JP2016074326A - Working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working vehicle in which the unintended postural change of a ladder mechanism is prevented.SOLUTION: A working vehicle comprises: a lower moving body; an upper working body; a ladder mechanism capable of changing a posture to either storage or lifting; a piston rod 114 capable of changing the posture to either locking or nonlocking; a tank 122 compressing and storing a fluid; and an actuator changing the postures of the ladder mechanism and the piston rod 114 using the fluid stored in the tank 122. The actuator comprises: a positioning cylinder 111 changing the posture of a lock member by supply of the fluid; an oscillation cylinder 101 and a turning cylinder 106 changing the posture of the ladder mechanism by supply of the fluid; a valve 124 opening or closing the flow path of the fluid from the tank 122 to the cylinders 101, 106, 111; and valves 125, 126 opening or closing the flow path of the fluid from the valve 124 to the oscillation cylinder 101 and the turning cylinder 106.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a work vehicle including a ladder mechanism for an operator to access the upper work body from the ground.

  A crane vehicle, a construction machine, or the like generally has a lower traveling body and an upper working body provided on the upper traveling body. For example, an upper working body in a crane vehicle includes a boom device that performs expansion and contraction operations and a cabin that accommodates an operator who operates the boom device. Since the upper working body is disposed above the lower traveling body, the distance from the ground to the cabin is generally longer. For this reason, the ladder mechanism for an operator to access a cabin from the ground conventionally is provided (for example, refer patent document 1-patent document 2).

  FIG. 13 is a diagram showing a conventional typical ladder mechanism 1 mounted on a vehicle 2. As shown in FIG. 13, the ladder mechanism 1 includes a ladder body 3 and support pins 4 that support the ladder body 3. In general, the support pins 4 are fixed to the upper surface of the lower traveling body 5. An end portion of the ladder body 3 is rotatably supported by the support pin 4. Moreover, the intermediate part of the ladder main body 3 can be refracted through the hinge 6 (see Patent Document 1 and Patent Document 2).

Japanese Utility Model Publication No. 4-35944 Japanese Utility Model Publication No. 4-35945

  In order to change the position of the ladder mechanism 1 configured as described above between the retracted position (position stored in the vehicle 2) and the raised / lowered position (position where the operator can move up and down), the ladder body 3 is rotated around the support pin 4. An operation of moving the ladder main body 3 around the hinge 6 is required. However, since a large force is required for the operation of the ladder body 3 as described above, if the above-described operation is performed manually, a heavy burden is imposed on the operator.

  Therefore, it is conceivable to change the posture of the ladder mechanism 3 by an actuator. However, if the actuator malfunctions due to equipment trouble or the like, the ladder mechanism 1 may change its posture unintentionally, for example, the ladder mechanism 1 will be in a lifted posture while the vehicle 2 is traveling.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a work vehicle that suppresses an unintended posture change of a ladder mechanism.

  (1) A work vehicle according to the present invention includes a lower traveling body, an upper working body disposed above the lower traveling body, a retracted posture stored in the lower traveling body, and a side of the lower traveling body. A ladder mechanism that can change its posture to a lifting posture that overhangs and assists the operator to move up and down, a lock posture that restricts the posture change of the ladder mechanism, and a non-locking posture that allows the posture change of the ladder mechanism A lock member capable of changing the posture, a tank for storing fluid, and an actuator for changing the posture of the ladder mechanism and the lock member using the fluid stored in the tank. The actuator includes: a lock cylinder that changes the posture of the lock member when supplied with fluid; a step cylinder that changes the posture of the ladder mechanism when supplied with fluid; and a fluid from the tank to each cylinder. And a second valve for opening and closing a fluid flow path from the first valve to the step cylinder.

  According to the above configuration, the first valve and the second valve are provided in the flow path between the tank and the step cylinder. As a result, even if one of the first valve and the second valve fails, no fluid is supplied to the step cylinder. As a result, unintended changes in the attitude of the ladder mechanism can be suppressed.

  (2) Preferably, the lock member is attached to the ladder mechanism, protrudes from the ladder mechanism in the retracted position in the locked position and engages with the lower traveling body, and the ladder in the unlocked position. It has an engaging part that retreats toward the mechanism and is disengaged from the lower traveling body, and an urging member that urges the engaging part in a direction in which the engaging part protrudes. Then, the lock cylinder retracts the engagement portion toward the ladder mechanism against the urging force of the urging member when the fluid stored in the tank is supplied.

  According to the above configuration, while the supply of fluid from the tank is stopped, the locking member is in the locked posture by the urging force of the urging member. Thereby, compared with the case where the lock attitude | position of a lock member is maintained using power, such as fluid pressure and electric power, for example, it can suppress that a lock member becomes a non-lock attitude | position unintentionally.

