GB2276139A - Tipper truck stabilisation mechanism and control means therefor - Google Patents

Abstract

A stabilisation mechanism (16) for resisting lateral movement of a tippable body section (4) of a tipper truck when it is raised. The stabilisation mechanism (16) includes hingeably interconnected upper and lower sections (10 and 18) which are respectively connected at their distal ends to the body section (4) and a support frame (12) which is connected to the chassis of the truck. The lower section (18) of the stabilisation mechanism acts as a hydraulic fluid reservoir for supplying the actuator (10) and is made from a rectangular frame of box section members closed by sheet metal welded to the box section members. According to a second aspect of the invention there is provided a control means for preventing subsequent raising of the tippable body section of such a vehicle once tilt beyond a certain threshold has been reached. Preferably a tilt sensor prevents extension of the arm via a control valve moved by pressurised gas. <IMAGE>

Description

TIPPER TRUCK STABILISATION MECHANISM AND CONTROL MEANS THEREFOR The present invention relates to a mechanism suitable for stabilising the tippable body section of a tipper truck and to a truck including such a mechanism.

A conventional tipper truck is in the order of 9 metres long and typically weighs 10 tonnes when unladen and 32 tonnes when laden. The load is accommodated in a body section which is tippable about an axis which is transverse to the truck's longitudinal axis and lifted and lowered by means of one or two hydraulic actuators positioned to push upwards on the underside of the tippable body section. As a typical angle of repose of material carried by such trucks is approximately 400 the tippable body section is normally raisable by about 500. If material sticks in an upper region of the tippable body section while that in a lower region flows out as required, an undesirable raising of the centre of gravity of the truck will occur. Other factors which will increase the truck's tendency to be overturned, are high cross winds, and the parking of the truck on a significant cross fall.

The current trend to design such trucks without a conventional rigid chassis aggravates this problem as flexing of the truck may allow it to adopt an unstable state causing it to overturn.

The addition of any stabilising means to a tipper truck of the type described above will tend to increase the truck's overall weight thus reducing its potential pay load. Furthermore the incorporation of any new elements into the design of a tipper truck will be subject to severe space constraints.

The object of the invention is to provide a stabilisation mechanism for a tipper truck of the type described above which can be easily accommodated in the design of a conventional tipper truck and does not unnecessarily add to the truck's unladen weight.

Thus according to the first aspect of the invention there is provided a stabilisation mechanism for a tippable body section of a tipper truck for restraining the tippable body section against movement transverse to the longitudinal axis of the truck, wherein the stabilisation mechanism includes one section which constitutes a hydraulic fluid reservoir for supplying hydraulic fluid to an actuation means for raising and lowering the tippable body section.

The inventors found that by using part of the stabilising mechanism as a hydraulic fluid reservoir, the need for a separate tank for this purpose can be completely eliminated. The one or more actuators required for such a tipper truck customarily require a hydraulic fluid reservoir having a capacity in the order of 100 litres.

Obviating the requirement for a separate hydraulic fluid reservoir thus provides the double advantage of reducing the truck's unladen weight (and hence increase its pay load) and also making space available for accommodating other equipment. Furthermore the closed form of the section constituting the reservoir necessitated by its secondary function as a reservoir, tends to make it particularly rigid and thus effective for reducing movement of the tippable body section transverse to the longitudinal axis of the truck.

The section constituting the reservoir preferably includes a frame of structurally rigid members e.g. of a box section with sheet material connected to opposing surfaces of the frame. Such an arrangement provides a particularly rigid section, the entire volume of which can be used as a hydraulic fluid reservoir.

The reservoir section preferably further comprises additional sway bracing in the form of stiffening plates welded to the structurally rigid members. This will increase the section's ability to resist sideways movement of the tippable body still further.

The mechanism preferably includes lower and upper sections which are hingeably connectable to a truck chassis and a tippable body section respectively and are hingeably interconnected. Such an arrangement can be conveniently designed to fold down compactly when the tippable body is lowered and extend so as to stabilise the tippable body when it is raised. In order to minimise the lateral space taken up by the mechanism when not in use the hinging between the upper and lower sections and between the sections and other parts of the truck, is preferably about axes positioned substantially perpendicularly to the truck's longitudinal axis.

