GB2024148A - Refuse vehicle tailgate - Google Patents

Abstract

A refuse vehicle tailgate 24 has a hydraulically operated refuse packing mechanism and the tailgate pivotally mounted on the refuse container 26 by hinges at 162 which also permit non pivotal sliding movement of the tailgate, and the tailgate can be raised by pivotally connected lift rams 46 to a discharge position in which refuse is pushed out of the container by a refuse pushing member mounted for sliding movement in the refuse container. Interengageable catch elements are provided on the tailgate and on the refuse container to hold the tailgate against pivotal movement, and the relative positions of the centre mass of the tailgate, the tailgate pivot axis and the lift ram pivot points are such that initial pressurization of the lift rams automatically slides the tailgate upwards to disengage the catch elements. <IMAGE>

Description

SPECIFICATION Refuse Storage and Discharge apparatus This invention relates to refuse storage and discharge apparatus, for example to such apparatus adapted to be mounted on a self propelled road vehicle chassis to form a mobile rear discharge refuse collecting vehicle of the kind used for door-todoor collection of refuse from dustbins.

A more specific example of a vehicle in which such refuse storage and discharge apparatus could be incorporated is a self-propelled lorry constructed for rear loading of refuse into a refuse container through a tailgate having a hydraulically operated packing mechanism to pack the refuse into the container. The tailgate is pivotally mounted on the refuse container and can be raised by hydraulic lift rams when desired, to allow discharge of refuse by a refuse pushing member mounted in the container for sliding movement lengthwise of the container and actuated by a hydraulic refuse pushing ram.

A safety problem arises in such refuse storage and discharge apparatus when the tailgate is raised, as a direct consequence of such factors as: a) the considerable mass of the tailgate (typically) at last 2,400kg), which itself arises from the presence in it of a substantial hydraulically-operated refuse packing mechanism comprising pivoted and slidable packer and sweeper plates and associated pairs of double-acting hydraulic rams; b) the position of the centre of the mass of the tailgate when the latter is raised, in relation to the tailgate pivot axis, i.e. the moment arm of the tailgate mass.The position of the centre of mass of the tailgate is a considerable distance rearwardly of the tailgate pivot axis, even in the lowered position of the tailgate - this arising from the layout and locus of the packer and sweeper plates; c) the need to mechanically latch or lock the tailgate in its lowered working position, against forces arising from compaction of refuse; and d) the need to unlatch the tailgate for discharge purposes and then to positively discharge all refuse from within the refuse container.

Requirements c) and d) above should preferably be met by providing full remote control (e.g. from the driver's cab) of these operations so that there is no need for personnel to pass near or below a raised tailgate.

However, to guard against the possibility of operating personnel or other persons unwittingly or by foolhardiness becoming trapped by a descending tailgate following a failure in a hydraulic circuit, there is a need to provide some means to reduce the likelihood of such hydraulic failure with the tailgate in fts raised position. It is an object of the present invention to provide refuse storage and discharge apparatus offering improved safety standards in one or more of the respects discussed above.

