Patent Description:
A horizontal axis wind turbine is known to have an electric generator in a nacelle on top of a tower, where a rotor with a substantially horizontal axis mounted to the nacelle and arranged to drive the generator. The nacelle is usually arranged to be rotated in relation to the tower, to point the rotor towards the wind.

With growing sizes of horizontal axis wind turbines, challenges in handling of components, such as blades, increase. One such challenge is to control a component when the component is suspended from a crane boom assembly, i.e. during installation of the component on a wind turbine. For example, a suspended wind turbine blade, which may be <NUM>-<NUM> metres long and have a mass of <NUM>-<NUM> tons, may be sensitive to wind gusts, and may present inertia forces.

<CIT> presents a system for controlling the swivel of a load suspended with a crane. Two guide lines are stretched along a boom of the crane. Two wheel assemblies are provided, each of which is arranged to engage and move along a respective of the guide lines. Two control lines are provided. Each control line extends along a respective of the guide lines, and from the respective wheel assembly to the load. Thereby, each wheel assembly may move vertically with the load, by means of the respective control line, while the control lines prevent swiveling of the load. A wheel assembly for co-operation between a crane boom guide wire and a load control wire is described in <CIT>. The wheel assembly comprises three or more pulley wheels captured in a rigid housing.

Although the systems according to <CIT> or <CIT> have benefits, a problem with them is that the guide lines may flex by forces in the control lines, which reduces the control over the load by the control lines. Such forces in the control lines could be caused e.g. by wind gusts and/or load inertia. This prevents precise management of the load, which limits the reduction of the installation time of a component, and/or prevents an increase of the weather window for the component installation. Moreover, it can be seen from <CIT> that the guide wire extends only along and up a first, lower boom of the crane shown therein. In <CIT>, there is no guide wire arrangement for controlling the load when it is lifted higher up than the level of the first, lower boom. i.e. there is no guide wire up the second, upper, jib-type boom. Also from <CIT>, the guide wire does not extend up the angled jib atop the crane boom. <CIT> discloses a crane with a hoist rope and a load hook wherein a control element of a frame suspended at the load hook is guided along a guide rope region of the crane hoist rope. This document discloses the preamble of claim <NUM>.

It is an object of the present invention to facilitate the handling of components, in particular wind turbine components. It is also an object of the invention to increase the precision in the management of a load suspended from a support structure, such as a crane boom assembly. It is a further object of the invention to reduce the installation time of a component, in particular a wind turbine component. It is also an object of the invention to increase the weather window for the installation time of a component, in particular a wind turbine component.

The objects are reached with a lifting assembly according to claim <NUM>, some preferred optional embodiments thereof are defined in appended subclaims <NUM>-<NUM>. Thus, the invention provides a lifting assembly comprising a support structure arranged to support a load suspended from the support structure, a guide line arranged to extend from a first location to a second location, a wheel assembly with one or more wheels arranged to engage, and roll along the guide line, and a control line assembly arranged to extend from the wheel assembly to the load. The lifting assembly comprises a retainer arranged to connect, between the first and second locations, the guide line to the support structure. The wheel assembly is arranged to ride over the retainer on the guide line.

The support structure may have elongated shape. The guide line is arranged to extend along the support structure. The first location may be at a height lower than the second location. The first location may be on the support structure. The first location may be on a supporting element supporting the support structure, such as a crane base or an overcarriage of a crane; the ground, or a marine vessel. The second location may be on the support structure. The first location may be at a height less than half the height of the second location, in relation to a ground level at the lifting assembly. Alternatively or additionally, the first location may be less than half the distance up the support structure, measured along the support structure from the lower end of the support structure. The second location may be further than half way up the support structure, measured along the support structure from the lower end of the support structure. Alternatively or additionally, the first location may be in the vicinity of the base of the support structure. Alternatively or additionally, the second location may be in the vicinity of the top of the support structure.

The control line assembly forms a connection between the wheel assembly, and the load.

The lifting assembly may be arranged so that when the load is moved upwards while suspended from the support structure, the wheel assembly moves along the guide line, by means of the connection to the load, away from the first location, and towards the second location. The lifting assembly may be arranged so that when the load is moved downwards while suspended from the support structure, the wheel assembly moves along the guide line, under control of the connection to the load, away from the second location, and towards the first location.

The guide line, the wheel assembly, and the control line assembly may form, or form a part of, a control line system for controlling the suspended load. The control of the suspended load may include controlling the swivel of the load. The load may comprise a component, for example a wind turbine component. The load may comprise a yoke holding a component. The control line assembly may be arranged to extend from the wheel assembly to a yoke holding a component, or to the component.

It is understood that the wheel assembly may move along the guide line, by means of the control line assembly. In particular, the wheel assembly may be drawn along the guide line, by the lifting or lowering movement of the load, to which the wheel assembly is connected, via the control line. Thus, the suspended load may use the guide line as a guide. The control line assembly may be provided in a variety of ways. For example, the control line assembly may comprise a control line and a winch. The winch may be provided e.g. at a lower part of the support structure, at an over carriage of a crane presenting the supporting structure, or on the ground. Thereby an upper end of the control line may be fixed, e.g. to the support structure, and a lower part of the control line may be wound by the winch. Thereby, the control line may be tensioned between the suspended load and the guide line by tensioning of the control line by the winch. In alternative embodiments, a lower end of the control line may be fixed, and an upper part of the control line may be wound by a winch. Thereby, the winch may the mounted on the support structure. Alternatively, the control line assembly can comprise a winch on a yoke included in the suspended load.

