Backhoe Loader Steering Cylinder May Malfunction Caterpillar

Problem:

We have received reports from C-Series Backhoe Loader operators that the front wheels will not respond to steering wheel movement when making slow steering corrections. Testing has concluded that the hydraulic oil must be hot (greater than 82°C (180°F)) and the operator must be turning the steering wheel very slow. Under these conditions, on some machines, an operator can turn the steering wheel and the front wheel will not steer. The root cause of the problem is leakage pass the piston seal being equal to the flow from the steering control unit which prevents developing the pressure required to steer the front wheels. We have found that manufacturing tolerances and seal design can result in a seal compression that does not seal effectiviely at low pressures.

Solution:

If this problem is reported by an operator of a C-series backhoe loader, built before January 1, 1999, verify that the malfunction will not occur when the operator turns the steering wheel at a faster rate. To eliminate the problem replace the piston seal in the cylinder with a 166-5295 Seal Assembly. A new cylinder group, 167-4235, was introduced to control identification of the new seal design. The new cylinder group replaces the 115-6497.

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