The mechanism preferably further comprises a support frame mountable on a truck chassis and which hingeably supports the lower reservoir section and the lower end of an actuator for tipping the tippable section. Such an arrangement facilitates installation of the mechanism on a vehicle and also assists in distributing the twisting forces experienced by the stabilising frame and the reaction force produced by the actuation means to the remainder of the truck. Part of an actuator for raising and lowering the tippable body section may conveniently be mounted on the support frame preferably by means of a gimballed mounting arrangement.

So as to reduce the space required by the extended or retracted actuator the actuator is preferably a multistage actuator.

In order to facilitate the flow of hydraulic fluid from the reservoir the reservoir section preferably includes a breather means through which air can enter and leave the reservoir when required. This breather means is preferably provided by a breather assembly incorporating a flow obturating means for preventing spillage of hydraulic fluid from the reservoir.

The breather assembly conveniently comprises a ball valve member urgeable by fluid pressure against a seal to prevent escape of hydraulic fluid.

The section constituting the reservoir preferably includes a fluid content indicator means such as a sight glass for indicating the amount of fluid in the reservoir.

When tipper trucks are used on sloping ground there is a danger that by raising the tippable body section an unstable situation will occur and the truck may topple sideways. In an attempt to alleviate this problem tipper trucks have been provided with audible alarms which will alert an operator to the fact that an unstable situation is being approached. In situations where, for example, only slight further raising of the tippable body section is required such warnings tend to be ignored by operators. It is a further object of the invention to overcome this drawback.

Thus, according to a second aspect of the invention there is provided a control means for controlling the tipping of a tippable body section of a tipper truck, the control means including an actuator for raising and lowering the tippable body section and tilt sensing means which is actuated when lateral tilt of a part of the truck exceeds a threshold wherein the tilt sensing means is operatively connected to the actuator so that tilt sensing means actuation arrests raising of the tippable body section.

Such a system will prevent further raising of the tippable body section when an unstable situation is encountered or approached.

Preferably, the tilt sensing means is connected to the tippable body section rather than a part of the chassis. Due to the flexible nature of modern vehicle chassis, the sensing of tilt at a location on the chassis may not accurately reflect tilt experienced by a raised tippable body section.

Conveniently the actuator is a hydraulic actuator and the control means includes a source of pressurised hydraulic fluid and valve means controlling flow of the hydraulic fluid to and from the actuator and wherein the tilt sensor is operatively connected to the valve means so as to effect interruption of flow of hydraulic fluid to the actuator upon actuation of the tilt sensing means.

So that a pump providing the pressurised fluid may be left running continuously rather than frequently started and stopped, the valve means preferably includes a first valve having a spool with a rest position in which the source of pressurised fluid is connected for free flow to a fluid reservoir from which the source of pressurised fluid is supplied. The valve spool is preferably resiliently biased towards this rest position.

Preferably, a further pressurised fluid such as compressed air or other gas is used to control movement of the valve spool.

It is possible that a short duration sway of the tippable body section may occur which does not result in a truly unstable situation arising. Accordingly, the control means preferably includes a false interruption prevention circuit which acts to prevent actuation of the tilt sensing means causing interruption of the flow of hydraulic fluid to the actuator unless the actuation occurs for more than a predetermined period.

In order to ensure that the tippable body section is lowered before further raising is effected, such lowering is preferably a precondition for removal of the interruption (of the raising process).

The invention also includes a combination of a stabilising mechanism and control means as described above and a vehicle including such a mechanism, control means or combination.

The invention will now be described by way of example only with reference to the following figures in which: Figure 1 shows the side view of a tipper truck provided with a mechanism according to the invention with the tippable body section raised; Figure 2 shows a side view of the vehicle illustrated in Figure 1 with the tippable body section almost completely lowered; Figure 3 shows a view in the direction of the arrow V in Figure 1 of the lower section of the stabilising mechanism; Figure 4 shows a side view of the lower section shown in Figure 3; Figure 5 shows a vertical transverse cross section through the breather assembly connected to the front end of the lower section; Figure 6 shows a cross section on the line YY of the lower section shown in Figure 3; Figure 7 shows a cross section on the line XX of the lower section shown in Figure 3.

