GB2202497A

GB2202497A - Tipping vehicles, and their stabilisation

Info

Publication number: GB2202497A
Application number: GB08803325A
Authority: GB
Inventors: Robert Reid
Original assignee: Craven Tasker Andover Ltd
Current assignee: Craven Tasker Andover Ltd
Priority date: 1987-03-26
Filing date: 1988-02-12
Publication date: 1988-09-28
Anticipated expiration: 2008-02-12
Also published as: GB2202497B; GB8707237D0; GB8803325D0

Abstract

A tipping vehicle provided with leveling apparatus to guard against overturning. So that the vehicle is particularly adapted for use on unstable ground, the levelling apparatus includes fluid operated jacking devices 22, 24 acting between the chassis of the vehicle and mounting means 12 for road wheels 10, 10 at the rear of the vehicle. A monitoring device such as a tilt switch 64 causes actuation of the appropriate ram if a predetermined degree of lateral tilt occurs e.g. 2 degrees and deactivates it when a horizontal attitude is attained. <IMAGE>

Description

Tipping vehicles.

The invention relates to tipping vehicles, for example vehicles for carrying sand and gravel and other tipping vehicles such as those for carrying compresed domestic waste material, coal, grain, beet and other agricultural produce, scrap metal and the like.

It is a particular problem that drivers of tipping vehicles are frequently required to tip their loads where the ground supporting the vehicle is not level. Indeed, the ground may not only be uneven but also unstable and liable to subside beneath the weight of the vehicle. This is particularly true of waste disposal tips which are made up of successive layers of baled refuse over which the tipping vehicles must be driven and on which they stand whilst the tipping mechanism is operated to discharge the load.

The result is that accidents involving tipping vehicles are quite frequent, particularly vehicles having a very long load-carrying body because, as the body is raised to tip the load, the centre of gravity of the vehicle is raised very substantially so that the effect of any initial tilting of the vehicle is accentuated as the load is lifted. The problem is of course made worse by the fact that, as the body is raised, the centre of gravity moves rearwards so that the rear wheels take an increasing share of the load with the result that any unusually unstable ground condition may only show itself when the body has been raised to some extent. Obviously, any subsidence of the ground beneath the wheels at one side or the other of the vehicle whilst the loaded body is raised can quickly result in overturning of the vehicle, especially if the body continues to rise.

Various attempts have been made to guard against the problem of vehicles overturning. For example, mobile cranes and the like are usually provided with auxiliary feet which can be brought to bear against the ground surface, the feet usually being mounted on outriggers so that they can be brought to bear, either by manually operable means or by means of hydraulic rams, against the ground surface some distance away from the sides of the vehicle.

Such arrangements generally work quite well when used on mobile cranes and the like because the auxiliary feet can generally be brought to bear on firm ground and also because, since such vehicles are usually set up -to operate for some time in one location, they are generally set up with care and with due regard for the fact that the crane must not be operated until it has been set up in a firm and level condition. The same cannot be said for tipping vehicles which for commerical reasons are usually required to operate with fast nturn roundn times when used for repeat journeys.Indeed, the use of such auxiliary feet would in many cases be impracticable where the ground conditions are unstable, as for example they invariably are on waste disposal tips, and such safety measures in any case rely on the vehicle driver taking the time and trouble to put them into operation. For a variety of reasons, a vehicle driver will frequently fail to use such safety measures which are provided if he considers the risk of overturning to be small, often with serious consequences.

The invention has for its object to at least alleviate the problem referred to.

According to the invention, a tipping vehicle is provided with a load-carrying body pivotally mounted for lifting movement about a transverse axis adjacent the rear of the vehicle; means for monitoring the inclination of the vehicle body from the vertical when veiwed longitudinally of the vehicle; and levelling apparatus including fluid operated jacking devices for acting between the chassis of the vehicle and mounting means for road wheels at the rear of the vehicle, the jacking devices on the opposite sides of the vehicle being operable selectively to counter any tendency for the ground to subside at one or the other side of the vehicle and causing the road wheels to tilt.

The fluid operated jacking devices will preferably be rigidly mounted on the chassis of the vehicle, respective metal cups being provided on the mounting means for the road wheels for receiving domed lower ends of respective rams of said jacking devices.