According to the invention there is provided refuse storage and discharge apparatus comprising: a refuse container; a tailgate mounted on the container at one end of the container to receive refuse; a hydraulically - operated packing mechanism in the tailgate and operable to pack received refuse into the refuse container;; the tailgate being mounted on the refuse container for pivotal up and down movement about a tailgate pivot axis between a raised discharge position and a lowered working position by means of at least one hydraulic lift ram pivotally connected between the tailgate and the refuse container, the arrangement being such as to permit in said raised position of the tailgate the discharge of the refuse through said one end of the container by an upright refuse pushing member mounted in the refuse container for sliding movement length wise of the container and actuated by a hydraulic refuse pushing ram; wherein the pivot between the tailgate and the refuse container comprises hinge elements mounted for up and down movement relative to each other whereby the tailgate can execute non-pivotal up and down movement relative to the refuse container;; and wherein interengageable catch elements are provided on the tailgate and on the refuse container, to hold the tailgate against pivotal movement,the catch elements being operatively engageable and disengageable upon such non-pivotal up and down movement of the tailgate; and wherein the relative positions of:: the tailgate pivot axis, and the pivots connecting the lift ram to the tailgate and to the container, and the centre of mass of the tailgate, are such that upon initial pressurization of the lift ram in the working position of the tailgate the tailgate executes non-pivotal upward movement relative to the refuse container thereby operatively disengaging the catch elements, and upon further pressurization of the lift ram the tailgate executes pivotal upward movement to its raised position, and the expression (k) given by the moment arm of the tailgate about the tailgate pivot axis divided by the moment arm of the lift ram about the same axis has, in the lowered position of the tailgate, at least 1.3 times the value of (k) in the raised position of the tailgate.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a side elevation view of a refuse collecting vehicle; Figure 2 shows a perspective rear elevation view of the vehicle of Figure 1 (see arrow II in Figure 1); Figure 3 shows a side elevation view of a refuse container also seen in Figure 1, but with the container partly cut away and showing certain details not seen in Figure 1; Figure 4 shows, in a side elevation view similar to that of Figure 1, a support frame and an associated cantilever forming part of the vehicle of Figure 1; Figure 5 shows a plan view (arrow V) of the assembly of Figure 4; Figure 6 shows a section (arrows VI-VI) through the assembly of Figure 4; Figure 7 shows a rear elevation view (arrow VII) of a cantilever seen in Figure 4;; Figure 8 shows a rear perspective view (arrow VEIL) of the cantilever seen in Figure 5; Figure 9 shows a section on the centre line (arrows IX-IX) of the cantilever seen in Figure 7; Figure 10 shows a front perspective view (arrow X) of a refuse pushing member indicated in Figure 3; Figure 11 shows a rear perspective view of the vehicle with its tailgate raised and showing the refuse pushing member in its rearmost position after discharging refuse; Figures 12 to 16 show diagrammatically, five successive stages in the operation of a hydraulic packer mechanism in the tailgate; Figures 17 to 20 show perspective views of the rear of the vehicle illustrating the relative dispositions of the parts of the packer mechanism in the stages shown in Figures 12 to 15 respectively;; Figure 21 shows on a much larger scale, catch elements of the vehicle seen in Figure 1,the direction of viewing being the same as in Figure 1; Figure 22 shows the catch elements as viewed in the direction of arrow XXII in Figure 21; and Figures 23 and 24 show diagrammatic side elevation views of the vehicle Figure 1 showing a tailgate in its lowered and raised positions respectively and indicating the moment arms of the tailgate and of the tailgate lift rams about the tailgate pivot axis.

As shown in the drawings, a rear discharge refuse collection vehicle 10 comprises a self-propelled non-articulated road vehicle chassis 12 having mounted thereon refuse storage and discharge apparatus 14.

Vehicle chassis 12 has its own vehicle support frame 16 carrying a driver's cab 18 housing a diesel engine (not shown), the vehicle support frame being mounted on steerablefrontwheels 20 and driven rear wheels 22.

The refuse storage and discharge apparatus 14 comprises: a tailgate 24 to receive refuse; a refuse container 26; a hydraulically operated packing mechanism 28 in the tailgate to pack refuse into container 26; an upright refuse pushing member 30 mounted in container 26 for movement lengthwise of the container between a non discharge end 32 thereof and a discharge end 34 to push refuse out of the container; a hydraulic refuse pushing ram 36 to actuate refuse pushing member 30; and a support frame 38 and an associated cantilever 40 connected to the forward end of ram 36 to resist the reaction thrust generated when ram 36 is extended.

These principal parts will now be described in more detail.

Tailgate 24 has a large rectangular rear opening 42 to receive refuse and is mounted at its upper end by pivots 44 on container 26 for pivotal movement by a pair of hydraulic lift rams 46 from its working position shown in Figures 1 and 2to a raised discharge position shown in Figure 11.

