EP1230460A1

EP1230460A1 - Releasable grip-and-hold device for lifting large boards and a method for releasing the device in the large board's mounting position

Info

Publication number: EP1230460A1
Application number: EP00959046A
Authority: EP
Inventors: Industri As Forus
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-09-16
Filing date: 2000-09-12
Publication date: 2002-08-14
Anticipated expiration: 2020-09-12
Also published as: AU7043500A; NO994477L; EP1230460B1; NO994477D0; ATE318972T1; DE60026328D1; WO2001020102A1; NO314048B1

Abstract

A releasable grip-and-hold device for panelling boards (28), pivotally mounted on the extreme end of a pivoted boom (18) of liftable/lowerable board-handling apparatus. Said device comprises a board-supporting frame (26) with hooks (32) for securely holding opposite board edges until the moment of release from the device in the mounting position of the board. The hooks (32) are formed on respective end sections (34) of said frame (26) and are connected to the frame (26) in a pivoted, spring-loaded manner. A wire (62) leads from a fixed point (60) on the supporting frame (26) at the pivot point (30) thereof, to a constructional element on the board-handling apparatus. When the boomwork (18) is pivoted, the wire (62) provides for the supporting frame (26) to be rotated 180 DEG from a stack of panelling boards (28) lying horizontally, and so that the supporting frame (26) with the panelling board (28) lying on top is sloping slightly in the longitudinal direction. This sloping position of the panelling board (28) resting on top of the supporting frame (26) via small pivoted supporting means (44), then bringing it into a displacing motion, so that it first pivots the supporting means (44) and then exerts a push force on the hooks (34), which pivot resiliently away in order to start the successive release of the panelling board (28) from its grip-and-hold device.

Description

RELEASABLE GRIP-AND-HOLD DEVICE FOR LIFTING LARGE BOARDS AND A METHOD FOR RELEASING THE DEVICE IN THE LARGE BOARD'S MOUNTING POSITION

This invention relates to a releasable grip-and-hold device formed for gripping large boards individually, and holding the individual board during subsequent swinging/lifting, comprising a board supporting frame which is connected, rotational about an essentially horizontal axis, to the end of a pivoted boomwork of a preferably drivable board-handling apparatus, there being arranged along a transversal side edge of the supporting frame, hooks, hook-like means or similar, parallel to one another, helping to hold the board securely during the swinging/lifting thereof and placing in its mounting position, where the board is released from the grip- and-hold device of the supporting frame. The grip-and-hold device can be used for the mounting of for example plaster boards .

The invention similarly relates to a method of releasing a grip-and-hold device of the kind in question from a large board, which has been brought into a mounting position, the supporting frame carrying small, pivoted supporting means on which the underside of the board is resting, when the supporting frame has been pivoted about said essentially horizontal axis from a position corresponding to the stacking position of the large board into a position at least approximately corresponding to the mounting position of the large board, all hooks being pivotal and spring-loaded.

In a known manner the grip-and-hold device comprises a supporting and holding frame with holding means positioned peripherally, securing the rectangular board in position on the frame during the pivoting and the lifting, moving and handling, from the stack of boards (the boards can be stacked standing at a steep inclination, or lying on top of each other) into the mounting position of the board, in which the board is to be released from the frame as soon as it has been brought into an accurately adjusted mounting position and secured - at least temporarily - for subsequent completing mounting.

According to the present invention the aim is to provide a grip-and-hold device for boards, whereby there is achieved, on the one hand, a secure holding of such boards individually during lifting, swinging movements and handling in general, and, on the other hand, a reliable release of the grip-and- hold device is ensured, once a board has been brought into its accurately adjusted mounting position.

By a board-gripping and holding device of the kind specified in the introductory part of Claim 1 , the above-mentioned object has been realized in that the device is formed and arranged so that it exhibits the features appearing from the characterizing part of Claim 1. Such a grip-and-hold device comprises, in a known manner, a supporting frame for the board.

