GB2029335A - Tipper Vehicles - Google Patents

Abstract

A tipper vehicle includes an hydraulic circuit (4) including rams (3) for raising and lowering a load-carrying body (1) on the vehicle and rams (7) for opening and closing a discharge gate (2) on the body, said circuit having therein a control valve (12) by which, in one mode of operation, supply lines (9, 11) to said rams are connected to a hydraulic pressure source (6) and in an other mode of operation, are connected to a hydraulic drain line (14), the supply lines to said gate rams and said body rams respectively including valves (8) arranged so that in the one mode of operation said body rams will not raise the body until the gate rams have opened the discharge gate and, in said other mode of operation, the gate rams will close the gate at a speed such that the body is fully lowered before the gate is closed. <IMAGE>

Description

SPECIFICATION Tipper Vehicle This invention relates to tipper vehicles having a body which can be raised for the discharge of material carried therein through a discharge opening closable by a gate on the body Hitherto, it has been the practice to provide a gate which is raised either by chains or rigid linkages as the body is raised for tipping. In these prior constructions, the gate often restricts discharge of a load because it is not fully opened before the body is raised and consequently the load jams.

The present invention provides for hydraulic operation of a tipper vehicle body in which in one mode of operation a discharge gate on the body is opened before the body is tilted or raised to discharge a load from the body through the open gate and, in another mode of operation the body is fully returned to its un-tilted or lowered position before the discharge gate is closed.

The appended claims define the scope of the monopoly claimed. The invention and how it can be performed are hereinafter particularly described with reference to the accompanying drawings in which: Figure 1 is a three-quarter view of an hydraulically operated motor vehicle tipper body according to the present invention Figure 2 is a schematic side view, to a larger scale, of the tipper body of Figure 1 and showing the hydraulic circuit and controls therefor; Figures 3, 4 and 5 show schematically the hydraulic circuit, controls, and rams in three different operational states.

The drawings show one embodiment of the present invention which a dump truck (chassis not shown) has a load-carrying tipper body 1 with a discharge gate, in this case a tail gate 2, openable for discharge of material carried by the body. The body 1 (Figure 2) is movable by a pair of hydraulic rams 3 (of which only one is shown) between a lowered load-carrying position, and a raised, discharged position. The pair of rams forms part of a closed hydraulic circuit 4 (Figure 2) having a storage tank 5 for liquid, a pump 6 for drawing liquid from the tank circulating it under pressure through the circuit 4 to two hydraulic rams 7 (of which only one is shown) connected to the tail gate 2 and to the pair of rams 3 for raising and lowering the body 1.A sequence valve 8 is provided in each of the hydraulic supply lines 9 (only one of which is shown) from circuit 4 to each of the rams 3 for raising and lowering the body: and a one way orifice valve 10 is included in a hydraulic supply line 11 from the circuit 4 to the tail gate rams. A manually-operable control valve 12 in the circuit 4 is selectively operable in one mode (Figures 3 and 4) to operate the pump 6 and direct liquid under pressure from the pump 6 to the hydraulic circuit 4, and in the other mode, (Figure 5) to connect the circuit 4 to a drain line 14 back to the tank 5. When the control valve 12 is operated to supply liquid under pressure to the circuit 4, and lines 9 and 1 the valve 10 does not restrict liquid flow to the gate rams 7, which extend and open the gate 2.The setting of the sequence valves 8 is such that the valves 8 do not open during this operation but, (as shown in Figure 3) when the tail gate 2 is fully opened liquid under pressure supplied to the tail gate rams 7 cannot extend them further and consequently a pressure build-up occurs in the circuit sufficient to open the sequence valves 8 and allow passage of liquid under pressure through the lines 9 to the body rams 3 to extend them and raise the body 1 so that material carried by the body can be discharged through the tail gate opening.

In its other mode of operation the control valve 12 switches off the pump and connects the circuit 4 to the storage tank 5 through line 14 so that liquid under pressure in the circuit can flow back to the tank 5 with the result that the rams retract and the tail gate 2 moves to its closed position and the body 1 is lowered.