Figure 8 shows a view in the direction of the arrow U in Figure 1 of the upper section; Figure 9 shows a cross section on the line WW of the upper section shown in Figure 8; Figure 10a shows a plan view of a support frame installed on a vehicle, with the lower section and actuator removed for clarity; Figure 10b shows a view similar to Figure 10a in which the support frame is provided with a gimbal led actuator support; Figure 11 shows a cross section on the line ZZ of the support frame shown in Figure 10a with an actuator keeper plate secured in place; Figure 12 shows in diagrammatic form a control means according to the second aspect of the invention; Figure 1 shows the rear end of a truck equipped with a stabilisation mechanism and actuation means according to the invention, with its tippable body in the raised position.The rear end of the chassis 2 is supported on wheels 14, and bears at its rear end, a body pivot 8, about which a tippable body 4 is rotatably connected. The rear end of the tippable body 4 is provided with a rotatably mounted tailgate 6 to allow material to flow from the tippable body 4 when it is raised. In front of the wheels 14 a support frame 12 is connected to the chassis 2.

Rotatably mounted in the support frame 12 are the lower end of a multi-stage actuator 10 and a lower end of a foldable stabilising mechanism 16. The upper ends of both the multi stage actuator 10 and the stabilising mechanism 16 are connected to the tippable body section 4. When the contents of the tippable body 4 have been tipped from the vehicle due to the raising of the tippable body as shown in Figure 1, the multi-stage actuator is retracted so that the tippable body 4 moves through the position shown in Figure 2 until the tippable body 4 comes to rest against the body stop 7. The vehicle is then ready to be reloaded with material to be transported.

The stabilising mechanism 16 comprises a lower section 18 shown in detail in Figures 3, 4, 6 and 7 and an upper section 19 shown in detail in Figures 8 and 9.

The lower section 18 comprises a rectangular frame of box section members 28 welded together at the four locations 30. Corner plates 29 and centre plate 31 are welded between the box section members to increase the rigidity of the section. Cover plates 32 are welded to opposing sides of the rectangular frame 28 and seal in the area surrounded by the rectangular frame. Centre pivot plates 42 are welded to either side of the upper end of the rectangular frame 28 and are each provided with a hole 44.

Inner holes 27 (Figures 6 and 7) are provided in the box section members 28 making up the rectangular frame in order to allow hydraulic fluid stored within a lower section to fill the space within the box section members as well as that between them. Projecting from the upper end of the lower section 18, and in fluid communication therewith is a lower section extension 46. This lower section extension is provided with an externally threaded boss 48 for connection to a breather assembly 90 which will be described in detail below. Welded to one of the box section members is a filler plug boss 34 into which a filler plug 36 is screwed. At the lower end of the lower section 18, fluid outlet boss 50 is provided, for supplying hydraulic fluid from the lower section 18 to a self priming centrifugal hydraulic fluid pump 116 (see Figure 12).

The upper section 19, shown in Figures 8 and 9, comprises a central box section 54 to each end of which, a tube 58 is transversely welded. Each tube 58 is also connected to the central box section 54 by two enclosed triangular reinforcing sections 56.

In the assembled configuration shown in Figure 1 the tube 58 at the lower end of the upper section 19 is located between the centre pivot plates 42 connected to the upper end of the lower section 18. The centre pivot bar 24 passes through holes 44 in the centre pivot plates 42 and a bore 60 in the tube 58. Circlips (not shown) located at outer ends of the centre pivot bar 24, hold it in place.

Lower pivot plates 38 which extend from the lower end of lower section 18 are provided with holes 40 and are located between and adjacent to pivot plates 84 welded to the rear end of the support frame 12. A lower section pivot bar 20 passes through the holes 40 in the lower plates 38 and holes 36 in the pivot plates 84. Circlips (not shown) located at the outer ends of the lower pivot bar 20 hold it in place.

A channel section member 26 is welded or bolted transversely to the underside of the tippable body 4. To either end of the channel section 26 stubshaft plates 62 are connected each of which supports an inwardly directed stubshaft 64 (shown dotted in Figure 1). These stubshafts are accommodated in a bore 60 in the upper section tube 58.