The support structure may be an elongate assembly comprising one or more elongate structure segments. A structure segment may define and extend along a longitudinal axis. In some embodiments, a structure segment may be an elongate element sometimes known as a tower or boom or telescopic boom or jib or other such terms denoting an elongate structural segment especially a lifting-load bearing segment. A support structure may comprise combinations of structure segments of a same type or of a different type. For example, a support structure may comprise a tower or telescopic boom by way of a first structure segment and a boom or jib by way of a second structure segment. A longitudinal axis of a structure segment may extend in a straight line or in a substantially straight line. Preferably in the present context, an elongate support structure assembly may comprise two or more elongate structure segments. Structure segments may also be simply referred to as boom segments, even though these may be of different types, such as tower or mast or telescopic tower or jib or tower jib or boom jib telescopic boom etc.. Similarly, herein, an elongate support structure assembly may also simply be referred to as a boom assembly. Thereby, the lifting arrangement may be a crane. The load may be suspended from the boom assembly. The crane may be of any suitable type. For example, the crane may be a mobile crane, or a tower crane. The crane may be a luffing tower crane. The lifting arrangement may comprise a tower crane which is erected by mounting crane parts on top of erected crane parts. Thus, a tower crane may have a capacity to build itself, i.e. to be self-erecting, wholly or partly avoiding the need for a larger crane during the build. It should be noted that the boom assembly may be provided in a variety of ways. A boom segments may, or may not, be telescopic. In the case of a tower crane, the vertical tower may for present purposes be referred to as a boom, in particular as a first boom or lower boom. The guide line may be arranged to extend along the boom assembly. The first location may be under the second location. The first location may be on the boom assembly. The first location may be on a supporting element supporting the boom assembly, such as the ground, or a marine vessel. The retainer may be arranged to connect, between the first and second locations, the guide line to the boom assembly. Preferably, the second location may be on a second boom or upper boom. The terms first boom and second boom may in particular refer to a respective lower and upper boom. A second boom may in particular be connected at its lower end to an upper end of a first boom. In many cases, such as in the context of a crawler type crane or telescopic boom crane, a second boom or upper boom may be referred to as a jib. The present invention may find particular advantage in a lifting assembly in which a second boom extends above a first boom. In particular, the first and second boom may define a kinked arrangement, wherein the longitudinal axes of the first and second booms are not aligned. The term "kink" in this context may refer to an inflection point, in particular along a support structure. Typically, a first boom may extend along an axis closer to the vertical than the second boom. In other words, the second boom may have a more shallow angle of elevation, i.e. a lower angle of elevation, than the first boom. In such an arrangement, e.g. as shown in <CIT>, it is not at present possible to extend the guide wire up higher than the top of the first, lower boom. One reason for this may be that the tendency for the guide line to flex, or bulge, and thereby undermine controllability of a suspended load via a control wire, may be increased if the guide line were stretched between the lower boom and the upper boom, e.g. from low on the lower boom, to high on the upper boom. A further reason may include that a tensioned guide line extending between a lower and an upper boom may tend to apply a bending load between the upper and lower boom which may be considered unacceptable. Preferably therefore, the retainer per the present disclosure may be arranged to connect the guide line to the boom assembly, between the first and second locations, at a location along the support structure where the support structure defines an inflection.

The retainer being arranged to connect, between the first and second locations, the guide line to the support structure, may involve the retainer being arranged to connect, at a distance from the first location, and at a distance from the second location, the guide line to the support structure. The retainer being arranged to connect the guide line to the support structure, restrains the guide line from being pulled away from the support structure by a load acting on the control line assembly, e.g. due to horizontal forces on the load and/or due to an inflection between a lower and an upper boom. The retainer may prevent the guide line from having too much "play" in relation to the support structure. This may apply to a guide line along a single longitudinally extending structural segment but also in relation to a support structure presenting an inflection between longitudinally extending structural segments thereof.

Preventing the guide line to flex away from support structure allows the control line system to maintain its geometry to a large degree, despite forces acting on the load. This allows more precise management of the load. Thereby, the installation time of components handled by the lifting assembly may be reduced. In addition, the reduced sensitivity to forces acting on the load allows an increase of the weather window for handling components by the lifting arrangement.

In some embodiments, the support structure may comprise a wind turbine tower with a crane mounted to the tower. The load may be suspended from the crane. The guide line may be arranged to extend along the tower. The first location may be on the ground or near the base of the tower. The second location may be on the crane or near the top of the tower. The retainer may be arranged to connect, between the first and second locations, the guide line to the tower. Advantageously, tower may have a capacity for introduction of moments between lower and upper ends of the tower. Thereby, the tower may be suited for absorbing a force, with a component perpendicular to its longitudinal direction, provided by the retainer.

The retainer comprises a retainer bracket for fixing the retainer to the guide line.

The retainer bracket may be provided in a variety of ways. For example, the retainer bracket may present a seat for accommodating the guide line. The guide line may be held in the seat by a tension in the connection between the guide line and the boom assembly by means of the retainer. In some embodiments, the retainer bracket may comprise a clamp arranged to engage the guide line.

The retainer may comprise a connection element, connecting the retainer bracket to the support structure. The connection element may comprise any suitable type of device for the connection, e.g. a wire, a rope, a pin, a beam, or a combination of one or more of these devices.

The wheel assembly may comprise a plurality of wheels which are distributed around the guide wire. The wheel may be distributed in an imaginary, flat wheel plane. Thereby, wheels may be distributed on two wheel assembly legs extending from the guide line. The wheel plane may be parallel and coincide with local part of guide line. One or more of the wheels may be located on a first side of the guide line, and one or more of the wheels may be located on a second side of the guide line, which second side is opposite to the first side. The wheels may be oriented in parallel with the wheel plane. Thereby, the wheels may be arranged to engage, and roll along, the guide line. In some embodiments, the wheels may be distributed on three or more wheel assembly legs extending from the guide line. Each wheel assembly leg may comprise one, two or more wheels. The distribution of wheels on two opposite sides of the guide line, or on three of more sides of the guide line, may provide a firm engagement of the wheel assembly with the guide line.

One or more of the wheels is spring loaded, so as to be biased against the guide line. This allows displacement of the spring-loaded wheel(s), away from the guide line, when the wheel rolls over the retainer bracket engaging the guide line. Thus, such a travelling wheel allows the wheel assembly to ride over the retainer.

Preferably, the wheel assembly extends, as seen along the guide line, less than a full turn around the guide line, the wheel assembly thereby presenting an assembly opening in the circumferential direction of the guide line. For example, the wheel assembly may comprise a support element providing the function of a carrier for the wheels in the wheel assembly. The support element may be a sole carrier for all the wheels in the wheel assembly. The support element may be arranged to extend past the guide line, on a single side of the guide line. The retainer bracket may be arranged to extend through the assembly opening. The retainer bracket may extend from the guide line, on a side of the guide line which is opposite to the side on which the support element extends past the guide line. Thereby, interference between the wheel assembly and the retainer, preventing the wheel assembly to pass the retainer, may be avoided.

In some embodiments, the retainer may be arranged to allow the guide line to change direction at the retainer. The support structure may comprise a first structure segment and a second structure segment. In some embodiments, the first structure segment may be referred to as a main boom. Herein, for some embodiments, the first structure segment may also be referred to as a first boom segment. In some embodiments, the second support segment may be a jib. Herein, for some embodiments, the second structure segment may also be referred to as a second boom segment. The second structure segment may be, in an erected condition of the support structure located above the first structure segment. A lower end of the second structure segment may be, in an erected condition of the support structure, connected to an upper end of the first structure segment via a flexible segment joint. This allows luffing of the second structure segment in relation to the first structure segment. The guide line may be arranged to extend past the segment joint. The retainer may be arranged to be located at substantially the same height as the segment joint. The retainer may be arranged to be located at substantially the same height as the segment joint, at least when the structure segments extend vertically.

