WO2006078218A1 - Arrangement of hook - Google Patents

Abstract

The present invention comprises a lifting hook arrangement (1) including a hook (2) and a housing (3) carrying the lifting hook, where said lifting hook section (2') has got a concave-shaped bearing surface (2a) intended to carry a load. The said hook section (T) is adapted to take a first setting position (A) where the concave bearing surface (2a) takes a position adjusted for holding and securing a load, alternatively a second setting position (B), where the concave bearing surface takes an adjusted position to loosen and uncover a load. The mentioned housing (3) is adapted to be able to carry bearings (31, 32) for a shaft ranging through the hook (2) and pivotally (21, 22) fastened to the hook.

Description

The background of the invention

Methods and arrangements of the above mentioned invention are earlier known

in a number of different designs.

As a first example of the technical background and field to which the invention

relates, what is shown and described in the Swedish Patent 9902120-6.

There it shows a part of a lifting hook in a claw-shaped instrument.

In this Patent Application is described a device where a hydraulic cylinder is

adapted to carry part of the lifting power, operating on the lifting hook.

To prevent a hanging load from coming from the lifting hook a hydraulic

cylinder with activated pressure must resist the powers of the load.

Even different constructions and arrangements adapted to fasten the load to the

hook in order to stop it from gliding off the hook belong to earlier stages of the

technique.

Different constructions and arrangements adapted to block the movement of the

hook in case of a bursting of a hose or other troble letting go of the powers of

the hydraulic system.

It is also known that when the load causes a large torsional moment on the hook

this might cause a pivotal movement of the hook in relation to its attachment, and thereby the attachment of the load might glide off the hook.

This is also known as for various hook arrangements where the hook it self is

via an arrangement pivotally related to a pivot shaft situated at a horizontal

distance from the hook itself, whereby the hook is moved in a shape of an arch

upwards and downwards to co-art with a U-shaped element allocated to the

device.

By the expression "pivoting" is meant that the hook is pivotal around an axis of

rotation placed at a great distance from the lifting hook section.

By the expression "revolving" is meant that the hook is pivotal around an axis

of rotation, passing through the hook and/or the hook section.

Summary of the present invention Technical problem

When taking into consideration the technical deliberations that a person skilled

in this particular art must make in order to offer a solution to one or more

technical problems that he/she encounters is partly necessary to initially

realise the measures and/or the sequence of measures that must be

undertaken and partly necessary to choose this or these means required. It will

be evident by this reason that the technical problems listed below are highly

relevant to the development of the present invention. To show technical measures and considerations needed to offer a new

construction of the arrangement in order to adapt said housing to carry bearings

for a shaft, extending through and non-pivotally mounted to the hook and

thereby offer a pivotal attachment of the hook and hook section, should

therefore considering the present state of art as described above be considered as

a technical problem. A person skilled in this particular art will be confronted by

at any hook-related arrangement, comprising a hook and a housing holding a

hook where a hook section should have a concave bearing surface intended for

earring load whereby the said hook with hook section is arranged to take a first

setting position where the concave bearing surface takes an adapted position for

holding a load alternatively a second position where the concave bearing surface

takes an adapted position to loosen and uncover a load.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to offer security from the load coming off the lifting hook

section during lift by a hydraulic system at work for some reason failing, for

instance a broken seal in the hydraulic piston-cylinder device,

hose bursting or something like that by creating conditions for relatively

small torques, if as much as that, active on the lifting hook section. Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let said rotating shaft and/or side-related part of the shaft

and said lifting hook be machined from and to form one single piece or one

single unit.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let, within said unit, two collar-shaped parts be

co-ordinated with the lifting hook and placed on each side of said part of the

lifting hook.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let collar-sections facing the lifting hook section be

oblique and diverging in a direction towards the outer part of the lifting hook or

fmger-tip.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed within said unit let one of the collars be integrated with a

first short part of shaft and the other collar be integrated with a second but somewhat longer part of shaft.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let a joint torsional line allocated to the parts of the shaft

be oriented to extend through the collars at a distance from the outmost part of

the lifting hook section corresponding to 20-30 % of the cross-oriented length

and/or diameter of the concave bearing surface.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let the first and second part of shaft with its joint

torsional line be eccentricly oriented to said collars in a direction to the outer

part of the lifting hook or finger-tip.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let said excentricity be 5-15 % as about 10 % of a

diameter adapted to the collar.

