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 tech tip focuses on the maintenance of steering gears.
“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.
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.”
Next, determine whether the issue lies in the steering gear or the steering pump – the two main steering gearbox components. This is most efficiently done using a power steering system analyzer (PSSA). A combination flow and pressure gauge all in one, the PSSA guides a technician through a set of procedures to determine whether the problem is in the gear or the pump – and that matters to the bottom line.
“One of the biggest problems is that people will start replacing parts without knowing which is malfunctioning,” Gerke said. “They tend to start with the pump, because it’s cheaper, although if the gear is easier to access, they’ll start there. In any case, if they’re wrong, now they’re out the time and cost of that repair, and they still have to replace the other part.”
Information provided by Bendix Commercial Vehicle Systems 