Packing mechanism 28 comprises a packer plate 48, a sweeper plate 50 and respective pairs of hydraulic rams 52 and 54 connected to a pump (not shown) driven by the vehicle engine. Packer plate 48 is slidably mounted in linear guides 56 in the tailgate sidewalls for movement over a fixed plate 58 under the control of packer rams 52. Sweeper plate 50 is pivotally mounted on the rear end of packer plate 48 for limited angular movement under the control of sweeper rams 54. A hydraulic control mechanism (not shown) is provided to sequentially operate rams 52 and 54 to cause the packer and sweeper plates to carry out the sequence of operations shown in Figures 12 to 20 whereby refuse 60 deposited in tailgate 24 is packed into container 26 against refuse pushing member 30.The sequence of operarionsis initiated by a push button control 62 at the rear of the tailgate and is advanced by micro switches (not shown) operating solenoid-controlled hydraulic valves.

Refuse container 26 is in the form of an openended rectangular section body having high tensile steel side walls 64, a top wall 66 and a bottom wall 68, all braced by pressed steel channels 70 each extending right round the container.

The open rear or discharge end 34 of container 26 is defined by a rigid rectangular frame comprising high tensile lateral girders 72 and fabricated top and bottom beams 74A, 74 to support tailgate 24. A maintenance access door 76 is provided at one side of the container.

Refuse pushing member 30 is seen in Figures 1,3, 10 and 11 and is a rigid structure fabricated from high tensile steel and comprises a substantially vertical upper portion 78, a hollow lower portion 80 sloping downwards and towards the discharge end 34 of refuse container 26 from the lower edge of upper portion 78, and side walls 82 stiffened by respective A-frames 84. At the lower end of each A-frame is a channel section guide 86 to receive a longitudinal guide rail 87 secured one to each of the side walls 64 of a refuse container 26 just above bottom wall 68, whereby the refuse pushing member 30 smoothly slides lengthwise of the container.

Guides 86 are braced by respective hollow fabricated wedge-shaped supports 88.

Upper portion 78 of refuse pushing member 30 comprises a flat vertical plate 90 stiffened by three horizontal channel section members 92 at its rear side.

The hollow lower portion 80 of refuse pushing member 30 is generally triangular in section (as viewed in Figure 1) comprising upwardly converging front and rear plates 94,96 respectively, a base plate 98 and internal stiffening plates (not shown). A central channel 100, facing the non-discharge end 32 of container 26, is formed in lower portion 80 of refuse pushing member 30 to receive refuse pushing ram 36.

Support frame 38 and cantilever 40 are seen in Figures 1 and 3 to 9. Frame 38, which is positioned below refuse container 26, comprises two main support beams 102, 104 formed of rolled steel channel and extending lengthwise of refuse contain er 26, which are secured to vehicle frame 16.

The pressed steel channels 70 which brace refuse container 26 form, at the underside of the container, an integral part of frame 38. Thus the horizontal lower portion of each channel 70 comprises a centre section 106 and two side sectins 108, 110 welded to beams 102, 104 to form a rectangular framework therewith. Likewise, bottom wall 68 of container 26, which is welded to frame 38, is formed in three sections 112, 114 and 116 of which the side sections 114 and 116 have upturned flanges 118 at their outer edges.

Cantilever 40 is secured to beams 102 and 104 of frame 38 at the non-discharge end 32 of refuse container 26, extending upwards from the frame and forming therewith a rigid load-resisting structure.

The cantilever is positioned (see Figure 1) immediately behind driver's cab 18.

The details of the structure of cantilever 40 are best seen in Figures 7,8 and 9. It is a rigid hollow fabricated steel structure which tapers upwardly from support frame 38 to provide a strong mounting for a connection 120 to refuse pushing ram 36.

Upwardly converging side plates 122, 124 provide at their lower edges a pair of downwardly-extending flanges 126 which are welded to beams 102,104 (see Figjre 7). A flat front plate 128, a rear frame 130, and an inclined plate 31 form, with side plates 122,124, the main structural items of cantilever 40.

Ram connection 120 comprises a pair of parallel mounting plates 132 welded to inclined plate 131 and apertured and provided with sleeves 134 to receive a connecting pin 136. Mounting plates 132 are braced by a pair of flanges 138 and a horizontal top plate 140.

