ELYRIA, Ohio –With the continued integration of more technologies into automated commercial vehicle safety systems, steering gear maintenance is an often neglected, yet key element in the effective operation of advanced driver assistance systems (ADAS). This installment of the Bendix Tech Tips Series focuses on inspection, maintenance, and installation of steering gears, which provide hydraulic power assist when the driver turns the steering wheel.
“Now that steering gears are evolving to provide lateral ADAS control through features like Lane Keeping Assist and Lane Centering, it’s even more important to driver and vehicle safety that they’re kept in good operating condition,” said Jonathon Gerke, Bendix product manager – Steering.
Begin with the Basics
The most common steering gear location is on the steer axle’s left-side frame rail, although vehicles with large front axle ratings – such as vocational or high-load applications – may have two gears, one mounted on each side. Regular visual inspection should include the steering reservoir and fluid level, plus checking hoses for weathering or cracks and keeping an eye out for fluid leaks.
“You’ll also want to ensure that bolts are securely torqued across the system – the Pitman arms, drag links, even the tie rods,” said Mike Bolen, Bendix product manager – Reman Steering. “Check those connections to make sure nothing is loose. And it’s important to know the recommended steering fluid life, as well as the replacement schedule for the filters on the system that protect the steering gear by keeping the fluid clean.”
Another important observable factor is one key difference between the two most popular steering gears in North America: the presence of an external grease fitting on the output shaft. Technicians need to be able to recognize the difference and understand if it’s a “lube-for-life” gear or one requiring manual grease application.
Additionally, never use a high-pressure wash to clean the steering gear, as this can compromise the seals and create leak paths.
Gather the Facts
How do you spot steering gear troubles? From the outside, leaks or cracked hoses will be the giveaway. For a driver in the cab, the usual first sign is that the vehicle will be harder to steer, or the steering feels “sloppy.”
The first step in tackling the problem is identifying what gear is on the truck.
“There are currently two major gear providers to the North American market, and it’s relatively easy to tell them apart by looking at how the Pitman arm connects to the output shaft,” Bolen explains. “If there’s a retaining nut at the connection, that’s a Sheppard gear; if it’s a pinch bolt connection, it’s a TRW/ZF gear. In either case, you’ll be able to find more specific component information stamped on the gear.”
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