GB2234413A

GB2234413A - Large stone and boulder separating device

Info

Publication number: GB2234413A
Application number: GB8917296A
Authority: GB
Inventors: Timothy Needham; David Weston
Original assignee: Richard Pearson Ltd
Current assignee: Richard Pearson Ltd
Priority date: 1989-07-28
Filing date: 1989-07-28
Publication date: 1991-02-06
Also published as: GB8917296D0

Abstract

A large stone and boulder separating device comprises two spaced, substantially parallel rotatable members (1, 2) mounted for rotation in the same direction, and each carrying a plurality of axially-spaced starwheels (5) having angularly- spaced, resilient fingers (7). The rotatable members (1, 2) are mounted to allow adjustment of the gap between the ends of the fingers of the starwheels on one of the rotatable members (1, 2) and the ends of the fingers of the starwheels on the other rotatable member (2, 1). <IMAGE>

Description

Large Stone and Boulder Separating Device The present invention relates to a large stone and boulder separating device.

Conventional stone separators usually comprise two webs having spaced laterally-extending bars. The size of sieving is determined by the distance between the bars.

The maximum distance between the bars is about 50mm.

Stones, clods and soil having a smaller size fall between the bars and are returned directly to the ground. i.e. to the sowing area directly beneath, since objects of this size are acceptable.

Stones larger than say, 50mm pass over the end of the second conveyor to a stone-separating device comprising a plurality of spaced metal discs mounted on spaced shafts. Most of the larger stones fall between the discs to a cross-conveyor arranged therebelow and are returned to the ground on either side of the growing area. Such larger stones can normally be pressed down into the ground by, e.g., tractor wheels. However, a number of the larger stones will be too large to be pressed into the ground or will interfere with the growing area. Such stones, or small boulders are too large to fall between the discs and are passed into a bin or trough for removal.

Instead of spaced discs, it is known to provide a stone separating device having a rake comprising reciprocating, longitudinally-extending bars. The larger stones fall between the bars onto the cross conveyor, whereas the still larger stones and small boulders fall off the end of the bars into a bin for removal.

A disadvantage of the known above-described stone-separating devices is that irregularly-shaped stones, e.g. wedge-shaped stones, tend to jam between the discs or bars and eventually clog the separating device and also damage the discs or bars.

An object of the present invention is to provide a stone separating device which can cope with larger stones than previously, and even small boulders without producing undue wear and tear.

The invention provides a large stone and boulder separating device as claimed in claim 1.

The invention further provides a method of separating stones using such a large stone and boulder separating device. Thus, complete stone separation may be achieved without jamming of the large stone and boulder separating device.

The invention also provides a stone separator comprising a large stone and boulder separating device as described above.

An embodiment of the invention will now be described with reference to the accompanying drawings, wherein: Figure 1 is a diagrammatic side view of a stone separator, and Figure 2 is a plan view of the stone separator of Figure 1.

In the drawing, a stone separator has a large stone and boulder separating device comprising a pair of spaced, parallel rotatable members 1, 2 mounted for driving rotation in the same direction as indicated by the arrows 3. Each rotatable member 1, 2 comprises a shaft 4, 4' carrying a plurality of starwheels 5 separated axially by spacers 6. Each starwheel has six angularly-spaced fingers 7 extending from a hub portion 8 having a central bore 9 for receiving the shaft 4 or 4'.

As can be seen from Figure 1, each finger 7 is "parrot-beak" shaped with a convex leading edge and a concave trailing edge. Although conventional starwheels may be used, in order to stand up to the weight of small boulders the starwheels have a diameter of 20 to 30cm, preferably 25cm, which is substantially larger than known starwheels.

The shafts 4, 4' are separated so that there is a gap 10 between the ends of the fingers 7 of the starwheels 5 of the starwheels of the two rotatable members 1, 2. This gap 10 is from 0 to 5 cm, preferably 2.5cm. The starwheels 5 are preferably formed from heavy-duty polyurethane having a Shore hardness of 70-85.

Upstream of the large stone and boulder separating device, there is a feed conveyor 11 for feeding a mixture of large stones and boulders 12 in the direction of arrow 11'. Beneath the rotatable members 1, 2, a cross conveyor 13 is arranged for carrying away in the direction of arrow 13' the larger stones 14 separated out by the large stone and boulder separating device.

Still larger stones and boulders 15 pass over the large stone and boulder separating device and fall into a hopper 16 pivotally mounted at 17 and swingable in the direction of arrow 18 for emptying.

Claims

Claims:

1. A large stone and boulder separating device comprising two spaced, substantially parallel rotatable members mounted for rotation in the same direction, and each carrying a plurality of axially-spaced starwheels having angularly-spaced, resilient fingers, the rotatable members being mounted to allow adjustment of the gap between the ends of the fingers of the starwheels on one of the rotatable members and the ends of the fingers of the starwheels on the other rotatable member.

2. A stone separating device as claimed in claim 1, wherein the diameter of the starwheels is substantially from 20 to 30cm.

3. A large stone and boulder separating device as claimed in claim 1 or 2, wherein the starwheels on one rotatable member are staggered with respect to the starwheels of the other rotatable member, so that the fingers of the starwheels of one rotatable member are aligned with the axial gaps between the starwheels of the other rotatable member.

4. A large stone and boulder separating device substantially as herein described with reference to the accompanying drawing.

5. A stone separator comprising a large stone and boulder separating device as claimed in any one of the preceding claims, a first conveyor for conveying stones to the large stone and boulder separating device, and a second conveyor arranged below the large stone and boulder separating device for removing stones separated thereby.

6. A stone separator as claimed in claim 5, wherein a hopper is arranged downstream of the large stone and boulder separator for collecting the large stones and boulders.

7. A stone separator substantially as herein described with reference to the accompanying drawing.