At two or more straight, mutually parallel frame parts of the supporting frame, there is arranged at both free ends a hook- shaped gripping/holding means, said hooks pointing towards one another by their points in the position of use, the end portions of the parallel frame parts with a respective hook each - at least on one transversal side of the supporting frame, being pivotally arranged about an axis parallel with the pivot axis of the supporting frame, and being held in a swung up active gripping and holding position by spring means, which allow a down-pivoting for the release of a board from the grip-and-hold device at least at one of two opposite securely held board side edges, the board then actually being released from the grip-and-hold device, which only needs to be moved in a direction away from the rear hooks in order to bring their gripping of the adjacent transversal board edge to an end.

The downward pivotal mounting of the outer end portion with a hook, of two or more frame parts at least at one transversal side of the supporting frame, and the tendency of said end portion to swing by spring-loading back towards its active position, in which the parallel end portions suitably adopt a position sloping slightly upwards from the pivot of the adjacent hook, in combination with hooks at both transversal sides of the frame enable the gripping and holding of one board from a stack, the pivoting of the board and the handling of it in the securely held position until it has been brought into an accurately adjusted mounting position, and been secured. Preferably the end portions of the hook-carrying frame parts of the supporting frame are all pivoted and can be returned resiliently into their active position, which facilitates the gripping of a board from a stack, and also release of the board in its fixed mounting position, but this pivotability at both transversal sides of the supporting frame is not critical for the implementation of the principal function of the invention.

The pivoted, hook-carrying end portions, which can be influenced by springs, and are located at one transversal side of the supporting frame, can with advantage be provided with a controlling and deflecting means for the respective pivoted end portion. This means may in an advantageous embodiment have the form of a curved element resembling a blade spring, secured to the hook-carrying, pivoted end portion of the frame part and curving downwards (convexly in the upward direction) when the respective hook is in a position directed upwards (for example in the mounting position of the board). When its free end hits a wall, when a board has been brought into its mounting position, the direction of motion of the controlling element is deflected, and the controlling element pulls the hook-carrying end portion along, which will consequently pivot resiliently downwards, releasing its grip round the edge of the board. The board is then actually released from the grip-and-hold device of the board-handling apparatus, because the grip-and- hold device can be displaced linearly forward by said boomwork until the board is stopped by a wall or similar at its front edge, after which the boomwork can be displaced in the opposite direction.

The supporting frame can be provided with small supporting means, which are also upright when the grip-and-hold hooks are in a position oriented upwards, and which may have an upward convex supporting surface, on which the surface of the board underside is resting during the different board- handling operations. These small supporting means may pivot/tilt in a limited manner, when the board is about to be brought into the accurately adjusted mounting position, and their curved supporting surfaces are gentle to the board and facilitates the release of the board from the gripping device in the board mounting position.

By proceeding as specified in the characterizing part of Claim 12, based on a device as specified in Claims 1 and 9, there can be achieved an easy and reliable release of a large board in its mounting position from the grip-and-hold device s according to the invention.

By a board thickness of about 13 millimetres the dimension of each hook, parallel to the edge surface of the board, may be about 15 millimetres, and the point portion of the hook may have a freely ending finger-like extension of about 1.5 o millimetres, forming an (obtuse) angle with the surface of the primary hook.

The primary hook surface extends approximately perpendicular from a linear end portion of a frame part incorporated in the supporting frame, the hook being formed on the outer free end 5 of the frame part, which has an upper edge surface and a lower one parallel thereto. The outer end of said lower edge surface and the upper end of the hook surface are connected to each other by a curved transition edge surface, curved convexly in a direction away from the pivot point of said o hook-carrying end portion of said frame part. The small finger-like extension hook may extend in all events approximately tangential to said convexly curved transitional edge surface. The so-called secondary extension hook must be of a very insignificant extent relative to the effective extent of the primary hook, which depends on the thickness of the relevant board dimension.