  (3) Preferably, the work vehicle further includes a switch that receives an instruction of an operator who changes the posture of the ladder mechanism, and a control unit that opens and closes the first valve and the second valve. Then, the control unit opens the first valve in response to the switch receiving an instruction from an operator to change the position of the ladder mechanism to the up / down position, and the lock member is set to the unlocked position. In response to this, the second valve is opened, and the first valve and the second valve are closed in response to the ladder mechanism being in the raising / lowering posture.

  (4) Preferably, the control unit opens the first valve and the second valve in response to the switch receiving an instruction from an operator to change the ladder mechanism to the retracted position. The first valve and the second valve are closed in response to the ladder mechanism being in the retracted posture.

  As described above, the posture of the ladder mechanism is changed by supplying fluid from the tank, and the posture of the ladder mechanism is maintained by stopping supply of fluid from the tank. Thus, by not using power for maintaining the attitude of the ladder mechanism, it is possible to suppress an unintended change in attitude of the ladder mechanism.

  (5) Preferably, the work vehicle further includes a parking brake capable of changing a state to a restricted state that restricts the traveling of the lower traveling body and a released state that permits the traveling of the lower traveling body. The fluid stored in the tank is compressed air. And the said parking brake will be in the said cancellation | release state by supplying the air stored in the said tank, and will be in the said control state by stopping supply of the air stored in the said tank.

  According to the above configuration, it is possible to prevent the ladder mechanism from changing its posture when the parking brake is released. That is, an unintended change in posture of the ladder mechanism can be suppressed while the lower traveling body is traveling or when the lower traveling body is traveling.

  (6) The actuator is disposed between the first valve and the second valve, is closed by air supplied to the parking brake, and air supply to the parking brake is stopped. The work vehicle according to claim 5, further comprising a third valve opened by.

  According to the said structure, a lock cylinder and a step cylinder can be operated using the compressed air which changes a parking brake state. As a result, an increase in the number of parts of the work vehicle can be suppressed.

  According to the above configuration, since the first valve and the second valve are provided in the flow path between the tank and the step cylinder, an unintended change in the attitude of the ladder mechanism due to a failure or the like can be suppressed.

FIG. 1 is an external side view of a rough terrain crane 10 equipped with a ladder mechanism 40 according to an embodiment of the present invention. FIG. 2 is an enlarged side view of a main part of the rough terrain crane 10. FIG. 3 is a side view and a front view of the rough terrain crane 10. FIG. 4 is a perspective view of the ladder mechanism 40 in the retracted position. FIG. 5 is a perspective view of the ladder mechanism 40 in the retracted position. FIG. 6 is a perspective view of the ladder mechanism 40 in which the swing arm 56 is in an extended posture and the ladder body 70 is in a parallel posture. FIG. 7 is a perspective view of the ladder mechanism 40 in an up / down posture. FIG. 8 is an enlarged perspective view of the periphery of the connection portion between the swing arm 56 and the ladder body 70. FIG. 9 is a diagram showing the drive mechanism 100 and the pneumatic system 120. FIG. 10 is a block diagram showing each component connected to the control unit 140. FIG. 11 is a flowchart of the ladder mechanism control process. FIG. 12 is a flowchart of the notification process. FIG. 13 is a view showing a structure of a conventional typical ladder mechanism 1.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate. In addition, this Embodiment is only one aspect | mode of the ladder mechanism which concerns on this invention, and it cannot be overemphasized that an embodiment may be changed in the range which does not change the summary of this invention.

[Rough terrain crane 10]
As shown in FIG. 1, the rough terrain crane 10 according to this embodiment mainly includes a lower traveling body 20, an upper working body 30, and a ladder mechanism 40. The rough terrain crane 10 travels to the destination by the lower traveling body 20, and causes the upper working body 30 to perform a predetermined operation at the destination. The rough terrain crane 10 is an example of a work vehicle. However, a specific example of the work vehicle is not limited to this.

[Lower traveling body 20]
The lower traveling body 20 includes a front axle 22 and a rear axle 23 supported by a frame 21. The front axle 22 has a biaxial structure having two axles 24 and 25 adjacent in the front-rear direction. The rear axle 23 is a uniaxial structure having a single axle 26. Wheels 24A, 25A, and 26A are attached to the axles 24 to 26, respectively. The reason why the front axle 22 has a biaxial structure is that the axle weight of the front axle 22 is dispersed and supported by the axles 24 and 25. Therefore, when the axle weight of the front axle 22 is small, the front axle 22 may have a uniaxial structure. Further, when the axle weight of the rear axle 23 is large, the rear axle 23 may have a multiaxial structure.

