WO1991019657A1

WO1991019657A1 - Method of transferring waste and apparatus for use in the method

Info

Publication number: WO1991019657A1
Application number: PCT/GB1990/000906
Authority: WO
Inventors: Peter Green
Original assignee: Jack Allen (Sales & Service) Limited
Priority date: 1990-06-12
Filing date: 1990-06-12
Publication date: 1991-12-26

Abstract

Refuse is collected from a number of premises in a collection unit (14) mounted on a collection vehicle (50). The loaded collection unit is then demounted from the collection vehicle and is transferred to a transporter (51) which transports a number of loaded collection units to a disposal site. Each collection unit includes hoists (15), compacting means (24) and an ejector. The waste is maintained in a compact condition until it is discharged at the disposal site.

Description

Title: i ethod of transferring waste and apparatus for use in the method

Description of Invention

The present invention relates to the transfer of waste from a plurality of premises to a disposal site. The premises may include dwellings and commercial premises. The disposal site may be a land-fill site, an incineration plant or some other site where waste is treated. The waste may be domestic rςfuse, other mixed waste or scrap material and may include or may be material which is to be recovered for re-use.

It is common for domestic and other mixed refuse to be accumulated in containers, for example bins or bags, at the premises where the waste is generated. A refuse collection vehicle is driven to each of these premises, in turn, and the refuse is loaded into a chamber defined by a body of the vehicle. Bags containing refuse may be loaded by hand into the vehicle. In a case where the refuse is accumulated in bins, it is usual to provide on the vehicle a hoist which will raise a bin and tip the contents of the bin into the vehicle body, before returning the bin to the ground. It is usual to compact waste in the vehicle body, in order that the load-carrying capacity of the collection vehicle can be used more or less fully.

A team of persons is required to operate a single collection vehicle. For this and other reasons, it has become the practise to drive the loaded collection vehicle to a transfer station which is local to the premises from which the waste has been collected, and to expel the waste from the collection vehicle at the transfer station so that the collection vehicle can then be used again without undue delay to collect refuse from different premises.

The refuse is normally expelled from the collection vehicle onto a heap of refuse in a yard at the transfer station. Refuse is then picked up from this heap by means of a grab and is dropped into the open- opped body of a relatively large vehicle which is subsequently driven to the disposal site. The waste is then discharged from the large vehicle at the disposal site and the large vehicle returns to the transfer station.

Although serious disadvantages of the procedure described are generally recognised, this procedure is being adopted generally because no more satisfactory procedure has been found. One disadvantage arises from the accumulation of waste in the yard at the transfer station. Some of the waste can remain in the yard indefinitely. The resulting odours constitute a nuisance. The presence of waste in the yard attracts vermin which are able to thrive at the transfer station and constitute a further nuisance and risk to health. Ejection of refuse from the body of the collection vehicle into the yard changes the condition of the refuse from a compacted condition to a loose condition and releases dust from the bulk of the refuse. Manipulation of the refuse by the grab and dropping of the refuse into the larger transfer vehicle releases further quantities of dust and this is a further nuisance. The refuse is not compacted in the larger transfer vehicle as it is compacted in the collection vehicle, because it is not considered appropriate to provide compaction means in the transfer vehicle.

We have recognised the desirability of maintaining refuse in a compacted condition during transfer of the refuse from a collection vehicle to a transfer vehicle and during transfer of the refuse to the disposal side. However, no satisfactory equipment for achieving this has been available. Equipment which has been proposed prior to making of the present invention and which might be useful in this context would be complex and expensive and would not offer a satisfactory solution to the problems arising from the procedure hereinbefore described.

According to a first aspect of the present invention, there is provided a method of transferring waste from a plurality of premises to a disposal site wherein there is provided a plurality of collection units, at least one collection vehicle suitable for carrying one of said units and a transporter suitable for carrying a plurality of said units, each collection unit comprising a hollow body defining a -chamber for receiving waste and compacting means for compacting waste in the chamber, wherein a first of said units is mounted on the collection vehicle, the collection vehicle, carrying the first unit, is driven to some of said premises, waste discarded at the premises is loaded into the first unit, the waste loaded into the first unit is compacted by the compacting means of the first unit, the loaded first unit is demounted from the collection vehicle, a second of said units is mounted on the collection vehicle, waste is collected from further premises and loaded into the second unit, the loaded second unit is demounted from the collection vehicle, the loaded first unit is mounted on the transporter, - at least one further collection unit loaded with waste is mounted on the transporter with the first unit and the loaded collection units are transported by the transporter to the disposal site.