As mentioned, each pivoted hook-carrying end portion of the supporting frame has a spring arranged thereto, which works among other things as a return spring, which allows the hook- carrying end portion to pivot down when a ceiling board is released form the grip-and-hold device according to the invention, when the board has been brought into its mounting position. In the position of use, the respective spring pulls the respective pivoted end portion somewhat upwards into a slightly inclined position, in which the hook is somewhat higher up than the pivot point of the end portion. Such a position favours the grip-and-hold capacity of the combined hook (the primary hook with the secondary hook) straight opposite the adjacent board edge portion.

An example of a preferred embodiment will be explained in further detail in the following, with reference to the accompanying drawings, in which

Fig. 1 shows, in a side view, a drivable board-lifting and handling apparatus which carries, at the outer, free end of an articulated pivoted boomwork, a grip-and-hold device formed in accordance with the invention;

Fig. 2 shows the situation of Fig. 1 on a considerably larger scale; Fig. 3 shows - compared to Fig. 1 - the apparatus, device and board in positions, in which the grip-and-hold device with the board has been rotated 180° about the horizontal axis of the end of the boomwork, and in which the boomwork of the handling apparatus has lifted/swung the board up into a horizontal position at a relatively short distance from the ceiling of a room;

Fig. 4 shows by and large the same situation as that in Fig. 3, but with the board in a position somewhat closer to the ceiling, wherein the board-releasing (slightly) inclined position has made the small pivoted supporting means pivot and the pivotal spring-loaded hooks be swung away as a consequence of the displacement of the large board towards the lowest point of the supporting frame, whereby the transversal board edge positioned uppermost has been allowed to be pulled out of the hooks located on the left-hand side, after which the board is actually free;

Fig. 5 shows the curved controlling and motion-deflecting resilient element secured to a hook, abutting a wall immediately below the ceiling;

Fig. 6 corresponds to Fig. 5, but shows downward pivoting of the pivoted end portions;

Fig. 7 shows an enlarged partial view of the situation shown in Fig. 6;

Fig. 8 is a side view, partially in a vertical section, in which the board in question is to be mounted in the extension of an ceiling board already mounted; and Fig. 9 shows an immediately following phase of the situation shown in Fig. 8;

Fig. 10 shows the supporting frame alone, seen from above.

Reference is first made to Figs. 1 - 4, in which there is shown, in Fig. 1, a board-lifting and handling device comprising a carriage 10 with driving wheels 12, a boomwork post 14 mounted upright on the carriage 10, carrying at the top a telescopically extendable/retractable boom 18 pivotable about a horizontal pivot axis 16. Between a point 20 on the boom 18, positioned substantially closer to the pivot axis 16 than to the outer end thereof, and a lower point 22 on the boomwork post 14, there is inserted a piston-and-cylinder 24, which initiates the pivoting motion of the boom 18 about the pivot axis 16.

Between the outer free end of the boom and a supporting frame 26 for the individual large board 28 which is to be lifted, turned and moved by means of the handling apparatus, a joint 30 with a horizontal axis, placed centrally relative to the supporting frame 26, ensures the pivotability of the supporting frame 26 relative to the boom 18. The supporting frame 26 is provided with a grip-and-hold device according to the invention, in which there are incorporated grip-and-hold hooks 32 pointing towards one another. Two or more parallel hooks 32 can be arranged on each of the transversal side edges of the supporting frame 26, the side edge of the supporting frame 32 appearing from most figures, being considered as one of the two longitudinal sides of the supporting frame 26, because they extend parallel to the boom According to Fig. 1, and particularly Fig. 2, each hook 32 is formed at the end of an end portion 34 or an end section of a longitudinal frame part, the supporting frame conceivably being configured in a known manner with mutually connected longitudinal and transversal frame parts, located essentially in the same plane.

At its end opposite the hook 32, each end portion 34 of at least one transversal edge is pivotally connected about a horizontal axis 36 to the associated frame part of the supporting frame. The hooks 32 located to the right may be rigidly connected to the associated frame part, but a more flexible supporting frame is provided, in particular for the gripping and securely holding of a board, when all grip-and- hold hooks 32 are pivotally arranged in the manner shown.

