NL2014214B1

NL2014214B1 - A method of performing an operation with respect to a heavy object, as well as a driving unit for attachment to a lower section of a crane.

Info

Publication number: NL2014214B1
Application number: NL2014214A
Authority: NL
Inventors: Lanser Arie
Original assignee: Iv-Consult B V
Priority date: 2015-01-30
Filing date: 2015-01-30
Publication date: 2016-10-12

Abstract

To reduce the wear and tear exerted by a mobile crane when performing an operation with respect to a heavy object, the mobile crane is moved 5 using at least one device comprising a plurality of wheel units, each wheel unit of said plurality of wheel units being rotatable about an upright rotational axis for said wheel unit, each wheel unit comprising at least one wheel having - a first main side relatively close to the upright rotational axis and - a second main side relatively far from the upright rotational axis, the wheels of a wheel unit being rotatable about an axis transverse to the upright rotational axis; and 15 the mobile crane is moved over a surface comprising a relatively hard cover layer on top of relatively soft soil.

Description

A method of performing an operation with respect to a heavy object, as well as a driving unit for attachment to a lower section of a crane

The present invention relates to a method of performing an operation with respect to a heavy object of at least 100 tons using a mobile crane, the operation involving - lifting at least one of i) a component of the heavy object, said component having a weight of at least 20 tons, and ii) at least part of the heavy object, - moving the mobile crane over a surface while carrying a load.

It is known to manufacture heavy objects, such as off-shore jackets using one or more mobile cranes. Such a moveable crane has caterpillar tracks for moving over the ground. A disadvantage is that the moveable crane exerts large forces on the surface, tearing it up. In case of sand as the surface, the caterpillar crane can move freely but leaves leave deep tracks. Also, the working conditions are undesirable, especially when rain turns the sand into mud. This is avoided if the surface is paved with concrete, which is capable of withstanding the forces exerted to a large extent, but even concrete still suffers from damage because of the scraping of the tracks over the concrete surface.

The object of the present invention is to provide a method which reduces the wear and tear exerted by the mobile crane when performing an operation involving a heavy object, i.e. an object having a weight of at least 100 tons (1 ton being equal to 1000 kg).

To this end, a method according to the preamble is characterized in that the mobile crane is moved using at least one device comprising a plurality of wheel units, each wheel unit of said plurality of wheel units being rotatable about an upright rotational axis for said wheel unit, each wheel unit comprising at least one wheel having - a first main side relatively close to the upright rotational axis and - a second main side relatively far from the upright rotational axis, the wheels of a wheel unit being rotatable about an axis transverse to the upright rotational axis; and the mobile crane is moved over a surface comprising a relatively hard cover layer on top of relatively soft soil.

By using such a device for moving the crane, the detrimental forces exerted on the surface are reduced to a great extent. At least two of the wheels are driven, e.g. hydraulically. Suitable devices are already known in the art, and are called SPMTs (self-propelled modular transporter). Typically however all the wheels will be driven wheels. The wheel units are preferably rotatable over 180° or more, which allows the mobile crane to be moved sideways, something that takes more time with a mobile crane comprising caterpillar tracks and also causes wear and tear on the surface.

In the present application, the term "mobile crane" refers to a non-rail bound crane capable of moving, including being moved, as a whole freely in two dimensions over a plot, such as a wharf, while carrying a load hanging from the crane's boom. In the present application, the load may be the component and/or the heavy object.

The operation performed may be raising the load, lowered the load or even merely moving the load.

The relatively hard cover is for example concrete (such as reinforced concrete); or soil mixed with and hardened with cement. It may also be a tiled surface, e.g. provided using concrete slabs. According to the method of the present invention a paved surface cover may be used without the concomitant excessive wear and tear associated with a method where the mobile crane comprising caterpillar tracks is in direct contact with the surface.

The distance between the upright rotational axis and the first main side of the wheel is in general at least 10 cm, preferably at least 20 cm, more preferably at least 25 cm. This allows the wheel to revolve about the upright rotational axis with relatively little wear and tear to the surface.

The term performing an operation with respect to a heavy object comprises any of manufacturing said heavy object, dismantling said heavy object, repairing said heavy object, and moving said heavy object.

For a typical off-shore project, the heavy object is often 1000 tons or more. The component will typically have a weight of at least 50 tons, such as at least 100 tons.

The relatively hard cover layer may be provided with visual markers such as road paint applied using regular road lining marking machines, e.g. as a grid. Thanks to the reduced wear and tear of the method according to the present invention, the visual markers can remain visible for a long time. They may be used to provide a reference with respect to the position and/or orientation of the mobile crane.

According to a favourable embodiment, each wheel unit comprising a pair of wheels with the wheels being at opposite sides of the rotational axis, the wheels of a wheel unit being rotatable about an axis transverse to the upright rotational axis.

Thus weight that can be carried is increased, and the loads in the wheel unit can be distributed more evenly. This further reduces the wear and tear of the surface.

