During the operation of this excavator, the upper structure swings excessively due to inertia after the swing control lever returns to the neutral position. This fault is typically caused by delayed swing braking or insufficient braking force; the troubleshooting steps are as follows:
09.2026 CNH EST 9.15 Engineering Diagnostic Software for Case & New Holland
(1) Check the swing lock valve circuit Verify that the wiring connections for the swing lock valve are secure and free of short or open circuits, and confirm that the solenoid valve coil and spool are functioning correctly.
(2) Measure the brake release hydraulic pressure The measured brake release pressure is 3 MPa, which is within the normal range.
(3) Remove and inspect the swing motor Remove the swing motor and inspect the springs; ensure they are unbroken and have normal tension, and that the seal ring on the brake pressure plate is intact. Upon inspecting the brake return oil circuit, a rubber particle was found at the orifice. Although the orifice was not completely blocked, the return oil flow was restricted, causing a delay in braking and resulting in excessive swing overrun.
[2018.11] CASE IH NGPC Agriculture North American Electrical Parts Catalogue
After cleaning the swing motor components (paying special attention to the orifice and narrow oil passages) and testing the machine, the swing overrun was found to be within the specified limits, and the fault was resolved.