In a method embodying the first aspect of the invention, waste is confined by the same collection unit from the time when the waste is collected from various premises until it is discharged from the collection unit at the disposal site. Nevertheless, the collection vehicle is available for making further collections before the waste is transported to the disposal site and a single transporter carries two or more collection unit loads of waste concurrently to the disposal site.

In a method embodying the first aspect of the invention, the compaαing means of each loaded collection unit is transported with the other parts of the collection unit and the load of waste contained therein to the disposal site. The compacting means may be used to maintain the load of waste in the collection unit in a compacted condition during transfer to the transporter and transportation to the disposal site.

It will be understood that the transporter may be a road or rail vehicle or may be a vessel suitable for transporting the collection units on water.

Each collection unit may include expulsion means for expelling waste from the chamber of that unit and, at the disposal site, the waste may be expelled from the collection unit by the expulsion means of that unit. Power for operation of the expulsion means may be supplied from a power supply unit on the transporter or at the disposal site. Alternatively, suitable expulsion means may be provided on the transporter or may be provided at the disposal site.

When a collection unit is on the collection vehicle, power for operating the compacting means of that unit may be provided from power supply means on the collection vehicle.

Each collection unit may further include a hoist suitable for lifting from the ground a container containing refuse, tipping the container to discharge the refuse therefrom into the chamber of the collection unit and then lowering the container to the ground. In a case where each collection unit includes a hoist, the hoist preferably remains with other parts of the collection unit when that unit is demounted from the collection vehicle, is mounted on the transporter and is transported to the disposal site.

According to a second aspect of the invention, there is provided, in combination, a collection unit and a collection vehicle wherein the collection unit comprises a body defining a chamber and compacting means for compacting waste in the chamber, wherein the collection vehicle is suitable for carrying the collection unit and wherein the collection unit is demountable from the collection vehicle.

The collection vehicle preferably comprises a power supply unit for supplying power to the compacting means of the collection unit, there being a releasable connection between the power supply unit and the compacting means. There may be provided on one of the collection unit and the collection vehicle a number of headed retainers which project into respective sockets provided in the other of the collection unit and collection vehicle, the retainers being setable in retaining positions in which they are trapped in the sockets and in releasing positions in which they can leave the sockets.

The collection unit preferably includes a substantially flat bottom wall and end walls at opposite ends of the bottom wall. A collection unit having this configuration is particularly suitable for mounting with other collection units on a transporter. It will be understood that refuse collection vehicles in common use have a body with a substantially flat bottom wall and, at a rear end of that wall, a hopper which projects below the level of the bottom wall. In the known collection vehicles, the hopper and a compactor are incorporated together in a tailgate which is pivoted to the body at the top of the body so that the hopper and the compactor can be swung rearwardly and upwards away from the bottom wail to facilitate expulsion of waste from the body. In a combination in accordance with the second aspect of the present invention, the end wall which is adjacent to the compacting means is preferably movable without the compacting means to open the chamber for expulsion of waste from the chamber. The compaαing means is preferably mounted on a top part of the body independently of the end wall.

According to a third aspeα of the invention, there is provided a set comprising a plurality of substantially identical collection units, a transporter suitable for transporting a plurality of said collection units together and at least one collection vehicle suitable for carrying one only of the colleαion units at a time, wherein each colleαion unit is mountable on the colleαion vehicle and includes a body defining a chamber for receiving waste and compacting means for compaαing waste in the chamber.

Generally, the set will comprise a plurality of collection vehicles, the number of collection vehicles will exceed the number of transporters and the number of collection units will exceed the number of collection vehicles.

A method embodying the first aspeα of the invention and which involves the use of a combination according to the second aspeα of the invention and a set according to the third aspect of the invention will now be described, with reference to the accompanying drawings, wherein:

FIGURE 1 shows diagrammatically a collection unit in combination with a collection vehicle and

FIGURE 2 shows diagrammatically, and on a smaller scale, a transporter in combination with three colleαion units.

The colleαion vehicle illustrated in Figure 1 comprises a chassis 10 supported on front, steerable wheels, one of which is shown at 11, and on driven rear wheels, two of which are illustrated at 12. The particular example of vehicle illustrated in Figure 1 has a pair of rear wheels at each side of the vehicle. Other known arrangements of rear wheels may be used. For example, there may be a single rear wheel at each side of the vehicle. There is mounted on the chassis adjacent a front end thereof a cab 13 for the driver and other crew of the vehicle.

