GB2306128A

GB2306128A - Mobile Screening Apparatus

Info

Publication number: GB2306128A
Application number: GB9521033A
Authority: GB
Inventors: Paul Douglas
Original assignee: Extec Screens and Crushers Ltd
Current assignee: Extec Screens and Crushers Ltd
Priority date: 1995-10-13
Filing date: 1995-10-13
Publication date: 1997-04-30
Also published as: GB9521033D0; DE19642370A1; DE29617836U1

Description

1 MOBILE SCREENING APPARATUS 2306128 This invention relates to a mobile

screening apparatus which comprises a wheel-supported main frame, a loading hopper mounted on the main frame at the forward end thereof, a screening device mounted on the main frame at or near to the rear end thereof, and a conveyor arranged to receive material from the hopper at one end of the conveyor and to deliver the material from its opposite end to the screening device.

A screening apparatus (screening plant) is normally used to separate bulk material supply into different size ranges of particulate material, such as separation of crushed stone into different ranges of size of aggregate, gravel and sand. It can also be used to separate land clearance material i.e. soil, tree roots, and stone into top-soil as the desired end product, and to remove undesired material in the form of roots, stone and rubble.

The screening elements used in the screening device and or in the hopper will be selected to suit the particular types of screening operation which are required.

Use of so-called "bar grizzly" screens, and screen decks (one or more to suit the number of separated fractions) are well-known to those of ordinary skill in the art, and need not be described in more detail herein.

Screening plants may be installed on site as permanent or semi-permanent fixtures, and this may be suitable for quarry installations, in which case the plant can be transported to the site in component form, and then assembled on site when long term usage at any particular site is contemplated. The labour cost of assembly, and eventual dis-assembly for subsequent transfer to another location may be acceptable in such situations.

However, for many site operators, and especially land clearance, or site clearance, it is much more preferable to employ screening plants which are readily transportable (usually being towed behind a suitable tractor unit), in which case it is desirable to provide apparatus which can be converted relatively easily and quickly between a transport mode and an operative mode.

a Given the very large volume taken up by a screening plant, when it is deployed into its operative mode, it is usually necessary to provide complicated folding structures which allow at least some of the significant component parts of the apparatus to be folded to positions of reduced volume (and minimum projection from the general plane of the main frame of the apparatus) for transport purposes, but which can be unfolded on site to take up an operative position. Examples of this include folding side conveyors and folding tail conveyors as disclosed in more detail e.g. in EP 0506812 and EP 0407549, and also a tilting screen as disclosed in more detail e.g. in EP 0301798.

The present invention is concerned with a screening apparatus of the general type referred to in the introduction, and in which the screening device is moveable linearly as a unit, relative to the main frame, between a transport position and an operative position.

According to the invention there is provided a mobile screening apparatus which comprises a wheel-supported main frame, a loading hopper mounted on the main frame at the forward end thereof, a screening device mounted on the main frame at or near to the rear end thereof, and a conveyor arranged to receive material from the hopper at one end of the conveyor and to deliver the material from its opposite end to the screening device; in which the screening device is moveable as a unit relative to the main frame, between a rearwardly projecting operative position, and a forwardly displaced transport position which reduces the overall length of the apparatus.

Therefore, for transport purposes, the screening device can be linearly displaced forwardly to the transport position, and thereby reducing significantly the overall length of the apparatus, and which is usually necessary in order to meet highway regulations, for the purposes of transport of the apparatus to a site, but which can be readily deployed to its operative position, by linear rearward displacement to the operative position, and to allow screening operations then to take place.

In addition to providing a reduced volume of the apparatus, when converted to the transport mode, so that it may then be more suitable for towing along the public highway, the reduced volume for transport or stowage purposes also reduces the volume of crating which may be required for lorry, rail or ship transport of the apparatus to customers abroad. Crating costs are substantial, and based on volume, and therefore the ability to reduce the volume of the apparatus for such purposes can result in significant savings in transport costs.

