DK201970104A1

DK201970104A1 - Wheeled vehicle with chassis mounted tipper body

Info

Publication number: DK201970104A1
Application number: DKPA201970104A
Authority: DK
Inventors: Lavmand Müller Per
Original assignee: Skan Trailer As
Priority date: 2019-02-18
Filing date: 2019-02-18
Publication date: 2020-09-24
Also published as: WO2020169157A1; DK180275B1

Abstract

A wheeled vehicle (1) with a chassis mounted tipper body (3) and a hydraulic cylinder (6) arranged between the chassis (2) and the tipper body (3) for providing lift of the tipper body (3) by supplying pressurized hydraulic medium to the hydraulic cylinder (6), a tank for a hydraulic medium (7), a control valve (8), a hydraulic pump (9) connected with an inlet fluidically connected to the tank (7) and with an outlet fluidically connected a main conduit (10) fluidically connecting the manually operated valve (eight) to the hydraulic cylinder (6), a pressure sensor (11) configured to issue a pressure signal indicative of the pressure in the main conduit (10), a drain conduit (12) fluidically connecting the main conduit (10) the tank (7), a control valve (13) controlling flow through the drain conduit (12), a controller (50) in receipt of the pressure signal and operably connected to the control valve (13), the controller (50) being configured to move the control valve (12) to an open position when the pressure signal indicates that the pressure in the main conduit (10) is below a first pressure threshold P1.

Description

DK 2019 70104 A1 1

WHEELED VEHICLE WITH CHASSIS MOUNTED TIPPER BODY

TECHNICAL FIELD The disclosure relates to a wheeled vehicle with a chassis mounted and hydraulically operated tipper body such as e.g. a dump body.

BACKGROUND Wheeled vehicles with chassis mounted hydraulically operated tipper bodies, such as tipper lorries or tipper trucks or tractors with tipper trailers, are widely used for transport of bulk materials. Typically, such a wheeled vehicle has a tipper body, which is pivotally mounted on the vehicle chassis and is capable of being raised and lowered by a hydraulic actuator.

The tipper body, such as e.g. a ladle is moved to its raised position by a hydraulic cylinder, e.g. a single acting linear hydraulic actuator. In order to raise the tipper body, an operator manipulates a valve that connects the hydraulic cylinder to a hydraulic pump. In order lower the tipper body, the operator manipulates the valve that connects the hydraulic cylinder to tank until the tipper body rests on the chassis, so that there is no load on the hydraulic cylinder when the vehicle is driving.

Wheeled vehicles with chassis mounted hydraulically operated tipper bodies, such as dump trucks or tractors with tipper trailers face several challenges. The tipper body must be returned to its fully lowered position before the wheeled vehicle is driven for two reasons.

DK 2019 70104 A1 2 The first reason is that the hydraulic cylinder that is used to move the tipper body will be damaged if it is loaded, especially when the vehicle drives and passes over bumps or other irregularities of the road surface. In order to meet this challenge, it has to be ensured that the tipper body is in its fully lowered position with the tipper body resting on the chassis when the wheeled vehicle is driven. However, an operator may not be able to judge whether or not the tipper body is completely resting on the chassis and is in its fully lowered position, and an operator may be in a rush and not patient enough to ensure that the tipper body is in its fully lowered position before driving the wheeled vehicle.

The second reason for the tipper body needing to be in its completely lowered position when the vehicle is driven is the risk of a raised tipper body crashing into overhead structures, such as e.g. bridges, pipelines or wires thereby causing damage to the wheeled vehicle and to the overhead structures.

SUMMARY It is an object to provide a wheeled vehicle with a tipper body that overcomes or at least reduces the problems mentioned above.

The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

DK 2019 70104 A1 3 According to a first aspect, there is provided a wheeled vehicle comprising: a chassis mounted tipper body, a hydraulic cylinder operably arranged between the chassis and the tipper body, a tank for a hydraulic medium, a manually operated valve, a hydraulic pump connected with an inlet fluidically connected to the tank and with an outlet fluidically connected to the manually operated valve, a main conduit fluidically connecting the manually operated valve to the hydraulic cylinder, the manually operated valve having at least: a first position in which flow of hydraulic medium to and from the hydraulic cylinder is prevented, a second position in which flow from the hydraulic pump to the hydraulic cylinder is enabled, a third position which flow from the hydraulic cylinder to the tank is enabled, a pressure sensor configured to issue a pressure signal indicative of the pressure in the main conduit, a drain conduit fluidically connecting the main conduit the tank, a control valve controlling flow through the drain conduit, a controller in receipt of the pressure signal and operably connected to the control valve, the controller being configured to move the control valve to an open position when the pressure signal indicates that the pressure in the main conduit is below a first pressure threshold Pl.