A collection unit is releasably mounted on the chassis 10 of the collection vehicle, the collection unit occupying a position to the rear of the cab 13 and extending a little beyond the rear of the vehicle. The collection unit comprises a hollow body 14 defining a chamber for receiving waste which is to be coileαed in the unit.

The collection unit further comprises a pair of hoists 15, 16 for raising bins from the ground and tipping the bins to discharge contents of the bins into the chamber defined by the body 14. A typical bin is represented at 18 in the drawing. The bin 18 may be- raised and tipped by either of the hoists 15 and 16 acting independently of the other hoist. Alternatively, a larger bin may be raised and tipped by the hoists 15 and 16 acting together. The hoists 15 and 16 may be known hoists. A suitable hoist is disclosed in GB 2211167A and the disclosure of this published specification is incorporated hereby in the present application by reference.

The body 14 comprises an elongated, rectangular bottom wall 19, upstanding side walls, one of which is shown at 20, a front wall 21 adjacent to the cab 13, a top wall 22 which spans the gap between the side walls and which extends rearwards from the front wall 21, and a rear wall 23 which lies at a rear end of the bottom wall 19 and also spans the gap between the side walls. The rear wall has a height which is considerably less than the height of the body 14 so that there is above the rear wall and between the side walls an opening through which waste can enter the chamber of the body, either from a bin which is tipped above the rear wall, as shown at 16 in Figure 1, or by being thrown or lifted over the rear wall. The top wall 22 extends rearwards from the front wall 21 for only a part of the length of the body 14 so that the loading opening above the rear wall 23 extends forwards along a part of the length of the body.

The hoists 15 and 16 are mounted on respective ones of the side walls of the body. The hoist 15 includes a carrier 17 for carrying the bin 18. The carrier has suitable formations for engaging the bin, the form of these depending upon the form of the bin in a known manner. The carrier lies to the rear of the rear wall 23. The carrier is mounted on a carriage 28 for pivoting relative to the carriage about a horizontal axis during tipping of the bin, the pivot axis being defined by a bearing structure 29. The carriage is guided for vertical movement relative to the body 14 by a pair of bars 32 and 33 which lie at the outside of the side wall 20. Hoist drive means in the form of a piston and cylinder unit 37 is provided for raising the carriage along the bars 32 and 33 and for controlling descent of the carriage along the bars. The carrier 17 has an element for engaging a curved track during movement of the carriage along the bars. This engagement causes tipping of the carrier in the manner described in GB 2211167 A.

The carriage 28 may be releasable from one of the bars 32 and 33 so that the carriage and the carrier can be pivoted about a vertical axis of the other bar from a position behind the rear wall 23 to a position spaced laterally outwardly from the rear wall. This arrangement facilitated expulsion of waste from inside the body 14 as will be described hereinafter.

The hoist 16 is construαed and arranged in the manner corresponding to that in which the hoist 15 is construαed and arranged. The hoists are mounted side-by-side at the rear of the body 14 so that respective carriers of the hoists lie adjacent to each other. It will be noted that, when the carriages are in lowered position, the carriers of the hoists lie at a level below the top edge of the rear wall 23. The carriers of the hoists may include chutes for guiding waste which leaves a tipped bin along a path over the rear wall into the chamber defined by the body.

The rear wall 23 may be connected with the bottom wall 19 for relative pivoting about an axis which lies at the bottom of the rear wall. Additionally or alternatively, means may be provided for guiding the rear wall for upward and downward movement relative to the bottom wall from a closed position where it meets the bottom wall to an open position where it is at a level similar to or above that of the top wall 22. Driving means (not shown) may be associated with the rear wall for moving the rear wall relative to the bottom wall, either pivoting the rear wall relative to the bottom wall or displacing the rear wall relative to the bottom wall. It will be noted that the bottom wall 19 extends without substantial interruption right up to the rear wall. The bottom wall does not include relatively movable portions and does not include a recess adjacent to the rear wall.

