WO1988010231A1

WO1988010231A1 - Grapple device

Info

Publication number: WO1988010231A1
Application number: PCT/SE1988/000329
Authority: WO
Inventors: Astrid HAMMARBÄCK
Original assignee: Hammarbaeck Astrid
Priority date: 1987-03-18
Filing date: 1988-06-16
Publication date: 1988-12-29
Also published as: FI890773A; AU1959188A; FI890773A0; SE8701108A0; SE8701108D0; NO890722D0; NO890722L

Abstract

The present invention relates to a grapple device, preferably designed to load and unload pulpwood or bulk material, including two towards each other movable prongs or bucket halves being connected at their upper ends to a central shaft. The invention is characterized in that a knee-joint mechanism (4, 5) is connected between prongs (1, 2) or bucket halves (1, 2) at both sides of their central shaft (3), and that at least one force performing device (7) is connected between the knee-joint mechanism and one of the prongs (2).

Description

GRAPPLE DEVICE

The present invention relates to a grapple device, preferably designed tobe used iriloading and unloading of goods, such as timber or bulk material.

Grapple devices for timbe /pulp and bucket devices for pulp material often have different design, although the mechanism performing the opening can be the same for the two devices. Timber grapples have during the last 30 years developed from comparatively heavy constru tions towards smaller and lighter constructions where the geometry of grip- and movement of the grapple device all the time has developed to better suit its purpose. Sometimes the lifetime of the more complex mecanism of the modern grapple devices has become unacceptably short at the same time as the need for service has increased. One explanation to this negative development can probably be found in the choose of just one hydraulic cylinder.

The main purpose of the present invention is to obtain a grapple device beeing both compact - low construction hight - and per¬ forming a very favourable geometry of movement.

An other purpose of the invention is to obtain a grapple device performing a very favourable geometry of forces.

Yet an other object of the present invention is to obtain a grapple device combined with a conventional rotator and a crane, which forms very effective device for loading and unloading of pulpwood.

The objects mentioned above are obtained by a grapple device with the characterisics given in the patent claims.

By connecting on the one hand a knee-joint mechanism between the prongs or bucket-halves at the two sides of their central joint and on the other hand double acting hydraulic piston device between the knee-joint mechanism and one of the prongs/bucket- halves, a surprisingly well-balanced and suitable geometry of gripping and movement is obtained at the prongs/bucket halves.

By placing two hydraulic devices at each side of a central holder for a rotator, a favourable geometry of forces is obtained, i.e. the power transmission takes place via a minimum of levers and joints. Furthermore it is possible to obtain a big gripping force and a rapid opening movement between the grapples/bucket halves, which properties are desirable at a device of this art.

The invention will now be described in connection to an example shown in the accompanying drawing, wherein

The figure is a schematic perspective view of a grapple device according to the invention.

The prongs 1 and 2 are both movably articulated around the shaft 3. A knee-joint mechanism 4 and 5 connects the prongs 1 and 2 at both sides of the shaft 3. Between the cross-bars 6 and 7 is a double acting hydraulic piston-cylinder device 7. The inlet of hydraulic fluid at the +-side of the device provides a powerful and slow closing movement and inlet at the —side provides a faster and less powerful opening movement of the^"two prongs.

At the upper side of the knee-joint mecanism a rotator can be placed.

The gripping geometry shown by the prongs 1 and 2 is surprisingly favourable. The prongs can be opened to an extend where their points will be directed substantially in parallell and downwards. This is of advantage for the ability to from above be able to grip into e.g. a pulpwood stack. When the prongs grip the load, this will at the same time be moved a little bit upwards, which in a favourable way makes it easier for the logs to roll in between the prongs.

As the lever point of the grapple is variable in relation to the attachment of the cylinder, it is favourable to arrange this with a casing yoke attachment to make it possible for the most favour¬ able force development of the grapple device to occur.

The waist mounting of the hydraulic devices preferably takes place at both sides of the vertical symetrical axis of the grapple device. The invention is not restricted to the embodiments described above, thus modifications can be done within the scoop of the following claims.

Claims

P AT E N T C L A I M S

1. Grapple device, preferably designed to load and unload pulp¬ wood or bulk material, including two towars eachother movable prongs or bucket-halves beeing connected to a central shaft at their upper ends, c h a r e c t e r i z e d i n that a knee-joint mechanism (4,5) is connected between the prongs (1,2) or the bucket-halves at both sides of their central shaft (3) , and that at least one force performing device (7) is connected between the knee-joint mechanism and one of the prongs (2).

2. Device according to claim 1, ch ar e c t e r iz ed in two force performing means in the shape of double acting and waist mounted piston-cylinder devices.