CN206127838U - Make level instrument and have its paver - Google Patents

Abstract

The utility model provides a make level instrument and have its paver, the instrument of making level includes: rotary angle transmitter, the sensing arm, the first end and the rotary angle transmitter of sensing arm are connected, and the second end of sensing arm rotationally sets up around its first end, wherein, rotary angle transmitter is connected the turned angle in order to detect the sensing arm with the sensing arm to confirm the lift height of the second end of sensing arm for rotary angle transmitter according to turned angle. The utility model provides a problem that paver among the prior art is difficult to to guarantee the planarization on the road surface that paves has been solved to the instrument of making level.

Description

Levelling instrument and the paver with which

Technical field

This utility model is related to pavement construction field, in particular to a kind of levelling instrument and the paver with which.

Background technology

With the raising of human living standard, driving by bus to go on a journey has become indispensable during people live one Point, and the quality of highway is also serious has had influence on trip quality.

When being paved using paver road pavement, as the hollow on former road surface rises and falls, pure mechanical execution cannot Ensure the smooth of roadbed, be the planarization that cannot ensure road surface direction of advance entirely with human eye and workmen's working experience, this is just Needs improve the operating accuracy of paver by complementary electronic machine during construction.

Utility model content

Main purpose of the present utility model is to provide a kind of levelling instrument and the paver with which, to solve existing skill Paver in art is difficult to ensure that the problem of the planarization on the road surface for paving.

To achieve these goals, according to one side of the present utility model, there is provided a kind of levelling instrument, including：Turn Angle transducer；Pickup arm, the first end of pickup arm are connected with rotary angle transmitter, and the second end of pickup arm is rotatable around its first end Ground is arranged；Wherein, rotary angle transmitter is connected with pickup arm to detect the rotational angle of pickup arm, and determines biography according to rotational angle Adjustable height of second end of sense arm relative to rotary angle transmitter.

Further, levelling instrument also includes：Find part accurately, find part accurately and be connected with the second end of pickup arm, finding part accurately is used for It is placed in reference body.

Further, part is found accurately to sense piston shoes, reference body is curb or the road surface for having paved.

Further, part is found accurately for sensing slide bar, rope on the basis of reference body.

Further, rotary angle transmitter includes：Potentiometer, pickup arm are connected with the rotating shaft transmission of potentiometer with band electrokinetic potential The axis of rotation of device.

Further, rotary angle transmitter also includes：Housing；Power transmission shaft, power transmission shaft are rotationally located on housing, transmission Axle is connected with the rotating shaft transmission of potentiometer, and pickup arm is connected with power transmission shaft.

Further, the first drive is provided with power transmission shaft, in the rotating shaft of potentiometer, is provided with the second drive, first Drive and the second drive are connected by transmission belt.

Further, there is location division on the body of rod positioned at hull outside of power transmission shaft, is provided with pickup arm and positioning The location hole that portion is adapted.

Further, power transmission shaft is cylinder, and end of the location division for cylinder, the outer peripheral face of location division are provided with positioning Tangent plane.

According to another aspect of the present utility model, there is provided a kind of paver, including fuselage, fuselage includes above-mentioned levelling Instrument, levelling instrument are arranged on fuselage.

Further, screed is provided with fuselage, the two ends of screed are provided with levelling instrument.

Further, paver also includes：Control device, is connected with the rotary angle transmitter signal of levelling instrument, for obtaining The adjustable height at the second end of the pickup arm of the levelling instrument of rotary angle transmitter determination is taken, and road surface is determined according to adjustable height Concavo-convex change.

Further, paver is also included for controlling the levelling oil cylinder that its screed is moved, control device and levelling oil Cylinder communication connection, and the flexible of levelling oil cylinder is controlled according to the concavo-convex change on road surface.

Levelling instrument in this utility model includes rotary angle transmitter and pickup arm, as pickup arm is connected with rotary angle transmitter Connect, so, when pickup arm is rotated, rotary angle transmitter just can detect the rotational angle of pickup arm, and then can be passed The height that second end of sense arm is risen or fallen relative to rotary angle transmitter.On this basis, the levelling instrument is arranged on into stand The concavo-convex change on road surface on paving machine, just can be detected, the levelling of road pavement is realized, so as to solve paver of the prior art It is difficult to ensure that the problem of the planarization on the road surface for paving.