The arrangement will preferably be such that the operation of the levelling apparatus whilst a hydraulic ram is still being extended to lift the load-carrying body, causes said hydraulic ram to pause in its movement until the means for monitoring the inclination of the body, when viewed longitudinally of the vehicle, detects that said levelling apparatus has brought it back to the vertical or substantially the vertical. The arrangement will preferably also be such that if the levelling apparatus has been operated to bring the vehicle body back to the vertical or substantially the vertical as viewed longitudinally of the vehicle, during the lifting of said body to a discharge position, the fluid in the one or the other, or in both, of the jacking devices will be locked therein until the vehicle body has been returned to its lowered position or almost to its lowered position.In this case, a solenoid operated valve capable of inhibiting return flow of fluid from the jacking devices of the levelling apparatus and being electrically activated to open may be connected to the electrical supply of the vehicle by way of a limit switch, the vehicle body holding the limit switch in its closed condition when in a lowered position, whereby as the vehicle body is lifted the limit switch opens automatically and remains open until the body has been returned to its fully lowered, or substantially fully lowered, condition, the arrangement being such that if the levelling apparatus is operated whilst the vehicle body is being lifted, the hydraulic fluid in the or each actuated jacking device is locked therein and continues to hold the body in its vertical or substantially vertical condition until the body has been returned to its fully lowered or substantially fully lowered condition to close the limit switch.

The jacking devices may be single acting spring return jacking devices or may be double acting jacking devices.

The hydraulic circuit of the tipping trailer may include a power driven pump driven by a donkey engine or by an electric motor carried by the tipping trailer. Alternatively, the hydraulic circuit of the tipping trailer may be provided with a hose coupling -by means of which the levelling apparatus can be coupled to the hydraulic system of a tractor vehicle by means of which the trailer is to be towed.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which:- Figure 1 is a side view of a tipping vehicle embodying the invention, Figure 2 is a view on the rear of the vehicle, Figure 3 is a perspective view illustrating a detail of construction which will be referred to, Figure 4 is a diagrammatic view illustrating levelling apparatus which has been fitted to the vehicle, Figure 5 is a view similar to Figure 4 and illustrating the levelling apparatus adapted for fitment to a tipping trailer not provided with its own in-built power system, and Figure 6 illustrates a further possible modification.

Referring now to Figures 1 to 3 of the drawings, the tipping trailer there illustrated is the kind of vehicle commonly used for the carrying of sand and gravel for example. It is a trailer vehicle provided with wheel sets 10 at or adjacent a rear end of a main frame 11. A conventional suspension system is provided for the axles 12 of the wheel sets, this being illustrated in Figure 3 where the axles are shown to be located by respective leaf springs 13 which are mounted in conventional fashion beneath longitudinal I-section beams 14 forming part of the main frame.

A load-carrying body 16 is pivotally connected to the main frame for lifting movement about a transverse axis 18 adjacent the rear of the vehicle, as shown in chain-dotted lines in Figure 1. A hydraulic ram 20 is connected betweeen the main frame and said load-carrying body for lifting the front end of the body when the load is to be discharged from its rear end.

Referring now to Figures 2 and 3, it will be seen that there are provided pairs of hydraulic jacking devices 22,22 and 24,24 on opposite sides of the main frame. Each jacking device is in the nature of a hydraulic cylinder 23 rigidly mounted on one or the other of the I-section beams of the main frame and having a ram 25 extending beneath it.

Respective metal cups 27 are provided on the axles, as shown in Figures 2 and 3, and these can receive the domed lower ends of the respective rams when the jacking devices are brought into operation.

The rams of the jacking devices visible in Figure 3 are shown retracted. However, as will presently be described, the rams of the jacking devices on the one side or the other side of the vehicle can be extended, selectively, to act against the axles beneath them, as shown in Figure 2.

In Figure 4 there is illustrated a hydraulic circuit in which the hydraulic ram 20 is included.

As shown, the hyraulic ram 20 is connected by way of conduit 26 to a power driven pump 28 which can draw hydraulic fluid from a tank 30. A tipping valve 32, operated by a manually operated tipping control lever 34, is provided for directing the output of the pump to the hydraulic ram, so that the vehicle body can be lifted, or for diverting the flow of fluid back to the tank by way of conduit 36. In a third position of the control lever, hydraulic fluid in the hydraulic ram 20 is able to return to the tank by way of valve 32 so that the vehicle body is lowered. (The part of the hydraulic circuit so far referred to is provided as standard equipment on tipping trailers with their own self contained power pack, the power driven pump either being driven by a donkey engine or by an electric motor).

The hydraulic circuit also includes the hydraulic jacking devices 22,22 and 24,24 referred to above, these being in this instance single acting spring return jacking devices extendable by hydraulic fluid delivered from the output side of the pump by way of a solenoid operated diverter valve 38; a conduit 40 containing a one-way valve 42; and respective conduits 44,46 containing respective flow restrictors 48,50 and respective solenoid operated diverter valves 52,54. When the solenoid operated diverter valves 52,54 are de-activated, they connect the respective jacking devices to a fluid return conduit 56 by way of respective oneway valves 58,60, the fluid return conduit being connected to tank 30.A further solenoid operated valve 62 is located in the fluid return conduit 56, this being electrically activated to open and allow fluid in the hydraulic jacking devices to return to tank subsequent to the valves 52 and 54 having been de-activated.

