It’s a topic we don’t talk much about, even in our ongoing Technician’s Log blog series: Steering. But that ends today! Because the reality is steering problems can make truck drivers miserable. And miserable truck drivers make for miserable technicians. Do you want to be that technician?
Look, we get it, no one is losing sleep over steering maintenance, but steering is a critical component. Still, steering systems are generally reliable and shouldn’t regularly require a technician’s touch. Still, there are specific maintenance requirements you must pay attention to when it comes to steering. Whether it be fluid, filters, or lubrication – it all plays a part. Visual inspections are critical to ensuring your steering system stays fully operational and problem-free.
Everything Gets Old
Everything ages. It is a simple fact of life. And big rig tractor trailers are not exempt from it. As trucks get older, parts come loose, hoses become brittle, and seals begin to allow leaks. This is simply normal wear and tear and happens on all vehicles, regardless of type. When you conduct routine preventative maintenance, you need to conduct a visual inspection of the steering system. The following components should be part of your checklist:
- Ball joints
- Drag links
- Kingpins
- Pitman arms
- Tie rods
- Bolts
- Nuts
You also want to ensure that the connections are secure, and nothing is loose. Also, double check the recommended steering fluid life and put a replacement schedule together for filters in the steering system.
Also make sure you conduct regular visual inspections that include the steering reservoir and fluid levels. Check all hoses for weathering or cracks and double check there are no fluid leaks. If steering fluid is leaking out of the system, that could mean air is leaking in, which is a big problem. Always keep your steering fluid levels topped up and keep an eye out for signs of entrained air in the fluid. These will look like miniscule crystalline bubbles.
Also make sure you keep an eye on the hoses going to through the reservoir down to the inlet of the power steering pump. And finally, have a look at the input seal on the pump. The input seal will be the primary source of air getting into the system and is multi-directional. Depending on its condition, it could pull air into the system or transfer steering fluid into the crankcase.
Air is a Big Problem
One of the biggest problems in a steering system is air penetration. Be on a careful look out for it because it can cause major damage to the pump. A similar problem – called cavitation – can occur if the reservoir runs dry. Once the reservoir is dry, air will leak in. You may not realize this, but it only takes a small amount of air to cause the pump to squeak.
The noises coming from a cavitating pump are not hard to miss. The squeak should get consecutively louder over time. There is also a distinctive liquid that results from entrained air in the steering system. If you see a pink-colored foam in the reservoir or tiny bubbles in the steering fluid, you have a big cavitation problem on your hands.
Other telltale signs of air in the steering system include a loud whine from the steering pump or a lumpy feel in the steering. Steering the vehicle will no longer be a smooth process but instead may bump and “chatter” with steering wheel vibrations.
Make a Proper Diagnosis
Typically, when a truck driver reports a steering problem, they may not provide a ton of information for technicians to deduce a problem from. Furthermore, if your shop is not using a power steering system analyzer, it is important to try and get as much information from the truck driver as you can. You need information to know where to start the troubleshooting process.
The fact is, there are simply too many variables involved. Truck drivers are good at helping you isolate those variables. For instance, does the problem occur when the rig is empty or loaded? Is the problem more noticeable when the vehicle is turning to the right or left? If there is nothing wrong with the front end, it wouldn’t hurt to have a second look at the steering gear.
Even without a PSSA test, you should be able to deduce the problem by isolating whether the problem only occurs in one direction or not. Because the power steering pump is going to provide pressure and flow in both directions. Thus, a loss of steering assist in a particular direction is often a sign of problems with the steering gear.
In the end, it is important not to replace parts without knowing what the malfunction is. The wrong thing to do is to replace the pump in a knee-jerk reaction simply because it is the cheapest part. If you are wrong, you have just wasted a lot of time and treasure and you still must diagnose the proper failure point and address it.
What Could Be the Problem?
In many cases, an inadvertent installation of problematic or incorrect steering components can be a big problem. The wrong pitman arm or incorrectly positioned drag link can cause major steering problems. Symptoms of incorrect installations include bumps in the steering or brake dive because of a change in the system’s internal steering geometry.
Air in the hydraulic system can also cause problems that look like a failed steering system. Instead of going through and changing the steering gear outright, instead try a common first tactic and conduct an air bleed through the systems. A basic diagnostic test should include this step and eliminate problems step by step.
And while excess air in the hydraulic system could cause the system to push the steering hard in one direction, truck drivers may also experience hard pushes in both directions. This could indicate an incorrectly set poppet valve inside the steering gear. The poppet itself is an internal unloading valve contained within the steering gear. It is there to prevent pressure from building against the axle stops. The pressure itself could lead to unnecessary loads across the steering linkage.
Finally, have a look at the axle stops to ensure they are set properly. This will ensure the valve timing is correct and provide clearance between the front tire and other components, from the frame rail to the tire. Also ensure you verify that all fasteners are securely torqued across the system. And don’t rotate the steering gear input or output shaft until it is installed and connected with the wheels pointed straight ahead.
Should You Worry About Active Steering Systems?
Active steering systems have become in vogue in big rig manufacturing. Active steering systems can be grouped into other truck driver assist functions such as lane keeping assist and speed control. These safety systems will add an electronic motor to your steering system. The question is: Will that create a more complex maintenance environment for technicians? In short, it shouldn’t.
When viewed from a steering system component perspective, active steering systems, from lane keeping assist to torque overlay, should not change proven maintenance tactics already in use. Obviously, these systems will create new troubleshooting paradigms, but there are additional benefits to consider, such as digital error notifications built into the system.
Active steering technologies provide fleets with a way to get a bird’s eye view into the steering system status and proactively address steering system maintenance concerns before they become major issues and negatively impact the performance of the steering system overall. Steering system requirements should remain the same, but just remember that the electric motor added to the system could cloud other minor issues in the system.
Therefore, regular checks are so important. If you do not regularly check your vehicles’ steering system, something that may seem minor could cause a domino effect that wrecks the entire system, leaving you with a huge repair job. These problems could be masked by the centering capability of the assist system. How do you avoid falling into this trap? Make sure you create and follow regular maintenance and inspection protocols and pay close attention to what your truck drivers tell you. Only by doing so will you ensure your steering systems stay in good shape for a long time to come.