The collection unit further comprises compacting means 24 for compacting waste in the chamber defined by the body 14. The compacting means is mounted on the body independently of the hoists 15 and 16 and independently of the rear wall 23. In the example illustrated, the compaαing means is mounted on a top part of the body 14 and protrudes upwardly beyond the body. In the illustrated example, the compacting means is mounted partly on the top wall 22 and partly on respective brackets which projeα upwardly from the side walls of the body, the bracket on the side wall 20 being indicated by the reference numeral 25. It will be noted that these brackets are spaced rearwardly from the top wall 22 and are preferably adjacent to the rear ends of the side walls.

The compaαing means 24 includes a compression member which, in the example illustrated, has the form of a plate 26. A dimension of the plate which extends in the direαion between the side walls of the body is such that the plate can be received between these sides walls with a small clearance. As shown in Figure 1, the plate can occupy an inoperative position in which it is withdrawn entirely from the chamber defined by the body 14 and lies at or slightly above the level of the top wall 22. In the inoperative position, the plate is at least approximately horizontal.

The plate 26 is mounted on a mounting member 27 for pivoting relative to the mounting member about a plate pivot axis 34 which is adjacent to that margin of the plate which is foremost, when the plate is in the inoperative position. Guide means is provided for guiding the mounting member 27 for movement relative to the body 14 and thereby guiding the axis 34 along a predetermined path relative to the body. The guide means include a bearing supported by the bracket 25 for conneαing the mounting member with the body for relative pivoting about a mounting member axis 36. In the example illustrated, the axis 36 lies above the level of the top wall 22 and is adjacent to the rear o^*f the body 14. The bracket 25 projeαs upwardly from a rear end portion of the side wall 20. There are preferably a pair of mounting members, one adjacent to each end of the plate 26 and a pair of brackets 25, one on each side wall of the body. The mounting member axis 36 extends through these brackets and is parallel to the upper surface of the bottom wall 19. The plate 26 has adjacent to each of its ends an upstanding web 35 and the mounting members are connected with these webs by suitable bearings. There may be associated with these bearing a shaft which extends between the webs.

The guide means of the compacting means 24 further comprises a carriage 38 mounted on a guideway 39 for reciprocation along the guideway. The guideway is mounted on top of the top wall 22 and the carriage 38 lies forwards of the plate 26, when the plate is in the inoperative position. The carriage 38 is conneαed with the mounting member 27 by a link 40 which is pivoted at one of its ends to the carriage and at the other of its ends to the mounting member adjacent to the axis 34 or to the shaft which extends along that axis. There may be provided a pair of carriages and guideways, one adjacent to each side of the body 14. In a case where a single guideway is provided, this is preferably disposed at a longitudinal centreline of the body 14 and the link 40 is pivotally connected at a mid-portion of the shaft extending horizontally between the webs of the plate 26.

The compacting means 24 further includes driving means for moving the mounting member 27 relative to the body 14 and for pivoting the plate 26 relative to the mounting member. For pivoting of the plate relative to the mounting member, there is provided an hydraulic piston and cylinder unit 41, one end of which is pivotally connected with the carriage 38 and the other end of which is pivotally connected with the webs of the plate 26 at a position spaced from the plate pivot axis 34. Conveniently, the unit 41 is connected with a mid- portion of a further shaft extending between the webs. For moving the carriage 38 along the guideway 39, the driving means includes a piston and cylinder unit 42 pivotally conneαed at one of its ends with the carriage 38 and pivotally connected at the other of its ends with a bar (not shown) extending between the brackets 35. The carriage and the link 40 constitute transmission elements through which motion is transmitted from the piston and cylinder unit 42 to the mounting member 27.

Inside the chamber defined by the body 14, there is provided expulsion means including an ejector 43 and ejector driving means 44. The ejeαor driving means is conveniently in the form of a multi-stage hydraulic ram which lies between the ejeαor and the front wall 21 adjacent to the bottom wall 19. The ejeαor 43 may be construαed and arranged in a known manner. The stroke of the ejeαor driving means 44 is such that the ejeαor can be moved along the body 14 from the retraαed position illustrated in Figure 1 to the rear end of the bottom wall 19.

Power for operating the drive means of the hoists 15 and 16, the drive means of the compacting means 24 and the ejeαor drive means 44 is provided by a power supply unit on the collection vehicle. The collection vehicle has an engine 45 for driving of the rear wheels 12 of the vehicle and the power supply unit includes a hydraulic pump 46 associated with the engine in a known manner to be driven thereby. Hydraulic fluid under pressure is supplied from the pump 46 to the various driving means via hydraulic lines (not illustrated) which include suitable control valves (not illustrated) and releasable conneαors (not illustrated). When these connectors are released, the power supply unit is disconnected from the collection unit.