Thereby, the guideline may be allowed to run along the first structure segment as well as along the second structure segment. The guide line may be allowed to run past the segment joint. Thus, the retainer may be used for allowing the guide line to "turn a corner", at the segment joint. Thereby, a crane jib with a guide line is allowed. Also, the control line system may be allowed to maintain its functional geometry even when jib is luffed.

The lifting assembly may comprise a further guide line arranged to extend from a first location to a second location. The lifting assembly may comprise a further wheel assembly with one or more wheels arranged to engage, and roll along, the further guide line. The lifting assembly may comprise a further control line assembly arranged to extend from the further wheel assembly to the suspended load. The lifting assembly may comprise a further retainer arranged to connect, between the first and second locations, the further guide line to the support structure. The guide lines may extend substantially in parallel. The control line assemblies may extend to respective points on the suspended load, which points are located at a distance from each other. Thereby, the control of the load is further increased. The further guide line may be arranged to extend along the support structure. The first location may be under the second location. The first location may be on the support structure. The first location may be on a supporting element supporting the support structure, such as an over carriage of a crane, the ground, or a marine vessel. The second location may be on the support structure.

In some embodiments, a plurality of retainers, each arranged to connect a respective guide line to the support structure, may be arranged distributed along the guide line. Thereby, the retention of the guide line may be further secured. This may be beneficial in the case of a very long guide line. For example, there may be two or three or four or more retainers arranged spaced apart along a guide wire between a first location and a second location.

The objects are also reached with a method for handling a component, in particular a wind turbine component. The method is defined in appended subclaim <NUM>. A preferred optional embodiment thereof is defined in appended subclaim <NUM>. The method comprises erecting a support structure. The method comprises arranging a guide line to extend from a first location to a second location comprising. The method comprises arranging a wheel assembly with one or more wheels engaging, and arranged to roll along, the guide line. The method comprises arranging a control line assembly to extend from the wheel assembly to a load, the load comprising the component and being suspended from the support structure. The method comprises arranging a retainer to connect, between the first and second locations, the guide line to the support structure.

Advantages with such a method is understood from the disclosure above of embodiments of the lifting assembly. The guide line may be arranged to extend along the support structure. The first location may be under the second location, in the erected condition of the support structure. The first location may be on the support structure. The first location may be on a supporting element supporting the support structure, such as an over carriage of a crane, the ground, or a marine vessel. The second location may be on the support structure. It should be noted that the guide line could be arranged to extend from the first location to the second location, before or after the erection of the support structure. In preferred embodiments, the guide line is arranged to extend along the support structure, while the support structure is substantially horizontal. Thereby, the arrangement of the guide line along the support structure can be done on a supporting element, such as the ground. Thereafter, the support structure may be erected.

The method comprises erecting the support structure so that a lower end of a second structure segment of the support structure is connected to an upper end of a first structure segment of the support structure via a flexible segment joint, and, while controlling the second structure segment so as to extend in a non-zero angle to a longitudinal direction of the first structure segment, allowing the retainer to limit or prevent a movement of the guide line in relation to the joint so as to keep the guide line substantially parallel to the structure segments. Thus, the method may comprise allowing the guide line to extend past the segment joint. Thereby, the method may beneficially comprise keeping the guide line substantially parallel to the structure segments while luffing second structure segment.

Arranging a retainer comprises fixing the retainer to the guide line by means of a retainer bracket and adjusting the height of the suspended load, and allowing the wheel assembly to follow, by means of the control line assembly, the load, to thereby allow at least one of the wheels of the wheel assembly to roll along the guide line, and over the retainer bracket.

Below, embodiments of the invention will be described with reference to the drawings, in which.

<FIG> shows a lifting assembly <NUM> in the form of a crane, according to an embodiment of the invention. A lifting assembly <NUM> according to embodiments of the invention may be adapted to lift a load <NUM>. The load may also include a yoke <NUM>. The yoke <NUM> may be adapted to hold a wind turbine component <NUM>. The wind turbine component may be a wind turbine blade <NUM>, as illustrated in <FIG>. The lifting assembly <NUM> might be used for installing a wind turbine <NUM>, as illustrated in <FIG>. For example, the lifting assembly <NUM> might be used to install one or more blades <NUM> of the wind turbine <NUM>, as exemplified in <FIG>.

The crane may comprise an undercarriage <NUM>. The undercarriage may be arranged to be supported by the ground. The crane may be a mobile crane. The undercarriage may comprise a plurality of wheels <NUM>. The undercarriage may present one or more outriggers <NUM>, to stabilise the crane. In some embodiments, the undercarriage may be supported by a marine vessel, e.g. for offshore wind turbine installation.

The crane may comprise an over carriage <NUM>. The over carriage <NUM> may be arranged over the under carriage <NUM>. The over carriage <NUM> may be connected to the undercarriage <NUM> via a slewing bearing <NUM>. The over carriage <NUM> may be arranged to rotate, around a substantially vertical axis, in relation to the undercarriage <NUM>, by means of the slewing bearing <NUM>. The undercarriage may present a crane operator's cabin <NUM>.

The lifting assembly <NUM> comprises an elongated support structure <NUM>. The support structure may be an elongated boom assembly, as exemplified in <FIG>. The boom assembly may be mounted on the over carriage <NUM>. The support structure <NUM> may comprise one or more structure segments, e.g. in the form of a respective lower and an upper structure segment <NUM>, <NUM> as exemplified in <FIG>. The support structure <NUM> may comprise a first structure segment <NUM>, e.g. in the form of a first boom segment as exemplified in <FIG>. The support structure <NUM> may comprise a second structure segment <NUM>, e.g. in the form of a second boom segment, as exemplified in <FIG>. The first structure segment <NUM> may form a main boom, as exemplified in <FIG> or a main tower. The second structure segment <NUM> may form a jib, as exemplified in <FIG> or a tower jib or boom jib or boom. One or more of the structure segments <NUM>, <NUM> may be telescopic.

A lower end of the second structure segment <NUM> may be, in an erected condition of the support structure <NUM>, connected to an upper end of the first structure segment <NUM>. The second structure segment lower end may be connected to the first structure segment upper via a flexible segment joint <NUM>, as exemplified in <FIG>. Flexible segment joint <NUM> may be a type of articulation such as a hinge. This may allow luffing of the second structure segment <NUM> in relation to the first structure segment <NUM>. More specifically, the angle subtended between a longitudinal direction of the second structure segment <NUM> and a longitudinal direction of the first structure segment <NUM>, may be of the order of <NUM> degrees or more, or <NUM> degrees or more or <NUM> degrees or more. Still more specifically, the angle of a longitudinal direction of the second structure segment <NUM>, in relation to a longitudinal direction of the first structure segment <NUM>, may be adjustable. Such adjustment may be performed by any suitable means such as by a hydraulic coupling or for example by means of a winch and jib guy line <NUM>, as exemplified in <FIG>.