Description of the drawings

The Figure of description for constituting the part of the application is used for providing further understanding to of the present utility model, this practicality New schematic description and description is used to explain this utility model, does not constitute to improper restriction of the present utility model. In the accompanying drawings：

Fig. 1 shows the structural representation of the embodiment according to levelling instrument of the present utility model；

Fig. 2 shows the structural representation of the rotary angle transmitter of the levelling instrument in Fig. 1；

Fig. 3 shows the structural representation that the pickup arm of the levelling instrument in Fig. 1 is connected with sensing piston shoes；

Fig. 4 shows the structural representation that the pickup arm of the levelling instrument in Fig. 1 is connected with sensing slide bar；And

Fig. 5 shows the structural representation of the embodiment according to paver of the present utility model.

Wherein, above-mentioned accompanying drawing includes the following drawings labelling：

10th, rotary angle transmitter；11st, housing；12nd, potentiometer；121st, rotating shaft；13rd, power transmission shaft；131st, position tangent plane；14th, One drive；15th, the second drive；16th, transmission belt；20th, pickup arm；30th, find part accurately；40th, curb；50th, screed；60、 Levelling oil cylinder；70th, large arm.

Specific embodiment

It should be noted that in the case where not conflicting, the feature in embodiment and embodiment in the application can phase Mutually combine.Below with reference to the accompanying drawings and in conjunction with the embodiments describing this utility model in detail.

This utility model provides a kind of levelling instrument, refer to Fig. 1 to Fig. 5, and the levelling instrument includes：Rotary angle transmitter 10；Pickup arm 20, the first end of pickup arm 20 are connected with rotary angle transmitter 10, and the second end of pickup arm 20 can turn around its first end Arrange dynamicly；Wherein, rotary angle transmitter 10 is connected with pickup arm 20 to detect the rotational angle of pickup arm 20, and according to angle of rotation Degree determines the adjustable height of second end relative to rotary angle transmitter 10 of pickup arm 20.

Levelling instrument in this utility model includes rotary angle transmitter 10 and pickup arm 20, as pickup arm 20 is passed with corner Sensor 10 connects, and so, when pickup arm 20 is rotated, rotary angle transmitter 10 just can detect the rotational angle of pickup arm 20, And then the height that the second end of pickup arm 20 is risen or fallen relative to rotary angle transmitter 10 can be obtained.On this basis, will The levelling instrument is arranged on paver, just can be detected the concavo-convex change on road surface, be realized the levelling of road pavement, so as to solve Paver of the prior art is difficult to ensure that the problem of the planarization on the road surface for paving.

In the present embodiment, shown as shown in Figure 1, Figure 3 and Figure 4, levelling instrument also includes：Find part 30 accurately, find part 30 accurately and pass The second end connection of sense arm 20, finds part 30 accurately for being placed on reference body.The present embodiment finds part 30 accurately by arranging, and makes which It is connected with the second end of pickup arm 20, a benchmark can be found to the second end of the pickup arm 20, and then be conducive to detecting The concavo-convex change on road surface.Second end of pickup arm 20 herein as turns relative to the height that rotary angle transmitter 10 rises or falls The flying height of angle transducer 10.

As an embodiment of the present embodiment, as shown in figures 1 and 3, part 30 is found accurately to sense piston shoes, reference body is Curb 40 or the road surface for having paved.

Used as the another embodiment of the present embodiment, as shown in figure 4, finding part 30 accurately to sense slide bar, reference body is base Criterion.

Different according to paver working environment in the course of the work, the instrument (levelling instrument) has three kinds of mode of operations, These three patterns are, by rotary angle transmitter 10 and pickup arm 20, to sense slide bar, sense different groups before piston shoes three respectively Close to coordinate what is completed.Both compound modes are separately in three kinds of mode of operations of instrument, and these three patterns are road surfaces Pattern, curb pattern and criterion pattern.

Lower mask body introduces these three patterns：

(1) road surface pattern

This model application is when several road surfaces pave simultaneously.Although the screed length maximum of paver can be covered The width of roadway that 12 meters of lid, but due to the effect of gravity, the screed of paver can be put on the basis of paver itself to Both sides stay, more more serious to two ends, and this road surface that this may result in paving out is laterally arch rather than flat.Cause This, when several road surfaces need to pave, generally uses two pavers one in front and one in back, and left and right cooperation of staggering paves Form completing, to mitigate the road surface transversely deforming caused because screed is stayed.