According to a favourable embodiment, the mobile crane is moved over asphalt as the relatively hard cover layer. A surface cover comprising asphalt is significantly cheaper than one of concrete, saving a large amount of money. With a method according to the state of the art, it is not possible to use asphalt because it is much more sensitive to wear and tear by caterpillar tracks than concrete. The asphalt is preferably porous asphalt, allowing the passage of rain water, improving working conditions where the object is built even more.

According to a favourable embodiment, a mobile platform comprises at least one device, the mobile crane is positioned on top of the mobile platform, and the mobile crane is moved by moving the mobile platform using said at least one device.

This method allows existing mobile cranes comprising caterpillar tracks to be used without any modification. They can be driven onto the mobile platform, e.g. using a ramp, following which the crane is moved while on top of the mobile platform by moving the mobile platform using the at least one device. More specifically, the known mobile crane comprising caterpillar tracks can be moved and because it is not in direct contact with the surface, said surface isn't damaged. The device may be a standard SPMT, SPMTs being known to be operable in combination (e.g. to move building-sized objects).

According to a favourable embodiment, the mobile crane comprises a lower section comprising a first lateral side and a second opposite lateral side, and the first lateral side and the second lateral side of the lower section each being provided with at least one device.

Such a mobile crane can be very stable. By way of example, the device will comprise at least one lug comprising a hole for receiving a male member of the mobile crane normally used to attach the caterpillar track.

Finally, the present invention relates to a driving unit for attachment to a lower section of a crane, said driving unit comprising a beam, said beam - comprising two organs for mounting, and - being provided with means for moving the mobile crane; wherein the means comprise at least one device, said device comprising a plurality of wheel units, each wheel unit of said plurality of wheel units being rotatable about an upright rotational axis for said wheel unit, each wheel unit comprising at least one wheel having a first main side relatively close to the upright rotational axis and a second main side relatively far from the upright rotational axis, the wheels of a wheel unit being rotatable about an axis transverse to the upright rotational axis.

Such a driving unit is suitable for use in the method according to the invention. The organs for mounting comprise, for example, through holes are capable of receiving a male member present at the lateral side of the undercarriage of a mobile crane for attaching a beam provided with a caterpillar track, allowing the device to be attached to the undercarriage of the crane in a similar manner as a caterpillar track. Thus outfitted, such a mobile crane is capable of moving into side directions more easily without the excessive wear and tear exerted by caterpillar tracks when moving a mobile crane sideways .

The wheels of the wheel units are generally powered wheel units, typically hydraulically powered. The wheel units are preferably rotatable over 180° or more (about the upright rotational axis), which allows the mobile crane to be moved sideways, something that takes more time with a mobile crane comprising caterpillar tracks and also causes wear and tear on the surface. The device can be manufactured easily by attaching a SPMT to a mounting beam.

Thus weight that can be carried is increased, and the loads in the wheel unit can be distributed more evenly.

The present invention will now be illustrated with reference to the drawing where

Fig. la shows a side view of a crane on top of a mobile platform;

Fig. lb shows a front view of the lower part of the mobile crane of Fig. la;

Fig. 2 shows a top view of a mobile platform with its deck removed;

Fig. 3a shows a side view of a crane modified using SPMTs; and

Fig. 3b shows a front view of the lower part of the mobile crane of Fig. 3a.

Fig. la shows a mobile crane 100 comprising caterpillar tracks 101 on top of a mobile platform 150. The mobile crane 100 can drive on the mobile platform 150 via a ramp 190 which may be a stationary ramp 190 or a ramp 190 that can be relocated.

The mobile platform 150 can be moved over the surface 196 provided by a relatively hard cover layer 195, here a 30 cm thick layer of asphalt 195, on top of relatively soft soil 197 (sand).

In the embodiment shown here, the mobile crane 100 comprises a first boom 110 and a second boom 120. The second boom 120 is for lifting counterweights 121 and can be used to move the counterweights further from the mobile crane 100 in case a component 198 lifted by the first boom is very heavy, as is known in the art. Fig. la shows the counterweights 121 in three different positions.

The component 198 lifted by the first boom 110 is typically a part of a heavy object 199 that is constructed using the method according to the invention.

Fig. lb shows a front view of the lower part of the mobile crane 100 of Fig. la.

The mobile platform 150 comprises two downwardly extending support sides 151 (not shown in Fig. la) supporting a deck 152 on which the mobile crane 100 is positioned.

Four SMPTs 160 (Self-Propelled Modular Transporter; device 160) are driven below the deck 152 while the mobile platform 150 rests on the support sides 151. Then the SMPTs 160 are extended hydraulically, as a result of which the mobile platform 150 together with the mobile crane 100 are lifted. Now, the mobile crane 100 can move across the asphalt cover layer 195 without breaking the asphalt. That is, the SMPTs 160 are used for moving the mobile crane 100 instead of its caterpillar tracks 101 which would destroy the asphalt.