The support structure <NUM> may be connected to the over carriage <NUM> via an assembly joint <NUM>. More specifically, a lower end of the first structure segment <NUM> may be connected to the over carriage <NUM> via the assembly joint <NUM>. This may allow luffing of the first structure segment <NUM> in relation to the over carriage <NUM>. More specifically, the angle of the longitudinal direction of the first structure segment <NUM>, in relation to the over carriage <NUM>, may be adjusted. Such adjustment may be performed by means of a boom guy line <NUM>, as exemplified in <FIG>.

The lifting assembly <NUM> is adapted to keep the load <NUM> suspended from the support structure <NUM>. The lifting assembly <NUM> is adapted to keep the load <NUM> suspended from the second structure segment <NUM>. The lifting assembly may be adapted to keep the load <NUM> suspended from an upper end of the second structure segment <NUM>. The lifting assembly <NUM> may be adapted to keep the load <NUM> suspended by means of a lifting wire <NUM>. The lifting assembly <NUM> may be adapted to keep the yoke <NUM> suspended by means of a lifting wire <NUM>. The height of the load <NUM> may be controlled by a winding drum <NUM> on the over carriage <NUM>. Thus, the winding drum <NUM> may be arranged to reel the lifting wire <NUM> in or out.

The lifting assembly <NUM> comprises a control line system. The control line system comprises one or more guide lines <NUM>, <NUM>. In embodiments of the invention, two guide lines <NUM>, <NUM> are arranged to extend along the support structure <NUM>. The guide lines <NUM>, <NUM> are herein also referred to as a guide line <NUM>, and a further guide line <NUM>. The guide lines are herein also referred to as a first guide line <NUM> and a second guide line <NUM>. In some embodiments, the guide lines <NUM>, <NUM> extend substantially in parallel. The guide lines <NUM>, <NUM> may be provided at a distance from each other. The guide lines may be provided on opposite sides of an imaginary plane in which the support structure <NUM> and the lifting wire extends. In embodiments, only a single guide line <NUM>, <NUM> may be installed at a lifting assembly <NUM>.

The first guide line <NUM> extends from a first location to a second location. The first location may be on the over carriage <NUM>. A first guide line winch <NUM> may be provided at the first location. The first guide line winch <NUM> may allow adjustments of the tension in the first guide line <NUM>. The second location may be towards the top of a structure segment <NUM>, <NUM>.

Alternatively or additionally, the second location may be towards the top of a support structure <NUM>. In <FIG>, the guide lines <NUM>, <NUM> extend to near the top of a second structure segment <NUM>. In <FIG>, the guide lines <NUM>, <NUM> extend to a respective holding element <NUM>, <NUM> extending, e.g. laterally, from the second structure segment <NUM>. A holding element <NUM>, <NUM> may otherwise be known as a traverse.

The second guide line <NUM> may extend from a second guide line winch <NUM> at a first location to a second location. The first location may be on the over carriage <NUM>. The second guide line winch <NUM> may allow adjustments of the tension in the second guide line <NUM>.

The control line system comprises one or more wheel assemblies <NUM>, <NUM>. A first wheel assembly <NUM>, with a plurality of wheels, arranged to engage, and roll along, the first guide line <NUM>. A second wheel assembly <NUM>, with a plurality of wheels, may be arranged to engage, and roll along, the second guide line <NUM>. The first and second wheel assemblies <NUM>, <NUM> are herein also referred to as a wheel assembly <NUM>, and a further wheel assembly <NUM>, respectively.

The control line system comprises one or more control line assemblies. A first control line assembly <NUM> arranged to extend through or from the first wheel assembly <NUM> to the suspended load <NUM>. A second control line assembly <NUM> may be arranged to extend through or from the second wheel assembly <NUM> to the suspended load <NUM>. The first and second control line assemblies <NUM>, <NUM> are herein also referred to as a control line assembly <NUM>, and a further control line assembly <NUM>, respectively.

The control line assemblies <NUM>, <NUM> extends to respective load points of the suspended load. Said load points are preferably located on the yoke <NUM>, as exemplified in <FIG>. Alternatively, one or both of said load points may be located on the component <NUM>. Said load points are preferably located at a distance from each other. Said load points are preferably located at opposite sides of a centre of gravity of the load <NUM>. Thereby, the control line assemblies <NUM>, <NUM> may be used for controlling the orientation of the load <NUM>. For example, the control line assemblies <NUM>, <NUM> may be used for controlling swivel motions of suspended load <NUM>.

As the suspended load <NUM> moves vertically, each wheel assembly <NUM>, <NUM> follows, by means of the respective control line assembly <NUM>, <NUM>, along the respective guide line <NUM>, <NUM>.

In some embodiments, as the one in <FIG>, each control line assembly <NUM>, <NUM> comprises a control line <NUM>, <NUM> extending from a first position below the respective wheel assembly <NUM>, <NUM>, to a second position above the respective wheel assembly. A control line winch <NUM>, <NUM> may be provided at the respective first position. Each control line winch <NUM>, <NUM> may be provided by way of example at a crane base e.g. on an over carriage <NUM> thereof. Each control line winch <NUM>, <NUM> may be arranged to reel the respective control line <NUM>, <NUM> in or out. Each second position may be on a respective holding element <NUM>, <NUM>, extending, e.g. laterally, from the second structure segment <NUM>. In some embodiments, each second position may be on a second, especially an upper, structure segment <NUM>. The respective control line <NUM>, <NUM> may extend from the respective first position, via a respective first pulley wheel <NUM> mounted on the respective wheel assembly <NUM>, <NUM>, to a respective second pulley wheel <NUM> at the respective load point, and back to a respective third pulley wheel <NUM> mounted on the respective wheel assembly <NUM>, <NUM>, and from the respective third pulley wheel <NUM> to the respective second position. Thereby, distance between the respective wheel assembly <NUM>, <NUM> and the respective load point may be adjusted by means of the respective control line winch <NUM>, <NUM>.

In alternative embodiments, each control line assembly <NUM>, <NUM> may comprise a control line extending from a respective of the wheel assemblies <NUM>, <NUM> to a respective control line winch at a respective of the load points on the load <NUM>.

Embodiments of the invention comprises a first retainer <NUM> arranged to connect, between the first and second locations, the first guide line <NUM> to the support structure <NUM>. A second retainer <NUM> may be arranged to connect, between the first and second locations, the second guide line <NUM> to the support structure <NUM>. The first and second retainer <NUM>, <NUM> are herein also referred to as a retainer <NUM>, and a further retainer <NUM>, respectively. Numerals <NUM> and <NUM> in <FIG> may designate a second location to which a guide wire may extend.