As the bottom surface of screed is flat, so it is flat that we have been generally acknowledged which spreads out the road surface do not rolled come 's.Screed is flat, so the road surface directly got off out from screed is also flat, but as road surface now is empty , rather than be compacted, so after road roller rolls compacting, the depression or projection of roadbed originally will show Come, levelling purpose is exactly in order in many stones of recess, in high spot, stone is levelling after being compacted to realize less.

Now, pickup arm can be connected to rotary angle transmitter up, sensing piston shoes is connected to into other one section of pickup arm Up, the direction that one end for tilting is advanced towards paver on piston shoes is sensed, is placed into the uncompacted road surface that paved and gets on work Make, this pattern becomes road surface pattern.

(2) curb pattern

When being commonly used to single paver work, such as cell street, middle is asphalt roads, and there is curb on both sides Stone, the above is square brick path, and paving for bituminous paving is generally all that laying is completed in square brick path, curb lay after Start.

When curb is laid, workman can be laid on the basis of the datum line for determining, and so spread in curb If after good, it is believed that curb face is level, smooth.On the basis of curb, face is using instrument.Equally it is sensing Arm and sensing piston shoes are installed as the method previously described, and are placed into curb up, and the front end for sensing piston shoes tilts part court To the direction of advance of paver, this is curb pattern.

(3) criterion pattern

When single paver work is applied to, such as some township roads, national highway are not lay curb, The both sides of road is exactly directly turf or gutter, now, it is necessary to using criterion pattern.Workmen along need paving If road direction of advance, in the both sides of road, establish datum level with leveling device, plug the steel of setting every several meters on ground Muscle, and the datum level confirmed according to leveling device helps rope on reinforcing bar, tightens, and paves in this, as datum level Road.

When in use, pickup arm is still installed on rotary angle transmitter according to above-mentioned method, the other end of pickup arm, connection Sensing slide bar, slide bar is taken on rope, the direction of advance of the direction transverse horizontal of slide bar perpendicular to paver, and this is criterion mould Formula.

The concrete structure of the rotary angle transmitter 10 in the present embodiment is, as shown in Fig. 2 rotary angle transmitter 10 includes：Current potential Device 12, pickup arm 20 are connected to drive the axis of rotation of potentiometer 12 with the rotating shaft transmission of potentiometer 12.So, by band galvanic electricity Position device 12 is rotated, and just mechanical signal can be converted into the signal of telecommunication, is easy to the detection of the concavo-convex situation of road pavement.

In the present embodiment, as shown in Fig. 2 rotary angle transmitter 10 also includes：Housing 11；Power transmission shaft 13, power transmission shaft 13 can Rotationally it is located on housing 11, power transmission shaft 13 is connected with the rotating shaft 121 of potentiometer 12, and pickup arm 20 is connected with power transmission shaft 13 Connect.The power transmission shaft 13 is arranged on the housing 11 by bearing.

In order to realize the transmission between power transmission shaft 13 and potentiometer 12, as shown in Fig. 2 the first biography is provided with power transmission shaft 13 Driving wheel 14, is provided with the second drive 15 in the rotating shaft 121 of potentiometer 12, the first drive 14 and the second drive 15 are by passing Dynamic band 16 connects.Preferably, the first drive 14 and the second drive 15 are gear, and transmission belt 16 is toothed transmission belt.

Central module of the rotary angle transmitter in the levelling instrument for instrument, contains mechanical transducing part, signal and receives Circuit, amplifying circuit, counting circuit, change-over circuit and output circuit.

Its mechanical transducing part is configured to：A piece power transmission shaft has run through the whole shell of instrument, is fixed by two bearing blocks On tool housing, it is possible to free to rotate, in power transmission shaft on the part of enclosure, there is the biography of a steel Moving gear jackscrew is fixed on power transmission shaft, and belt, the gear on the other end of belt and the rotating shaft of potentiometer are cased with gear Connection, the potentiometer is fixed on inside the shell, in the rotating shaft that gear jackscrew is fixed.Thus, the rotation of axle can just drive fixation Pinion rotation thereon, gear driven belt are rotated, the pinion rotation on belt drive potentiometer, then drive potentiometer to rotate, So as to mechanical action is become the signal of telecommunication.