Another technical problem is one realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let the lifting hook related arrangement according to the introduction of claim 1, offer such conditions that a centrally oriented section

of said bearing surface with the lifting hook oriented in said first setting

position will be oriented under and next to a torsional line meant for the torsion

of the lifting hook, while an end-oriented section of said bearing surface

and with the lifting hook oriented in a second setting position should be oriented

in a second setting position.

Another technical proble^4sjlne of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let a distance between the part centrally oriented to the

bearing surface and the said torsional line be small as going beyond 2 cm

and going below 10 cm.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let said housing show a connection or coupling means for

a mechanical linkage in close co-operation with a crane arm.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures considerations

that will be needed to let the house contain er have two bearings one for each horizontal shaft section. These shaft sections are coordinated to carry said lifting

hook as unit -integrated shaft sections.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let a torsional line adapted to the bearings be adjusted to

extend in or mainly in a normal direction allocated to a spreading range of the

hook section.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed that a power producing organ arranged to turn the hook in

relation to said torsional line and the housing between a first position in which

the concave surface carrying the load of the lifting hook section is turned

upwards and a second position in which the inner surface of an outer part in the

shape of a finger-tip, allocated to the lifting hook section is tilted

downwards/outwards to allow a load carried by the lifting hook or the lifting

hook section to be able to glide off said outer part of finger-tip.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations that will be needed to let the power producing organ comprise in any case a

hydraulic piston-cylinder arrangement which is arranged to linearly move a rack

meshing with a gearwheel related to a shaft section. The rack should be side-

related oriented to one, the longer one, of the hook which is firmly connected to

and being an integrated part of the hook.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let the rack carry a piston unit being part of the said

piston-cylinder arrangement alternatively two piston units being part of a piston

cylinder arrangement each related to each end of the rack and that each piston

unit should be moveably arranged in its cylinder unit that can in a co-ordinated

way be put under pressure respectively be pressure released to achieve an axial

dislocation of the rack and a rotation of the hook.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let the cylinder units which are reversely oriented to the

piston-cylinder arrangement and whose open end sections co-act with their

piston unit be firmly fastened to said housing.

Another technical problem is one of realising the significance of and the advantages associated with and/or the technical measures and considerations

that will be needed to let the concave bearing surface belonging to the lifting

hook section have a centre of curvature which in the loaded condition of the

hook and in its first setting position is situated directly under the torsional line

and above the bearing surface.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measured and considerations

that will be needed to let said torsional line, a centre of curvature of the

concave bearing surface of the lifting hook and a point for the greatest distance

to the pivot shaft be placed in a common point.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed let the housing hold a unit of rotation built in between an

attachment means and the housing.

Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let both shaft sections be pivotally mounted in bearings in

the housing via axially separated roller bearing. Another technical problem is one of realising the significance of and the

advantages associated with and/or the technical measures and considerations

that will be needed to let the rack be adjusted to one or mainly to a

horizontally oriented reciprocal movement.

Solution

The present invention takes as its starting point the first mentioned known

technique where a lifting hook related arrangement is to comprise a hook and

a housing carrying the lifting hook.

The mentioned hook has a concave-shaped hook section for a bearing surface

intended to carry a load.

The said hook is adapted to take a first setting position where the concave

bearing surface takes a position adjusted for holding and securing a load,

alternatively a second setting position where the concave bearing surface can

take an adjusted position to loosen and uncover a load.

To solve one or more of the above mentioned technical problems the present

invention shows especially that the known technique should be completed by

letting said housing be adapted to carry bearings for a shaft extending

through the hook section and non-pivotally mounted to the hook. As the suggested designs within the frame of the basic idea of this invention is

shown that mentioned shaft with mentioned hook should be shaped and formed

in one single piece or one single unit.

It is also proposed that two parts shaped as collars should be oriented on each

side of the hook section.

Collar sections facing the hook section should be oblique and diverging in a

direction towards the outer part or finger-tip of the hook.