DK 2019 70104 A1 4 By providing a drain conduit, and by controlling the drain conduit to be open when the pressure in the main conduit is below a first pressure threshold, it is ensured that the hydraulic cylinder is connected to tank, for example when the tipper body is not or not completely in its fully lowered position. The first threshold is chosen to be slightly lower than the pressure required to obtain lift (upward movement) of the tipper body. Thus, the control valve is open and allows hydraulic medium to be drained until the pressure in the main conduit raises above the first pressure threshold Pl.

In a possible implementation of the first aspect, lift of the tipper body is provided by supplying pressurized hydraulic medium to the hydraulic cylinder.

In a possible implementation of the first aspect, lowering of the tipper body is provided by connecting the hydraulic cylinder to the tank.

In a possible implementation of the first aspect, the restriction to flow from the main conduit to tank through the drain conduit is lower, preferably is substantially higher than the flow restriction from the manually operated valve through the main conduit to the hydraulic cylinder, thus ensuring that the pressure in the main conduit rises quickly above the first pressure threshold Pl, upon which the control unit closes the control valve. The required restriction to flow through the drain conduit can e.g. be obtained by choosing a conduit with a diameter that is less than the diameter of the main conduit, or by applying a dedicated

DK 2019 70104 A1hydraulic restriction in the drain conduit or in the control valve.

In a possible implementation form of the first aspect the 5 manually operated valve is configured to automatically returned to the first position In a possible implementation form of the first aspect the main conduit comprises a coupling, preferably a quick coupling.

In a possible implementation form of the first aspect the wheeled vehicle comprises a tractor and a trailer with the tipper body mounted on the chassis of the trailer, the quick coupling 1s arranged between the tractor and trailer, with the portion of the main conduit associated with the trailer being connected to the hydraulic cylinder that is arranged between the chassis of the trailer and the tipper body.

In a possible implementation form of the first aspect the controller is in receipt of a handbrake signal indicative of a handbrake of the wheeled vehicle being on or off, the controller being configured to issue an alarm when the pressure signal indicates that the hydraulic pressure in the main conduit is above a second pressure threshold P2, and the handbrake signal simultaneously indicates that the handbrake is off.

The second pressure threshold can be lower, higher or equal to the first pressure threshold Pl.

In a possible implementation form of the first aspect the controller is in receipt of a vehicle speed signal indicative

DK 2019 70104 A1 6 of the speed of the wheeled vehicle, the controller being configured to issue an alarm when the pressure signal indicates that the hydraulic pressure in the main conduit is above a given threshold P2, and the speed signal indicates simultaneously that the speed of the wheeled vehicle is above a given speed threshold V1. The speed threshold can be equal to zero or can be a relatively low speed such as e.g. a few kilometers per hour, preferably 12 km/h, more preferably 8 km/h, even more preferably 6 km/h and most preferably 4 km/h.

In a possible implementation of the second aspect the hydraulic cylinder is a single acting hydraulic linear actuator.

In a possible implementation form of the first aspect the flow resistance for flow of hydraulic medium from the main conduit to the tank when the control valve is open is lower than the flow resistance from the manually operated valve through the main conduit to the hydraulic cylinder.

In a possible implementation form of the first aspect the controller is configured to close the control valve when the pressure signal indicates that the pressure in the main conduit is above a third pressure threshold P3. The third pressure threshold P3 can be higher or equal to the first pressure threshold Pl.

In a possible implementation form of the first aspect the wheeled vehicle comprises a handbrake sensor that issues a signal indicating of a vehicle handbrake being on or off, and the controller is configured to open the control valve on thefurther condition that the handbrake sensor indicates that the vehicle handbrake is off. In a possible implementation form of the first aspect the wheeled vehicle further comprises a handbrake sensor that issues a signal indicating of a vehicle handbrake being on or off and the controller is configured to open the control valve on the further condition that the handbrake sensor indicates that the vehicle handbrake is off.

In a possible implementation form of the first aspect the drain conduit fluidically connecting said main conduit directly to tank. These and other aspects will be apparent from and the embodiments described below.

BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed portion of the present disclosure, the aspects, embodiments and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which: Fig. 1 is a side view of an embodiment of a wheeled vehicle with a tractor and a trailer with a tipper body, Fig. 2 is a diagrammatic representation of a hydraulic system and controller of the wheeled vehicle Fig. 1, Fig. 3 is a side view of embodiment of a wheeled vehicle with a tipper body,

DK 2019 70104 A1 8 Fig. 4 is a diagrammatic representation of a hydraulic system and controller of the wheeled vehicle of Fig. 3, and Fig. 5 is a diagrammatic representation of a hydraulic system and controller of Fig. 2.

DETAILED DESCRIPTION Fig. 1 shows a wheeled vehicle 1 in the form of a combination of a tractor 4 and a trailer 5 connected to the tractor 4. Both the tractor 4 and the trailer 5 are provided with wheels. The wheeled vehicle 1 is suitable for participating in road traffic. The tractor 4 is of conventional overall design and comprises a cab 19 and an engine (not shown) for traction. The engine is also used to power a hydraulic pump 9 that will be described in greater detail with reference to Figure 2. The trailer 5 is provided with a chassis 2 on which a tipper body (such as e.g. a ladle) is pivotally mounted. A hydraulic cylinder 6 is used to raise and lower the tipper body between the lowered, rest position (shown in solid lines) and the raised, tipping position (shown in broken lines). In the fully lowered position, the tipper body 3 rests completely on the chassis 2 and there is not (and must not) be any load of the tipper body 3 on the hydraulic cylinder 6. Fig. 2 shows diagrammatically the electrohydraulic control system that is used to control the movement of the tipper body 3. The electrohydraulic control system comprises a hydraulic system comprising a tank 7 for the storage of

DK 2019 70104 A1 9 hydraulic medium, a hydraulic pump 9 that is powered by the engine of the vehicle or by an electric motor that in turn receives electrical power from the electric system of the wheeled vehicle 1 or form the engine. The hydraulic pump 9 is in an embodiment a suitable positive displacement pump such as e.g. a gear pump or a piston pump. An inlet of the hydraulic pump 9 is fluidly connected to the tank 7 and an outlet of the hydraulic pump 9 is connected to a feed conduit 14.

Movement (lift) of the tipper body 3 is achieved by a linear hydraulic actuator such as e.g. a single acting hydraulic cylinder 6. The hydraulic cylinder 6 is in an embodiment a telescopic hydraulic cylinder. One end of the hydraulic cylinder 6 is secured to the chassis 2 and the opposite end of the hydraulic cylinder 6 is secured to the tipper body 3. A manually operated valve 8 controls the flow to and from the hydraulic cylinder 6. The manually operated valve 8 has at least three ports and has at least three positions. An inlet port of the manually operated valve 8 is connected to the feed conduit 14 to receive pressurized hydraulic medium from the hydraulic pump 9. Another port of the manually operated valve 8 is connected to a tank conduit 17 that connects the port to the tank 7. Another port of the manually operated valve 8 is connected to a main conduit 10. The main conduit 10 connects the manually operated valve 8 to the hydraulic cylinder 6. In an embodiment at least a part of the main conduit 10 is formed by a hydraulic hose.

The manually operated valve 8 is biased to automatically return to a first position in which flow to and from the

DK 2019 70104 A1 10 hydraulic actuator 6 via the main conduit 10 is prevented. Thus, the tipper body 3 is kept in position when the manually operated valve is in its first position. A handle 18 is operably connected to the manually operated valve 8. The handle 18 can be electronically connected to the manually operated valve 8 via an electric signal line, as shown in Fig. 2, but it is understood that the handle 18 could also be pneumatically, hydraulically or mechanically connected to the manually operated valve 8.

An operator can move the manually operated valve 8 by operation of a handle 18 into a second position or into a third position. In the second position of the manually operated valve 18 the outlet of the hydraulic pump 9 is connected to the hydraulic cylinder 6 via the main conduit

10. In this position flow of pressurized hydraulic medium from the pump 9 to the hydraulic cylinder 6 will raise the tipper body 3.

In the third position of the manually operated valve 8 the hydraulic cylinder 6 is connected to the tank 7 via the main conduit 10 and via the tank conduit 17. In the third position load on the hydraulic cylinder 6 will cause the drive medium in the cylinder 6 to flow to tank. This process is driven by the weight of the tipper body 3 on the hydraulic cylinder 6. A quick coupling 15 in the main conduit 10 allows the hydraulic system to be coupled and decoupled when the trailer 5 is connected and disconnected from the tractor 4.