The sequence valves 8 each include a one-way check valve 1 5 (Figure 2) to permit the return flow of liquid without substantial pressure drop.

But the one-way orifice valve 10 in the line 11 supplying liquid under pressure to the tail gate rams 7 throttles return flow of liquid from the tail gate rams 7 to the tank 5 and reduces the speed at which the taii gate 2 closes so that the body 1 is completely lowering on to the vehicle chassis before the tail gate is closed.

The manually-operable control valve includes a relief valve (not shown) so that, while the body rams are kept fully extended by liquid under pressure circulating through the circuit, any overpressure liquid is safely discharged to the storage tank.

The hydraulic rams also act as dampers and so prevent tail gate bounce, a problem which afflicts mechanical systems.

Additionally, the above-described sequential operation for the tail gate and the body has the advantages that the tail gate is automatically raised to its fully opened position before the body is raised, thus ensuring that there is no restriction of the discharge of the load from the body; the opening of the tail gate automatically occurs when the manually-operable valve is actuated to operate in its first mode, that is to raise the body; the control of both tail gate and body is from one operating station, conveniently by one control lever for the control valve and, because of the hydraulic circuitry no external safety interlock is required.

Although the above-described form of the invention relates to a rear dump truck with a rear tail gate, the invention is equally applicable to other forms of tipper vehicle, for example side tippers having one or more gates along the side or sides of the body.

The pump may be driven by its own motor, independently of the vehicle engine, or be driven from the vehicle engine by a belt or chain drive or through a train of gears.

In the case of a tipper vehicle having powerassisted steering the pump for the supply of fluid for the power steering mechanism could be used to supply liquid under pressure for the tipper body and gate circuit. Conveniently, the tipper body and gate circuit could be integral with the power steering mechanism circuit.

Although the invention has been described with reference to a rear dump body having two rams to raise the body it is feasible to use a single ram for raising the tipper body.

Suitable pressures for the liquid in the circuit are 0--25 psi (0--17576.75 kg/m2) when the liquid is not being pumped to open the tail gate or raise the body, the pressure rising to 1400 psi (984298 kg/m2) as the liquid is pumped to open the tail gate and then to open the sequence valve for passage of liquid to the body raise rams. Any rise in pressure above 1400 psi (984298 kg/m2) will open the relief valve on the manuallyoperable valve and allow flow of liquid back to the tank. When the tail gate close and body lower, that is the ether mode of operation, is selected pressure in the circuit falls gradually to between 0-25 psi again (0--17576.r5 kg/m2)

Claims (6)

Claims

1. A tipper vehicle having an hydraulic circuit including rams for raising and lowering a loadcarrying body on the vehicle and rams for opening and closing a discharge gate on the body, said circuit having therein a control valve by which, in one mode of operation, supply lines to said rams are connected to an hydraulic pressure source, and in another mode of operation, are connected to an hydraulic drain line, the supply lines to said gate rams and said body rams respectively including valves arranged so that in the one mode of operation said body rams will not raise the body until the gate rams have opened the discharge gate and, in the other mode of operation, the gate rams will close the gate at a speed such that the body is in a fully lowered position before the gate is closed.

2. A tipper vehicie according to Claim 1, in which the valves in the supply lines to the body rams each include a one-way check valve to permit return flow of hydraulic pressure fluid to a supply tank without substantial pressure drop upon retraction of the body rams.

3. A tipper vehicle according to Claim 1 or Claim 2, in which a throttle valve restricts return flow of hydraulic pressure fluid from the gate rams whereby closure of the gate is made at a speed such that the body is in the fully lowered position before the gate is closed.

4. A tipper vehicle according to any preceding claim in which in the one mode of operation the hydraulic pressure source supplies hydraulic fluid at a pressure of 1400 psi (984298 kg/m2) and, in the other mode of operation the pressure falls to between 0-25 psi (0--17576.75 kg/m2).

5. A tippper vehicle according to any one of the preceding claims, in which operation of the rams is controlled by a manually-operable control valve.

6. A tipper vehicle including an hydraulic circuit substantially as hereinbefore particularly described with reference to and as shown in Figures 2-5 of the accompanying drawings.