The various solenoid operated valves referred to are operated by an electrical system drawn in chain-dotted lines, this including a tilt switch 64, carried by the main frame, for monitoring the inclination of the vehicle body from the vertical, when viewed longitudinally of the vehicle as in Figure 2.

The tilt switch 64 is powered by means of a relay 66 which is only switched into operation when a pressure switch 68 detects a certain minimum hydraulic pressure in the conduit 26 connected to hydraulic ram 20. The arrangement is such that, when the tilt switch detects an inclination of the vehicle body of 2 degres or more from the vertical, it causes the appropriate one of the solenoid operated valves 52 or 54 to open to flow of fluid from the pump and simultaneously, by way of a relay 70 or 72 actuates the diverter valve 38 so that hydraulic fluid previously flowing to the hydraulic ram 20 is diverted to flow via conduit 40 to the appropriate jacking devices 22,22 or 24,24.

The solenoid operated valve 62, which as previously mentioned is electrically activated to open, is connected to the electrical supply by way of a limit switch 74 (which is shown open in Figure 4). The arrangement is such that the vehicle body holds the limit switch in its closed condition when in a lowered position. As soon as the vehicle body is lifted by the ram 20, the limit switch opens automatically and remains open until the body has been returned to its fully lowered, or substantially fully lowered, condition.

The operation of the levelling apparatus is as follows: When the vehicle has been driven to a location in which the load is to be tipped, the driver will position the vehicle on level ground and will then operate the tipping control lever 34 so that hydraulic fluid from the pump will start to extend the hydraulic ram. As the loaded body starts to lift, the limit switch 74 will open causing the valve 62 to close.

If at this stage the ground beneath the, say, left hand side wheels, as viewed in Figure 2, starts to subside so that the vehicle as a whole tilts over at more than 2 degrees from the vertical the tilt switch 64 will detect the fact and will cause the appropriate one of the selectively operable diverter valves to open to flow of hydraulic fluid from the pump. It will simultaneously cause the diverter valve to open the conduit 40 to the flow of hydraulic fluid from the pump and close off conduit 26. Consequently, the hydraulic ram 20 will be immediately brought to a halt and the jacking devices 22,22 will be caused to extend to bring the vehicle body back to the vertical or substantially the vertical. The presence of the flow restrictors in the respective flow lines to the jacking devices ensures that the vehicle body is restored to the vertical with a steady but not violent motion. As the tilt switch carried by the main frame detects that the vehicle body has been brought back substantially to the vertical, it allows the diverter valves to revert back to their former condition so that the tipping movement of the body by the hydraulic ram is resumed. However, by virtue of the fact that the valve 62 is closed, the hydraulic fluid which has been pumped into the jacking devices 22,22 is locked therein and continues to hold the body in its vertical or substantially vertical condition (as viewed in Figure 2).

It will be understood that if further subsidence of the ground beneath the same side of the vehicle should occur during the further lifting of the vehicle body by the hydraulic ram 22, the levelling apparatus will operate again in an exactly similar manner to that just described to extend still further the jacking devices 22,22. It will also be understood that if during the further lifting of the vehicle body by the hydraulic ram 20 the ground beneath the wheels at the other side of the vehicle should begin to subside, this also will be detected by the tilt switch and hydraulic fluid will be caused to extend the jacking devices 24,24 as soon as a tilt of the vehicle body of 2 degrees or more from the vertical is detected.Extension of the hydraulic ram 20 will once again be halted during the extension of the jacking devices 24,24 and will be resumed when the vehicle body has been restored substantially to the vertical. However, as in the case of the jacking devices 22,22 the hydraulic fluid which has been pumped into the jacking devices 24,24 is locked therein and continues to hold the body in its vertical or substantially vertical condition until the vehicle body has been lowered by the retraction of the hydraulic ram 20.

When the body is almost fully lowered, the limit switch 74 will be re-closed so that valve 62 opens and allows hydraulic fluid in the jacking devices to be returned to the tank 30. Whatever tilting of the body this then causes will not be likely to be dangerous because the body will be empty by that time and will be almost fully lowered so that its centre of gravity will be relatively low.