Refuse pushing ram 36 is connected by pin 136 at its front end to the upper end of cantilever 40, and extends downwardly and towards discharge end 34 of container 36 and is connected in a similar way by a connection 142 to refuse pushing member 30 at the rearmost end of channel 100. A small roof-shaped housing 144 is provided to cover and protect connection 142. Ram 36 itself is a three stage (or draw) double-acting telescopic ram.

As shown in Figures 1 and 3, the two laterally spaced pivots 44 between tailgate 24 and container 26 each comprise a pair of hinge elements: a primary hinge element fixed to container 26 and in the form of a bracket 146 formed as a casting with an upwardly extending slot 148 to receive a secondary hinge element comprising a hinge pin 150 mounted at the bifurcated upper end of a main structural side beam 151 of tailgate 24.

Hinge pins 150 can slide up and down in slots 148 and it will thus be seen that the hinge elements of each pair are mounted for up and down movement relative to each other, whereby tailgate 24 can execute non-pivotal up and down movement relative to container 26.

Two pairs of interengageable catch elements 152 are provided, one pair near each side of vehicle 10 on tailgate 24 and on container 26 to hold the tailgate against pivotal movement. The catch elements are operatively engageable and disengageable upon downward and upward non-pivotal movement of tailgate 24 as permitted by slots 148.

The catch elements are seen in Figures 11,21 and 22, from which it can be seen that each pair of catch elements comprises a downwardly opening hook 154 fixed to a transverse beam 156 on tailgate 24 and a complementary transverse pin 158 to receive hook 154 and mounted between a pair of brakcets 160 secured to the underside of lower beam 74 at the rear of container 26.

Figures 23 and 24 show the tailgate 24 in its lowered working position and its raised discharge position respectively. These Figures also show the relative positions of the following items, which form an important part of the invention: the tailgate pivot axis 162; the upper and lower pivots 164 and 166 respectively, connecting each of the lift rams 46 to tailgate 24 and to container 26 respectively; and the centre of mass 168 of tailgate 24.

Several construction lines are also shown in Figures 23 and 24. They are: the vertical lines of action 170 and 172 of the centre of mass 168 of tailgate 24 in its lowered and raised positions respectively; a vertical line 174 through tailgate pivot axis 162; the lines of action 176 and 178 of lift rams 46 in the lowered and raised positions respectively of tailgate 24; and lines 180 and 182 through tailgate pivot axis 162 and parallel to lines of action 176 and 178 respectively.

These construction lines define, as indicated in Figures 23 and 24, the moment arms, 184 and 186 of the tailgate mass about pivot axis 162 in the lowered and raised positions of the tailgate respectively, and the moment arms 188 and 190 of rams 46 about the same axis in those tailgate positions respectively.

As can be seen from a comparison of Figures 23 and 24 there is a considerable increase in the moment arm of th lift rams 46 as tailgate 24 is raised.

In this embodiment, the expression (k) given by k = Moment Arm of tailgate about axis 162 Moment Arm of lift rams about axis 162 has in the lowered position of the tailgate a value of approximately 1.8 times its value in the raised position of the tailgate.

For the purposes of the invention, (k) must decrease by a factor of at least 1.3 on raising the tailgate. A preferred range of values of this (k) change factor is from 1.5 to 2.0 and above.

Lift rams 46 are double acting and incorporate hydraulic fluid flow restrictors (not shown) to limit the maximum rate of retraction of the rams under the weight of tailgate 24 in the event of a complete hydraulic failure such as a blow out in a hydraulic hose supplying fluid to the rams.

In use, when container 26 is full, tailgate 24 is raised by lift rams 46 and ram 36 is extended to push refuse out of the discharge end 34 of the container as shown in Figure 11. After lowering the tailgate refuse is deposited in the tailgate and is packed by mechanism 28 into container 26. Refuse pushing member 30 is automatically sequenced forwards in stages to provide substantially uniform compaction of refuse throughout the container filling process.