  The lower traveling body 20 includes an engine 27 supported by the frame 21. The engine 27 is a drive source that generates power for driving the front axle 22 and the rear axle 23. The engine 27 is a drive source that generates power for operating the upper working body 30, a pneumatic system 120 described later, and outriggers 28 and 29 described later. The engine 27 is, for example, a diesel engine.

  The front axle 22 and the rear axle 23 rotate the axles 24 to 26 by the driving force of the engine 27 transmitted through a transmission (not shown). The hydraulic system (not shown) steers the wheels 24 </ b> A to 26 </ b> A with hydraulic oil supplied from a hydraulic pump (not shown) driven by the power of the engine 27, and the upper working body 30 and the outrigger 28. , 29 etc. are operated. Further, the generator (not shown), for example, charges the battery 12 (see FIG. 10) with electric power for operating each part of the rough terrain crane 10 when the driving force of the engine 27 is transmitted.

  The lower traveling body 20 includes outriggers 28 and 29 supported on a lower front end and a lower rear end of the frame 21. The outriggers 28 and 29 can be changed between an overhanging state in which the outriggers 28 and 29 protrude from the frame 21 in the left-right direction and a storage state in which the outriggers 28 and 29 are stored in the frame 21 while being separated from the ground. By placing the outriggers 28 and 29 in the overhanging state during the operation of the upper work body 30, the posture of the rough terrain crane 10 is stabilized. On the other hand, the outriggers 28 and 29 are in a retracted state when the lower traveling body 20 travels.

[Upper working body 30]
The upper working body 30 has a turntable 31 that can turn with respect to the frame 21. The swivel base 31 is supported by the frame 21 via the swivel bearing 11. For example, the swivel base 31 is swung on the frame 21 when a driving force is transmitted from a hydraulic motor. Moreover, the swivel base 31 supports the component of the upper working body 30 mentioned later.

  The upper working body 30 has a boom device 32 supported by a swivel base 31. The boom device 32 is connected to the swivel base 31 via a undulation center pin. The boom device 32 is raised and lowered around a undulation center pin by a undulation cylinder (not shown) provided between the boom device 32 and the swivel base 31, for example. In addition, the boom device 32 includes a telescopic boom 33. The telescopic boom 33 is expanded and contracted in the longitudinal direction of the telescopic boom 33 by, for example, a built-in telescopic cylinder (not shown). Further, the boom device 32 has a winch 34. The winch 34 raises and lowers a hook (not shown) suspended from the tip of the telescopic boom 33 when a driving force is transmitted from the hydraulic motor.

  The upper working body 30 has a cabin 35 supported by a swivel base 31. The cabin 35 is provided above the front axle 22, for example. More specifically, the cabin 35 according to the present embodiment is provided above the axle 25. Inside the cabin 35, a space for accommodating an operator who controls the operations of the lower traveling body 20 and the upper working body 30 is formed. In other words, the operator can perform an operation of traveling the lower traveling body 20 and a control of operating the upper working body 30 inside the cabin 35. Note that the cabin 35 according to the present embodiment has a box shape surrounded by a periphery, as shown in FIG. However, the specific configuration of the cabin 35 is not limited to this, and may be an open type, for example.

  Although not shown, an operation unit is provided inside the cabin 35. The operation unit of the cabin 35 includes, for example, a steering for causing the lower traveling body 20 to travel, a shift lever, an accelerator pedal, a brake pedal, an operation lever of the parking brake 36 (see FIG. 9), and the like. The operation unit of the cabin 35 includes, for example, a telescopic lever for extending and retracting the telescopic boom 33, a hoisting lever for hoisting the boom device 32, a winch lever for driving the winch 34, and the like. Furthermore, the operation part of the cabin 35 includes an upper operation switch 145, an ignition switch 146, an indicator lamp 147, and an alarm buzzer 148, as will be described later with reference to FIG.

  Further, the upper working body 30 has a counterweight 37 supported by the swivel base 31. The counterweight 37 is placed on the turntable 31 in order to stabilize the operation of the upper work body 30 including turning of the turntable 31, raising and lowering of the boom device 32, and expansion and contraction of the telescopic boom 33. .

[Ladder mechanism 40]
The ladder mechanism 40 assists the operator in raising and lowering the upper working body 30 (particularly, the cabin 35). The ladder mechanism 40 is provided on the side of the frame 21 of the lower traveling body 20 (on the right side in the present embodiment). The ladder mechanism 40 is provided below the cabin 35. More specifically, the ladder mechanism 40 is provided below the frame 21 and between the axles 24 and 25 as shown in FIG.