Thus there is provided a tipping vehicle with levelling apparatus by means of which it is thought the danger of overturning during a tipping operation will be reduced, although obviously there may be certain situations where a ground subsidence can be so sudden that an overturning of the vehicle can occur before the levelling apparatus has been able to react. On the other hand, the flow restrictors may be made adjustable so that the response time of the apparatus can be reduced in a vehicle likely to encounter such ground conditions rather than a progressive subsidence due to the compaction of loose material.

Various modifications may be made. For example, in Figure 5 there is illustrated a levelling apparatus identical to that described with reference to Figure 4 except that the apparatus is adapted for fitment to a tipping trailer vehicle not provided with its own in-built power system.

In other words, the hydraulic circuit of the tipping trailer does not include a power driven pump driven by a donkey engine or by an electric motor carried by the tipping trailer; it is instead provided with a hose coupling 76 by means of which the apparatus can be coupled to the hydraulic system of a tractor vehicle by means of which the trailer is to be towed. In addition, in series connection with the solenoid operated diverter valve 38, by way of an electrical coupling 78 to the electrical system of the tractor vehicle, is a hold switch 80 combined with the tipping control lever (not shown) on said tractor vehicle. It will be understood that the basic operation of the apparatus is as previously described with reference to Figure 4.

In Figure 6 there is illustrated a further possible modification which can be made if it is thought that difficulties may be likely to arise as a result of using single acting spring return jacking devices 22,22 and 24,24. As shown, in the hydraulic circuit of Figure 6, the single acting spring return jacking devices have been replaced by double acting devices 222,222 and 224,224. As a consequence of this, the pressure switch 68 has been omitted and a further solenoid operated valve 225 has been added, the latter being located in a conduit 226 connected to the return sides of the plurality of jacking devices. The conduit 226 is connected to receive a supply of hydraulic fluid under pressure from the supply conduit on the output side of diverter valve 38. A fluid return conduit 228 is connected between the valve 225 and the return conduit 56 which is connected to tank 30.

In the operation of this modified arrangement, when the tilt switch causes one or the other of the selectively operable diverter valves 52 and 54 to open to flow of hydraulic fluid from the pump, the diverter valve 225 will open to allow the return sides of the jacking devices to communicate with tank 30. Conversely, when the valve 62 is opened by the closure of limit switch 74, the diverter valve 225 will close the communication of conduit 226 to tank 30 and will open it to communication to hydraulic fluid under pressure from the outlet side of diverter valve 38 and the jacking devices (or those of the jacking devices which have been extended) will be retracted.

It will of course be understood that the arrangement just described could be adapted (in substantially the same way that the arrangement of Figure 4 has been said to be adaptable) for fitment to a tipping trailer vehicle not provided with its own in-built power system.

The invention can of course be applied to a tipping trailer with any number of axles, i.e. from a single axle arrangement upwards and the number of jacking devices may be varied accordingly. It will also be understood that the invention is not limited to vehicles provided with leaf spring suspension; the invention may equally well be applied to vehicles with pneumatic or fluid suspensions or indeed to any combination of these.

Claims

CLAIMS:

1. A tipping vehicle provided with a loadcarrying body pivotally mounted for lifting movement about a transverse axis adjacent the rear of the vehicle; means for monitoring the inclination of the vehicle body from the vertical when viewed longitudinally of the vehicle; and levelling apparatus including fluid operated jacking devices for acting between the chassis of the vehicle and mounting means for road wheels at the rear of the vehicle, the jacking devices on the opposite sides of the vehicle being operable selectively to counter any tendency for the ground to subside at one or the other side of the vehicle and causing the road wheels to tilt.

2. A tipping vehicle according to claim 1, in which the fluid operated jacking devices are rigidly mounted on the chassis of the vehicle, respective metal cups being provided on the mounting means for the road wheels for receiving domed lower ends of respective rams of said jacking devices.

3. A tipping vehicle according to either one of the preceding claims, in which the arrangement is such that the operation of the levelling apparatus whilst a hydraulic ram is still being extended to lift the load-carrying body, causes said hydraulic ram to pause in its movement until the means for monitoring the inclination of the body, when viewed longitudinally of the vehicle, detects that said levelling apparatus has brought it back to the vertical or substantially the vertical.

4. A tipping vehicle according to any one of the preceding claims, in which the arrangement is such that if the levelling apparatus has been operated to bring the vehicle body back to the vertical or substantially the vertical, as viewed longitudinally of the vehicle, during the lifting of said body to a discharge position, the fluid in the one or the other, or in both, of the jacking devices will be locked therein until the vehicle body has been returned to its lowered position or almost to its lowered position.