A return spring 38 is arranged for each end section 34 with a hook 32. This return spring in the form of a tension spring allows the end section 34 with the hook 32 to be swung down with the hook 32 leading, when the board is to be released from the grip-and-hold device.

Each hook point can be extended by a short finger 40, which can have an orientation, see Fig. 7, whereby its longitudinal direction extends approximately tangential to a curved end surface 32a of the hook-carrying end section 34 of the supporting frame 26, which is pivotally supported at the end of the boom 18 about said horizontal axis 30.

The hook-carrying end sections 34 by one (the left-hand) transversal side edge of the supporting frame 26, are each provided with a controlling and motion-deflecting element 42 for the pivoted hook-carrying end section 34, in order to initiate the pivoting motion of the end section 34, when the free farthest projecting end/end portion of the motion- deflecting, controlling element contacts for example a vertical wall surface 44, Figs. 5 - 7, and cooperate therewith during the continued linear advancing of the supporting frame 26 with the board 28.

Of important components, the supporting frame 26 also carries four or more (two are visible in the side views according to the figures in the drawings) small pivoted supporting means 44, whose individual pivot points 46 are parallel with the pivot point 30 of the supporting frame 26.

According to for example Fig. 5 each of the small pivot- ed/tiltable supporting means 44 has a supporting surface 44a curved convexly upwards for a board 28.

A ceiling and a vertical wall immediately adjacent thereto are identified by 48 and 50, respectively, whereas the floor in the same room is identified by 52, Fig. 3.

The controlling and motion-deflecting element 42 may with advantage have a rounded, for example hook-shaped, end 42a, which helps to enhance the deflecting power of the element 42. The rounding at the end of the controlling and motion- deflecting element thereby ensures that on abutment against a wall 50 or another vertical surface/edge, the element is brought into end-section-controlling, downward pivoting, displacing motion along said surface/edge.

In Fig. 9 the adjacent side edge surfaces 28b and 28c of the boards 28 and 28a have been brought together and form a joint 54. The element 42 is resilient and flexible. The hook-point- extending finger 40 may have the same properties, especially by the pivoting down of the hook-carrying end section 34 by the mounting of the carried/handled board 28 into abutment against the free transversal side edge surface 28b of a board 28a already mounted, Fig. 8, wherein the curved hook end surface 32a, ending in the hook point, in combination with the resilient, flexible hook-point-extending finger 40, in a controlling cooperation with the board edge surface 28b, initiates a sufficient down-pivoting of the hook-carrying end section 34 about the pivot axis 36, in order to release the leading edge 28c of the board 28 handled from the hook 32 with the securing finger 40.

When a board 28 is to be mounted in a ceiling 48, the grip- and-hold device of the carriage frame 26 picks up a board 28 from a stack of horizontal boards lying on top of each other, Figs. 1 and 2. In this position the carriage frame 26 is rotated 180° about the axis 30 relative to the board- supporting position according to Figs. 3 - 9.

When the supporting frame 26 with the hooks 32 facing downwards, Fig. 2, is lowered on to the board 28 positioned uppermost in the stack, the hook-carrying end sections 34 of the supporting frame 26 pivot resiliently upwards, whereby the hooks 32 are moved somewhat outwards in the longitudinal direction of the frame 26, and then downwards, after which they will grip opposite side edges of the board 28 in a securing manner, when the supporting frame 26 is lifted by means of the piston-and-cylinder operated boom 18.

In order to swing the supporting frame 26 from the large- board-gripping position, shown in Fig. 1, by the stack of boards 28 lying horizontal on top of each other, in which the supporting frame 26 is positioned above the board 28 which is taken from the stack, there is arranged, e.g. Fig. 1, a very elongate, flexible rope-like element, for example in the form of a wire. This rope-like wire element and its effect in combination with the pivoting motion of the boomwork 18, will be explained in further detail later. For the moment, it should only be mentioned that the length and points of attachment of the wire are adjusted so relative to the pivoting motion of the boomwork 18, that the supporting frame 26 with one large board 28 is rotated approximately 180°.