DK 2019 70104 A1 11 A drain conduit 12 connects the main conduit 10 to the tank

7. A control valve 13 in the drain conduit 12 controls the flow through the drain conduit 12. In an embodiment the control valve 13 has two positions; an open position and a closed position. In an embodiment the control valve 13 is biased to the closed position. In Fig. 2 the control valve 13 is shown in its closed position, i.e. in the position that the control valve 13 has when the pressure in the main conduit is above the first pressure threshold Pl.

A pressure sensor 11 is connected to the main conduit 10 and issues a signal indicative of the pressure in the hydraulic medium in the main conduit 10.

The electronic hydraulic control system comprises a controller in the form of an electronic control unit 50. The electronic control unit 50 is in receipt of the signal from the pressure sensor 11 and the electronic control unit 50 controls the operation of the control valve 13.

In an embodiment, the electronic control unit 50 is also in receipt of a signal from the handle 18 or from the manually operated valve 8, that informs the electronic control unit 50 of the position of the manually operated valve 8.

In embodiment the electronic control unit 50 is connected to a further number of sensors and components, as described in more detail further below.

The electronic control unit 50 instructs the control valve 13 to move to its open position when the signal of the pressure

DK 2019 70104 A1 12 sensor 11 indicates that the pressure the hydraulic medium in the main conduit 10 is below a first threshold Pl. The first threshold Pl is a pressure that is slightly below the pressure that is required to move the tipper body 3 upwards when the tipper body is empty, i.e. free of any load. In an embodiment, it is a further requirement that a handbrake signal indicates that the handbrake of the vehicle is released before the electronic control unit 50 issue a signal to the control valve 13 to move to its open position. Thus, in the latter embodiment the control valve 13 is not moved to its open position when the above conditions apply but the handbrake signal indicates that the handbrake is on.

The electronic control unit 50 instructs the control valve 13 to move to its closed position when the signal of the pressure sensor indicates that the pressure in the hydraulic medium in the main conduit 10 is above a third pressure P3. The third pressure threshold P3 can be equal to the first pressure threshold Pl or be slightly higher than the first pressure threshold Pl. Thus, it is ensured that the tipper body 3 will always return to the its lowermost position with the hydraulic cylinder 6 completely depressurized, even if an operator ends the lowering procedure prematurely or when the tipper body 3inadvertently does not reach its lowermost position. Further, it is ensured that the hydraulic cylinder 6 is drained continuously when the vehicle is being driven, so

DK 2019 70104 A1 13 that pressure that may occur in the hydraulic cylinder 6 due to e.g. temperature fluctuations, movements of the construction or leakage from the manually operated valve 8 is removed.

The resistance to flow for the hydraulic medium from the main conduit 10 to tank through the drain conduit 12 is significantly larger than the resistance to flow for the drive medium from the manually operated valve 8 through the main conduit 10 to the hydraulic cylinder 6. This difference in flow resistance can e.g. be obtained by the drain conduit 12 having a lesser cross sectional area than the main conduit 10, or by a dedicated flow resistance 16 in conduit 12 or by the control valve 13 having a flow resistance in its open position that provides the required lower resistance.

Thus, it is ensured that the pressure buildup in the main conduit 10 quickly exceeds the first pressure threshold Pl, whereupon the controller 50 closes the control valve 13 and prevents a further draining of hydraulic medium through the drain conduit 12 to the tank 7. Thus, there will be a minimum loss of hydraulic medium through the drain conduit 12 during the initial phase of a lift operation.

In an embodiment the electronic control unit 50 is connected to a handbrake sensor 20 that issues a signal representative of the handbrake of the wheeled vehicle 1 being on or off. In this embodiment, the electronic control unit is configured to issue an alarm when the handbrake signal indicates that the handbrake is off and the pressure signal indicates that

DK 2019 70104 A1 14 simultaneously the pressure in the main conduit 10 is above a second pressure threshold P2 or above the second pressure.

The second pressure threshold P2 can be equal to the first pressure threshold Pl or be higher than first thresher pressure Pl.

In an embodiment, it is further required that the wheeled vehicle 1 in a state where the ignition is on in order to issue an alarm.

In an embodiment, the electronic control unit 50 is configured to prevent driving the wheeled vehicle when the alarm is issued, or after a given time span after the alarm is issued on the basis of the handbrake being off.

