BACKGROUND

The invention relates to a hoisting device for hoisting a package bricks or blocks , wherein the hoisting device comprises a scissors grab for grabbing the package and a safety device to reach underneath the grabbed package .

Such hoisting device is for example known from EP1324942B1 . The known hoisting device comprises two safety claws that reach underneath the grabbed package to prevent that bricks or blocks fall out of the hoisting device . The safety claws are provided with wheels and when the grabbed package is put onto the ground, firstly the wheels roll over the ground to spread the safety claws away from the package . The wheels convert the vertical movement of the package into a spreading movement of the safety claws .

SUMMARY OF THE INVENTION

A disadvantage of the known hoisting device is that the safety claws are spread evenly only when all the wheels have the same roll resistance on the ground . In practice there are small obstacles on the ground or the ground is uneven, whereby one of the safety claws opens first, causing the hoisting device to swing . This is a risk for workers that stand close to the loaded hoisting device . It is an obj ect of the present invention to provide a hoisting device of the abovementioned type, having safety claws that open in a controlled manner .

The invention provides a hoisting device for hoisting a package bricks or blocks , wherein the hoisting device comprises a scissors grab for grabbing the package and a safety device to reach underneath the grabbed package , wherein the scissors grab comprises a hoisting frame, a first grab claw and a second grab claw that are hingeable connected to each other to hinge around a scissors axis between a spread position to receive the package between the first grab claw and the second grab claw, and a clamping position to engage and clamp the package between the first grab claw and the second grab claw, and a clamping mechanism between the hoisting frame and the first grab claw and the second grab claw, wherein the clamping mechanism is configured to hinge the first claw and the second claw around the scissors axis between the spread position and the clamping position when the hoisting frame vertically moves with respect to the scissors axis , wherein the safety device comprises a first safety claw that is hingeable with respect to the first grab claw around a first hinge axis , and a second safety claw that is hingeable with respect to the second grab claw around a second hinge axis , to hinge between a released position to allow the package to pass between the first safety claw and the second safety claw, and a safety position to reach underneath the package, wherein the hoisting device is moveable between an unloaded position, a loaded clamping position and a secured clamping position, wherein in the unloaded position the first grab claw and the second grab claw are in the spread position and the first safety claw and the second safety claw are in the released position, and wherein in the loaded clamping position the first grab claw and the second grab claw are in the clamping position and the first safety claw and the second safety claw are in the released position, and wherein in the secured clamping position the first grab claw and the second grab claw are in the clamping position and the first safety claw and the second safety claw are in the safety position, wherein the hoisting device comprises a spring provision that biases the first safety claw with respect to the first grab claw and that biases the second safety claw with respect to the second grab claw, wherein in the secured clamping position of the hoisting device the spring provision biases the first safety claw and the second safety claw towards the released position .

The hoisting device according to the invention comprises a spring provision that in the secured clamping position of the hoisting device biases the first safety claw and the second safety claw towards the released position . The spring provision thereby helps to hinge the first safety claw and the second safety claw to the spread position, for example when external forces by act on them at the moment they hit the ground . In this manner the package can be lowered vertically in a controlled manner .

In an embodiment engages in the secured clamping position of the hoisting device the first safety claw the first grab claw, and engages the second safety claw the second grab claw, whereby the safety positions of the safety claws is defined and limited by the grab claws .

In an embodiment the spring provision biases in the loaded clamping position of the hoisting device the first safety claw and the second safety claw towards the safety position, which is in the opposite direction to urge the safety claws towards the safety position after the grab claws are brought into their clamping position .

In an embodiment the spring provision comprises one or more springs that are connected with and that extend between the grab claws and the safety claws .

In an embodiment the springs extend in the secured clamping position of the hoisting device as from the connection with the grab claw at one side of a force axis through the hinge axis of the safety claw and the connection with the grab claw, and wherein in the loaded clamping position of the hoisting device the springs extend as from the connection with the grab claw at the opposite side of the force axis through the hinge axis of the safety claw and the connection with the grab claw . The springs thereby toggle over the force axes to change the bias of the safety claws towards the safety position into a bias of the safety claws towards the released position, depending on the respective clamping position and spread position of the grab claws .