In a preferred arrangement, the screening device may take the form of a so-called "screen box", which will be well-known to those of ordinary skill in the art, and which may have at least one screen deck in order to separate the material discharged by the conveyor into at least one desired fraction of separated material e.g. so-called "fines", and which, after discharge from the screening device, can then be discharged to a stockpile, via a discharge conveyor.

Desirably, the discharge conveyor also is adjustably mounted on the main frame of the apparatus, so as to be folded between a transport position of minimum or nil lateral projection from the main frame of the apparatus (as seen in plan), to a laterally outwardly displaced position for discharge of material screened by the screening device.

The hopper, which is mounted at the forward end of the main frame, may include suitable screening elements in order to carry out preliminary separation of bulk material supply e.g. it may include bar grizzly screen(s) to separate out tree roots and branches from land clearance material delivered thereto.

The conveyor, which delivers material from the hopper to the screening device, preferably takes the form of a discharge elevator, in which its forward and lower end is arranged to receive material directly from the hopper, whereas its rearward and upper discharge end allows the material delivered by the conveyor to fall under gravity on to the screen deck (s) of the screening device.

The screening device may take any suitable form, and may be entirely gravity operated, for the purposes of separating the material, or may have suitable vibrational devices coupled thereto in order to assist the screening operation.

In a particularly preferred embodiment of the invention the apparatus comprises a towable apparatus, having a wheel set (at least one pair of wheels), arranged to support the main frame at or near the rear end thereof, whereas the forward end of the main frame has suitable means to allow the main frame to be mounted on a coupling arrangement of a tractor unit. In a particularly preferred arrangement, the main frame comprises a platform, arranged below the hopper, and which allows the main frame to be mounted on a usual "fifth wheel,, coupling of a tractor unit.

The elevator is preferably adjustably mounted, directly or indirectly, on the main frame of the apparatus, and is capable of being adjusted between an operative position, in which its upper discharge end can readily discharge material to the screening device, (when the latter has been rearwardly adjusted to its operative position), but in which the elevator can be adjusted to an inoperative position, out of the path of linear movement of the screening device to its transport position.

In a preferred arrangement, the discharge elevator comprises two separate portions, hingedly connected together, with the forward portion of the elevator remaining fixed, but the rearward and upper portion being foldable to a position substantially overlying the forward portion, and thereby allowing a clear path of forward movement of the screening device to the transport position.

A preferred embodiment of mobile screening apparatus according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a side view of the apparatus, when partly deployed to an operative position; and Figure 2 is a view, similar to Figure 1, but showing the component parts of the apparatus when adjusted to a transport position for towing along the public highway, or a stowage position of reduced volume for crating purposes.

Referring now to the drawings, a mobile screening apparatus according to the invention is designated generally by reference 10 and comprises a wheel-supported main frame 11 having a triple axle rear wheel set 12, and with a loading hopper 13 mounted on the main frame at the forward end thereof. The loading hopper 13 can be of any suitable known design, to receive a supply of bulk material which is to be screened.

A screening device 14, in the form of a so-called screen box is mounted on the main frame 11 at or near to the rear end thereof, and a conveyor 15 is arranged to receive material from the hopper 11 at one end of the conveyor, and to discharge the material from its opposite end and to the screen elements of screen box 14.

The conveyor 15 comprises an elevator which is in twopart form, having a forward part 16 which remains fixed, and a rear part 17 which is adjustable between a deployed or operative position shown in Figure 1, and a folded horizontal transport position shown in Figure 2. A horizontal hinge 18 allows this adjustment of the conveyor parts of the elevator conveyor. Adjustment of the elevator conveyor to the inoperative position, as shown in Figure 2, allows the screen box 14 to be moved linearly, as a unit relative to the main frame 11, between the operative or deployed position shown in Figure 1, and to the transport or stowage position which is forwardly displaced, as shown in Figure 2, whereby the overall length of the apparatus is reduced. Screen box 14 is carried on a platform 19, and screen box 14 and platform 19 move bodily as a unit, on suitable guide rails or the like on the main frame 11, between the deployed position and the transport position.

