Crane having a closed hydraulic circuit

A control device for actuating a closed hydraulic circuit of a crane, the hydraulic circuit having a hydraulic pump hydraulically connected to at least one hydraulic motor via a feed and a discharge to provide a fluid flow delivered to the at least one hydraulic motor, and in which the feed is hydraulically connected to the discharge via at least one bypass which bypasses the at least one hydraulic motor, wherein the at least one bypass comprises a continuously adjustable proportional valve, the continuously adjustable proportional valve being operatively coupled to an operator control member,

• wherein the control device is in contact with the hydraulic pump and the at least one continuously adjustable proportional valve via at least one interface, and
• wherein the control device is configured to initiate:
• an acceleration of the at least one hydraulic motor by actuating the hydraulic pump to provide the fluid flow delivered to the hydraulic motor at a pressure that is higher than a pressure of a fluid flow received at the hydraulic pump from the at least one hydraulic motor;
• a coasting state of the at least one hydraulic motor by actuating the at least one continuously adjustable proportional valve to open, and by actuating the hydraulic pump to reduce the fluid flow delivered to the at least one hydraulic motor,
• wherein a fluid flow delivered from the at least one hydraulic motor is directed through the at least one bypass;
• and
• deceleration initiated by a valve-controlled deceleration of the at least one hydraulic motor in the coasting state by actuating the at least one continuously adjustable proportional valve to proportionally close, wherein the continuously adjustable proportional valve is directly controlled by the operator control member to cause deceleration such that a fluid flow received at the at least one hydraulic motor from the at least one continuously adjustable proportional valve is maintained at a lower pressure than the fluid flow delivered from the at least one hydraulic motor to the at least one continuously adjustable proportional valve.

A crane having a closed hydraulic circuit comprising:

• a hydraulic pump hydraulically connected to at least one hydraulic motor via a feed and a discharge to deliver a fluid to the at least one hydraulic motor;
• a first bypass hydraulically connecting the feed to the discharge;
• a first proportional valve arranged in the first bypass being operatively coupled to
• an operator control member;
• a second bypass hydraulically connecting to the feed to the discharge;
• and
• a second proportional valve arranged in the second bypass being operatively coupled to the operator control member,
• a control device which is in contact with the hydraulic pump and the first and second proportional valves via at least one interface and is configured to actuate the hydraulic pump and the first and second proportional valves during crane operations in a coordinated way;
• wherein the at least one hydraulic motor is operable in an acceleration state for a first slewing direction and a second slewing direction and in a coasting state for the first slewing direction and the second slewing direction,
• wherein the control device is configured to initiate the acceleration state and the coasting state;
• wherein in the acceleration state for the first slewing direction, the hydraulic pump is configured to deliver the fluid to the at least one hydraulic motor at a first volumetric flow, the first proportional valve is open, the second proportional valve is closed, and wherein the fluid in the feed is at a higher pressure than the fluid in the discharge, and
• wherein in the coasting state for the first slewing direction, the hydraulic pump is configured to deliver the fluid to the at least one hydraulic motor at a second volumetric flow less than the first volumetric flow, the first proportional valve is open, the second proportional valve is closed, and the fluid is directed into the first bypass in a first flow direction, wherein to initiate deceleration during the coasting state, the first proportional valve is directly controlled by the operator control member and is proportionally closed so as to variably reduce a fluid flow in the first bypass to decelerate the at least one hydraulic motor, and the fluid in the discharge to be maintained at a higher pressure than the fluid in the feed.