In practice the tippable body 4 will project some way past the channel section 26, so as to cover the stabilising mechanism when in its lowered position.

Also connected to the channel section 26 is a ball pivot 9 or eye to which one end of the multi-stage actuator 10 is connected. The lower end of the multi stage actuator is provided with trunnions 80 which are supported in inwardly projecting saddle blocks 70 (see Figures 10 and 11) in the support frame 12.

The support frame 12 is shown in detail in Figures 10a and 11 and includes a pair of transverse box section members 72 longitudinally interconnected by L section saddle support members 74. The box section members 72 rest on the upper surface of chassis 2 and are also interconnected by outer plates 82 which are positioned so as to pass down outer surfaces of the chassis 2, and be connected thereto by some suitable means, such as bolting or welding. A pair of saddle blocks 70 are welded to the confronting surfaces of saddle support members 74 and are provided with tapped holes 76. When the actuator trunnions 80 (shown in dotted lines in Figure 11) are located in the saddle blocks, keeper plates 78 are bolted to upper surfaces of the saddle blocks by bolts engaging tapped holes 76 to hold the actuator trunnions 80 in place.Pivot plates 84 project rearwardly from and are welded to the rear box section member 72. Each pivot plate 84 contains a hole 86 for accommodating the lower section pivot bar 20.

Figure lOb shows a view similar to Figure 10a of an alternative arrangement of support frame. Like parts in Figures 10a and lOb are designated by like numerals. In the Figure lOb arrangement the saddle blocks 70 are connected directly to confronting faces of the box section members 72 and support gimbal trunnions 81 of a gimbal frame 83. The actuator trunnions (not shown in Figure lOb) will be supported in hemicylindrical gimbal bearings 71 and held there by keeper plates bolted to further tapped holes 76. This arrangement of support frame will allow transverse movement of the top of the actuator relative to the truck's chassis to occur without putting undue stress on the actuator and support frame components.

The breather assembly 90 is shown in detail in Figure 5. The breather body 92 is divided by a dividing wall 94 into two chambers. The righthand chamber as shown in Figure 5 is provided with a first internally threaded boss 104. Spigot 106 which acts to retain a captive nut 108 threadably engages the boss 104. The captive nut 108 is used to connect the breather assembly 90 to the threaded boss 48 connected to the lower section extension 46. V support 102, supports a ball valve member 95 in the righthand chamber. Flow of hydraulic fluid towards the left hand chamber urges the ball valve member 98 against a seal 100 located around the periphery of an aperture 96 in the dividing wall 94. The lefthand chamber as shown in Figure 5, is provided with a second internally threaded boss 110, into which a breather cap spigot 112 is screwed.

A breather cap 114, of conventional design, is slidingly fitted to the breather cap spigot 112. In normal circumstances the ball valve member will be positioned away from the seal 100, thus allowing air to enter and leave the reservoir constituted by the lower section 18 via the breather assembly. Should fluid attempt to leave the reservoir via the breather assembly the ball valve member 95, will be urged against the seal 100 thus preventing hydraulic fluid spillage. A tendency for such spillage to occur would arise when the stabilising structure is collapsed, and the truck is pointing down hill and or brakes abruptly.

When the tippable body 4 is raised to the position shown in Figure 1 by the multi-stage actuator 10, the stabilising structure 16 will resist movement of the upper end of the tippable body transverse to the vehicle's longitudinal axis, and thus increase the vehicle's stability. As the tippable body is lowered through the positions shown in Figure 2, the fluid accommodated within the multi-stage actuator will be allowed to flow into the reservoir constituted by the lower section 18.

The enclosed form of the lower section 18 provides the stabilising mechanism with a very rigid form and its ability to act as a reservoir obviates the need for locating a separate reservoir elsewhere on the truck.

Figure 12 shows in simplified diagrammatic form a hydraulic control means according to a second aspect of the invention comprising hydraulic, electrical and pneumatic circuits suitable for controlling the hydraulic actuator 10.

A hydraulic pump 116 is connected to pump hydraulic fluid (e.g. oil) from a reservoir 115 to a multi-stage hydraulic actuator 10.