After mechanical action is converted into the signal of telecommunication, signal is received by receiving circuit, signal is amplified by amplifying circuit, Counting circuit calculates output size, then has change-over circuit that the analogue signal of generation is converted into digital signal, by rotation angular sensing Connection cable between device and paver, is delivered to output in machine controller with the communication modes of CAN bus, control machine The action of the levelling oil cylinder of device, it is levelling so as to reach control machine, it is that road surface tends to smooth purpose.

In order to realize the connection between power transmission shaft 13 and pickup arm 20, as shown in figure 1, power transmission shaft 13 outside housing 11 There is on the body of rod of side location division, the location hole being adapted with location division on pickup arm 20, is provided with.

Specifically, power transmission shaft 13 is cylinder, and end of the location division for cylinder, the outer peripheral face of location division are provided with positioning Tangent plane 131.Positioning tangent plane 131 is arranged by the outer peripheral face in location division, it is ensured that between power transmission shaft 13 and pickup arm 20 Bonding strength.

It can be seen that, extended outside shell respectively through the two ends of the power transmission shaft of the shell of rotary angle transmitter, and stretch out Part have respectively a plane, i.e. axle the part for being in instrument internal be it is round, but the part stretched out is not complete circle, But circle scarce shape, the planar section that two circles lack be common point in a big plane, this point can be from Fig. 3 and Tu Find out in 5.

The present embodiment arranges positioning tangent plane 131 and has following purpose：

First, although rotary angle transmitter itself can determine new zero-bit (zero-bit i.e. zero by the controller on machine Point position, at this position, sensor itself is without any output), but instrument itself is also have a zero-bit of itself, This zero-bit designs, after instrument production is finished it is confirmed that.

After client takes instrument, instrument is placed on horizontal plane, makes two circles of axle lack plane dorsad instrument work When paver direction of advance, and make the scarce plane of circle perpendicular to horizontal plane, be at this moment exactly instrument dead-center position itself.Confirm this zero The purpose of point position is, because when instrument is in itself dead-center position, instrument is to be in its own height that can be measured in itself On the centre position of degree, the surveying range farthest using sensor is ensure that.

In addition, in follow-up description, because the use of pickup arm can be related to, the confirmation of this zero-bit is also to pickup arm Use cause tremendous influence, can describe in detail when subsequent descriptions pickup arm use.

Second, as rotary angle transmitter needs to coordinate pickup arm to use, pickup arm is directly to the two ends of power transmission shaft , respectively there is a hole at pickup arm two ends, and for being connected with power transmission shaft, the hole of this position is and transmission in one of hole The shape that axle two terminal circle lacks is on all four, and size is fitted close, and makes power transmission shaft be closely linked with pickup arm, and The circle of pickup arm lacks the circle in the hole of shape and lacks plane side, has jackscrew completely through to inside hole, for holding out against axial plane, makes biography It is even closer that moving axis and pickup arm are combined, and the height change on ground is accurately delivered in sensor.

This utility model additionally provides a kind of paver, as shown in figure 5, levelling instrument including fuselage including above-mentioned, looks for Level device is arranged on fuselage.Paver in this utility model can detect the concavo-convex change on road surface, realize road pavement It is levelling.

In the present embodiment, screed 50 is provided with fuselage, the two ends of screed 50 are provided with levelling instrument.

In order to determine the concavo-convex change on road surface, paver also includes：Control device, the rotary angle transmitter 10 with levelling instrument Signal connects, for obtaining the adjustable height at the second end of the pickup arm 20 of the levelling instrument of the determination of rotary angle transmitter 10, and root The concavo-convex change on road surface is determined according to adjustable height.

In order to ensure the planarizing on road surface, paver is also included for controlling the levelling oil cylinder 60 that its screed 50 is moved, Control device is connected with the communication of levelling oil cylinder 60, and controls the flexible of levelling oil cylinder 60 according to the concavo-convex change on road surface.So, look for Flat oil cylinder 60 can drive large arm 70 to move, and then make large arm 70 drive screed 50 to move.

Asphaltene is mainly spread out by screed and is flattened on road surface by paver in the course of the work, screed It is out of gear mesh with the fuselage of paver, is only that fuselage is connected to by lift cylinder and levelling oil cylinder by the large arm of screed On.