In an embodiment the safety device comprises first wheels under the first safety claw and second wheels under the second safety claw .

In an embodiment thereof the first wheels and the second wheels form in the secured clamping position of the hoisting device the lowest parts of the hoisting device .

In an embodiment the scissors grab comprises one or more supports to engage and rest on a top side of the package in the unloaded position of the hoisting device .

In an embodiment the clamping mechanism comprises a lock between the hoisting frame and the first grab claw and the second grab claw, wherein the lock is operable between a locked working position in which the first grab claw and the second grab claw are fixed in the spread position, and a released working position that allows the first grab claw and the second grab claw claws to move to the clamping position .

The various aspects and features described and shown in the specification can be applied, individually, wherever possible . These individual aspects , in particular the aspects and features described in the attached dependent claims , can be made subj ect of divisional patent applications . BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings , in which :

Figures 1A, IB and 1C are two isometric side views and a front view of a hoisting device for a package bricks or blocks according to the invention, in a secured clamping position;

Figures 2A and 2B are an isometric view and a front view of the hoisting device and the package according to figures 1A and IB in an unloaded position; and

Figure 3 is a front view of the hoisting device and the package according to figures 1A and IB in a loaded clamping position .

DETAILED DESCRIPTION OF THE INVENTION

Figures 1A-1C show a hoisting device 1 for a package 100 according to an embodiment of the invention . The package 100 comprises a series of identical bricks or blocks 101 , for example masonry bricks , such as sand-lime bricks or blocks , or masonry stones , that are positioned adj acent to each other . The bricks or blocks 101 are aligned both when the package 100 stands on the ground 200 and when the package 100 is clamped and hoisted above the ground 200 by means of the hoisting device 1 .

The hoisting device 1 comprises a steel scissors grab 10 having a hoisting frame 20 that comprises a hoisting connection or hoisting eye 21 to connect the hoisting device 1 to a hoisting hook of a crane , a front suspension 23 , a rear suspension 24 , and two interconnected locking arms 25 that pend downwards between the front suspension 23 and the rear suspension 24 and that carry a locking pin 26 at the ends .

The scissors grab 10 comprises a first grab claw 30 and a second grab claw 40 that are hingeable with respect to each other around a central scissors axis C . The first grab claw 30 comprises a first front bracket 32 and a first rear bracket 33 that are both formed as a L-shaped plate, having an elongate base section 35 and a shorter end section 36 . The end sections 36 are connected with a first gripper bar 37 on which a first elastic grip strip 38 is attached . The scissors grab 10 comprises a first support roller 31 that is at its ends rotatable connected with the base sections 35 of the first grab claw 30 .

The second grab claw 40 comprises a second front bracket 42 and a second rear bracket 43 that are both formed as a L-shaped plate, having an elongate base section 45 and a shorter end section 46 . The end sections 46 are connected with a second gripper bar 47 on which a second elastic grip strip 48 is attached . The first elastic grip strip 38 and the second elastic grip strip 48 are facing the package 100 to engage the opposite sides thereof . The scissors grab 10 comprises a second support roller 41 that is at its ends rotatable connected with the base sections 45 of the second grab claw 40 . The scissors grab 10 comprises two sliders 49 that are at the ends of the second roller 41 hingeably connected with the base sections 45 of the second grab claw 40 and that are at the ends of the first roller 31 slidably supported by the base sections 35 of the first grab claw 30 to slide over a limited stroke . The sliders 42 thereby limit the innermost and the the outermost mutual hinging position of the first gripper bar 37 and second gripper bar 47 in a horizontal clamping direction F .

The scissors grab 10 comprises a first front link bar 51 having at one end a hinge connection 52 with the end of the first front bracket 32 and at the opposite end a hinge connection 53 with the front suspension 23 . The scissors grab 10 comprises a first rear link bar 55 having at one end a hinge connection 56 with the end of the first rear bracket 33 and at the opposite end a hinge connection 57 with the rear suspension 23 . The first front link bar 51 and the first rear link bar 55 thereby hinge with respect to each other around a common first hinge axis D that extends parallel to the central scissors axis C .