This combination of conditions ensures that an alarm is issued, or driving of the wheeled vehicle 1 is prevented, when the tipper body 3 is not in its fully lowered position.

In an embodiment the electronic control unit 50 is connected to a speed sensor 21 that issues a speed signal representative of the speed of the wheeled vehicle 1. In this embodiment, the electronic control unit is configured to issue an alarm when the speed signal indicates that the vehicle speed is above a speed threshold and simultaneously the pressure signal indicates that the pressure in the main conduit 10 is above a second pressure threshold P2. The second pressure threshold P2 can be equal to the first pressure threshold Pl or be higher than the first pressure threshold Pl.

DK 2019 70104 A1 15 The speed threshold is e.g. a few kilometers per hour, preferably 12 km/h, more preferably 8 km/h, even more preferably 6 km/h and most preferably 4 km/h. in an embodiment the electronic control unit 50 is configured to slow down the wheeled vehicle 1 to a halt when an alarm is issued on the basis of the vehicle speed. This combination of conditions ensures that an alarm is issued or driving of the wheeled vehicle 1 is prevented when the tipper body 3 is not in its fully lowered position. Thus, driving with a raised tipper body is prevented by an alarm or by the controller 50 bring the wheeled vehicle to a stop. The control valve 13 is configured such that it is in its closed position when it does not receive any electrical power and is in its open position when it is electrically powered. The pressure sensor 11 is in an embodiment a pressure indicator that it provides a pressure signal only when the measured pressure is below a set pressure. In an embodiment the indicator issues no pressure signal when the measured pressure is below the set pressure and the indicator issues a pressure signal when the measured pressure is above the set pressure.

The set pressure corresponds to the first pressure threshold Pl and the pressure threshold Pl is selected to be slightly below the pressure that is required to obtain lift for the tipper body 3. The pressure required to attend if the tipper body 3 can either be calculated, simulated or tested.

DK 2019 70104 A1 16 In an embodiment, and alarm can be delayed by an operator pressing a button within a given time span.

In embodiment an alarm can be suppressed to a lower sound level or less intrusive optical signal by an operator pressing a button within a given time span.

Alarms can be issued in the form of sounds or indicators or light signals or a combination thereof.

Alarms can be graded, starting off with a lower alarm level increasing to higher alarm levels.

Fig. 3 shows another embodiment of a wheeled vehicle 1, in the form of a dump truck.

In this embodiment, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are denoted by the same reference numeral as previously used for simplicity.

The embodiment of Fig. 3 1s essentially identical to the embodiment of Fig. 1, except for the feature that the tipper body 3 is pivotally mounted to the chassis 2 of the dump truck.

Fig. 4 shows the electronic control system of the embodiment of Fig. 3, which is essentially identical to the electronic control system of Fig.2 except that there is no quick coupling in the main conduit 10, since there is no need for decoupling the hydraulic cylinder 6. In Fig. 4 the control valve 13 is shown in its closed position, i.e. in the position that the control valve 13 has when the pressure in the main conduit is above the first pressure threshold Pl.

DK 2019 70104 A1 17 In an embodiment the control valve 13 is an on/off valve In an embodiment the control valve 13 is a pneumatically controlled control valve. In an embodiment the control valve 13 is a hydraulically controlled control valve. In an embodiment the control valve 13 is an electronically controlled control valve. In an embodiment the control valve 13 is a magnetic valve. In an embodiment the control valve 13 is a drain valve.

In an embodiment the pressure sensor issues a pressure signal that is representative of the pressure level in the main conduit, and the controller 50 is configured to open said drain valve 13 when the pressure signal indicates that the pressure in said main conduit is above the first pressure threshold Pl.

Fig. 5 shows another embodiment of the control system of the wheeled vehicle shown in Fig. 1 In this embodiment, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are denoted by the same reference numeral as previously used for simplicity.

The embodiment of Fig. 5 is essentially identical to the embodiment of Figs. 1 and 2, except for the feature that the control valve 13 is a hydraulically controlled pressure release valve. In this embodiment the hydraulic pressure in the main conduit 10 is communicated via a hydraulic signal conduit 22 either directly or as shown via the drain conduit 12 to the control valve 13. The control valve 13 moves to its

DK 2019 70104 A1 18 closed position under influence of the pressure in the main conduit 10 against the bias of a spring 23 that urges the control valve 13 to its open position. The balance between these two forces is selected such that the control valve 13 moves to its open position when the pressure in the main conduit is below the first pressure threshold Pl and moves to its closed position when the pressure in the main conduit is above the first pressure threshold Pl. In an embodiment a switch or sensor 24 associated with the hydraulically controlled valve 13 sends a signal to controller 50 with information on the position of the control valve 13. In Fig. 5 the control valve 13 is shown in its open position, i.e. the position that control valve 13 has when the pressure in main conduit 10 is below the first pressure threshold Pl.

