AU651225B2 - Grain harvester sieves - Google Patents

Description

65122i

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Regulation 3.2 Name of Applicant: HARVESTAIRE PTY LTD i Actual Inventor: Donald George Brooks Address for Service: C' R K &ASSOCIATS, 3415--i William Street, Adl.aido, South At-Australa 4 ev\ l^^Alecn ate IVlo-x' Invention title: GRAIN HARVESTER SIEVES Aals.Ae s.oo.

Details of Associated Provisional Application No: PK 7115 dated 9th July 1991 The following statement is a full description of this invention, including the best method of performing it known to us.

AL'TtRE.D) BACKGROUND OF THE INVENTION This invention relates to adjustable sieves used in harvesters. It is common practice in the machines used to harvest cereal grains, legumes and small seed crops to use two and sometimes three sieves to clean the grain or seeds (referred to as grain hereinafter) and to separate them from any chaff or other plant material.

The crop is initially cut then fed into a threshing cylinder which separates the grain from the protective husk and other plant material. A mixture of grain and plant material is then passed over a reciprocating top sieve (sometimes called a chaffer). Air i3 passed upwardly through this top sieve. The heavier grain fal.s through the sieve while the lighter plant material (husks, chaff, stems, straw etc.) is blown over the rear of the sieve on to the ground behind the harvester.

geese• S" The grain then passes over a reciprocating bottom sieve.

Air is also passed upwardly through this sieve, also to blow away any remaining light plant material and shrivelled or cracked light grains.

The grain is also graded by size on the bottom sieve with :°coo the major part of the clean and sized grain falling through the bottom sieve to be augered away to a main grain tank for 25 eventual discharge to trucks for transport off farms. The minor part, usually non sized grain or heads, is either blown

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or walked over the rear of the sieve to be augered back to the threshing cylinder to be passed through the system again.

It is very common to find that the overall capacity of the harvester is limited by the capacity of the sieves to carry out their required functions.

Ground speed during harvesting is commonly regulated to ensure that a minimum amount of clean grain is lost on to the 2 ground behind the harvester. Excess losses are caused by attempting to pass a greater volume of material over the sieves than they are capable of cleaning properly in the time allowed.

It is common in modern harvesters to have sensitive acoustic monitor pads at the rear of the top sieve constantly measuring losses and displaying this information on a gauge visible to the harvester operator.

Field research has led to the realisation that prior art adjustable sieves are limited in their capacity due to them not having sufficient open area towards the front of the sieve where the majority of material falls on to the sieve initially, and nor are they designed such that the operator can remove any of the louvres as desired and so vary the amount of open area V, 0.

in any part of the sieve to control the grain loss.

We have established that, in some areas, by removing every second row of louvres an increase of at least 50% in open area eee has been experienced in some machines. By doing this, a greater volume of grain is able to fall through the sieve in a given time thereby increasing the capacity of the sieve and therefore the overall harvester. It is often only necessary to increase the open area a distance of 300-400mm rearwardly from the front of the sieve to achieve a large increase in capacity 25 and in some trials increases of up to 80% have been experienced oe ~by removing louvres for up to half the length of the sieve but in other trials on other makes of harvesters it was found o advantageous to remove more louvres over the full length of the ego.

sieve to get better results.

Adjustable sieves are usually constructed of an outer rectangular frame to which are fitted and welded intermediate longitudinal supports with a plurality of formed sheet metal louvres spot welded on to support rods whiqh pass through these longitudinal supports via positioning holes, alO through similar positioning holes in side rails of the outer framework.

These louvres are usually adjustable from a fully closed 3 position to an open position by rotation of the rods and louvres via an adjustable strap attached to a lever. These sieves are constructed with the louvre rods passing through round holes in the side rails of the frame and intermediate supports. The louvres are normally spot welded onto the rods after they are in position and so cannot be easily removed without cutting or grinding and expending much time also.

It is an object of this invention to provide means whereby the number of rows of louvres can be varied, and in an embodiment of this invention, a grain harvester sieve comprises a peripheral frame having side rails and end rails, wire retaining apertures in the side rails, and at least one intermediate support parallel co the side rails, and is characterised by slots extending downwardly from upper edges of 15 the intermediate rail, a rod having at least two spaced louvres extending between its ends, and a bush on the rod between the louvres, the bush being inserted into and retained in said slot.

An embodiment of the invention is described hereunder with reference to and is illustrated in the accompanying drawings, wherein: Fig 1 is a partial perspective view of a sieve without the features of this invention; Fig 2 is an "exploded" perspective view of a wire, bush and intermediate rail; Fig 3 is a fragmentary section showing a louvii assembly supported by an intermediate rail; and Fig 4 shows both side and end views of a bush.