The board thickness may for example be 13 millimetres, and it then comes natural to choose a hook height of about 15 millimetres and a hook-point-extending finger length of 1.5 millimetres. By these hook dimensions relative to an estimated board thickness, a secure grip about a board 28 is ensured.

Fixed in such a grip-and-hold device the board 28 is turned somewhat more than 180° about the axis 30 into the position sloping slightly downwards, as appears in particular from Fig. 4.

Fig. 4 shows the board 28 in a position, in which it is essentially in its mounting position, i.e. in the position where the board 28 should desirably be released from the grip-and-hold device, i.e. from the hooks 34, which are pivoted and spring-loaded at both transversal edges of the supporting frame 26 in Fig. 4.

The position sloping slightly downwards in the longitudinal direction (from left to right), in the direction towards the board-handling apparatus 10,14, is established after the supporting frame with the board was first positioned in a horizontal position, in which the board 28 was resting on the small pivoted supporting means 44, which then had positions directed perpendicularly to the plane of the supporting frame/board.

The relatively insignificant slope of the frame 26 with the overlying board 28 and intermediate supporting means 44, creates a displacing motion component for the board 28 in the plane thereof. With fixed hooks 34 the board 28 would be fixed and said motion component would be resisted. Contrary to this, by pivoted spring-loaded hooks 34 at both transversal edges of the supporting frame 26 two different releasing movements complementary to one another will now take place, each being an absolute condition for the implementation of the other.

Said motion component effective in the plane of the large board 28, initiates an extraction of the left-hand edge portion of the large board 28 from the hook portions 32,40, said beginning extracting movement at the left-hand transversal edge of the supporting frame 26 providing at the same time a pressure effect in the plane of the board 28, directed towards the hooks 34 at the right-hand transversal edge of the supporting frame. The pivoted resilient hooks 34 at the right-hand transversal edge will thereby swing down by their outer free hook portions 32, 40. This down-swinging of the right-hand hooks allows the downward sloping displacement of the board 28 towards the right, so that the left-hand edge portion of the board 28 is pulled completely out of the adjacent hooks 34, whereby the board 28 is actually completely released from the grip-and-hold device according to the invention.

In Figs. 4 - 7 is illustrated how the controlling and motion- deflecting element 42,42a causes a down-pivoting of the respective hook-carrying, spring-loaded end section 34 by utilization of the abutment and possibility of gliding displacement of the controlling and motion-deflecting element 42,42a down along the side wall 50, Figs. 6 and 7, the curved hook end surface 32a also participating in the gliding displacement.

When a board 28 together with the supporting frame 26 has been rotated 180°, the board 28 has reached a supported position, in which it rests on at least four restrictedly pivoted/tiltable small supporting means 44 with supporting surfaces 44a curved convexly upwards and individual pivot axes 46 on the supporting frame 26.

Such supporting means 44, each having a horizontal pivot axis, represent supporting elements, from which the boards 28 can easily be released in its mounting position after the board has been released from the pivoted hook-carrying end sections. By studying Fig. 6 in connection with Fig. 5, one can see the possibility for the supporting means 44 to pivot, when a board 28 has been brought into its mounting position in abutment on the ceiling surface 48, its leading edge surface abutting on the adjacent wall surface 50.

As mentioned initially, it is sufficient that the hooks 32 at one transversal edge of the supporting frame can be pivoted downwards. By letting the hook-carrying end sections 34 at the left-hand transversal side edge of the supporting frame 26 individually be downwards pivotable about a horizontal axis 36, and have returning, up-swinging tension springs 38 arranged thereto, and by preferably providing each of them with a controlling and motion-deflecting resilient, element 42 with a rounded outer edge and preferably with a hook-point- extending flexible finger 40. The right-hand hook-carrying end sections 34 of the supporting frame 26 may be rigidly connected to the rest of the frame 26 because a supported board 28 carried, which is released from the left-hand hook devices 32,34,36,38 of the grip-and-hold device, is practically released already from the gripping device. By placing such a supported board, whose free (left-hand) leading edge 28c abuts on a wall 50 at the top thereof by the ceiling 48 or on the transversal edge 28b of a board 28a already mounted, only a linear displacing motion of the supporting frame 26 is required in order to release the grip about the board 28. However, it is the most advantageous that all the hook-carrying end sections 34 can be swung down individually.