In this respect one collar is integrated with a first short shaft section and the

other collar integrated with a second, somewhat longer shaft section.

A common torsional line allocated to the shaft sections is oriented to extend

through the collars at a distance from the outmost part or finger-tip of the

hook section corresponding to 20-30 % of the cross-oriented length or diameter

of the concave bearing surface.

The first and the second shaft sections with their common torsional line are

excentric oriented to said collars in a direction towards the outer part of

the hook or finger-tip.

The mentioned excentricity is 5-15 % as about 10 % of a diameter adapted

to the collar. Furthermore the invention proposes that a centrally oriented section of the

mentioned concave bearing surface and oriented with the hook in the said first

setting position is oriented under and next to said torsional line, whereas an end-

oriented outer part of section for the said hook section and its bearing surface

and oriented with the hook in the said second position is oriented under and next

to the mentioned torsional line.

A distance between the centrally-oriented section of the bearing surface and a

torsional line should go beyond 2 cm, alternatively go below 10 cm.

The invention also proposes that mentioned housing should show an attachment

means to a rotating combination to a crane arm.

It is also proposed that the housing should contain two bearings one for each

horizontal shaft section. These shaft sections are coordinated or integrated

to carry the mentioned hook.

A torsional line adapted to the bearings is adjusted to extend in or mainly in a

normal-direction to a spreading range of the hook section.

A power producing organ is also proposed and should be arranged to be able to turn the hook in relation to the said torsional line and the housing between a

first position in which the concave load-carrying surface of the hook section is

turned upwards, and a second position in which an inner surface of outer part of

the hook section in the shape of a finger is tilted downwards/outwards to allow a

load carried by the hook to glide off from the said finger-tip.

Furthermore the invention proposes that the power producing organ should

comprise at least a hydraulic piston-cylinder device which is arranged to

linearly move a rack, meshing with a gearwheel related to a shaft section.

The rack should be side related attached to the shaft section of the hook

which is firmly connected to the hook.

Furthermore the invention proposes that the rack should be adjusted to carry a

piston unit as one at each end of its end-sections and that each piston unit should

be moveably arranged in a belonging firmly arranged cylinder unit which is put

under pressure and pressure released for a movement of the rack.

Furthermore the invention proposes that each of the two piston-cylinder

arrangements should comprise reversely oriented cylinder units whose open

ends should cooperate with their piston unit whereby each piston unit is

firmly fastened with its end^{^} section of lheτack; The concave bearing surface of the hook section should further have a center of

curvature which in the loaded condition of the hook is situated under the

torsional line and above the bearing surface.

A torsional line, a centre of curvature of the concave bearing surface of the hook

and a point of the greatest distance of the bearing surface to the pivot shaft

should be able to be placed in a common point.

The said housing should also cooperate with and carry unit of rotation built

in between attachment means and housing.

Furthermore the invention proposes that the device with the hook should be

arranged in order to make shaft sections pivotally mounted in the house via

axially separated roller bearings.

It is also proposed that the rack should be adjusted to a reciprocal horizontally

or mainly horizontally oriented movement.

Advantages

The advantages that can be considered to be primarily characteristic of the

present invention and the significant characteristics proposed in that way are

that thus conditions have been created to offer a lifting hook related

arrangement with a low or small construction height adapted to the arrangement.

Furthermore an arrangement is proposed where the load will remain in a

hanging position in the hook section even in case of failure of hydraulic

pressure to the power producing organ.

Furthermore the arrangement of the invention offers an extremely low

construction height thanks to the pivotal attachment in a housing.

By a mechanical machining of the hook from one single piece to one unit and by

the unit-shaped being pivotally mounted in a housing it has turned out that the

hook could be dimensioned for high load and at the same time as the hook can

be manufactured with an extremely low weight, the latter important to

mobile cranes.

By the hook being shaped by integrated shaft sections and by orienting the

torsional line within the surface of the hook conditions are also created for

turning the hook with a low torque between a first position and a second

position or vice versa and thereby a less complicated power producing organ to

be able to offer a self-retarding function.

