Note: This is the second in a multi-part series that will publish in advance of this year’s Commercial Vehicle Safety Alliance (CVSA) International Roadcheck blitz from June 4-6. The first, Highway patrol shares inspection tips ahead of CVSA Roadcheck blitz, can be found here. This year’s inspections focus on steering and suspension systems.
Obviously, a steering system consists of several moving parts that are up against the day-to-day grind of demanding duty cycles that can include rough roads and extreme temperatures. With that in mind, what are some of the typical points of failure?
“Power steering leaks and worn tie rod ends,” says Matt Copot, vice president of maintenance at Transervice. “Leaks can come from hoses, reservoirs, or gearboxes and officers will most certainly enforce any leak as a violation.”
While too much steering wheel play is a red flag it doesn’t necessarily mean that steering is to blame.
“It can be a couple things but I would start with jacking up the front end and checking the wheel bearings to insure they are adjusted correctly and if those check out fine you would move to the steering gearbox and see if the excessive free play is in the gearbox,” Copot says.
Listen to what your engine has to say, too, says ZF’s Commercial Vehicle Technical Trainer Mark Sessions. While resting at idle, note any excessive RPMs while turning the steering wheel.
“Check the amount of rotation in the steering wheel before a positive reaction to the vehicle can be noticed,” Sessions suggests. “Are there any tight spots in the feel to the rotation of the wheel? The wheel should rotate smoothly and consistently. Do the engine revs drop when turning the wheel? ZF offers a specific rolling resistance to rotation of the wheel that is set when the application is signed off. Only a small amount of engine RPM should be noticed until the steering reaches its bump stops and steering blows off internally where you can then hear an audible hiss to the system. This is normal.”
While there are no quick fixes to excessive steering wheel play, Sessions says it’s often worn and damaged components that are to blame with king pin wear, wheel balance and quite often poor quality tires especially retreads being at the center of this issue.
Rowland George, senior manager 24/7 Roadside Assistance at Penske Truck Leasing, credits the company’s periodic maintenance (PM) program for helping to keep steering and other systems up and running.
Drag links and tie rod ends require regularly scheduled inspections and maintenance which means proper lubrication. “These components can wear quickly and develop excessive play if it isn’t maintained on a regular schedule,” George says.
Homer Hogg, TA/Petro’s director of technical service, says steering components such as tie rod and drag link ball joints tend to require more maintenance than others because they’re constantly twisting and turning.
“Adding insult to injury, modern engines are more receptive to extended oil drain intervals, but lubrication is still necessary on truck parts that frequently experience movement, such as the steering ball joints,” Hogg adds.
According to CVSA, last year’s Roadcheck blitz took 11,910 vehicles off the road for out-of-service violations in the U.S. and Canada. Roughly two percent, or 262 vehicles, were OOS violations for steering
Rely on a buddy system & drivers to keep things rolling
Art Trahan, senior manager for national accounts technical support at Ryder, credits periodic maintenance – coupled with driver pre- and post-trip inspections – for preventing steering and other problems down the road.
“If you have a regular inspection, lubrication and your people are taught what to look for you can eliminate that,” says Trahan who’s worked at Ryder the past 42 years. “It’s rare where we’ve got a lot of play in the steering like from a worn ball socket. We teach our people to inspect the ball socket by hand by pulling up on it with about a 100 pounds of force and if it moves it’s out of service.
“That’s exactly how TRW and the rest of them teach it,” Trahan continues. “The other thing we ask them to do is use a buddy system when you’re inspecting the components in the front end. One guy rocks the steering wheel from resistance to resistance. The other guys looks and that way you can see if there’s a worn bushing or if there’s a loose U-bolt—any of that stuff. Again, the key is proper inspection done on time with trained technicians and lubricate. If it moves, lube it.”
Drivers can also play a key role in helping to catch problems before they result in costly downtime.