In the course of the work, lift cylinder is locked, and is not controlled by leveling unit, and floating cylinder is to float , the upper and lower action of large arm is driven by the control to floating cylinder, so as to drive the upper and lower action of screed.

The application is related to a kind of levelling instrument in longitudinal direction for sub-base grader, and the levelling instrument in longitudinal direction contains corner biography Sensor, pickup arm, sensing litter, sensing piston shoes and the cable for connecting are each one.

During use, the rotary angle transmitter cable in instrument is connected to paver, and using in corner biography At the top of sensor hold out against firmware be fixed on paver screed two ends (one end is one set of instrument, and two ends need two sets, The two ends of paver screed need to be separately controlled).

The support for retainer instrument at the screed two ends of paver is that screed two ends are got well and be arranged on to designed in advance, As shown in figure 5, rotary angle transmitter is seated on the two ends montant support of the screed of paver.There are handss above the support Dynamic bolt bar, when swing handle, support can drive instrument to move up and down, for conditioning instrumentation zero-bit.

When machine runs into projection or depression, rising or reduction that fuselage can be relative, the at this time biography of instrument Sense piston shoes or sensing slide bar can decline accordingly or rise, and drive pickup arm corresponding downward or rotate up, so as to Signal is produced to controller to control the levelling oil cylinder of paver downwards or be lifted up, levelling oil cylinder drive large arm downwards or Person moves up.

Be connected between screed and large arm 70 instrument and it is relative can with activity, be have one below screed Little unfilled corner, asphaltene is clamp-oned below screed from below this little unfilled corner.When large arm 70 is moved downwards or upwards When making, the little unfilled corner end of screed will be driven downward or action upwards, and then make to clamp-on the asphaltene below screed Tail off or become many, screed will be driven logical accordingly because on boring shoulder or increasing and downwards or moving up Cross montant support to be installed to the instrument at screed two ends downwards or move up, so as to balance out machine itself because projection or The upwardly or downwardly produced range difference that person is recessed and produces, makes machine in the few stone in raised position, in the position of depression Many stones, reach the later smooth purpose of compacting.

As instrument is suspended from machine screed two ends in itself, when paver runs into projection or depression, Paver can accordingly upwardly or downwardly, instrument because the drive of sensing piston shoes or sensing slide bar produce accordingly downwards or Person's action upwards, and then downward or output upwards is have issued, controller is produced and instrument output for the levelling oil cylinder of control The action of equidirectional, so as to screed is also generated and outbound course identical action.

After the impact of the height change that the action that screed is completely counterbalanced by machine is produced, instrument itself can be also driven to produce To balance out because of pickup arm and sensing piston shoes or sensing slide bar, height changes the corresponding action of life downwards or upwards, makes instrument Recover initial zero point state, so as to form a ring-closure reaction, reach complete control purpose.

In specific work process, no matter using which kind of pattern, operation principle and the process of instrument are consistent.

Already discussed above, instrument itself has a zero-bit state.Dorsad spread out when the circle of its power transmission shaft lacks plane The direction of advance of paving machine, and perpendicular to horizontal plane when, just reached instrument zero-bit.And on the pickup arm of instrument There is a hole for lacking shape with instrument power transmission shaft identical circle, the two is closely combined, preferably ground level is become Change is delivered in instrument.

According to the description of forward part, it can be seen that pickup arm is that rotation back and forth is put centered on power transmission shaft, but this Individual rotation is not 360 deg infinite rotational, but has a scope, when pickup arm is fully horizontal or substantially vertical Wait, just reach its limit.

Description according to forward part can be obtained, and when pickup arm level, instrument will touch ground, make sensing Arm does not have interval again upwards, and when pickup arm reaches vertical, is further continued for upwards, will be by sensing piston shoes or sensing Slide bar is lifted completely, in fact departing from datum level, loses levelling meaning, that is to say, that the range of activity of pickup arm is exactly 90 degree.