What in the first place could be regarded as significant of the present invention

will be proposed in the significant part of the following Patent demand 1. Brief description of the drawings

An arrangement at present proposed and having characteristic features

significant of the invention and illustrating the construction of said arrangement

and its application will now be described by way of example with reference to

the accompanying drawings in which

Figure 1 is a perspective description of a complete lifting hook-related

arrangement with a hook belonging to a co-ordinated housing

Figure 2 is a perspective view of the lifting hook itself and with the hook

a power producing organ attached to it to turn or rotate the hook

between two end-related setting-positions.

Figure 3 is a side view which shows the hook- related arrangement and with

the higher bearing housing (figure 1) facing the observer

Figure 4 shows a perspective side view corresponding to the one shown in

figure 1, merely the hook in form of an integrated unit. Description of embodiments at present preferred

By way of introduction it should be emphasized that in the following descciption

of a at present proposed design that has the significant features associated with

the invention. These features will be made plain in the shown figures given in

the following drawings. We have chosen terms and a special terminology in

order to, in the first place, and in that respect make the idea of the invention

plain.

In this connection it should however be taken into consideration that

expressions chosen here should not be considered limited just to the terms used

and chosen here, but it should be implied that each term thus chosen should be

understood furthermore to comprise any technical equivalent working in the

same way or essentially in the same way in order thereby to reach and achieve

the same or essentially the same purpose and/or technical effect.

Referring to figure 1, the fundamental conditions of the present invention and

thus shown diagrammatically there via a perspective description and there the

significant peculiarities associated with the invention generally concretized by

the design now proposed and in the following described in greater detail.

Thus figure 1 is showing a hook-related device 1, including a specially

constructed hook 2 and a housing (3) carrying the lifting hook co-ordinated with the hook.

The hook is shaped in one unit and shows a number of details with special

functions, which will be further described in the following.

Thus the lifting hook 2 shows a centrally oriented hook section 2' with an

utmost part 2" designated finger-tip and as for the rest the lifting hook is shaped

like an arc or in any way is almost shaped as an arc.

The hook itself 2' is here given an inner concave formed bearing surface 2a

intended for carrying a load.

The bearing surface 2a shows and comprises a concave shaped centrally

oriented section 2b and an outer section 2b' that ranges obliquely upwards and

outwards in the setting position according to the figures.

The mentioned housing 3 is adapted to be able to carry two bearings 31.32

one of which is integrated or extending through the hook 2 and pivotally

fastened to the hook 2.

The said hook 2 with its hook section X is pivotally arranged between a first

Setting position (A) shown in the figures 1 and 2 where the concave bearing

surface 2a- takes a position adapted for holding s load, and a second position

(B) where the concave bearing surface 2a with the surfaces 2b and 2b' takes a position adapted for letting loose and uncovering a load.

This second position (B) for the lifting hook 2 and hook section 2' is drawn in

figure 3 with dashed lines.

A centrally oriented section 2b for said bearing surface 2a and oriented with

the hook section in said first setting position (A) will be oriented under and

next to a pivot shaft or -line 20, while an end-oriented section 2b' for said

bearing surface 2a and with the hook 2' oriented in said second setting position

(B) is oriented outside an by the side (horizontal) of said torsional line 20.

More specifically is shown that said torsional line 20, passing through shaft

sections 21 and 22 and passing by hook section T is allocated one

mechanically machined piece of material.

Furthermore is shown the existence of two collars 23, 24, oriented on each side

of the lifting hook section T ^'.

Collar-related surfaces 23 a, 24a facing the lifting hook section are oblique and

diverging in a direction towards the outer part 2" of the lifting hook section T.

One of the collars 23 is an integral part of a first short shaft section 21 and the

second-collar 24 is an integral part of a second somewhat longer shaft section

22. The common torsional line 20 of the shaft sections 21, 22 are oriented to range

through the collars 23, 24 at a distance from the utmost part 2" of the hook

section T or part 2b' corresponding to 20-30 % of the cross-section or

diameter "d" of the concave bearing surface 2a.

The first 21 and the second 22 shaft sections with their common torsional line 20

are excentrically oriented to said collars 23, 24 in a direction towards the outer

part 2" of the hook.

The mentioned excentricity is 5-15 % as about 10 % of a diameter "dl"

adapted to the collars 23, 24.

A fixed distance between the centrally-oriented section 2b of the bearing surface

and a torsional line 20 should go beyond 2 cm and preferably go below 10 cm.