The hydraulic fluid flow from the hydraulic pump 116 is controlled by a three position hydro-pneumatic control valve 117. This valve 117 is controlled by a pneumatic switch 119 which receives an operational pressurised air supply via tubing 118. The valve includes a spool 117g which is biased by springs 117f towards a central operating state represented by 117c in which hydraulic fluid from the pump is returned directly to the reservoir 115 by a return hose 132. When the pneumatic switch 119 is operated to command the hydraulic actuator 10 to lift, pressurised air is supplied to the raising port 117a of the pneumatic control section of valve 117 via tubing 120 and 122 and through an electro-pneumatic valve 121. This causes valve spool 117g to move to position 117d and allow high pressure hydraulic fluid from pump 116 to raise the hydraulic cylinder 10.The operating air passing through valve 121 is shown as a solid line. To lower the hydraulic actuator 10, the pneumatic switch 119 is operated to supply pressurised air via pneumatic tube 123, electro-pneumatic switch 133 and pneumatic tube 126 to the lowering port 117b of the hydro-pneumatic control valve 117. This moves the spool to position 117e allowing the hydraulic fluid to return from the hydraulic actuator 10 to the reservoir 115 via valve 117 and hydraulic fluid return hose 132. This allows the actuator 10 to lower under the force provided by the weight of the tipper body 4.

Under normal circumstances (no lateral tipper body tilt) the electro-pneumatic valve 121 provides a straight through connection from the pneumatic switch 119 to the raising port 117a of the hydro-pneumatic valve 117.

To an upper section of the tippable body 4 of the tipper truck as described above, an adjustable lateral tilt sensor 125 is attached. The lateral tilt sensor, as shown as part 13 in Figure 1, may depend from the tippable body section so as to always hang vertically below a pivot axis transversely positioned relative to the truck. The tilt sensor is so adjusted that when the tippable body 4 becomes transversely inclined more than a predetermined amount from the horizontal, an electrical signal is generated which passes via an electrical connection 142 to an electrical control circuit 127. The purpose of the control circuit 127 is to prevent any signal generated by the tilt sensor 125 as a result of a short duration tilt from reaching the electro-pneumatic valve 121 and causing interruption of the body raising process.

The control circuit 127 includes a false operation rejection circuit, an adjustable timer and a solenoid valve driver with an electronic latching and re-set system. When the tilt sensor 125 is activated by tilting beyond a predetermined extent, an electrical signal is sent to control circuit 127. The rejection circuit is then initiated in conjunction with the timer. If after a preset time interval the tilt sensor 125 is still active the solenoid driver is activated. This causes the electropneumatic valve 122 to interrupt the operating air supply to the hydro-pneumatic valve 117 through pneumatic tubes 120 and 122. In this condition the electro-pneumatic valve 121 will block the air supply from pneumatic switch 119 via tube 120 and will exhaust the pressurised air from the valve 117 through tube 122 and the valve 121 to pneumatic exhaust 124.The dotted line through valve 121 indicates the path of air being exhausted. The exhaust of air from valve 117 is assisted by means of the spring loading of the spool 117g. When the air from valve 117 is exhausted the valve is automatically placed in a hold position (117c) by the spring loading of the spool. In this condition hydraulic fluid from pump 116 flows through valve 117 and returns to the supply tank 115 via the return hose 132.

The hydraulic fluid supply to the actuator 10 from valve 117 is stopped, so preventing the actuator 10 extending further and thus preventing the tipper truck body 4 being elevated further. Thus the raise command from the pneumatic switch 119 is overridden.

To lower the actuator 10 the pneumatic switch 119 is operated to provide a pneumatic lowering command to valve 117 via pneumatic tubes 123 and 126 and lowering port 117b.

This action will cause the contacts of an electro-pneumatic switch 133 to connect. Switch 133 is connected, via electrical cable 141, to a re-set system of the control circuit 127. Closing of switch 133 effects re-setting of the pneumatic valve 121 to its original condition. This will enable the actuator 10 to be raised when the truck is moved to more level ground and the tipping operating reattempted.

A control means such as that described above will ensure that at the predetermined transverse angle of tilt of the tippable body 4 an operator will be unable to continue raising the tippable body section. The action of lowering the tippable body section, and thus reducing the transverse angle of tilt of the tippable body section will re-set the control means. This will enable the operator to safely re-attempt the tipping operation once the truck has been re-positioned on more level ground.