If setting up plane right-angle coordinate by co-ordinate zero point of the power transmission shaft of instrument, it is what paver advanced that x-axis is positive Direction, it is vertically forward direction perpendicular to paver direction of advance upwards that y-axis is, then the range of activity of pickup arm is exactly coordinate axess 90 degree of scopes of third quadrant.According to aforementioned, there is the plane of the scarce shape of circle at power transmission shaft two ends, and also have what is run through on pickup arm Jackscrew holds out against round scarce face, but or the hole for having the scarce shape of circle on pickup arm is because working as scarce with two circles for positioning, just After the position of fixed conveyor axle and pickup arm, when instrument is in itself zero-bit, pickup arm is just in third quadrant The position of angle separated time, it is ensured that rotation distance when which can rotate upwardly and downwardly extreme position be it is the same, more accurately Ensure the measurement range of instrument.

The transmission signal of the instrument in this programme uses the digital signal of CAN communication, more accurately can transmit Data, facilitate the maintenance conditions of instrument, more can guarantee that the accuracy of construction detection.

Preferred embodiment of the present utility model is the foregoing is only, this utility model is not limited to, for this For the technical staff in field, this utility model can have various modifications and variations.It is all it is of the present utility model spirit and principle Within, any modification, equivalent substitution and improvements made etc. are should be included within protection domain of the present utility model.

Claims (13)

1. a kind of levelling instrument, it is characterised in that include：

Rotary angle transmitter (10)；

Pickup arm (20), the first end of the pickup arm (20) are connected with the rotary angle transmitter (10), the pickup arm (20) The second end around its first end rotatably arranged with；

Wherein, the rotary angle transmitter (10) is connected to detect the angle of rotation of the pickup arm (20) with the pickup arm (20) Degree, and the lifting of second end relative to the rotary angle transmitter (10) of the pickup arm (20) is determined according to the rotational angle Highly.

2. levelling instrument according to claim 1, it is characterised in that the levelling instrument also includes：

Find part (30) accurately, the part (30) of finding accurately is connected with the second end of the pickup arm (20), and the part (30) of finding accurately is used for It is placed in reference body.

3. levelling instrument according to claim 2, it is characterised in that described to find part (30) accurately to sense piston shoes, the base Quasi- body is curb (40) or the road surface for having paved.

4. levelling instrument according to claim 2, it is characterised in that described to find part (30) accurately to sense slide bar, the base Restrict on the basis of quasi- body.

5. levelling instrument according to claim 2, it is characterised in that the rotary angle transmitter (10) includes：

Potentiometer (12), the pickup arm (20) are connected to drive the potentiometer with the rotating shaft transmission of the potentiometer (12) (12) axis of rotation.

6. levelling instrument according to claim 5, it is characterised in that the rotary angle transmitter (10) also includes：

Housing (11)；

Power transmission shaft (13), the power transmission shaft (13) are rotationally located on the housing (11), the power transmission shaft (13) and institute The rotating shaft (121) for stating potentiometer (12) is connected, and the pickup arm (20) is connected with the power transmission shaft (13).

7. levelling instrument according to claim 6, it is characterised in that be provided with the first drive on the power transmission shaft (13) (14), it is provided with the second drive (15) in the rotating shaft (121) of the potentiometer (12), first drive (14) and described Second drive (15) is connected by transmission belt (16).

8. levelling instrument according to claim 6, it is characterised in that the power transmission shaft (13) positioned at the housing (11) There is on the body of rod in outside location division, the location hole being adapted with the location division is provided with the pickup arm (20).

9. levelling instrument according to claim 8, it is characterised in that the power transmission shaft (13) is cylinder, the positioning Portion is the end of the cylinder, and the outer peripheral face of the location division is provided with positioning tangent plane (131).

10. a kind of paver, including fuselage, it is characterised in that including the levelling instrument any one of claim 1 to 9, The levelling instrument is arranged on the fuselage.

11. pavers according to claim 10, it is characterised in that screed (50) is provided with the fuselage, it is described The two ends of screed (50) are provided with the levelling instrument.

12. pavers according to claim 10, it is characterised in that the paver also includes：

Control device, is connected with rotary angle transmitter (10) signal of the levelling instrument, for obtaining the rotary angle transmitter (10) adjustable height at the second end of the pickup arm (20) of the described levelling instrument for determining, and road is determined according to the adjustable height The concavo-convex change in face.

13. pavers according to claim 12, it is characterised in that the paver is also included for controlling its screed (50) the levelling oil cylinder (60) for moving, the control device are connected with levelling oil cylinder (60) communication, and according to the road surface Concavo-convex change control the flexible of the levelling oil cylinder (60).