The said housing 3 shows a mechanically attachment means 5 for a firm but

easily detachable connection to a not shown mobile lifting device 6.

The housing 3 comprises two bearings, one for each of two horizontal shaft

sections 21.22. These shaft sections 21.22 are integratedly formed with and/or

carry the said lifting hook section 2' ^'.

The lifting-hook 2 adapted to a rotation or atorque around the torsional line 20

is adjusted to extend in a normal-direction to a spreading range of the hook section 2'.

A power producing organ 8 is arranged to be able to turn the hook 2 and the

hook section T in relation to the housing 3 between a first position (A) in which

the T concave load-carrying surface 2b of the hook is turned upwards, and a

second position (B) in which an inner surface of an outer part of the hook

section in the shape of a finger 2" is tilted downwards/outwards to allow a load

carried by the hook to glide off from said finger which will be clearly illustrated

in figure 3.

The concave load -carrying surface 2b of the lifting hook section 2' is in said

first position (A) situated straight under said pivot shaft 20.

The power producing organ 8 comprises at least a hydraulic piston-cylinder

device 100, which is arranged to linearly move a rack 8a, meshing with a

gearwheel 8b whose rack 8b is attached in a side-related way to the axis of

rotation or torsional line 20 of the lifting hook 2.

One of the end-sections 8c of the rack 8a carries a piston unit 9a and the end-

section 8d can carry a piston unit 9b.

Each piston unit 9a, 9b is moveably arranged in a belonging cylinder unit 10,10'

which via a not-shown connection is put under pressure and pressure released for a reciprocal movement of the rack 8a.

Furthermore is shown that a piston-cylinder device 100 in use comprises a

cylinder unit 10, of which one open end section 10a co-acts with its piston unit

9a.

Each of the piston units 9a, 9b are firmly fastened with their end-sections of the

rack 8a, while belonging cylinder units 10, 10' are firmly related to the housing

3.

The concave load-carrying surface 2b of the lifting hook section 2' has a centre

of curvature which in the loaded condition of the hook will be situated under the

torsional line 20 and above the bearing surface 2a.

The torsional line 20, the centre of curvature of the concave bearing surface 2a

of the hook and a point of the greatest distance of the bearing surface to the

pivot shaft will be situated in a common plane.

The housing 3 has a unit of rotation 40 which has been added to, between an

attachment means 5 and said housing 3.

The piston shafts 21, 22 of the hook 2 are as well pivoted in the housing 3 via

axially separated roller bearings.

The rack 8a is adapted to a reciprocal mainly horizontally oriented movement. The invention is of course not restricted to the design as described above in an

example but can undergo modifications within the frame work of the idea of the

invention illustrated in the following claims.

In particular, it should be taken into consideration that each shown unit and/or

circuit can be combined with any other shown unit and/or circuit within the

frame to be able to achieve technical function wanted.

Claims

1. A lifting hook-related arrangement ( 1 ) including a hook ( 2 ) and a

housing ( 3 ) carrying the hook, where said lifting hook with its hook section has

got a concave-shaped bearing surface ( 2a ) intended to carry a load. The said

hook ( 2 ) is adapted to take a first setting position ( A ) where the concave

bearing surface ( 2a ) takes a position adjusted to holding and securing a load,

alternatively a second setting position ( B ) where the concave bearing surface

( 2a ) takes an adapted position to loosen and uncover a load, characterized by

said housing ( 3 ) being adapted to be able to carry bearings ( 31, 32 ) for a shaft

ranging through the hook ( 2 ) and pivotally fastened to the hook.

2. An arrangement according to claim 1, characterized by said shaft

( 21, 22 ) and said hook section ( 2') being formed as and/or from one single

piece.

3. An arrangement according to claim 1 or 2, characterized by two

collars ( 23, 24 ) being oriented on each side of the lifting hook section ( 2').

4. An arrangement according to claim 3, characterized by collar

sections ( 23 a, 24a ) facing the lifting hook section ( 2') being oblique and-

diverging in a direction towards the utmost part ( 2" ) of the lifting hook section.