The chassis 10 has a front sub-frame 47 and a rear sub-frame 48. These sub-frames have co-planar upwardly facing surfaces on which the collection unit can rest by downwardly facing surfaces of the body 14. With the body 14 and the sub-frames 47 and 48, there are associated spigot and socket retaining devices for retaining the body on the chassis of the vehicle. Known retaining devices may be used. By way of example, there is illustrated in Figure 1 a retainer 48 mounted in the front sub-frame 47 for turning about an upright axis and having a head which protrudes above the sub-frame and is received in a socket formed in the body 14. Once the head of the retainer has been received in the socket, the retainer can be turned to trap the head in the socket in a known manner. One other retainer is provided on the front sub-frame at the opposite side of the vehicle and further retainers are provided in the rear sub- frame. The collection unit can be released from the vehicle chassis by turning the retainers to respective positions in which they are no longer trapped in their sockets.

The collection unit may be provided with legs which can be extended below the body 14 to support the body above the ground when the body is separated from the collection vehicle. Known legs incorporating jacks may be used for raising the body 14 from the colleαion vehicle so that the collection vehicle can be driven away without the colleαion unit.

Alternatively, an extraneous machine may be used for lifting the colleαion unit from the colleαion vehicle. Known container-handling machines are suitable. A fork-lift truck may be used, if the colleαion unit is suitably adapted to receive the forks of the truck.

In Figure 2, there is shown a transporter for transporting three colleαion units, each identical with that shown in Figure 1. By way of example, there is shown a transporter comprising a motor road vehicle 50 coupled with a trailer 51. In the example illustrated, a single colleαion unit is mounted on the vehicle 50 and two collection units are mounted on the trailer 51 in end-to-end relation. Preferably, the rear walls of these colleαion units are at opposite ends of the trailer and the rear wall of the collection unit on the vehicle 50 is at the rear end of that vehicle. The colleαion units are retained on the transporter by retainers corresponding to those hereinbefore described with reference to the colleαion vehicle of Figure 1.

The vehicle 50 has an engine 52 for driving rear wheels of the vehicle and a power supply unit 53 incorporating an hydraulic pump drivingly conneαed with the engine 52 in a known manner. When the colleαion units are placed on the transporter, respective hydraulic circuits of the collection units are conneαed with the power supply unit 53 by hydraulic lines and releasable conneαors in a known manner. At least the ejector drive means of each colleαion unit is so conneαed with the power supply unit 53. Other elements of the collector unit drive means may be connected with the power supply unit 53.

Use of the equipment illustrated in Figures 1 and 2 in the transfer of waste from a plurality of premises to a disposal site will now be described.

An empty collection unit is mounted on the colleαion vehicle, the hydraulic circuits of the collection unit are collected with the power supply unit of the vehicle and the retainers are operated to retain the collection unit on the vehicle. The vehicle is then driven to different premises in turn. At each of these, waste is loaded into the chamber defined by the collection unit body. In cases where the waste has been accumulated in suitable bins, the hoists 15 and 16 are operated to lift the bins and tip them to discharge contents of the bins into the body of the collection unit through the opening above the rear wall thereof. In a case where the waste has been accumulated in bags, these are thrown over the rear wall into the collection unit body.

The plate 26 of the compaαing means is maintained in a forward position, during loading of- waste into the collection unit body. When waste occupying several hundreds of litres has been loaded into the collection unit, the compacting means is operated to compaα that waste before further waste is loaded into the unit. The piston and cylinder unit 41 is contraαed to pivot the plate 26 upwards into a horizontal attitude. The carriage 38 is then driven along the guideway 39 in a direαion away from the front wall 21. The piston and cylinder unit 41 is then extended to pivot the plate downwardly about the plate pivot axis 34 into contaα with refuse which lies inside the chamber of the body 14 near to the rear wall 23. This contaα of the plate with the refuse moves some refuse away from the rear wall towards the front wall 21 and may bring about a partial compaction of the refuse. The carriage 38 is then driven forwards along the guideway 39, pivoting the plate 26 and the mounting member 27 forwards about the axis 36. The plate thus exerts continued pressure on the refuse in the chamber of the body 14, compacts the refuse further and moves the refuse along the chamber away from the rear wall 23 towards the front wail 21. The plate 26 then remains in engagement with the refuse in the chamber whilst a fuπher quantity of waste is loaded into the chamber to lie between the plate 26 and the rear wall 23. By operation of the piston and cylinder unit 41, the plate can then be pivoted upwardly about the axis 34 into the inoperative position once more. A repetition of the cycle of operation of the compacting means will compaα the further quantity of waste which has been introduced into the chamber.

