Parking brake device and work machine equipped with the same

A work machine comprising:

• a lower traveling body;
• an upper turning body mounted on the lower traveling body capably of turning;
• an attachment attached to the upper turning body;
• and
• a parking brake apparatus that includes:
• a parking brake switchable between a braking state of braking turning of the upper turning body with respect to the lower traveling body and a braking release state of releasing braking of the turning;
• a brake operation device that allows a braking operation and a braking release operation to be applied to the brake operation device, the braking operation being an operation for bringing the parking brake into the braking state, the braking release operation being an operation for bringing the parking brake into the braking release state;
• a braking controller configured to judge whether or not a preset turning judgment requirement for judgment that the upper turning body is performing a turning motion with respect to the lower traveling body is satisfied and configured to execute a braking operation invalidation control only when judging that the turning judgment requirement is satisfied, the braking operation invalidation control being a control to invalidate the braking operation applied to the brake operation device;
• a turning speed detector that detects a turning speed of the upper turning body, wherein the turning judgment requirement is a turning speed requirement that the turning speed detected by the turning speed detector exceeds a turning speed threshold;
• and
• a load detector that detects a load by a suspended load that is suspended from the attachment,
• wherein the braking controller is configured to set the turning speed threshold in accordance with the load detected by the load detector, and
• wherein the braking controller is configured to execute the braking operation invalidation control only when judging that the turning speed detected by the turning speed detector exceeds the turning speed threshold that is set in accordance with the load detected by the load detector.