The scissors grab 10 comprises a second front link bar 61 having at one end a hinge connection 62 with the end of the second front bracket 42 and at the opposite end a hinge connection 63 with the front suspension 23 . The scissors grab 10 comprises a second rear link bar 65 having at one end a hinge connection 66 with the end of the second rear bracket 43 and at the opposite end a hinge connection 67 with the rear suspension 24 . The second front link bar 61 and the second rear link bar 65 thereby hinge with respect to each other around a common second hinge axis E that extends parallel to the central scissors axis C .

The first front link bar 51 , the first rear link bar 55 , the second front link bar 61 and the second rear link bar 65 all hinge around a common hoisting frame hinge axis B . The scissors grab 10 comprises two lock pin catchers 27 on in this example the first front bracket 32 and the first rear bracket 33 . The lock pin catchers 27 have a slot 28 to receive the lock pins 26 and to pass it through via a lock-and-unlock traj ectory Q .

The first gripper bar 37 and the second gripper bar 47 move towards each other in the hori zontal clamping direction F from a spread position to a clamping position by hoisting the hoisting frame 20 in vertical direction A upwards wherein the common hoisting frame hinge axis B and the central scissors axis C move away from each other and the common first hinge axis D and the common second hinge axis E move towards each other while they all remain parallel to each other . In the opposite way the first gripper bar 37 and the second gripper bar 47 spread or move away from each other in the horizontal clamping direction F from the clamping position to the spread position by lowering the hoisting frame 20 and thereby the hoisting frame hinge axis B in vertical direction A downwards towards the central scissors axis C . The lock-and-unlock traj ectories Q for the lock pins 26 are formed to receive and temporary confine the lock pins 26 so as to lock and maintain the spread position while the hoisting device 1 is suspended free above the ground 200 . The lock pins 26 escape from the lock-and-unlock traj ectories Q by further or again lowering the hoisting frame 20 over a short stroke, whereafter the first gripper bar 37 and the second gripper bar 47 can scissor or hinge with respect to the central scissors axis C to the clamping position by hoisting the hoisting frame 20 .

The hoisting device 1 comprises a steel safety device 69 to prevent that the grabbed package 100 or individual bricks 101 thereof fall out of the scissors grab 10 when hoisted above the ground 200 . The safety device 69 comprises a first safety claw 70 and a second safety claw 80 to reach underneath the package 100 .

The first safety claw 70 comprises a first front bracket 71 and a first rear bracket 73 both having an L- shape, having an elongate base section 75 that is composed with rigidly interconnected bars , and an end section 76 under an angle therewith . The end sections 76 are connected with a first scoop profile 77 . The first safety claw 70 is at the end of the base sections 75 rotatably connected with the first grab claw 30 by means of two hinge connections 78 to hinge around the common first hinge axis D . The first safety claw 70 can thereby hinge with respect to the first grab claw 30 and come from aside in contact with the first gripper bar 37 . The first safety claw 70 comprises two first wheels 79 under the first scoop profile 77 .

The second safety claw 80 comprises a second front bracket 81 and a second rear bracket 83 both having an L-shape, having an elongate base section 85 that is composed with rigidly interconnected bars , and an end section 86 under an angle therewith . The end sections 86 are connected with a second scoop bar 87 . The second safety claw 80 is at the end of the base sections 85 rotatably connected with the second grab claw 40 by means of two hinge connections 88 to hinge with around the common second hinge axis E . The second safety claw 80 can thereby hinge with respect to the second grab claw 40 and come from aside in contact with the second gripper bar 47 . The second safety claw 80 comprises two second wheels 89 under the second scoop profile 87 .