“Understand that that driver is inside that truck more than any of our technicians will ever be,” Trahan says. “Listen to the driver. A driver doing good pre- and post-trip inspections is probably the most valuable thing you have on limiting any kind of roadside inspection issues.”
Hogg agrees and says drivers can play a big role in preventing a typical steering violation like a power steering leak.
“The good news is that this kind of leak is typically easy for a driver to detect,” Hogg explains. “A simple visual check of the steering gear box, hoses, power steering pump and reservoir will help identify if there is leaking fluid from the power steering system.”
At Penske, George says, “Making proper use of DVIRs (Driver Vehicle Inspection Reports) can be invaluable.”
Perform maintenance relative to duty cycle
To help lower costs and keep drivers on the road, Jerry Frech, president and CEO of Fleet Group, says to follow a regular maintenance plan that addresses various driving conditions.
“There are lot of factors that affect how long a steering component lasts. Road conditions effect steering component life,” Frech says. “If the vehicle is driven on roads that are under maintained or driven off-road then you can expect components to wear or fail sooner versus driving on smooth, paved roads.”
Load weight and proper load distribution can also affect steering life, Frech adds, along with route types. For instance, trucks subject to making more turns, like those largely confined to metro and regional routes, demand more work from steering components than long haul trucks. Either way, routine maintenance is key.
“Steering components that are not properly lubricated and maintained will cost you more,” Frech says.
Costly steering components include the steering gear (or steering box), power steering pump, hydraulic assist cylinder, ball joints and kingpins.
“Depending on how soon issues are found and corrected can contribute to total cost of steering component replacement,” says Jim Lana, Fleet Group’s director of operations. “If you have worn tie rod ends and your toe is not correct, you now have the added cost of tires worn out prematurely to consider.”
Poorly lubricated kingpins can lead to worn out bushings, Lana adds, which if neglected long enough can lead to steering knuckle failure and a grounded truck with an OSS violation.
Aside from being stuck along the highway waiting on a costly roadside repair, what are some other consequences for a poorly maintained steering system?
“There are many ways to see it, and it all depends on the component of the steering system that is worn out,” explains David Brinkman category director of suspension products at Stemco. “It can be a safety issue per loss of steering, or fatigue to an operator as he needs to have a permanent focus on the vehicle’s steering or wandering on the road. The lowest impact on the daily journey, but one of the biggest impacts to the fleet’s top cost is tire wear, and other suspension components prematurely wearing as well due to a steering system issue. The sooner the steering system is addressed the better for the fleet, operator and all on the road.”
George echoes the importance of keeping up an effective maintenance program and says it’s enabled Penske’s fleet to avoid costly OSS violations.
“At our 24/7 Roadside Assistance Center we don’t see a spike in call volume during inspection blitzes,” George explains. “I attribute that in part to Penske’s excellent PM program and the late-model trucks that we have in our fleet. We also advocate to our customers the value of the pre- and post-trip inspections. If a fleet manager sticks to a good PM schedule and enforces consistent pre- and post-trip inspections, I am confident this will lead to a lot less inspection blitz issues and the roads will be safer for everyone.”
Expert insight and advice on steering systems
Jim Lana, director of operations at Fleet Group:
The most cost-efficient thing that can be done for any part of the vehicle is to do a quality preventive maintenance inspection and lubricate on a regular basis. PM intervals should be determined by manufacturers recommendations and driving conditions. It is always cheaper to replace a worn tie rod before you have to replace tires too. It is always cheaper to lubricate steering components so they don’t wear prematurely than it is to replace parts because of lack of lubrication or maintenance.
Periodic inspection and regular lubrication are key elements to making sure that you are going down the road safely. The chosen maintenance program should match the vehicle vocation and the inspection intervals determined accordingly. Finding worn steering components and replacing them before they fall apart will help keep you safe and also off the side of the road, broke down or tagged out of service.
Art Trahan, senior manager for national accounts technical support at Ryder:
Keep in mind that a power steering system is a closed loop system. You don’t have combustible gasses going into it. If you can keep the dirt out and the clean oil in, then it becomes a matter of how much work did that oil do and has it oxidized, which would be the reason that you would change it.
David Brinkman, category director of suspension products at Stemco:
Excessive play means a worn-out component. A leak means a worn-out seal or internal damage to the system which then damages the seal. Simply putting it, a broken component is out of service and cannot be operational, needing immediate repair. A broken component is a major event resulting from a lack of inspection or external loads. It would seem that a broken component was abused, possibly from an excessive play that could have been identified during preventive inspections, or an excessive amount of force occurred to the component from outside of its designed functions. The broken component could have been supporting forces from other related items out of spec, or an external force (impact) to the system that ultimately got the part to break away.
This is where Stemco proves out to be a great partner to fleets and truck owners. Stemco provides solutions that are easy to install and durable—like the Stemco Qwik Kit and the Universal QwikTie Tie Rod Assembly—for when parts are worn out and need replacement.
Homer Hogg, director of TA Truck Service Technical Service, TravelCenters of America:
Excessive steering wheel play typically indicates that one or a combination of steering components is loose. Loose components, such as steering shaft joints or splines, pitman arm, tie rod and drag link joints can all cause excessive steering wheel play.
Operating a vehicle with excessive steering wheel play can result in a total loss of steering control while the vehicle is in motion. Drivers who suspect or notice excessive steering wheel play should not operate the vehicle until the root cause of the problem is determined and corrected.
To maximize the life of your steering system and to keep it running at peak performance, TA Truck Service recommends that you ensure all steering components are lubricated and inspected per the truck manufacturer’s schedule.
Fleets should also have their vehicles periodically inspected for fluid leaks and have any leaks repaired in a timely manner. This helps eliminate excessive heat from the fluid in the in the power steering system, which can help extend the life of your gear box and power steering pump.
Matt Copot, vice president of maintenance at Transervice:
Adhere to your schedule maintenance interval and work with your technicians on what your expectations are for component replacement. Implement PM quality inspection program to audit and provide feedback to ensure the vehicles are up to DOT standards. Also take a good look at your steer tires as their wear can indicate issues with your steering components.
Mark Sessions, commercial vehicle technical trainer at ZF:
Check the power steering fluid level with the engine running. Check the oil reservoir for a clean constant oil level that conforms to the manufacturer’s recommendations. Always make sure that if you are topping off the oil, that the new oil meets the OEM specifications. If the level is low this should trigger questions to why? Search the hydraulic circuit for leakages and even damp spots that could indicate damage to a hose, pipe, coupling or seals.
With the engine off, check the following steering components:
- Closely inspect the steering box for damage. There should not be any tangential movement to the input shaft and pitman arm. There should only be a minimal amount of rotational movement which with everything connected should be almost impossible to detect. If there is, then disconnect the drag link from the pitman arm and make a measurement. Confirm with the OEM spec to establish if the unit is ok or requires overhaul or replacement.
- Check the Tie Rods Ends on the drag link and Tie Rod for obvious visual damage and check for wear using a Pry bar, looking for lift with audible noise to highlight wear usually caused by damage to the boots, leaking grease etc. (This is often visual if a third party can operate the steering while the technician watches the movement under the vehicle).
- Check Kingpins for wear. Make a visual inspection of the bearings grease should be present. Dry joints are usually an indication of premature failure and poor maintenance. The kingpin joints are often overlooked for a fault in the steering, but ultimately exaggerates the smallest amount of wear in the steering assembly. ZF specification for lift in the knuckle on new axles is 0.004” +/- 0.002.” However, vehicles with wear as high as 0.040” can still be run, but must be repaired as soon as possible. A measurement of 0.056” is the maximum allowable lift and the vehicle should be taken out of service. There should be zero tangential movement in the hub when measured.