A gravity actuated crane stop for a crane is disclosed. The gravity actuated crane stop has a first connector at a first end configured to couple to a first crane member and an interface at a second end configured to interface with a second crane member. A gravity actuated mechanism is disposed on the body and has a first configuration in which gravity actuated mechanism disables the interface, and a second configuration in which the gravity actuated mechanism does not disable the interface. The gravity actuated mechanism is automatically changeable from the first configuration to the second configuration as the body is moved from a first orientation relative to a horizontal plane to a second orientation relative to the horizontal plane.

A backstop to prevent contact between a spacer and a peripheral member includes a rear jib backstop for a crane, having an outer cylinder, an inner cylinder, a spacer, a spacer holder and a lock mechanism. The spacer holder supports the spacer pivotally and swingably about an axis thereof and allows the spacer to fit on the inner cylinder, to keep the rear jib backstop from contracting in accordance with a change in a posture of the rear jib backstop when a boom rises. The lock mechanism enables locking of the spacer in such a manner as to keep the spacer from swinging about a swing central axis in a state where the spacer is located away from an outer surface of the inner cylinder.

A backstop to prevent contact between a spacer and a peripheral member includes a rear jib backstop for a crane, having an outer cylinder, an inner cylinder, a spacer, a spacer holder and a lock mechanism. The spacer holder supports the spacer pivotally and swingably about an axis thereof and allows the spacer to fit on the inner cylinder, to keep the rear jib backstop from contracting in accordance with a change in a posture of the rear jib backstop when a boom rises. The lock mechanism enables locking of the spacer in such a manner as to keep the spacer from swinging about a swing central axis in a state where the spacer is located away from an outer surface of the inner cylinder.

A compressible stop for use in a crane has a housing, a rod slidably mounted within the housing, a floating piston, and a valve assembly. The floating piston divides the housing into a gas portion biasing the floating piston towards an end of the housing and a liquid portion containing a hydraulic fluid. The valve assembly divides the liquid portion into a support portion and a reserve portion. The valve assembly includes a check valve allowing a liquid to flow from the reserve portion into the support portion, a pressure sensitive valve inhibiting the liquid from flowing from the support portion into the reserve portion unless the pressure is above a threshold pressure, and a frangible divider configured to rupture when the liquid pressure exceeds a rupture pressure.

A compressible stop for use in a crane has a housing, a rod slidably mounted within the housing, a floating piston, and a valve assembly. The floating piston divides the housing into a gas portion biasing the floating piston towards an end of the housing and a liquid portion containing a hydraulic fluid. The valve assembly divides the liquid portion into a support portion and a reserve portion. The valve assembly includes a check valve allowing a liquid to flow from the reserve portion into the support portion, a pressure sensitive valve inhibiting the liquid from flowing from the support portion into the reserve portion unless the pressure is above a threshold pressure, and a frangible divider configured to rupture when the liquid pressure exceeds a rupture pressure.

Provided is a construction machine capable of suppressing deformation of a boom in a simple configuration and at low costs. The construction machine includes a pair of backstops having respective hydraulic cylinders; a supply device which supplies the hydraulic cylinders with hydraulic fluid; a deformation sensing device which senses deformation of the boom; and a control device which controls the supply device so as to make a thrust of the hydraulic cylinder of one backstop having a larger pressing force, out of the pair of backstops, be larger than a thrust of the hydraulic cylinder of the other backstop, the pressing force being applied due to the deformation of the boom.

Provided is a construction machine capable of suppressing deformation of a boom in a simple configuration and at low costs. The construction machine includes a pair of backstops having respective hydraulic cylinders; a supply device which supplies the hydraulic cylinders with hydraulic fluid; a deformation sensing device which senses deformation of the boom; and a control device which controls the supply device so as to make a thrust of the hydraulic cylinder of one backstop having a larger pressing force, out of the pair of backstops, be larger than a thrust of the hydraulic cylinder of the other backstop, the pressing force being applied due to the deformation of the boom.

Provided is a lifting device with a force-absorbing base to which a boom with hoisting cable for lifting a load in substantially vertical direction is tiltably connected. The lifting device is provided with an auxiliary device for counteracting tipover of the boom in the case of sudden loss of load. The auxiliary device is connected to the base of the lifting device, provides a contact surface which is in permanent contact with a contact surface of the boom or comes into contact therewith in the case of tipover, and further comprises a drive and control system which is configured to stop the boom movement when a predetermined force between the contact surfaces is exceeded as a result of the boom tipping over. The described auxiliary device can take an autonomous form and can be arranged on a lifting device.

Provided is a lifting device with a force-absorbing base to which a boom with hoisting cable for lifting a load in substantially vertical direction is tiltably connected. The lifting device is provided with an auxiliary device for counteracting tipover of the boom in the case of sudden loss of load. The auxiliary device is connected to the base of the lifting device, provides a contact surface which is in permanent contact with a contact surface of the boom or comes into contact therewith in the case of tipover, and further comprises a drive and control system which is configured to stop the boom movement when a predetermined force between the contact surfaces is exceeded as a result of the boom tipping over. The described auxiliary device can take an autonomous form and can be arranged on a lifting device.

A crane for use on an offshore vessel is provided with a boom restrainer, wherein the boom restrainer is a hydro-pneumatic boom restrainer, for reducing upward pivoting of the boom, when the boom is in the top zone, wherein the boom restrainer includes: multiple hydraulic cylinders, each having a hydraulic circuit and a cylinder rod with a cylinder head, wherein the cylinders are mounted on the crane structure with the cylinder heads directed towards the boom of the crane, preferably are mounted on a stay of the crane structure, a catcher for each hydraulic cylinder, wherein each catcher is mounted on the boom and is configured for receiving the cylinder head of the corresponding hydraulic cylinder, and to lock the cylinder head, preferably pivotable locks the cylinder head, relative to the boom, when the boom pivots upwards in the top zone; a gas buffer for each hydraulic cylinder, wherein each gas buffer is mounted to the corresponding hydraulic cylinder, and is connected to the hydraulic circuit of the corresponding hydraulic cylinder via a medium separator, wherein the gas buffer forces the hydraulic cylinder in an extended position, and wherein the volume ratio between the hydraulic cylinder and the gas buffer is such that the hydraulic cylinder acts as a progressive spring, e.g. the gas buffers each have a size in the range of 1000-1400 litre, for example 1200 litre and the hydraulic cylinders each have a size in the range of 800-1000 litre, for example 900 litre, and preferably the ratio between the volume of the gas buffer and the volume of the associated hydraulic cylinder is 4:3.