In an embodiment the drain conduit 12 is directly connected said main conduit 10 said tank 7. In an embodiment the hydraulic medium is hydraulic oil.

In an embodiment the controller operates hydraulically, pneumatically, and/or electronically. The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does notexclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope.

Claims

DK 2019 70104 A1 20 CLAIMS

1. A wheeled vehicle (1) comprising: a chassis mounted tipper body (3), a hydraulic cylinder (6) operably arranged between said chassis (2) and said tipper body (3), a tank for a hydraulic medium (7), a manually operated valve (8), a hydraulic pump (9) connected with an inlet fluidically connected to said tank (7) and with an outlet fluidically connected to said manually operated valve (8), a main conduit (10) fluidically connecting said manually operated valve (8) to said hydraulic cylinder (6), said manually operated valve (8) having at least: a first position in which flow of hydraulic medium to and from said hydraulic cylinder (6) is prevented, a second position in which flow from said hydraulic pump (9) to said hydraulic cylinder (6) is enabled, a third position which flow from said hydraulic cylinder (6) to said tank (7) is enabled, a pressure sensor (11) configured to issue a pressure signal indicative of the pressure in said main conduit (10), a drain conduit (12) fluidically connecting said main conduit (10) said tank (7), a control valve (13) controlling flow through said drain conduit (12), a controller (50) in receipt of said pressure signal and operably connected to said control valve (13),

DK 2019 70104 A1 21 said controller (50) being configured to move said control valve (13) to an open position when said pressure signal indicates that the pressure in said main conduit (10) is below a first pressure threshold Pl.

2. A vehicle according to claim 1, wherein said manually operated valve (8) is configured to automatically return to said first position

3. A wheeled vehicle (1) according to claim 1 or 2, wherein said main conduit (10) comprises a coupling (15), preferably a quick coupling.

4. A wheeled vehicle (1) according to any one of claims 1 to 3, wherein said wheeled vehicle (1) comprises a trailer (5) and a tractor (4), with said tipper body (3) mounted on the chassis (2) of said trailer (5) and with said hydraulic cylinder (6) being arranged between the chassis (2) of said trailer (5) and said tipper body (3).

5. A wheeled vehicle (1) according to any one of claims 1 to 4, wherein said controller (50) is in receipt of a handbrake signal indicative of a handbrake of said wheeled vehicle (1) being on or off, said controller (50) being configured to issue an alarm when said pressure signal indicates that the hydraulic pressure in said main conduit (10) is above a second pressure threshold P2, and said handbrake signal simultaneously indicates that said handbrake is off.

6. A wheeled vehicle (1) according to any one of claims 1 to 4, wherein said controller (50) is in receipt of a vehicle

DK 2019 70104 A1 22 speed signal indicative of the speed of said wheeled vehicle (1), said controller (50) being configured to issue an alarm when said pressure signal indicates that the hydraulic pressure in said main conduit (10) is above a given threshold P2, and said speed signal indicates simultaneously that the speed of said wheeled vehicle (1) is above a given speed threshold V1.

7. A wheeled vehicle (1) according to any one of claims 1 to 6, wherein said hydraulic cylinder (6) is a single acting hydraulic linear actuator.

8. A wheeled vehicle (1) according to any one of claims 1 to 6, wherein the flow resistance for flow of hydraulic medium from said main conduit (10) to said tank (7) when said control valve (13) is open is lower than the flow resistance from said manually operated valve (8) through said main conduit (10) to said hydraulic cylinder (6).

9. A wheeled vehicle (1) according to any one of claims 1 to 8, wherein said controller (50) is configured to close said control valve (13) when the pressure signal indicates that the pressure in said main conduit (10) is above a third pressure threshold P3.

10. A wheeled vehicle (1) according to any one of claims 1 to 9, further comprising a handbrake sensor (20) that issues a signal indicating of a vehicle handbrake being on or off, wherein said controller (50) is configured to open said control valve (13) on the further condition that the handbrake sensor indicates that the vehicle handbrake is off.