In this invention the round holes in intermediate rails are replaced by upwardly open slots 11, and plastic inserts or bushes 12 of shape to slide into the slots, are fitted onto 4 louvre rods 13 in spaces between adjacent louvres 14 and pushed into respective slots 11. Bush 12 has a pair of side flanges flanking a central boss portion 16, the width of boss portion 16 so matching the width of slots 11 that the slot edges are engaged by the bush. The distance between the upper portions of flanges 15 exceeds the width of boss portion 16 to accommodate flanges 20 of a cover strip 21 which cover strip 21 retains the bush (or a row of bushes) in place and so the rod and louvres also remain in place, the rod 13 extending through holes 22 in the bushes 12. The sieve can then be assembled with any appropriate number of louvre assemblies fitted to the frame to suit any desired crop or ground speed.

Rods without louvres attached may be fitted in place of the louvres if desired.

Cover strip 21 is a section strip of metal, and the flanges 20 are deflected so as to firmly and frictionally engage side faces of rail 10 when assembled thereto.

To assemble new louvre assemblies, all that needs to be done is to slip each end of each rod 13 through the holes in the side rails 24 of peripheral frame 25 and then flex the rod end of the louvre assemblies downwards until the bushes slide home into the upward facing slots 11 in the intermediate 25 supports 10. The retaining cover strip 21 is then positioned in place over each row of bushes and wires on each intermediate support bar and bolted in place.

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It can easily be seen that besides utilising slots to position and hold the rods of the louvre assemblies as an alternative, the intermediate rails could be "scalloped" and/or have attached or clamped to them other desired material which is scalloped which would hold and position the rods and then be retained by a cover strip fitted over the top.

Further, instead of slots or scallops raised portions could be attached to or be a part of the intermediate rails, 5 which would position and/or hold the louvre assemblies in a somewhat similar fashion to the slots or scallops.

The advantages of this new design are: Increased capacity of the sieve and therefore increased speed of the harvester over the ground is achieved by the ability to remove louvre assemblies to provide more open area for the grain to fall through.

Ability to easily replace damaged or worn louvres on the farm.

Reduction of wear between the wires and side rails and 15 intermediate supports by the use of bushes in slots, thus a "providing extended life of the louvre rods.

S S The louvres are commonly on rods fixed at around 1 1/8" centres and the invention provides a facility to remove or replace them easily. Most prior art adjustable sieves have louvres at fixed similar centres also but once manufactured they usually cannot be removed. Some have 9e had louvres on 1 5/8" centres and possibly other set measurements but they are all limited by the pitch 25 distance between adjacent louvres not being variable once 9 manufactured. On the claimed invention the louvres can be added or replaced to suit particular crop conditions such as very small seeds, light yield or any other condition as determined by the harvester operator and or field conditions.

The louvre rod holes in the side rails may be retained and only the intermediate supports are slotted so that there is little loss of strength in the frame. The method of fitting the louvre assemblies is also novel in that the rods need to be flexed up from being straight until they are V shaped to some 6 degree, which allows each end of each of the wires to be inserted into its hole in a main sieve frame side rails before straightening the rods by pushing them down and finally forcing them into the slots or scallops or other locating devices.

The bush shapes may vary, and if for example the bush aperture surface which engages the rod is of shape, the rod may be sandwiched between the bush and an edge surface of a slot, making it unnecessary to thread the bush onto the rod before welding.

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Claims (5)

1. A grain harvester sieve having a frame defined by side rails, end rails and at least one intermediate rail, a plurality or louvre assemblies extending between the side rails, each comprising a transverse rod carrying at least two adjacent but spaced louvres, each louvre assembly of at least some of said louvre assemblies being removable and having support means comprising slot surfaces defining a slot extending downwardly from an upper edge of at least one said rail, a bush 1o slidable within the slot and being engaged by said slot surfaces, an aperture in the bush a surface of which er-ges said rod between said adjacent but spaced louvres, and a removable cover strip surmounting at least one said rail having lower edges which abut said bush and retain said bush in said slot.

2. A grain harvester sieve according to claim 1 wherein said slot surfaces are edge surfaces of said at least one intermediate rail, and wherein said bush comprises a boss having a rod engaging surface, and a pair of side flanges flanking the boss, surfaces of said boss engaging said slot edge surfaces of said intermediate rod and flanges of said boss abutting side faces of said intermediate rail.

3. A grain harvester sieve according to claim 2 wherein the space between upper portions of said bush flanges exceed the boss width, and s said cover strip has a sectional shape with flanges which also abut said side faces of said intermediate rail and which have lower edges accommodated o, in said upper portions of said bush flanges.

4. A grain harvester sieve according to claim 3 wherein the cover strip flanges are resiliently deflected upon engagement with the intermediate rail to thereby frictionally engage side faces of the rail. o• e• A grain harvester sieve according to any preceding claim wherein said bush aperture is a circular hole.

6. A grain harvester sieve substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. DATED this 9th day of July, 1992. HARVESTAIRE PTY LTD By its Patent Attorneys R K MADDERN ASSOCIATES *l S IS 0 *0lS k 9 An adjustable sieve for a grain harvester wherein louvre assemblies, each comprising a rod (13) supporting at least two louvres are each provided with at least one bush (12) which slides down into an upwardly facing slot (11) in an intermediate rod support rail and is retained in position by a cover strip The louvre assemblies can be "removed or re-inserted so that an operator can adjust t.- open area of the sieve to suit crop conditions. *o S..s