This invention relates to an improved component (10) for replacing pipes, in particular underground pipes. The invention also relates to a trenchless method of removing pipes using the improved component, and a kit of parts for use in removing pipes. The improved component (10) is securable to a cable (14) and has a body (30) with a recess (26) to accommodate the end (18) of the pipe (12) in use, the recess being surrounded by a collar (24). The improved component is a two-part component, the first part (20) being securable to the cable (14) and the second part (22) including the body, the two parts being made of different materials. There is also provided a kit of parts including cooperating alignment elements of standard dimensions, and a method of removing an underground pipe.

This invention relates to an improved component (10) for replacing pipes, in particular underground pipes. The invention also relates to a trenchless method of removing pipes using the improved component, and a kit of parts for use in removing pipes. The improved component (10) is securable to a cable (14) and has a body (30) with a recess (26) to accommodate the end (18) of the pipe (12) in use, the recess being surrounded by a collar (24). The improved component is a two-part component, the first part (20) being securable to the cable (14) and the second part (22) including the body, the two parts being made of different materials. There is also provided a kit of parts including cooperating alignment elements of standard dimensions, and a method of removing an underground pipe.

A valve assembly and a hydraulic circuit including the valve assembly are provided. The valve assembly comprises a hydraulically actuated valve configured to be biased from a first control position to a second control position by a hydraulic pressure applied to a first fluid port of the hydraulically actuated valve. A first switching threshold pressure required to switch the hydraulically actuated valve to its second control position when applied to the first fluid port of the hydraulically actuated valve in its first control position differs from a second switching threshold pressure required to keep the hydraulically actuated valve in its second control position when applied to the first fluid port of the hydraulically actuated valve in its second control position.

A valve assembly and a hydraulic circuit including the valve assembly are provided. The valve assembly comprises a hydraulically actuated valve configured to be biased from a first control position to a second control position by a hydraulic pressure applied to a first fluid port of the hydraulically actuated valve. A first switching threshold pressure required to switch the hydraulically actuated valve to its second control position when applied to the first fluid port of the hydraulically actuated valve in its first control position differs from a second switching threshold pressure required to keep the hydraulically actuated valve in its second control position when applied to the first fluid port of the hydraulically actuated valve in its second control position.

A method for controlling a hydraulic winch includes acquiring measurements from sensors coupled to the hydraulic winch. A first control function is computed based on the measurements. The first control function sets pressure across a variable displacement motor that produces motion of the tool string following a desired motion trajectory. A second control function is computed. The second control function sets displacement of a variable displacement pump that causes the pressure across the variable displacement motor to track the first control function. A pump command is selected based on the second control function. The pump command is transmitted to the variable displacement pump. The tool string moves responsive to the pump command.

A method for controlling a hydraulic winch includes acquiring measurements from sensors coupled to the hydraulic winch. A first control function is computed based on the measurements. The first control function sets pressure across a variable displacement motor that produces motion of the tool string following a desired motion trajectory. A second control function is computed. The second control function sets displacement of a variable displacement pump that causes the pressure across the variable displacement motor to track the first control function. A pump command is selected based on the second control function. The pump command is transmitted to the variable displacement pump. The tool string moves responsive to the pump command.

A winch testing device for testing the winch pulling capacity and brake holding capacity of a forestry winch of forestry equipment, in particular of a mobile forestry machine or an accessory rear shield, wherein the forestry winch has a rope drum that can be driven by a drive motor and braked by means of a brake device and on which a rope is spooled. The winch test device has a hydraulic test cylinder which has a first attachment interface, with which the hydraulic test cylinder can be fastened to an attachment point of the forestry equipment, and a second attachment interface with which the hydraulic test cylinder can be connected with the rope of the forestry winch.

A method for an operation of a forestry winch, which has a rope drum driven by a drive motor and on which a rope is wound up, and has a rope ejector roller for the rope driven by an additional drive motor, whereby the rope is guided from the rope drum to the rope ejector roller and is deflected on the rope ejector roller. The drive motor of the rope drum and the additional drive motor of the rope ejector roller are operated so that when the rope is unspooled from the rope drum, and when the rope is wound up onto the rope drum, a minimum rope pre-tension, in particular a constant minimum rope pre-tension, is generated in the segment of the rope between the rope drum and the rope ejector roller.

A method for an operation of a forestry winch, which has a rope drum driven by a drive motor and on which a rope is wound up, and has a rope ejector roller for the rope driven by an additional drive motor, whereby the rope is guided from the rope drum to the rope ejector roller and is deflected on the rope ejector roller. The drive motor of the rope drum and the additional drive motor of the rope ejector roller are operated so that when the rope is unspooled from the rope drum, and when the rope is wound up onto the rope drum, a minimum rope pre-tension, in particular a constant minimum rope pre-tension, is generated in the segment of the rope between the rope drum and the rope ejector roller.

A system for controlling a winch assembly includes a rotatable winch drum with an attached cable. A winch motor is configured to rotate the winch drum. A sensor is configured to generate signals indicative of the number of layers of the winch cable on the winch drum. A winch controller is configured to receive a control input requesting a selected rotation of the winch drum, receive the signals from the sensor, determine a number of layers of the winch cable disposed on the winch drum, and generate control commands to control the winch motor to rotate the winch drum based on the control input and the number of layers of the winch cable. The control command rotates the winch drum to produce a substantially constant line speed based on the selected control input independent of the number of layers determined to be disposed on the winch drum.