Claims (24)

1. Stabilisation mechanism for a tippable body section of a tipper truck for restraining the tippable body section against movement transverse to the longitudinal axis of the truck, wherein the stabilisation mechanism includes one section which constitutes a hydraulic fluid reservoir for supplying hydraulic fluid to an actuation means for raising and lowering the tippable body section.

2. Stabilisation mechanism as claimed in claim 1 wherein the fluid reservoir section comprises a frame of structurally rigid members with sheet material connected to opposed surfaces of the frame.

3. Stabilisation mechanism as claimed in claim 2 wherein the structurally rigid members are box section members which are connected to form a frame.

4. Stabilisation mechanism as claimed in claim 2 or 3 wherein the structurally rigid members are apertured so as to enable fluid in the reservoir to occupy space within the structurally rigid members.

5. Stabilisation mechanism as claimed in claim 2, 3 or 4 wherein the frame includes additional sway bracing.

6. Stabilisation mechanism as claimed in any preceding claim including pivotably interconnected upper and lower sections distal ends of which are respectively adapted for pivotal connection to the tippable body part and the chassis of the tipper truck.

7. Stabilisation mechanism as claimed in any preceding claim wherein the reservoir section includes breather means through which air can enter or leave the reservoir.

8. Stabilisation mechanism as claimed in claim 7 wherein the breather means includes liquid spillage prevention means.

9. Stabilisation mechanism as claimed in claim 8 wherein the spillage prevention means includes a flow obturating means displaceable by movement of reservoir liquid so as to block the breather means.

10. Stabilisation mechanism as claimed in any preceding claim including a support frame for mounting on a chassis of the tipper truck and to which the reservoir section is hingeably connected.

11. Stabilisation mechanism as claimed in claim 10 wherein the support frame includes means for pivotably mounting a hydraulic actuator.

12. Stabilisation mechanism as claimed in claim 11 wherein the means for pivotably mounting the hydraulic actuator includes a gimballed mounting arrangement.

13. Control means for controlling the tipping of a tippable body section of a tipper truck, the control means including an actuator for raising and lowering the tippable body section and tilt sensing means which is actuated when lateral tilt of a part of the truck exceeds a threshold wherein the tilt sensor is operatively connected to the actuator so that tilt sensing means actuation arrests raising of the tippable body section.

14. Control means as claimed in claim 13 wherein the actuator is a hydraulic actuator and the control means includes a source of pressurised hydraulic fluid and valve means controlling flow of the hydraulic fluid to and from the actuator and wherein the tilt sensor is operatively connected to the valve means so as to effect interruption of flow of hydraulic fluid to the actuator upon actuation of the tilt sensing means.

15. Control means as claimed in claim 14 wherein the valve means includes a first valve having a rest position in which the source of pressurised fluid is connected for free flow to a fluid reservoir from which the source of pressurised fluid is supplied.

16. Control means as claimed in claim 15 wherein the first valve is resiliently biased towards the rest position.

17. Control means as claimed in claim 15 or 16 wherein further pressurised fluid is used to control movement of the first valve and the actuation of the tilt sensing means causes interruption of supply of the further pressurised fluid to the first valve.

18. Control means as claimed in claim 17 wherein the further pressurised fluid is a gas.

19. Control means as claimed in any one of claims 14 to 18 including a false interruption prevention circuit which acts to prevent actuation of the tilt sensing means causing interruption of the flow of hydraulic fluid to the actuator unless the actuation occurs for more than a predetermined period.

20. Control means as claimed in any one of claims 14 to 19 wherein lowering of the tippable body section is a precondition for removal of the interruption.

21. A stabilisation mechanism as claimed in any one of claims 1 to 12 in combination with a control means as claimed in any one of claims 13 to 20.

22. A vehicle including the stabilisation mechanism as claimed in any one of claims 1 to 12 or a control means as claimed in any one of claims 13 to 20.

23. Stabilisation mechanism as hereinbefore described with reference to the accompanying figures.

24. Control means substantially as hereinbefore described with reference to the accompanying figures.