Each of the ends of the individual tension springs 38 is secured to an attachment lug 56 on the supporting frame 26, and to an attachment lug 58 on the pivoted hook-carrying end section 34 thereof.

Finally, in the following a wire 62 will be described, which has a first fixed attachment point 60 on the supporting frame 26 and a second fixed attachment point 66 on the post-like constructional element 14 of the board-handling apparatus 10,14, at the top of which, the boomwork 18 is pivotally arranged.

The horizontal pivot axis 30 of the supporting frame 26 is established through a pin secured to the end of the boomwork and rotationally supported between two bearing lugs 68 which may have the form of a segment of a cord/groove wheel, by which the wire 62 is guided until it has entered the cavity of the square tube forming the boomwork 18. For the guiding of the wire 62 guide disks, not shown, can be arranged, and in the area of said second fixed attachment point 66 for the wire 62, the wire 62 has a tension spring or gas spring 64 arranged thereto, which is to resist tearing of the wire 62 by an incorrect pivot angle of the frame 26.

The length of the wire 62 and the choice of attachment points, are based on construction and/or experience. By the pivoting motion of the boomwork about the axis 16 by means of the hydraulic/pneumatic piston-and-cylinder 24, the supporting frame 26 with the board 28 (from the stack of boards in Fig. 1) will be forcedly rotated, first into the horizontal intermediate position below the ceiling 48, and then into a position of release, sloping slightly downwards, Fig. 4. The releasing of the board 28 from the grip-and-hold device of the supporting frame 26 has been described above.

Claims

C l a i s

1. A releasable grip-and-hold device configured for gripping large boards (28, 28a) individually and securely holding the individual board during the following swinging/lifting, comprises a supporting frame (26) which is connected, pivotal about an essentially horizontal axis (30), to the end of a pivoted boomwork (18) of a preferably drivable board-handling apparatus (10,12,14 16,20,22,24), in which there are arranged, along a transversal side edge of the supporting frame

(26), hooks, hook-like means or similar, parallel to one another, which contribute to the securing of the board (28, 28) during the swinging/lifting thereof and the placing thereof into a mounting position, in which it is released from the grip-and-hold device of the supporting frame (26), c h a r a c ter i z e d i n that the releasable grip-and-hold device comprises hooks (32) arranged at the two opposite transversal edges of the supporting frame (26), and that at least the hooks (32) at one of said transversal edges are each formed/ arranged on end sections (34), which are pivotally mounted by their opposite ends to the rest of the supporting frame (26) and are spring-loaded (38) towards the active position of the respective hook (32), in which it grips about the adjacent board edge, and in which there are forcedly acting transmission means (62,64), carrying the supporting frame (26) by the pivoting of the boomwork (18), from a first gripping position of the grip-and-hold device by horizontally/ vertically stacked large boards (28), through an angle of rotation about said essentially horizontal axis (30), which rotation brings the supporting frame (26) to be positioned underneath the large board (28).

2. A releasable grip-and-hold device according to claim 1, c h ar ac t e r i z ed i n that said transmission means comprise at least one very long rope-like tensile element, for example in the form of a wire rope (62), secured at one end to the supporting frame (26) at a fixed point (60) at the essentially horizontal axis (30) of this frame (26), said wire rope (62) extending along and preferably inside the boomwork (18), in order to be secured by its other end to another fixed point (66) on the upright constructional element (14) of the board- handling apparatus carrying the boomwork (18), preferably by an intermediate tension spring (64) or similar elastically yielding extendable/retractable element with a damping function.

3. A releasable grip-and-hold device according to claim 1, c h ar ac te r i z ed i n that the pivotal hooks (32) exhibit means (32a, 42, 42a), initiating, on abutment against a stationary surface, for example of a wall (50), the down-swinging of the pivoted spring- loaded end section (34) of the supporting frame of the respective hook (32), for the release of the board (28, 28a) from the hooks (32).