5. A tipping vehicle according to claim 4, in which a solenoid operated valve capable of inhibiting return flow of fluid from the jacking devices of the levelling apparatus, is electrically activated to open and is connected to the electrical supply of the vehicle by way of a limit switch, the vehicle body holding the limit switch in its closed condition when in a lowered position, whereby as the vehicle body is lifted the limit switch opens automatically and remains open until the body has been returned to its fully lowered, or substantially fully lowered condition, the arrangement being such that if the levelling apparatus is operated whilst the vehicle body is being lifted, the hydraulic fluid in the or each actuated jacking device is locked therein and continues to hold the body in its vertical or substantially vertical condition until the body has been returned to its fully lowered or substantially fully lowered condition to close the limit switch.

6. A tipping vehicle according to any one of the preceding claims, in which the jacking devices are single acting spring return jacking devices.

7. A tipping vehicle according to any one of claims 1 to 5, in which the jacking devices are double acting jacking devices.

8. A tipping vehicle according to any one of the preceding claims in which the hydraulic circuit of the tiping trailer includes a power driven pump driven by a donkey engine or by an electric motor carried by the tipping trailer.

9. A tipping vehicle constructed and arranged, and adapted to operate, substantially as hereinbefore described with reference to and as illustrated by Figures 1 to 4 or Figure 5 or Figure 6 of the accompanying drawings.

9. A tipping trailer according to any one of claims 1 to 7, in which the hydraulic circuit of the tipping trailer is provided with a hose coupling by means of which the levelling apparatus can be coupled to the hydraulic system of a tractor vehicle by means of which the trailer is to be towed.

10. A tipping vehicle constructed and arranged, and adapted to operate, substantially as hereinbefore described with reference to and as illustrated by Figures 1 to 4 or Figure 5 or Figure 6 of the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS: 1. A tipping vehicle provided with a loadcarrying body pivotally mounted for lifting movement about a transverse axis adjacent the rear of the vehicle; means for monitoring the inclination of the vehicle body from the vertical when viewed longitudinally of the vehicle; and levelling apparatus including fluid operated jacking devices for acting between the chassis of the vehicle and mounting means for road wheels at the rear of the vehicle, the jacking devices on the opposite sides of the vehicle being operable selectively to counter any tendency for the ground to subside at one or the other side of the vehicle and causing the road wheels to tilt, the arrangement being such that if the levelling apparatus has been operated to bring the vehicle body back to the vertical or substantially the vertical, as viewed longitudinally of the vehicle, during the lifting of said body to a discharge position, the fluid in the one or the other, or in both, of the jacking devices will be locked therein until the vehicle body has been returned to its lowered position or almost to its lowered position.

2. A tipping vehicle according to claim 1, in which a solenoid operated valve capable of inhibiting return flow of fluid from the jacking devices of the levelling apparatus, is electrically activated to open and is connected to the electrical supply of the vehicle by way of a limit switch, the vehicle body holding the limit switch in its closed condition when in a lowered position, whereby as the vehicle body is lifted the limit switch opens automatically and remains open until the body has been returned to its fully lowered, or substantially fully lowered condition, the arrangement being such that if the levelling apparatus is operated whilst the vehicle body is being lifted, the hydraulic fluid in the or each actuated jacking device is locked therein and continues to hold the body in its vertical or substantially vertical condition until the body has been returned to its fully lowered or substantially fully lowered condition to close the limit switch.

3. A tipping vehicle according to either one of the preceding claims, in which the fluid operated jacking devices are rigidly mounted on the chassis of the vehicle, respective metal cups being provided on the mounting means for the road wheels for receiving domed lower ends of respective rams of said jacking devices.

4. A tipping vehicle according to any one of the preceding claims, in which the arrangement is such that the operation of the levelling apparatus whilst a hydraulic ram is still being extended to lift the load-carrying body, causes said hydraulic ram to pause in its movement until the means for monitoring the inclination of the body, when viewed longitudinally of the vehicle, detects that said levelling apparatus has brought it back to the vertical or substantially the vertical.

5. A tipping vehicle according to any one of the preceding claims, in which the jacking devices are single acting spring return jacking devices.

6. A tipping vehicle according to any one of claims 1 to 4, in which the jacking devices are double acting jacking devices.

7. A tipping vehicle according to any one of the preceding claims in which the hydraulic circuit of the tiping trailer includes a power driven pump driven by a donkey engine or by an electric motor carried by the tipping trailer.

8. A tipping trailer according to any one of claims 1 to 6, in which the hydraulic circuit of the tipping trailer is provided with a hose coupling by means of which the levelling apparatus can be coupled to the hydraulic system of a tractor vehicle by means of which the trailer is to be towed.