The forward end of the main frame 11 includes a mounting platform 20, arranged below the hopper 13, and which is adapted to be mounted on a suitable coupling e.g. a fifth wheel coupling of a tractor unit (not shown) to allow the apparatus 10 to be towed along the public highway, when the component 0 R parts thereof have been adjusted to the transport or stowed mode shown in Figure 2. Evidently, when the conveyor 15 has been adjusted to the transport mode shown in Figure 2, it allows the screening device 14 to be moved bodily as a unit, and linearly forwardly from the deployed position shown in Figure 1, to the transport position shown in Figure 2.

When the screening device 14 is in the operative position, material screened by the screen box is directed to suitable discharge points below the screen box, and for subsequent discharge via one or more discharge elevator / conveyor(s) to form a stockpile alongside the apparatus. As shown in Figures 1 and 2, a side-mounted discharge conveyor 20 is provided, in which the drawings only show the main frame component parts 21, and is shown in both Figures 1 and 2 in the transport position, in which it lies along one side of the frame, and does not project laterally therefrom to any appreciable extent. However, via a pivot mounting 22 of the frame 21, the discharge conveyor can be pivoted to a laterally outwardly extending position, whereby material screened by the screen box can then be laterally discharged to a stockpile.

Any suitable collection arrangement may be mounted below the screen box 14, to collect screened portion (s), and may comprise e.g. a hoppershaped construction with a discharge slot extending longitudinally thereof, so that the material can fall onto a conveyor surface which then feeds the material to one or more side discharge conveyors.

1 &

Claims

CLAIMS:

1. A mobile screening apparatus (10) which comprises a wheel-supported main frame (11), a loading hopper (13) mounted on the main frame (11) at the forward end thereof, a screening device (14) mounted on the main frame (11) at or near to the rear end thereof, and a conveyor (15) arranged to receive material from the hopper (13) at one end of the conveyor and to deliver the material from its opposite end to the screening device (14); in which the screening device (14) is moveable as a unit relative to the main frame, between a rearwardly projecting operative position, and a forwardly displaced transport position which reduces the overall length of the apparatus.

2. Apparatus according to claim 1, in which the screening device (14) comprises a screen box having at least one screen deck.

3. Apparatus according to claim 1 or 2, including a discharge conveyor (21) mounted on the apparatus and operable to discharge material separated by the screening device laterally of the apparatus.

4. Apparatus according to claim 3, in which the discharge conveyor (21) is adjustably mounted on the apparatus to be moveable between a transport position of minimum or nil lateral projection from the main frame of the apparatus, as seen in plan, to a laterally outwardly displaced position for discharge of material screened by the screening device.

5. Apparatus according to any one of claims 1 to 4, in which the hopper (13) includes a bar grizzly screen.

6. Apparatus according to any one of the preceding claims, in which the conveyor (14) comprises a discharge elevator, having its forward and lower end arranged to receive material directly from the hopper (13), and its rearward and upper discharge end arranged to allow the material delivered by the conveyor to fall under gravity onto the screening device (14).

Apparatus according to claim 6, in which the 0 & . 1 elevator is adjustably mounted, directly or indirectly, on the main frame (11) of the apparatus, and is capable of being adjusted between an operative position, in which its upper discharge end can readily discharge material to the screening device, and an inoperative position, out of the path of linear movement of the screening device (14) to its transport position.

8. Apparatus according to any one of the preceding claims, and comprising a towable apparatus having a wheel set (.12) arranged to support the main frame (11) at or near the rear end thereof, and the forward end (20) of the main frame (11) having suitable means to allow the main frame to be mounted on a coupling arrangement of a tractor unit.

9. Apparatus according to claim 8, in which a platform (20) is arranged below the hopper (13) and is operative to couple the main frame to a fifth wheel coupling of a tractor unit.

10. Apparatus according to claim 7, i discharge elevator (15) comprises two separate portions, hingedly connected together, with the forward portion (16) remaining fixed, and the rearward and upper portion (17) being foldable to a position substantially overlying the forward portion (16), and thereby allowing a clear path of forward movement of the screening device (14) to the transport position.

n which the