Container Chassis Preventive Maintenance

CIE Manufacturing

The title references an age-old adage, but very applicable when it comes to preventive maintenance (PM) on not only container chassis, but all the equipment in a fleet. Just like all on-highway commercial vehicles, container chassis are required to have an FMCSA Annual Inspection. In extreme cases, the chassis may sit for the entire year between annual inspections, offering special challenges because of the occasional long periods of inactivity. Rubber parts can lose their elasticity, air lines get brittle and lubricant can separate from its soap medium. Component/equipment failures resulting from these causes can include CSA violations, delayed shipments or deliveries, customer dissatisfaction and ultimately loss of revenue among other things. This all means that PM checks must be extremely thorough and complete to prevent the need for the “Pound of Cure.”

If we look at some of the more common things at risk when PM checks aren’t completed in a thorough manner, the first thing to consider are the “Big Three” of the most susceptible components – brakes, tires and lights. With the advent of automatic slack adjusters, brakes being found out of adjustment has been reduced to the exception rather than the rule. Nonetheless, adjustment must be checked during PM inspections to be certain the auto-slacks are performing as intended. Brake checks aren’t limited to adjustment, however. Because chassis typically don’t accumulate the miles that other on-highway equipment does, shoe wear generally isn’t an issue. What can be an issue are some of the corrosive things that come into play when a piece of equipment sits for long periods. Checks must be done to be certain the brake shoes aren’t rust jacked or stuck to the brake drums if a chassis has been sitting for an extended period of time.

Tires are the next thing that must be paid close attention. Tires tend to lose pressure when sitting, so a chassis that has been inactive for a while should have the tires checked closely for proper inflation. Automatic tire inflation systems help with keeping tires inflated to the proper pressures, but many chassis don’t use this technology. Because under-inflated tires are the leading cause of failure, it is critical that the chassis have properly inflated tires. Because of the age and varying generations of the container chassis fleet in North America, many different styles, designs, sizes and types of tires are found on today’s equipment. For that reason, technicians must be vigilant when determining correct inflation pressures of different types of tires when performing PM checks.

Lights are the third component of the three most common failures found on container chassis. Light failures can take one (or more) of three forms – a wiring or connection failure, the bulb or LED being burned out or a damaged component. In the case of simple burn out or damage, replacing the light with a position-appropriate component is a relatively simple task to accomplish. A more difficult diagnosis or time-consuming repair is when a wiring system failure is at the root of a non-illuminating light. The wiring harness is also a system that can be susceptible to the age component of a container chassis. Additionally, older container chassis may well have had the wiring harness spliced at some point, opening the path for corrosion issues. No matter what the cause of the failure, all lights must be working when the chassis hits the road, so a proper inspection is important to a complete PM.

There are several other things outside the “Big Three” that standard PM checks look at during periodic inspections:

• Lug nut tightness – even though the only absolute way to ensure lug nights are tight is to check them with a torque wrench, loose lug nuts can show themselves through rust streaking on the wheels – a very quick visual way of finding obvious looseness. In extreme cases, loose lug nuts can result in a wheel and tire separating from the chassis and causing serious problems.
• Wheel seal Leaks – while checking items such as tires and lug nuts in the running gear area of the chassis, taking the opportunity to look for wheel seal leaks is timely. Wheel seals are one of the items made with materials that can harden over time if the chassis is not used and the seals aren’t kept moist with lubricant. Seals can also begin to leak if a wheel end isn’t kept in proper adjustment. If a leaking wheel seal is found during a PM inspection, replacing it and correctly adjusting the wheel end during reassembly should solve any of the issues that may have caused the seal to leak.
• Air leaks can be a maintenance headache because there are many air line connections from the front to the back of a chassis that can leak. Air lines are also susceptible to hardening and cracking over time. Air lines can also rub on crossmembers, frame rails or other structural components and develop leaks where they contact those things. Another potential source of air leaks are glad hand seals, which like wheel seals can harden or become less pliable over time. Because compressed air coming through these connections feeds the braking system, air leaks translate to a safety issue. They must therefore be identified, minimized and repaired when they are found. Catching air leaks during PM checks is important to maintaining the integrity of the braking system. Likewise, properly functioning brake valves are critical to proper braking system function.
• Landing gear is an area where a combination of functionality and a quick visual inspection are needed to provide adequate maintenance. In an environment where container chassis get stacked on end when not in use, the landing gear finds itself in a unique situation. If the chassis goes through a long period of inactivity, lubricant can separate from the soap in the grease and flow away from the internal components. This can potentially cause the landing gear to be difficult to crank. The landing gear must crank easily in both directions (both up and down) to be fully functional. It is also in a vulnerable position for physical damage if/when the chassis is stacked on end during storage. A visual inspection to detect any physical damage to the legs themselves or the stabilizing bracing is important to complete the preventive maintenance process.
• Twist locks are components that are unique to a container chassis. Because of the critical nature of their function to the usability of the chassis, proper function of them is vital. Checking their function to be sure there are no parts missing and that they work easily and properly is important. Corrosion is the biggest enemy of today’s twist locks.

Most of the balance of the PM items can be characterized as visual inspection items. Things such as the ICC bumper, general condition of the frame rails and attaching components are things that must be paid attention to. While not necessarily a critical part of PM, overall appearance of the entire chassis does play a part in the perception of thorough maintenance of the unit. Problems in any of these areas must be addressed in order to achieve a chassis that is safe to be on the roadways and visually acceptable from an overall appearance standpoint.

Spending the time and resources to perform a thorough and complete Preventive Maintenance Inspection at the correct interval will minimize the overall cost of ownership of not only a container chassis, but any piece of equipment expected to operate in the environment commercial vehicles experience. The ounce of prevention it takes to complete thorough PM inspections and associated repairs will almost always prevent needing to use the “Pound of Cure” at a later time.