In some embodiments, the respective retainer <NUM>, <NUM> is arranged to connect the respective guide line <NUM>, <NUM> to the first structure segment <NUM>, as exemplified in <FIG>. In some embodiments, the respective retainer <NUM>, <NUM> is arranged to connect the respective guide line <NUM>, <NUM> to the second structure segment <NUM>.

Each retainer <NUM>, <NUM> may comprise a retainer bracket, an example of which is described closer below, for fixing the respective retainer to the respective guide line <NUM>, <NUM>. Further, each retainer may comprise a connection element, connecting the respective retainer bracket to the support structure <NUM>. In some embodiments, the connection element comprises a securing element <NUM>, <NUM> protruding, e.g. laterally, from the support structure <NUM>. A securing element <NUM>, <NUM> for a retainer <NUM>, <NUM> may be known as an intermediate traverse.

The first and/or the second retainer <NUM>, <NUM> is preferably located at a distance from the respective first and second locations of the first and/or second guide line <NUM>, <NUM>. The first and/or the second retainer <NUM>, <NUM> is preferably located in between, and at a distance from, the respective first and second locations of the first and/or second guide line <NUM>, <NUM>. Each retainer <NUM>, <NUM> may restrain the respective guide line <NUM>, <NUM> from being pulled away from the support structure <NUM>, e.g. by loads acting on the respective control line assembly <NUM>, <NUM>.

It should be noted that in some embodiments a single guide line <NUM> or <NUM> may be arranged to extend along the support structure <NUM>, from a first location to a second location. Thereby, a single wheel assembly <NUM> or <NUM>, with one or more wheels, may be arranged to engage, and roll along, the guide line <NUM> or <NUM>. A single control line assembly <NUM> or <NUM> may be arranged to extend from the wheel assembly <NUM> or <NUM> to a load <NUM> suspended from the support structure <NUM>. A single retainer <NUM> or <NUM> may be arranged to connect, between the first and second locations, the guide line <NUM> or <NUM> to the support structure <NUM>.

The, or each, guide line <NUM>, <NUM> may be embodied in any suitable manner, e.g. as a wire, or as a rope. The, or each, control line <NUM>, <NUM> may be embodied in any suitable manner, e.g. as a wire, or as a rope.

In some embodiments, the, or each, retainer <NUM> or <NUM> may be arranged to allow the respective guide line <NUM> or <NUM> to change direction at the retainer <NUM> or <NUM>. Where a segment joint <NUM> is provided, as exemplified in <FIG>, the guide line(s) <NUM>, <NUM> may be arranged to extend past, e.g. upwards beyond, the segment joint <NUM>. Preferably, each retainer <NUM> or <NUM> is thereby arranged to be located at substantially the same height as the segment joint <NUM>. This allows the guide line(s) <NUM>, <NUM> to remain at a substantially constant distance from the segment joint <NUM>, as the second structure segment <NUM> is luffed, i.e. controlled so as to extend in a variety of non-zero angles to the longitudinal direction of the first structure segment <NUM>. This allows the guide line(s) <NUM>, <NUM> to remain substantially in parallel with each structure segment, when the second structure segment <NUM> is luffed. The, or each, guide line <NUM>, <NUM> may thereby present a corner along its extension. A corner along a guide line <NUM>, <NUM> may correspond to and/or compensate for an inflection between segments of a support structure <NUM>. A corner along a guide wire <NUM> or <NUM> may in particular ensure that the separation distance between the guide line <NUM> or <NUM> and an inflected support structure <NUM> remains substantially constant between the first and the second location. In other words, a corner along a guide line <NUM> or <NUM> may ensure that the guide line <NUM> or <NUM> runs parallel or substantially parallel to the structure segments <NUM>, <NUM> between the first and the second location of a lifting assembly <NUM> with an inflected support structure <NUM>. A lower section of a guide line <NUM>, <NUM> may be near a first location. A lower section of a guide line <NUM>, <NUM> may extend from a first location. An upper section of a guide line <NUM>, <NUM> may be near a second location. An upper section of a guide line <NUM>, <NUM> may extend to a second location. A corner along a guide line <NUM> or <NUM> may divide a first, lower section of a guide line <NUM>, <NUM> from a second, upper section of the guide line <NUM> or <NUM>. In other words, a lower section of a guide line <NUM>, <NUM> may run substantially parallel to a first structure segment <NUM> of a support structure <NUM>. An upper section of a guide line <NUM>, <NUM> may run substantially parallel to a second structure segment <NUM> of a support structure <NUM>. A corner along a guide line <NUM> or <NUM> may ensure that the guide line <NUM> or <NUM> runs parallel or substantially parallel to the structure segments <NUM>, <NUM> between the first and the second location of a lifting assembly <NUM> with an inflected support structure <NUM>.

Reference is made also to <FIG> and <FIG>, showing a part of one of the guide lines <NUM>, a part of one of the retainers <NUM>, one of the wheel assemblies <NUM>, and a part of one of the control line assemblies <NUM>, of the example in <FIG>. As suggested, the retainer <NUM> may comprise a retainer bracket <NUM> for fixing the retainer to the guide line <NUM>.

As suggested, the retainer <NUM>, <NUM> may also comprise a connection element, connecting the retainer bracket to the support structure <NUM>. The connection element may comprise a securing line <NUM>. The securing line <NUM> may extend from the retainer bracket <NUM> to the support structure <NUM>. Alternatively, the securing line <NUM> may extend from the retainer bracket <NUM> to a securing element <NUM> protruding, e.g. laterally, from the support structure <NUM>, as exemplified above with reference to <FIG>. In some embodiments, the connection element <NUM>, <NUM> may be formed by a pin or a beam extending from the retainer bracket <NUM> to the support structure <NUM>.

The retainer bracket <NUM> may form a seat <NUM> for a portion of the guide line <NUM>. The retainer bracket may partly, or fully enclose a portion of the guide line. The retainer may be engaged with the guide line <NUM>, <NUM> by a seat <NUM>. The guide line <NUM>, <NUM> may be held in the seat by a tension in the connection element <NUM>, <NUM>. The retainer bracket seat <NUM> may have a rounded shape, as seen perpendicularly to the guide line <NUM>, <NUM> to accommodate for the change in direction of the guide line <NUM>, at the retainer <NUM>. The rounded shape of a retainer bracket seat <NUM> may define a corner in a guide line <NUM>, <NUM>. In some embodiments, the retainer bracket <NUM> may present a clamp, arranged to engage a portion of the guide line <NUM>. In some embodiments the rounded shape of a retainer bracket seat <NUM> may define a corner having a greater subtended angle than a corner on a guide wire <NUM>, <NUM> passing around it. In other words, a guide line <NUM>, <NUM> may pass over an arc of a said retainer bracket seat <NUM> which arc extends along less than the full extent of the curvature of said retainer bracket seat <NUM>.