When loading of waste into the chamber of the body 14 commences, the ejector 43 may lie at a position approximately mid-way between the front wall 21 and the rear wall 23. This enables the plate 26 to compact waste against the ejector. As waste is accumulated in the chamber of the body 14. the ejector 43 may be permitted to move towards the front wall 21 against moderate resistance provided by the ejector drive mean 44 so that the ejector moves oniy when waste between the plate 26 and the ejector is subjeαed to a pre-determined force.

When sufficient waste has been loaded into the colleαion unit, the hydraulic circuits of the collection unit are disconneαed from the power supply unit 46, the retainers are released and the collection unit is demounted from the collection vehicle. ^" This operation may be performed at a transfer station. However, since the waste is to remain in the coileαion unit, it is not essential to transfer the waste and the collection unit from the colleαion vehicle at a transfer station dedicated to this use.

The loaded collection unit which is demounted from the colleαion vehicle may be transferred immediately to the transpoπer. Alternatively, the loaded collection unit may be stored prior to being mounted on the transporter. When three colleαion units, each loaded with waste, have been mounted on the transporter, the transporter is driven to a disposal site. It will be understood that the colleαion units are retained on the transpoπer by the retaining means hereinbefore described and that hydraulic circuits of the cormeαion units are releasably connected with the power supply unit 53 of the transpoπer. At the disposal site, the vehicle 50 and trailer 51 are manoeuvred into a "jack-knifed" configuration and the collection units are opened by movement of their rear walls and of their hoists. The compacting means of the collection units are moved to inoperative positions and the ejectors of the collection units are then operated to eject the waste from the collection units. Power for this operation is provided by the power supply unit 53 on the vehicle 50.

In an alternative procedure, the collection units are demounted from the transpoπer at the disposal station and a power supply unit at the disposal station is used to operate the ejectors to eject the waste from the collection units. This procedure may be suitable, for example, in a case where the disposal site is an incinerator. This procedure enables the waste to be retained in a compacted condition in the collection units until the waste is to be fed into the incinerator.

It will be noted that, once the waste has been loaded into a colleαion unit, it is retained in that collection unit in a compacted condition until the waste is discharged from the collection unit at the disposal site. During demounting of the collection unit from the colleαion vehicle, storage of the loaded colleαion unit, mounting of the collection unit on the transpoπer and transporting to the disposal site, the waste can be maintained in a compaαed condition by the compacting means 24, the plate 26 remaining in an operative position in which it is in contact with the waste and exeπing pressure on the waste. Preparatory to expulsion of the waste from the body 14, the plate 26 is moved to its inoperative position.

In the example illustrated in Figure 1, the blade 26, when in its inoperative position, lies outside the chamber defined by the body 14 at the top of the chamber. jAltematively, the plate of the compaαing means may lie, when in its inoperative position, within the chamber and overlying a rear poπion of the bottom wall 19, in substantially parallel relation thereto. Although the compacting means is conveniently mounted outside the body 14, as shown in Figure 1, it may be incorporated in the body.

The apparatus illustrated in Figures 1 and 2 is a pan of a fleet comprising at least one transpoπer, a number of collection vehicles exceeding the number of transpoπers and a number of. colleαion units exceeding the number of colleαion vehicles. The collection units of the fleet are identical with one another and the colleαion vehicles of the fleet are all identical with one another.

Claims

1. A method of transferring waste from a plurality of premises to a disposal site comprising the steps of: providing a plurality of colleαion units, at least one collection vehicle suitable for carrying one of said units and a transpoπer suitable for carrying a plurality of said units, each colleαion unit comprising a hollow body defining a chamber for receiving waste and compaαing means for compacting waste in the chamber; mounting a first of said units on the coileαion vehicle; driving the collection vehicle, carrying the first unit, to some of said premises; loading waste discarded at the premises into the first unit; compacting by the compacting means of the first unit the waste loaded into the first unit; demounting the loaded first unit from the collection vehicle; mounting a second of said units on the colleαion vehicle; colleαing waste from fuπher premises and loading said waste into the second unit; demounting the loaded second unit from the coileαion vehicle; mounting the loaded first unit on the transpoπer: mounting at least one fuπher collection unit loaded with waste on the transpoπer with the first unit and transpoπing the loaded colleαion units by the transpoπer to the disposal site.

