If the operating pressure is determined to be normal in the system shown in the illustration, yet the crane does not swing (slew) in either direction when the directional control valve is operated, the problem could be ________. Illustration GS-0161

Correct Answer: Option D — an obstruction in the brake release cylinder line (2)

Hydraulic crane slewing requires the release of mechanical brakes before rotation can occur. If the brake release cylinder line (2) is obstructed, the brake remains engaged despite normal system pressure. This prevents movement in either direction, as the mechanical holding force exceeds the torque capacity of the hydraulic motor.