The wheel assembly <NUM> comprises a plurality of wheels which are mounted so they can be distributed around the guide line <NUM>, <NUM> when in use. The wheels may be distributed in an imaginary, flat wheel plane, as exemplified in <FIG> and <FIG>. The wheels are preferably oriented in parallel with the wheel plane. The wheel plane is preferably parallel and coinciding with the guide line <NUM>, or at least with a portion of the guide line <NUM> which is in engagement with the wheels.

The wheel assembly <NUM>, <NUM> may comprise three wheels, as in the example in <FIG>. One or more of the wheels may be located at said wheel assembly <NUM> in a position corresponding to a first side of a guide line <NUM>. The first side of a guide line <NUM> may be the side of a guide line <NUM> on which the retainer connecting element <NUM>, <NUM> is provided. As exemplified in <FIG>, two wheels <NUM>, <NUM> may be located at said wheel assembly <NUM> in a position corresponding to a first side of the guide line <NUM>. One or more of the wheels may be located at said wheel assembly <NUM> in a position corresponding to a second side of the guide line <NUM>, <NUM>, which second side is opposite to the said first side. As exemplified in <FIG>, one wheel <NUM> may be located at said wheel assembly <NUM> in a position corresponding to the second side of a guide line <NUM>.

The wheels <NUM>, <NUM>, <NUM> are arranged to engage, and roll along, the guide line <NUM>. A wheel assembly <NUM>, <NUM> preferably comprises a support element <NUM> providing the function of a sole carrier for all the wheels in the wheel assembly <NUM>. The support element <NUM> is preferably arranged to extend past a position corresponding to a guide line <NUM>, <NUM>, on a single side of the guide line <NUM>, <NUM>. Preferably, the retainer bracket <NUM> is configured to extend from a position corresponding to the guide line <NUM>, on a side of the guide line <NUM> which is opposite to the side on which a support element <NUM> may extend past the guide line <NUM>, <NUM>. Thereby, when guide wire <NUM>, <NUM> extends over a retainer <NUM>, <NUM>, the wheel assembly <NUM> may pass the retainer <NUM>, without interference between the support element <NUM> and the retainer <NUM>. In other words, a wheel assembly <NUM> may ride over a retainer <NUM>, <NUM> on a guide wire <NUM>, <NUM>. In other words, a wheel assembly <NUM> may pass unhindered from a lower section of a guide line <NUM>, <NUM> to an upper section thereof. In other words, a wheel assembly <NUM> may pass unhindered from a lower section of a guide wire <NUM>, <NUM> near a first location to an upper section thereof near a second location. The wheel assembly <NUM>, <NUM> may extend, as seen along a guide line <NUM>, <NUM>, less than a full turn circumferentially around the axis of the guide line <NUM>, <NUM>. Thereby the wheel assembly <NUM> may present an assembly opening defining a sector in the circumferential direction of a guide line <NUM>. The assembly opening may be to a side of a guide line <NUM> which is opposite to the side on which the support element <NUM> extends past a guide line <NUM>. The retainer <NUM>, <NUM> may thereby pass through the assembly opening. Alternatively, the retainer <NUM>, <NUM> may be surrounded by the wheel assembly <NUM>, <NUM> as the wheel assembly <NUM>, <NUM> moves past it.

The one or more wheels located to be on the second side of a guide line <NUM>, <NUM> are spring loaded, so as to be biased to push against a guide line <NUM>, <NUM>. Moreover, these will be pushed against the retainer <NUM>, <NUM> while the wheel assembly <NUM>, <NUM> passes a retainer <NUM>, <NUM>. In the example shown in <FIG>, the wheel <NUM> located on the second side of a guide line <NUM>, <NUM> is spring loaded, so as to be biased towards a guide line <NUM>, <NUM> passing through the wheel assembly <NUM>, <NUM>. Thereby, the wheel <NUM> will be pushed against the retainer <NUM>, <NUM> while the wheel assembly <NUM>, <NUM> passes a retainer <NUM>, <NUM>. The support element <NUM> may comprise a leg <NUM> which is joined to the remainder of the support element <NUM> by a pivot joint <NUM>. Thereby, the leg <NUM> may be allowed to pivot around as axis which is perpendicular to the wheel plane. The wheel <NUM>, located at a position corresponding to the second side of a guide line <NUM>, may be mounted to the leg <NUM> at a distance from the pivot joint <NUM>. A spring <NUM> may be arranged to bias the leg <NUM>, with the wheel <NUM> mounted to the leg, so as to bias the wheel <NUM> against the guide line <NUM>. This allows displacement of the spring-loaded wheel <NUM> away from the guide line <NUM>, when rolling over the retainer bracket <NUM> engaging the guide line <NUM>.

Alternatives are of course possible for allowing wheel displacement, when rolling over the retainer bracket <NUM>. For example, the one or more wheels located at a wheel assembly <NUM>, <NUM> at a position corresponding to the first side of a guide line <NUM>, e.g. the side of the guide line on which the retainer connecting element <NUM>, <NUM> is provided, is spring loaded, so as to be biased against the guide line <NUM> when in use.

<FIG> shows an example of a control line assembly <NUM>. The control line assembly <NUM> may comprise, as suggested above, a control line <NUM> extending via a first pulley wheel <NUM> mounted on the wheel assembly <NUM>, to a second pulley wheel <NUM> (<FIG>) at the respective load point, and back to a third pulley wheel <NUM> mounted on the wheel assembly <NUM>. Reference is made also to <FIG>, depicting steps in a method for handling a wind turbine component <NUM>. The method could make use of a lifting assembly <NUM> according to a variety of embodiments of the invention, for example the one shown in <FIG>.

The method preferably comprises erecting S1 an elongated support structure, e.g. a boom assembly, comprising one or more structure segments, e.g. boom segments. Thereby, a lower end of a second structure segment may be connected to an upper end of a first structure segment via a flexible segment joint. The method further comprises arranging S2 a guide line to extend along the support structure, from a first location to a second location. Advantageously, the method comprises arranging S3 a retainer to connect, between the first and second locations, the guide line to the support structure. The method also comprises arranging S4 a wheel assembly with one or more wheels engaging, and arranged to roll along, the guide line. The method comprises in addition arranging S5 a control line assembly to extend from the wheel assembly to a load, comprising the component, suspended from the support structure.

Embodiments of the method may comprise, while controlling S6 the second structure segment so as to extend in a non-zero angle to a longitudinal direction of the first structure segment, e.g. while luffing second structure segment, allowing S7 the retainer to prevent the guide line from moving in relation to the segment joint. Thereby, the guide line may be kept substantially parallel to the structure segments.

