When an engine is started in a state where a support member of a multi-coupler is attached to a mating support member, the pressure of hydraulic oil increases in a detection target pipeline part. A pressure detection unit detects the pressure of the hydraulic oil in the detection target pipeline part. A connection state determining unit determines whether a tank-side pipeline part and a motor-side pipeline part are connected to each other, based on the pressure. 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, a pressure increase suppression unit carries out an operation for suppressing an increase in the pressure of a hydraulic motor.

When an engine is started in a state where a support member of a multi-coupler is attached to a mating support member, the pressure of hydraulic oil increases in a detection target pipeline part. A pressure detection unit detects the pressure of the hydraulic oil in the detection target pipeline part. A connection state determining unit determines whether a tank-side pipeline part and a motor-side pipeline part are connected to each other, based on the pressure. 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, a pressure increase suppression unit carries out an operation for suppressing an increase in the pressure of a hydraulic motor.

There is provided a crane winch device allowing a suspended load to freely fall due to a load thereof. The crane winch device includes a winch drum around which a rope for suspending the suspended load is wound, braking brake unit that brakes the winch drum, speed-increasing unit that performs speed-increasing assist of the winch drum in a direction of free fall acceleration when a braking force of the brake unit is smaller than a first threshold, and an adjustment unit that adjusts the first threshold.

There is provided a crane winch device allowing a suspended load to freely fall due to a load thereof. The crane winch device includes a winch drum around which a rope for suspending the suspended load is wound, braking brake unit that brakes the winch drum, speed-increasing unit that performs speed-increasing assist of the winch drum in a direction of free fall acceleration when a braking force of the brake unit is smaller than a first threshold, and an adjustment unit that adjusts the first threshold.

The present disclosure provides a winch overload protection system, a workover system, and a method for operating a workover system. The winch overload protection system, in one embodiment, includes an overload detection unit operable to detect when a load on a winch of a workover system exceeds a safety load limit. The winch overload protection system, in this embodiment, further includes an overload control unit configured to receive an overload signal from the overload detection unit, and in response thereto release a brake on the winch.

A hoist system including an air balancer having an air supply and an air exhaust, a lifting device, and a hoist control pendant to control supply and exhaust of pressurized air to and from the air balancer, respectively, the hoist control pendant configured to control vertical movement of the lifting device. The air exhaust from the air balancer includes a first exhaust flow path through a first exhaust opening and a second exhaust flow path through a second exhaust opening, the first exhaust flow path having a first length and the second exhaust flow path having a second length, the second length being shorter than the first length.

A hoist system including an air balancer having an air supply and an air exhaust, a lifting device, and a hoist control pendant to control supply and exhaust of pressurized air to and from the air balancer, respectively, the hoist control pendant configured to control vertical movement of the lifting device. The air exhaust from the air balancer includes a first exhaust flow path through a first exhaust opening and a second exhaust flow path through a second exhaust opening, the first exhaust flow path having a first length and the second exhaust flow path having a second length, the second length being shorter than the first length.

A crane calculates the resonance frequency of the fluctuation of a suspended load determined from the hanging length of a main wire rope or a sub wire rope, generates a control signal for actuators, in accordance with the operation of a turning operation tool, a hoisting operation tool and the like, and generates a filtering control signal for the actuators in which a frequency component in any frequency range has been attenuated from the control signal at any ratio in reference to the resonance frequency. When the actuators are controlled by the operation of the respective operation tool and when the actuators are controlled regardless of the operation of the respective operation tool, the frequency range to be attenuated and the attenuation ratio are switched to different settings.

A forestry winch may include a rope drum driven by a drive motor, wherein a rope is wound up on the rope drum, wherein the rope drum is functionally connected with a brake device, wherein the brake device is in the form of a spring-loaded brake which is impinged by a spring device toward a braking position and by a hydraulic brake release pressure present in a brake release pressure line toward a release position, wherein the drive motor is in the form of a hydraulic motor which is connected by a first pressure medium line and a second pressure medium line to a multi-port control valve device controlling the drive motor, and a bypass valve device connecting the first and second pressure medium lines and is located in a connecting line connecting the first and second pressure medium lines and has a closed position and a flow position.

A hydraulic control circuit for a hydraulic on-vehicle winch comprises a winch control circuit interposed between a main circuit pressure inlet and the hydraulic connectors on the winch and governed by a pilot-operated directional valve. When a reel-out pilot valve shifts the pilot-operated directional valve, hydraulic flow to a reel-out port is permitted while flow to a reel-in port is obstructed. Conversely, when a reel-in pilot valve shifts the pilot-operated directional valve, hydraulic flow to the reel-in port is permitted while flow to the reel-out port is obstructed. A selectively configurable enabling circuit is interposed between the main circuit pressure inlet and the winch control circuit. In an enabling configuration, hydraulic flow from the main circuit pressure inlet to the pilot-operated directional valve, the reel-out pilot valve and the reel-in pilot valve is permitted. In a disabling configuration in which hydraulic flow to the pilot-operated directional valve is obstructed.