The hoisting device 10 comprises a spring provision 90 between the scissors grab 10 and the safety device 69. The spring provision comprises in this example four coil springs 91 that are connected with and extend under tensile between the brackets 32 , 33 , 42 , 43 of the scissors grab 10 and the nearest brackets 71 , 73 , 81 , 83 of the safety device 69 . The coil springs 91 have main axes S between its connections , and the base sections 35 , 45 of the respective first grab claw 30 and the second grab claw 40 define force axes P through the connections of the coil springs 91 with the base sections 35 and through the respective first common hinge axis D and second hinge axis E .

When the first safety claw 70 and the second safety claw 80 are in contact with the respective first gripper bar 37 and second gripper bar 47 as shown in figures 1A, IB and 1C, the main axes S of the coil springs 91 are at the connections with the base sections 35 , 45 under an angle with the force axes P and extend downwards therefrom towards the connection with the brackets 71 , 73 , 81 , 83 of the safety device 69. The coil springs 91 bias the first safety claw 70 and the second safety claw 80 towards a released position, wherein the common spring force is set to keep the first safety claw 70 and the second safety claw 80 slightly in contact with the respective first gripper bar 37 and second gripper bar 47 when the loaded hoisting device 1 is suspended above the ground 200 with the first grab claw 30 and the second grab claw 40 in the clamping position . When the safety claws 70 , 80 are spread to the released position by external forces a shown in figure 3 , the coil springs 91 firstly rotate with their main axes S into alignment with the force axes P, and secondly toggle over the force axes P whereby they bias the first safety claw 70 and the second safety claw 80 in the opposite direction back towards engagement with the respective first gripper bar 37 and second gripper bar 47 . This opposite bias increases when the first grab claw 30 and the second grab claw 40 are unlocked and moved into the clamping position .

When the package 100 is hoisted with the hoisting device 1 , it is initially in an unloaded position in which the first grab claw 30 and the second grab claw 40 are in the locked spread position and the first safety claw 70 and the second safety claw 80 are kept in the released position by engagement of the respective first gripper bar 37 and second gripper bar 47 . In this unloaded position as shown in figures 2A and 2B the hoisting device 1 is lowered in direction A whereby the first wheels 79 and second wheels 89 land onto the ground 200 and subsequently roll the first safety claw 70 and second safety claw 80 away from the package 100 until the first support roller 31 and the second support roller 41 land onto the package 100 . By lowering the hoisting frame 20 slightly further, the scissors grab 10 is unlocked by the lock pins 26 and the lock pin catchers 27 . Subsequently the hoisting frame 20 is hoisted in direction A, whereby the hoisting device 1 initially comes in a loaded clamping position as shown in figure 3 in which the first grab claw 30 and the second grab claw 40 are hinged into the clamping direction into the clamping position in which the friction forces at the first elastic grip strip 38 and the second elastic grip strip 48 are sufficient to hoist the package 100 from the ground 200 . The spring provision 90 thereby biases the first safety claw 70 and the second safety claw 80 towards the safety position while the first wheels 79 and the second wheels 89 are still on the ground 200 and keep the first safety claw 70 and the second safety claw 80 in the released position .

As soon as the package 100 gets off the ground 200 as shown in figures IB and 1C, the hoisting device 1 comes into its secured clamping position in which the first safety claw 70 and the second safety claw 80 have moved towards each other in their safety position in which the first scoop profile 77 and the second scoop profile 87 reach underneath the package 100 . Over this stroke of the first safety claw 70 and second safety claw 80 , the coil springs 90 toggle over whereby in the safety position the first safety claw 70 and second safety claw 80 are biased towards the spread position while remaining in contact with the first gripper bar 37 and the second gripper bar 47 .

When the hoisted package 100 is put back onto the ground 200 , firstly the first wheel 79 and the second wheels 89 land on the ground 200 . The bias of the first safety claw 70 and the second safety claw 80 towards the spread position ensures that they can easily roll over the ground 200 towards the released position while the package 100 is lowered onto the ground 200 . In this manner it is ensured that the package 100 lands pure vertically onto the ground 100 , that is without sudden or unexpected hori zontal shocks due to sticking first wheels 79 or second wheels 89.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention . From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention .