape and any reflectors are clean and securely fastened

Tractor/Coupling

Air/Electric Lines

Carry air and electricity from power unit to trailer(s). Air- The loss of air to the trailer will result in a partial or total loss of braking to the towed unit. A low air condition will cause sudden application of the trailer’s spring brakes, which may result in loss of control. Electric Lines- Damaged lines may result in loss of the vehicle’s ability to communicate its maneuvers to other drivers (no brake, turn, or stop lights). Not being seen by other traffic at night is a serious traffic hazard.

• Listen for air leaks.
• Check that air hoses and electrical lines are not cut, chafed, spliced, or worn (steel braid should not show through).
• Make sure air and electrical lines are not tangled, pinched, or dragging against tractor parts.

Catwalk/Steps

• Check that the catwalk is solid, clear of objects, and securely bolted to tractor frame.
• Check that steps leading to the cab entry and catwalk (if equipped) are solid, clear of objects, and securely bolted to tractor frame.

NOTE: ONLY STUDY THE FOLLOWING SECTION IF YOU ARE TESTING IN A VEHICLE EQUIPPED WITH A FIFTH WHEEL HITCH

Mounting Bolts

Hold the fifth wheel to the tractor frame. Loose or missing bolts may cause movement between the frame and the coupling assembly resulting in handling and stability problems in turn and curves. Loose bolts could break off, resulting in loss of the trailer.

• Look for loose or missing mounting brackets, clamps, bolts, or nuts.
• Both the fifth wheel and the slide mounting must be solidly attached.
• On other types of coupling systems (i.e., ball hitch, pintle hook, etc.), inspect all coupling components and mounting brackets for missing or broken parts.

Sliding Fifth Wheel Locking Pins (If equipped)

Some fifth wheels slide forward and backward. Locking pins hold the sliding fifth wheel in fixed position along slider rails. If not locked, the trailer could move during travel and result in loss of trailer.

• If equipped, look for loose or missing pins in the slide mechanism of the sliding fifth wheel. If air powered, check for leaks.
• Make sure locking pins are fully engaged.
• Check that the fifth wheel is positioned properly so that the tractor frame will clear the landing gear during turns.

Locking Jaws

Locking jaws maintain a secure connection around the kingpin and the connection to the trailer. The trailer could uncouple during travel if the locking mechanisms is not secured.

• Look into fifth wheel gap and check that locking jaws are fully closed around the kingpin.
• On other types of coupling systems (i.e., ball hitch, pintle hook, etc.), inspect the locking mechanism for missing or broken parts and make sure it is locked securely. If present, safety cables or chains must be secure and free of kinks and excessive slack.

5th Wheel Skid Plate

Plate on which the trailer rests and secures the trailer kingpin. Faulty skid plate and improper connection with the tractor and fifth wheel can result in handling problems, rollover or separation of the tractor and semi-trailer.

• Check for proper lubrication
• Check that 5th wheel skid plate is securely mounted to the platform and that all bolts and pins are secure and not missing. Platform (Fifth Wheel)
• Check to see that there are no cracks or damage to the platform structure which supports the fifth wheel skid plate.

Release Arm (Fifth Wheel)

Release Arm (Fifth Wheel) releases fifth wheel locking jaws so that the trailer can be uncoupled. The release arm must be in the engaged position with locking jaws completely closed around the kingpin when pulling a trailer. This will prevent loss of the trailer during travel.

• Make sure the release arm is in the engaged position and the safety latch (if equipped) is in place.

Trailer Kingpin/Kingpin Plate (Apron)

• Check that the kingpin is not bent.
• Make sure the visible part of the kingpin plate (apron) is not bent, cracked, or broken.

Fifth Wheel Gap

When coupled, there should be no visible gap between the fifth wheel surface and the trailer apron. If there is a gap between the face of the fifth wheel (skid plate) and the metal kingpin plate (apron) of the trailer, the trailer is not coupled correctly and could result in the loss of the trailer during travel.

• Check that the trailer is lying flat on the fifth wheel skid plate (no gap).

Air/Electric Lines- Truck

Air supply hoses and/or electrical lines connecting truck to trailer.

• Check to see that hoses and lines are not cut, cracked, chafed, worn, spliced or taped.
• Check to see that no electrical conductor or steel braid is showing through.
• Listen for audible air leaks
• Make sure air and electrical lines are not tangled, crimped, pinched, or being dragged against truck or trailer parts.
• Check that electric trailer brake lines are not missing, worn or damaged.

Truck Mounting Bolts

Look for loose or missing mounting brackets, clamps, bolts, or nuts on the hitch assembly.

• Inspect all coupling components and mounting brackets on the tow vehicle for missing or broken parts.

Pintle Hook or Ball

• Check Pintle hook and trailer eye or ball mount to make sure the hitch is securely mounted and not damaged

Hitch Release Lever

• Check to see that the hitch release lever is in place, securely mounted, and not damaged.

Truck Safety Chains/Cables

Chains or cables attaching trailer to the truck to prevent a run-away.

• Check to see that safety cables or chains are securely hooked to tow vehicle.
• Check to see that cables or chains are free of damage, kinks, and excessive slack.

Air/Electric Lines- Trailer

Air supply hoses and/or electrical lines connecting trailer to truck.

• Same inspection criteria as the truck mentioned above.

Tongue Storage Area

• Check that the storage area is solid and secured to the tongue.
• Check that cargo in the storage area i.e. chains, binders, etc. are secure.

Tongue or Draw-bar

Trailer component attaching the truck to the trailer.

• Check that the tongue/draw-bar is not bent or twisted and checks for broken welds and stress cracks.
• Check that the tongue/draw-bar is not worn excessively.
• Check eye for welds or excessive wear.

Trailer mounting bolts

Look for loose or missing mounting brackets, clamps, bolts, or nuts on the hitch assembly.

• Inspect all coupling components and mounting brackets on the trailer for missing or broken parts.

Trailer Safety Chains/Cables

Chains or cables attaching trailer to the truck to prevent a run-away. There may be safety chains, a breakaway cable, or both.

• Check to see that safety cables or chains are secure.
• Check to see that cables or chains are free of damage, kinks, and excessive slack.
• On electric brake trailers: Check Battery that prevents the locking of electric brakes unless the trailer becomes un-attached from the truck.

Wherever located, check to see that:

• the battery (s) is securely mounted
• the battery is charged.
• connections are tight
• cell caps are present.
• no excessive corrosion.
• battery cables are secure and free of damage, kinks and excessive slack.

Locking Mechanism

The locking system on a ball hitch would be the lock that keeps the hitch locked over the ball. On a pintle hook, the locking system would be the part that locks the drawbar eye into the pintle hook.

• Check to see that the locking mechanism is locked securely.
• Check to see that there are no loose or missing components.

Sliding Pintle (if so equipped)

• Check that the sliding pintle is secured with no loose or missing nuts or bolts and cotter pin is in place.