The method may further comprise adjusting S8 the height of the suspended load. The method may also comprise allowing S9 the wheel assembly to follow the suspended load, by means of the control line assembly. Thereby, at least one of the wheels of the wheel assembly is allowed to roll S10 along the guide line, and over the retainer bracket.

Reference is made to <FIG>. In embodiments of the invention, a retainer is arranged to connect a guide line to the support structure, along a structure segment, (e.g. # <NUM> in <FIG>), of the support structure. Where the guide line is arranged to extend along the structure segment, from a first location to a second location, the first and second locations may be provided along the structure segment. For example, the first and second locations may be provided at respective ends of the structure segment. The retainer is arranged to connect the guide line to the structure segment, at a distance from the first and second locations. For example, the retainer may be arranged to connect the guide line to the structure segment, substantially half way between the first and second locations. The retainer may be arranged to connect the guide line to the structure segment, at a distance from the ends of the structure segment. For example, the retainer may be arranged to connect the guide line to the structure segment, substantially half way between the ends of the structure segment. The retainer may prevent the guide line from moving away from the structure segment, e.g. due to forces in a control line assembly arranged to extend from a load suspended from the support structure to a wheel assembly with one or more wheels arranged to engage, and roll along, the guide line. The retainer could be embodied as exemplified in <FIG>. Thus, the retainer <NUM> could present a seat <NUM> for the guide line <NUM>. In such embodiments, the retainer may not be arranged to create a corner in the guide line, e.g. when luffing a boom section, as exemplified above. The retainer <NUM> may simply prevent the guide line from moving away from the support structure <NUM>. The guide line <NUM> may be held in the seat by a tension in the connection element <NUM>. The retainer bracket seat <NUM> may be straight, as seen perpendicularly to the guide line <NUM>, <NUM>. This may accommodate the guide line <NUM> continuing straight past the retainer <NUM>. In some embodiments, the retainer bracket <NUM> may present a clamp, arranged to engage a portion of the guide line <NUM>.

In some embodiments, a plurality of retainers <NUM>, <NUM> may be provided along a guide line <NUM>, <NUM> arranged to extend along a support structure <NUM>, from a first location to a second location. Each retainer <NUM>, <NUM> may be arranged to connect the guide line <NUM>, <NUM> to the support structure <NUM>. The retainers <NUM>, <NUM> may be arranged to be distributed along the guide line <NUM>, <NUM>.

<FIG> shows a lifting arrangement <NUM> comprising a wind turbine tower <NUM> and a crane <NUM> mounted to the tower. The crane <NUM> may be arranged to a load, for example including a wind turbine component <NUM>, such as a blade, to be installed in the wind turbine. The load may include a yoke <NUM>.

The crane <NUM> may comprise a base <NUM>, mounted to the tower <NUM>, as exemplified in <FIG>. The base may the elongated. The base may be arranged to extend vertically along a portion of the tower. One or more fastening brackets <NUM> may be arranged to fastened the base to the tower. Each fastening bracket <NUM> may be arranged to embrace the tower, as exemplified in <FIG>.

The base may also be referred to as a first boom segment. The combination of the tower <NUM> and the crane base may comprise a first structure segment <NUM>. The arrangement including crane <NUM> may comprise a second boom segment. The second boom segment may be referred to as a second structure segment <NUM>. A lower end of the second structure segment may be connected to an upper end of the first structure segment <NUM>. Thus, a lower end of the second structure segment <NUM> may be connected to an upper end of the first structure segment <NUM>, comprising the first boom segment and the tower <NUM>. The second structure segment lower end may be connected to the first boom segment upper via a flexible segment joint <NUM>, as exemplified in <FIG>. This may allow luffing of the second structure segment <NUM> in relation to the first structure segment <NUM>. The second structure segment <NUM> may be arranged to rotate, around a substantially vertical axis, in relation to the first structure segment <NUM>.

The crane <NUM> may be adapted to keep the load <NUM> suspended from the support structure <NUM>. The crane may be adapted to keep the load <NUM> suspended from the second structure segment <NUM>.

The crane may be adapted to keep the load <NUM> suspended from an upper end of the second structure segment <NUM>. The crane may be adapted to keep the load <NUM> suspended by means of a lifting wire <NUM>.

The tower <NUM> and the crane <NUM> may form what is herein referred to as a support structure <NUM>.

The lifting assembly, <NUM>, <NUM> comprises a control line system. The control line system may comprise one or more guide lines. In embodiments of the invention, two guide lines <NUM>, <NUM> are arranged to extend along the tower <NUM> and the crane <NUM>. The guide lines are herein also referred to as a first guide line <NUM> and a second guide line <NUM>. In some embodiments, the guide lines <NUM>, <NUM> extend substantially in parallel. The guide lines may be provided at a distance from each other.

The first guide line <NUM> may extend from a first location to a second location. The first location may be on the ground. Alternatively, the first location may be on the tower <NUM>. A first guide line winch may be provided at the first location. The first guide line winch <NUM> may allow adjustments of the tension in the first guide line <NUM>. The second location may be on a second structure segment <NUM> or first structure segment <NUM>. In <FIG>, the second location is shown on a second structure segment <NUM>. In particular, in <FIG>, the second location is shown on a first holding element <NUM>, extending, e.g. laterally, from a second structure segment <NUM>. In some embodiments, the second location may be on the second structure segment <NUM> at a different arrangement.

A second guide line <NUM> may extend from a first location to a second location. The first location may be on the ground or near the ground. Alternatively, the first location may be on the tower <NUM>. A second guide line winch <NUM> may be provided at the first location. A second guide line winch <NUM> may allow adjustments of the tension in the second guide line <NUM>. The second location for the second guide wire <NUM> may be on a second structure segment <NUM>, in particular at a holding element <NUM>, extending, e.g. laterally therefrom.

The control line system may comprise one or more wheel assemblies <NUM>, <NUM>. A first wheel assembly <NUM>, with a plurality of wheels, may be arranged to engage, and roll along, the first guide line <NUM>. A second wheel assembly <NUM>, with a plurality of wheels, may be arranged to engage, and roll along, the second guide line <NUM>.

The control line system may comprise one or more control line assemblies. A first control line assembly <NUM> may be arranged to extend from the first wheel assembly <NUM> to the suspended load <NUM>. A second control line assembly <NUM> may be arranged to extend from the second wheel assembly <NUM> to the suspended load <NUM>. The control line assemblies <NUM>, <NUM> may extend to respective load points on the suspended load. Thereby, the control line assemblies <NUM>, <NUM> may be used for controlling the orientation of the load <NUM>.