5. An arrangement according to claim 3, characterized by one collar

being an integral part of a first short shaft section ( 21 ) and the second collar

( 24 ) being an integral part of a second somewhat longer shaft section ( 22 ).

6. An arrangement according to claim 5, characterized by a common

torsional line ( 20 ) of the shaft sections, being oriented to range through the

collars ( 23, 24 ) at a distance from the utmost part ( 2" ) of the hook,

corresponding to 20 - 30 % of the cross-section or diameter "d" of the concave

bearing surface.

7. An arrangement according to claim 3 or 5, characterized by the first

and the second shaft sections with their common torsional line being

excentrically oriented to said collars in a direction towards the outer part of the

hook.

8. An arrangement according to claim 7, characterized by said

excentricity being 5 - 15 % as about 10 % of a diameter adapted to the collar.

9. An arrangement according to claim 1, characterized by a centrally

oriented section ( 2b ) of said concave bearing surface and oriented with the

hook-( 2 ) in-said first setting position ( A-) being oriented under and next to said

torsional line, ( 20 ) while an end-oriented outer section ( 2" ) of said lifting hook section ( 2') and its bearing surface ( 26') and with the hook ( 2 ) oriented

in said second setting position ( B ), being oriented under and next to said

torsional line.

10. An arrangement according to claim 1 or 9, characterized by a

distance between the centrally oriented section and torsional line of

the bearing surface being settled to go beyond 2 cm.

11. An arrangement according to claim 10, characterized by the

distance being settled to go below 10 cm.

12. An arrangement according to claim 1, characterized by the said

housing ( 3 ) showing an attachment means ( 5 ) for a mechanical

connection with a mobile lifting device ( 6 ).

13. An arrangement according to claim 1, characterized by the housing

( 3 ) comprising two bearings for one horizontal shaft section each (21,22 ).

These shaft sections are co-ordinated to carry the said lifting hook section ( 2').

14. An arrangement according to claim 1, characterized by a torsional

line ( 20 ) of the bearings being adapted to range mainly in a normal direction to a spreading range of the hook section ( 2^r).

15. An arrangement according to claim 1 , characterized by a power

producing organ ( 8 ) being arranged to be able to turn the hook ( 2 )

in relation to a torsional line ( 20 ) and the housing ( 3 ) between a

first position ( A ) in which the concave load-carrying surface of the

hook is turned upwards and a second position ( B ) in which an inner

surface of an outer section of the lifting hook section in the shape of

a finger will be tilted downwards/outwards to admit a load carried by

the lifting hook part to glide off said finger.

16. An arrangement according to claim 1 or 15, characterized by the

power producing organ comprising at least a hydraulic piston-

cylinder device, which is arranged to linearly move a rack,

meshing with a gear-wheel related to a shaft section. This rack is

attached in a side-related way to the shaft section of the hook,

which is firmly mounted to the lifting hook.

17. An arrangement according tctclaim _16,_characterized by the-raek

being arranged to show a piston unit co-ordinated with each end of it and each piston unit being arranged moveably in an adherent

cylinder unit, which in a co-ordinated way is put under pressure

and pressure released to achieve an axial movement of the rack.

18. An arrangement according to claim 1, 16 or 17, characterized by

a piston-cylinder arrangement comprising reversely oriented

cylinder units, whose open end-sections co-act with their pistons

respectively whereby each piston unit is firmly fastened to its end

section of the rack.

19. An arrangement according to one of the previous claims,

characterized by the concave bearing surface of the lifting hook

section having a center of curvature which in the loaded condition

of the hook and in a first setting position will be situated under

the torsional line and above the concave bearing surface.

20. An arrangement according toclaim 19, characterized by the

torsional line, a center of curvature of the concave bearing

surface of the hook section and a point of the greatest distance of the bearing surface to the pivot shaft being situated in a common point.

21. An arrangement according to one of the previous claims,

characterized by the housing ( 3 ) carrying a unit of rotation

built in between an attachment means and said housing.

22. An arrangement according to one of the previous claims,

characterized by the shaft section of the hook ( 21, 22 ) being pivoted in the

housing ( 3 ') via one axially separated roller bearing each.

23. An arrangement according to one of the previous claims,

characterized by the rack being adapted for a reciprocal mainly

horizontally oriented movement.