On account of the relative dispositions of the various axes and the tailgate centre of mass shown in Figures 23 and 24, upon initial pressurization of lift rams 46 in the working position of the tailgate 24 (Figure 23), the tailgate executes non-pivotal upward movement relative to container 26 i.e. hinge pins 150 ride up to the top of slots 148. As the whole tailgate rises thus, hooks 154 are operatively disengaged from transverse pins 158 thereby freeing tailgate 24 to pivot upwards about axis 162. Further increase in pressure in rams 46 causes such pivotal movement of the tailgate. The pressure required to commence pivotal movement of the tailgate from the lowered position is, in this embodiment, approximately five times that required to hold the tailgate its raised position - this arising from th change of the length of the moment arms discussed above.

Upon lowering the tailgate 24, the abovedescribed sequence of events is reversed and catch elements 152 re-engage and thereby hold the tailgate in the Figure 23 position against the pressure developed in use by the packing mechanism and exerted by the refuse in a rearward direction on the tailgate.

The hydraulic circuit controlling lift rams 46 includes means for isolating the rams or for applying pressure in a retraction direction when the tailgate is lowered, thereby to lock the tailgate in that position.

The principal advantage offered by this embodiment of the invention lies in the geometry of the lift ram and pivot dispositions providing the combination of an automatic proof test of the hydraulic circuit every time the tailgate is raised, with the facility for an automatic remotely operable catch mechanism to hold the tailgate in its lowered position against the outward pressure of refuse on it. In this way, great security is provided for the vehicle operators with respect to the tailgate when raised.

Claims (6)

1. Refuse storage and discharge apparatus comprising : a refuse container; a tailgate mounted on the container at one end of the container to receive refuse; a hydraulically-operated packing mechanism in the tailgate and operable to pack received refuse into the refuse container; the tailgate being mounted on the refuse container for pivotal up and down movement about a tailgate pivot axis between a raised discharge position-and a lowered working position by means of at least one hydraulic lift ram pivotally connected between the tailgate and the refuse container, the arrangement being such as to permit in said raised position of the tailgate the discharge of refuse through said one end of the container by an upright refuse pushing member mounted in the refuse container for sliding movement lengthwise of the container and actuated by a hydraulic refuse pushing ram;; wherein the pivot between the tailgate and the refuse container comprises hinge elements mounted for up and down movement relative to each other whereby the tailgate can execute non-pivotal up and down movement relative to the refuse container; and wherein interengageable catch elements are provided on the tailgate and on the refuse container to hold the tailgate against pivotal movement, the catch elements being operatively engageable and disengageable upon such non-pivotal up and down movement of the tailgate; and wherein the relative positions of:: the tailgate pivot axis, and the pivots connecting the lift ram to the tailgate and to the container, and the centre of mass of the tailgate, are such that upon initial pressurization of the lift ram in the working position of the tailgate, the tailgate executes non-pivotal upward movement relative to the refuse container thereby operatively disengaging the catch elements, and upon further pressurization of the lift ram the tailgate executes pivotal upward movement to its raised position, and the expression (k) given by the moment arm of the tailgate about the tailgate pivot axis divided by the moment arm of the lift ram about the same axis has, in the lowered position of the tailgate, at least 1.3 times the value of (k) in th raised position ofthetailgate.

2. Refuse storage and discharge apparatus according to claim 1 wherein the expression (k) in the lowered position ofthetailgate has at least 1.5 times, and preferably at least 2.0 times the value of (k) in the raised position of the tailgate.

3. Refuse storage and discharge apparatus according to claim 1 or claim 2 wherein flow restricting means is provided in the lift ram to limit the rate of extension or retraction of the lift ram under the weight of the tailgate;

4. Refuse storage and discharge apparatus according to any preceding claim wherein said lift ram is double-acting and the hydraulic circuit controlling the lift ram includes means for isolating said lift ram in the lowered position of the tailgate, thereby to lock the tailgate in its lowered position

5. Refuse storage and discharge apparatus according to claim 1 substantially as described herein and as illustrated in Figures 23 and 24 of the accompanying drawings.

6. Refuse storage and discharge apparatus according to claim 1 substantially as described herein and as illustrated in any of the accompanying drawings.