In some embodiments, as the one in <FIG>, each control line assembly <NUM>, <NUM> comprises a control line <NUM>, <NUM> extending from a first position <NUM>, <NUM> below the respective wheel assembly <NUM>, <NUM>, to a second position <NUM>, <NUM> above the respective wheel assembly. A control line winch may be provided at the respective first position <NUM>, <NUM>. Each control line winch may be provided on the ground, as shown in <FIG>, or alternatively on the tower <NUM>. Each second position <NUM>, <NUM> may be on a respective holding element <NUM>, <NUM>, extending, e.g. laterally, from a second structure segment <NUM>. In some embodiments, each second position <NUM>, <NUM> may be on the second structure segment <NUM>. The respective control line <NUM>, <NUM> may extend from the respective first position <NUM>, <NUM>, via a respective first pulley wheel mounted on the respective wheel assembly <NUM>, <NUM>, to a respective second pulley wheel at the respective load point, and back to a respective third pulley wheel mounted on the respective wheel assembly <NUM>, <NUM>, and from the respective third pulley wheel to the respective second position <NUM>, <NUM>. Thereby, distance between the respective wheel assembly <NUM>, <NUM> and the respective load point may be adjusted by means of the respective control line winch.

Embodiments of the invention comprises a first retainer <NUM> arranged to connect, between the first and second locations, the first guide line <NUM> to the tower <NUM>. A second retainer <NUM> may be arranged to connect, between the first and second locations , the second guide line <NUM> to the tower <NUM>. One or more tower fastening elements <NUM> may be provided for fastening the retainer(s) to the tower <NUM>. A tower fastening element <NUM> may be arranged to embrace the tower <NUM>, as exemplified in <FIG>.

Each retainer <NUM>, <NUM> may comprise a retainer bracket, an example of which is described above, for fixing the respective retainer to the respective guide line <NUM>, <NUM>. Further, each retainer may comprise a connection element, connecting the respective retainer bracket to the tower, e.g. via a tower fastening element <NUM>.

Each retainer <NUM>, <NUM> may restrain the respective guide line <NUM>, <NUM> from being pulled away from the tower <NUM> by loads acting on the respective control line assembly <NUM>, <NUM>.

Reference is made also to <FIG>, showing a wheel assembly <NUM> according to an alternative embodiment of the invention. <FIG> also shows a lateral cross-section of a guide lines <NUM>, e.g. according to any of the embodiments described above. <FIG> also shows a part of a retainer <NUM>, e.g. according to any of the embodiments described above. <FIG> also shows a part of a control line assemblies <NUM>, e.g. according to any of the embodiments described above. As suggested, the retainer <NUM> may comprise a retainer bracket <NUM> for fixing the retainer to the guide line <NUM>. The retainer bracket <NUM> may form a seat for a portion of the guide line <NUM>.

The wheel assembly <NUM> comprises a plurality of wheels <NUM>, <NUM>, <NUM> which are distributed on three wheel assembly legs extending away from the position corresponding to a guide line <NUM>, <NUM>. Thereby, the wheels <NUM>, <NUM>, <NUM> are arranged to engage a guide line <NUM>. Each wheel assembly leg may comprise one, two or more wheels.

One or more of the wheels <NUM> may be located at a position corresponding to a side of the guide line <NUM> on which the retainer <NUM> extends to the support structure <NUM> (<FIG>). Thus, one of the wheel assembly legs may be located at a position corresponding to a side of the guide line <NUM> on which the retainer <NUM> extends to the support structure <NUM>. In the example shown in <FIG>, two of the wheel assembly legs are located at positions corresponding to respective sides of the guide line <NUM>, so as to be separated by more than <NUM> degrees from the wheel assembly leg which is located at a position corresponding to the side of the guide line <NUM> on which the retainer <NUM> will extends to the support structure <NUM>. Thereby, the wheels on separate wheel assembly legs may be oriented in respective planes. Each wheel plane may be oriented at an angle of approximately <NUM> degrees from each of the two other wheel planes.

The wheels <NUM>, <NUM>, <NUM> are preferably arranged to engage, and roll along, a guide line <NUM>. The wheel assembly <NUM> preferably comprises a support element <NUM> providing the function of a sole carrier for all the wheels in the wheel assembly. The support element <NUM> may comprise a plurality of brackets, as suggested in <FIG>. The support element <NUM> is preferably arranged to extend past a guide line <NUM>, on a single side of the guide line. Preferably, the retainer bracket <NUM> extends from a position corresponding to the guide line <NUM>, on a side of the guide line which is opposite to the side on which the support element <NUM> will extend past the guide line <NUM>. Thereby, the wheel assembly <NUM>, <NUM> may pass unhindered around the retainer <NUM> while moving along the guide line <NUM>, preferably without interference between the support element <NUM> and the retainer <NUM>. In other words, the wheel assembly <NUM> may extend, as seen along the guide line, less than a full turn around a guide line <NUM> running through it. Thereby the wheel assembly <NUM> may present an assembly opening <NUM> over a sector about the circumference of the guide line. The retainer <NUM> may thereby pass through the assembly opening <NUM>.

The wheels <NUM>, <NUM> located in said wheel assembly <NUM>, at a position corresponding to the second side of the guide line <NUM> are preferably spring loaded, so as to be biased to push in a direction against the guide line <NUM>, when positioned therein. On each leg, a spring <NUM>, for example a compression spring, may be arranged to bias the respective wheel <NUM>, <NUM> in a direction against a guide line <NUM>. This allows displacement of the spring-loaded wheels <NUM>, <NUM> away from the guide line <NUM>, when rolling over the retainer bracket <NUM> engaging the guide line <NUM>.

Claim 1:
A lifting assembly comprising a support structure (<NUM>) arranged to support a load (<NUM>) suspended from the support structure, a guide line (<NUM>) arranged to extend from a first location, to a second location, a wheel assembly (<NUM>) with one or more wheels (<NUM>, <NUM>, <NUM>) arranged to engage, and roll along the guide line (<NUM>), and a control line assembly (<NUM>) arranged to extend from the wheel assembly (<NUM>) to the load (<NUM>), wherein the lifting assembly comprises a retainer (<NUM>) arranged to connect, between the first and second locations, the guide line (<NUM>) to the support structure (<NUM>), wherein the retainer (<NUM>) comprises a retainer bracket (<NUM>) for fixing the retainer to the guide line (<NUM>), and wherein the wheel assembly (<NUM>) comprises a plurality of wheels (<NUM>, <NUM>, <NUM>) which are distributed around the guide line (<NUM>), is characterized in that one or more of the wheels (<NUM>, <NUM>, <NUM>) is spring loaded so as to be biased against the guide line (<NUM>), allowing displacement of the spring loaded wheel(s) (<NUM>, <NUM>, <NUM>), away from the guideline (<NUM>), when the wheel(s) (<NUM>, <NUM>, <NUM>) roll(s) over the retainer bracket (<NUM>) engaging the guideline (<NUM>), thus allowing the wheel assembly (<NUM>) to ride over the retainer (<NUM>).