The SMPTs 160 comprise a multitude of wheel units 161, in the embodiment shown comprising a pair of driven wheels 162, said pair being rotatable about an upright first rotational axis 163. The wheels 162 themselves can of course rotate about a second rotational axis 164 transverse to the first rotational axis 163. The wheels 162 of a pair will rotate in the same direction and with the same speed if the mobile crane 100 is to be moved in a straight line. To make a turn, the speed will be different. The wheels 162 may even be rotated in opposite direction, for example to rotate a wheel unit 161 sur place. In contrast to such a manoeuvre with caterpillar tracks on asphalt, this does not result in any significant wear and tear on the surface.

Fig. 2 shows the mobile platform 150 of Fig. 1 with its deck 152 not shown, allowing the arrangement of the SMPTs 160 to be visible.

The mobile platform 150 comprises a subframe 253 for connecting the devices 160. Reference number 263 indicates the location of first rotational axes 163.

Fig. 3a shows a front view of the lower part of a mobile crane 100', the mobile crane 100' having a first lateral side 301 and a second lateral side 302, each lateral side being outfitted with a driving unit 310 comprising a beam 311 with organs 312 (here holes 312) for mounting the driving unit 310 to a lower section 305 of the mobile crane 100'.

The driving unit 310 comprises two devices 160 for moving the mobile crane 100', said devices 160 comprising a plurality of wheel units 161, for example the wheel units 161 as discussed above. This allows for the mobile crane 100' to be moved across the cover layer 195 without the latter being significantly damaged.

In general, the wheels of a device 160 can be moved up and down to accommodate for bumps in the surface while avoiding local excessive loads on the device 160. This can be controlled for wheel units in an individual manner, allowing the mobile crane to be level even if it is moved over a sloping surface. This is known in the art for SPMTs, and does not require further elucidation.

Fig. 3b shows that a wheel 162 comprises a first main side 361 relatively close to and at a distance from the upright first rotational axis; and a second main side 362 relatively far from the upright first rotational axis 163. This in itself is known for SMPTs, and the wheel units 161 are controlled and driven in a similar manner.

Claims

A method for performing an operation with respect to a heavy object (199) of at least 100 tons using a mobile crane (100), the operation comprising - lifting at least one of i) a component ( 198) of the heavy object (199), wherein said component (198) has a weight of at least 20 tons, and ii) at least a part of the heavy object (199), - while carrying a load ( 198) moving the mobile crane (100) over a surface (196), characterized in that the mobile crane (100) is moved using at least one device (160) that has a plurality of wheel units (161) wherein each wheel unit (161) of said plurality of wheel units (161) is rotatable about an upstanding axis of rotation for said wheel unit (161), each wheel unit (161) having at least one wheel (162) comprises - a first main side (361) relatively close to the upright axis of rotation and - a second major side (362) relatively far away from the upright axis of rotation, wherein the wheels (162) of a wheel unit (161) are rotatable about an axis transverse to the upright axis of rotation; and the mobile crane (100) is moved over a surface (196) that comprises a relatively hard cover layer (195) on top of relatively soft soil (197).

The method of claim 1, wherein each wheel unit (161) comprises a pair of wheels (162), with the wheels (162) on opposite sides (151) of the axis of rotation, the wheels (162) of a wheel unit (161) are rotatable about an axis transverse to the upright axis of rotation.

The method of claim 1 or 2, wherein the mobile crane (100) is moved over asphalt (195) as the relatively hard cover layer (195).

The method of any preceding claim, wherein a mobile platform (150) comprises at least one device (160), the mobile crane (100) is positioned on top of the mobile platform (150), and the mobile crane (100) is moved by moving the mobile platform (150) using said at least one device (160).

The method of any preceding claim, wherein the mobile crane (100) comprises a lower section (305), which includes a first lateral side (301) and a second opposite lateral side (302), and wherein the first lateral side ( 301) and the second lateral side (302) of the lower section (305) are each provided with at least one device (160).

A drive unit (310) for attachment to a lower section (305) of a crane (100), said drive unit (310) comprising a beam (311), said beam (311) - two members (312) includes for attachment, and - includes means for moving the mobile crane (100); characterized in that the means comprise at least one device (160), said device (160) comprising a plurality of wheel units (161), each wheel unit (161) of said plurality of wheel units (161) is rotatable about an upstanding axis of rotation for said wheel unit (161), wherein each wheel unit (161) comprises at least one wheel (162) with a first main side (361) relatively close to the upstanding rotation unit axis and a second major side (362) relatively far away from the upright axis of rotation, wherein the wheels (162) of a wheel unit (161) are rotatable about an axis transverse to the upright axis of rotation.

The drive unit (160) of claim 6, wherein each wheel unit (161) comprises a pair of wheels (162), with the wheels (162) on opposite sides (151) of the axis of rotation, the wheels ( 162) of a wheel unit (161) are rotatable about an axis transverse to the upright axis of rotation.