Winch drive device in crane

A winch drive device in a crane, comprising:

• a hydraulic motor that rotates a winch drum disposed on the crane;
• a tank;
• a drain pipeline for feeding drain oil in the hydraulic motor back to the tank;
• a hydraulic pump driven by an engine, the hydraulic pump being configured to discharge hydraulic oil;
• a pressure supply pipeline connected to the hydraulic pump;
• a pressure detection unit;
• a connection state determining unit;
• a pressure increase suppression unit;
• and
• a multi-coupler having a first joint, a second joint, a support member supporting the first and second joints, a first mating joint, a second mating joint, the first and second mating joints being attachable/detachable respectively to/from the first and second joints, and a mating support member supporting the first and second mating joints, the mating support member being attachable/detachable to/from the support member,
• wherein the drain pipeline includes:
• a tank-side pipeline part having one end connected to the tank and the other end connected to the first joint;
• and
• a motor-side pipeline part having one end connected to the first mating joint and the other end connected to the hydraulic motor,
• the pressure supply pipeline includes:
• a pump-side pipeline part having one end connected to the hydraulic pump and the other end connected to the second joint;
• and
• a detection target pipeline part having one end connected to the second mating joint,
• when the support member is attached to the mating support member, the first joint and the first mating joint are connected to each other to couple the tank-side pipeline part and the motor-side pipeline part of the drain pipeline to each other, and the second joint and the second mating joint are connected to each other to couple the pump-side pipeline part and the detection target pipeline part of the pressure supply pipeline to each other,
• when the engine is started in a state where the support member is attached to the mating support member, to drive the hydraulic pump, a pressure of the hydraulic oil increases in the detection target pipeline part of the pressure supply pipeline,
• the pressure detection unit is configured to detect a pressure of the hydraulic oil in the detection target pipeline part,
• the connection state determining unit determines whether the tank-side pipeline part and the motor-side pipeline part of the drain pipeline are connected to each other, based on a pressure detected by the pressure detection unit, and
• the pressure increase suppression unit is configured such that, when the connection state determining unit determines that the tank-side pipeline part and the motor-side pipeline part are not connected to each other in a state where the engine is started, the pressure increase suppression unit carries out an operation for suppressing an increase in a pressure of the hydraulic motor.