4. A releasable grip-and-hold device according to claim 1, c h ar ac t e r i z ed i n that each pivotal hook

(32) has an arched or curved outer terminal edge surface (32a), extending from the hook surface and extending from the hook point to the straight outer terminal edge of the pivoted end section (34).

5. A releasable grip-and-hold device according to claim 1, c h a r a c t er i z e d i n that at least the pivotal hooks (32) are provided with a finger (40) extending from the hook point and having an at least approximately tangential course relative to the curved terminal edge surface (32a) of the hook.

6. A releasable grip-and-hold device according to claim 4 or 5, c h ar a c te r i z e d i n that the pivotal hooks (32) at one or both of the transversal edges of the supporting frame (26) are provided with a preferably flexible elongate element (42) controlling and deflecting the direction of motion, which projects in front of the outermost point in the longitudinal direction of the hook (32), and is secured to the hook- carrying end section (34), and has a curvature in the supporting and carrying position of the supporting frame (26) following a course curved convexly upwards, and which is formed to be displaced in a gliding manner along a surface/edge (50), which it might abut during the essentially horizontal movements of the supporting frame (26), and during its gliding displacement to pull along and pivot down the hook-carrying pivoted end section (34).

7. A releasable grip-and-hold device according to claim 6, c h ar ac te r i z ed i n that the element (42) controlling and deflecting the direction of motion of the hook-carrying pivoted end section (34) of the supporting frame (26) has an outer, for example hooklike terminal rounding (42a).

8. A releasable grip-and-hold device according to any one of the preceding claims, c h ar a c t e r i z e d i n that each hook-carrying, pivoted end section (34) of the supporting frame (26) has a return tension spring (38) arranged thereto, which has an end-attaching lug (58) on said pivoted end section (34) and an end-attaching lug (56) on the rest of the supporting frame (26).

9. A releasable grip-and-hold device according to any one of the preceding claims, c h ar a c t e r i z e d i n that the supporting frame (26) carries small, pivoted supporting means (44) on which the underside of the board (28) is resting when the supporting frame (26) has been rotated about said essentially horizontal axis (30) from a position corresponding to the stacking position of the large board (28) into a position at least approximately corresponding to the mounting position of the large board (28).

10. A releasable grip-and-hold device according to claim 9, c h ar ac te r i z e d i n that each pivoted supporting means (44) is provided with a supporting and carrying surface (44a) curved convexly outwards from the pivot point (46), the plane underside surface of the board resting on part of said curved surface (44a).

11. A releasable grip-and-hold device according to any one of the preceding claims 2-10, c h ar ac t e r i z ed i n that the essentially horizontal pivot axis (30) between the supporting frame (26) and the end of the boomwork (18) is established by means of a transversal bolt secured to the end of the boomwork and supported between a pair of bearing lugs (68), together forming for example half a cord/groove wheel, the point of attachment of the wire (62) to the supporting frame (26) being between the bearing lugs (68).

12. A method of releasing a grip-and-hold device, as configured in claim 9, from a large board (28), which has been brought into a mounting position, all the hooks (34) being pivoted and spring-loaded, c h ar ac te r i z e d i n that the supporting frame (26) with the large board resting thereon in or immediately adjacent to the mounting position of the board (28), and with the board (28) resting on the top of the upright pivoted supporting means (44), is placed in a position slightly inclined, so that the board (28) is brought into a displacing motion, which causes a pivoting of the supporting means (44) in the same direction as the downward sloping of the supporting frame (26), said pivoting of the supporting means (44) with the large board (28) lying thereon causing the so far gripped and securely held board edge portion to be pulled out of the pivoted spring-loaded hooks at one transversal edge of the supporting frame (26), as the large board (28), which has been brought into displacing motion, will exert a push force by its opposite board edge on the pivoted spring-loaded hooks (34) at the other opposite transversal edge and pivot these hooks resiliently away from their active position, so that said withdrawal of the board edge from the hooks first mentioned can take place.