2. A method according to Claim 1 comprising the fuπher step of using the compacting means to maintain the waste in a compacted condition during transport of the loaded collection unit to the disposal site.

3. A method according to Claim 1 wherein each of the collection units which are provided includes expulsion means for e;ψelling waste from the chamber and wherein the method includes the further step of using the expulsion means of the unit to expel the waste at the disposal site.

4. A method according to Claim 4 wherein the collection vehicle includes power supply means and, wherein, during the step of loading of one of the colleαion units, power is supplied from the power supply means to the collection unit to operate the compacting means of the collection unit.

5. A method according to Claim 4 wherein the transpoπer has power supply means for supplying power to each collection unit and wherein, during the step of expelling waste from the collection units on the transpoπer, there is performed the additional step of suppling power to the expulsion means of each unit from the power supply means of the transpoπer.

6. In combination, a colleαion unit and a colleαion vehicle, wherein the collection unit comprises a body defining a chamber and compacting means for compacting waste in the chamber, wherein the collection vehicle is suitable for carrying the collection unit and wherein the colleαion unit is demountable from the collection vehicle.

7. A combination according to Claim 6 wherein the colleαion vehicle has upwardly facing surfaces on which the collection unit rests and wherein releasable retaining means are provided for holding the colleαion unit on said surfaces.

8. A combination according to Claim 7 wherein the colleαion unit lies entirely above the level of said surfaces.

9. A combination according to Claim 7 wherein the retaining means can be set in either an operative condition or an inoperative condition whilst the colleαion unit remains on said surfaces.

10. A combination according to Claim 9 wherein the retaining means includes a plurality of retaining members which can be turned relative to the collection vehicle about respective upright axes to set the retaining means in either the operative or the inoperative condition.

11. A combination according to Claim ό wherein the colleαion unit includes a substantially flat bottom wall and respeαive end walls at opposite ends of the bottom wall.

12. A combination according to Claim 6 wherein the collection unit includes an end wall at an end of the chamber which is adjacent to the compacting means and wherein said wall is movable without the compacting means relative to the body to open the chamber at said end for expulsion of waste from the chamber.

13. A combination according to Claim 11 wherein the compaαing means includes a plate for applying pressure to the waste and wherein the plate is movable to an inoperative position where it is at least approximately parallel to the bottom wall and substantially the entire plate overlies a part of the bottom wall but is spaced therefrom by a distance which is at least approximately equal to the height of the chamber.

14. A combination according to Claim ό wherein the compacting means is mounted on a top pan of the body of the collection unit.

15. A combination according to Claim 14 wherein the compaαing means is conneαed with the body at positions spaced substantially from ends of the body.

16. A combination according to Claim 12 wherein said end wall is connected with the body for pivoting relative to the body about an axis adjacent to a bottom of the body.

17. A combination according to Claim 13 wherein said plate is mounted on a carrier for pivoting relative to the carrier about a first axis, the carrier is mounted on the body for movement relative thereto such that the first pivot axis moves generally along the body and drive means is provided for pivoting the plate relative to the carrier and for moving the carrier relative to the body.

18. A set comprising a plurality of substantially identical collection units, a transpoπer suitable for transporting a plurality of said units together and at least one colleαion vehicle suitable for carrying one only of the collection units at a time, wherein each collection unit is mountable on the collection vehicle, wherein each collection unit includes a body defining a chamber for receiving waste and wherein each colleαion unit includes compacting means for compacting waste in the chamber.

19. A set according to Claim 18 comprising a plurality of collection vehicles, the number of colleαion vehicles exceeding the number of transpoπers and the number of collection units exceeding the number of colleαion vehicles.

20. A set according to Gaim 18 wherein each collection unit is a unit as defined in combination with a colleαion vehicle in Claim 6.

21. A set according to Claim 18 wherein the collection vehicle includes power supply means for supplying power to the compacting means of a collection unit, when on the collection vehicle.

22. A set according to Claim 18 wherein each collection unit includes expulsion means for expelling waste from the chamber and wherein the transpoπer includes power supply means for operating the expulsion means of colleαion units on the transpoπer.