  The ladder mechanism 40 is configured such that the posture can be changed between a retracted posture shown in FIG. 3A and a lifted posture shown in FIG. The retracted ladder mechanism 40 is stored in the frame 21 (more specifically, a space surrounded by the frame 21 and the wheels 24A and 25A). The ladder mechanism 40 in the extended posture is extended to the outside of the frame 21 to allow the operator to move up and down with respect to the cabin 35. FIG. 3B shows the posture of the ladder mechanism 40 during the posture change from one of the overhanging posture and the raising / lowering posture to the other.

  As shown in FIGS. 4 to 7, the ladder mechanism 40 mainly includes a stabilizing member 41, a bracket 50, a swing arm 56, a ladder body 70, and a drive mechanism 100 (see FIG. 9). The posture of the ladder mechanism 40 shown in FIGS. 4 and 5 corresponds to the retracted posture shown in FIG. Moreover, the attitude | position of the ladder mechanism 40 shown by FIG. 6 is corresponded to the attitude | position shown by FIG. 3 (B). Furthermore, the posture of the ladder mechanism 40 shown in FIG. 7 corresponds to the raising / lowering posture shown in FIG.

[Stabilizing member 41]
As shown in FIGS. 5 to 7, the stabilization member 41 includes a top plate 42 and a pair of side plates 43 and 44. The pair of side plates 43 and 44 are provided at both ends of the top plate 42 in the front-rear direction. The stabilizing member 41 is formed by bending a steel plate, for example.

  The top surface of the top plate 42 is substantially flush with the top surface of the frame 21 as shown in FIG. That is, the top plate 42 functions as a scaffold for workers who move on the frame. The top plate 42 has a notch 45 formed therein. The notch 45 extends from the right end of the top plate 42 to the left. That is, the right end of the notch 45 is open. Fitting grooves 46 and 47 are formed in the innermost part (that is, the left end) of the notch 45. The fitting grooves 46 and 47 receive a cylinder connecting pin 79 and a rotation restricting pin 80 described later, and restrict the rotation of the ladder body 70 when the ladder mechanism 40 is in the retracted position. Further, a fixing rib 49 for fixing the stabilizing member 41 to the bracket 50 is provided on the lower surface of the top plate 42.

  The side plates 43 and 44 are formed by bending the edge of the top plate 42. Thereby, the rigidity of the stabilizing member 41 is improved. In the present embodiment, a through-hole 48 that penetrates the side plate 43 in the thickness direction is formed in the side plate 43 located on the rear side of the top plate 42. The through hole 48 receives the tip of a piston rod 114 of the positioning cylinder 111 described later.

[Bracket 50]
As shown in FIGS. 5 to 7, the bracket 50 includes a bottom plate 51 and a pair of side plates 52 and 53. The bottom plate 51 and the pair of side plates 52 and 53 are each formed of a long plate-shaped steel plate. The pair of side plates 52 and 53 are provided at both ends of the bottom plate 51 in the short direction. Thereby, the bracket 50 is formed in an elongated box shape. In other words, the cross-sectional shape in the short direction of the bracket 50 is generally U-shaped. In a space surrounded by the bottom plate 51 and the pair of side plates 52 and 53, a swing cylinder 101 described later is disposed.

  One end of the bracket 50 in the longitudinal direction (the upper end in this embodiment) is fixed to the frame 21 of the lower traveling body 20 and extends obliquely downward to the right. The bracket 50 supports the stabilizing member 41 via a fixing rib 49 that is fixed to an intermediate portion in the longitudinal direction by a bolt (not shown). Further, the bracket 50 rotatably supports the swing arm 56 at the other end portion in the longitudinal direction (lower end in the present embodiment).

  The lower end portion of the bottom plate 51 is bent. The back surface of the lower end portion of the bent bottom plate 51 constitutes an abutting surface 54 that abuts a positioning member 61 described later. The pair of side plates 52 and 53 are extended downward from the bottom plate 51. And the spindle 55 which supports the rocking | fluctuating arm 56 rotatably is inserted in the lower end part of a pair of side plates 52 and 53 which opposes in the front-back direction. The support shaft 55 is an example of a first rotation axis along the front-rear direction.

[Oscillating arm 56]
As shown in FIGS. 5 to 7, the swing arm 56 is formed in a generally T shape by combining a plurality of steel plates. The swing arm 56 is supported by the bracket 50 so as to be rotatable about the support shaft 55 and also supports the ladder body 70 so as to be rotatable. More specifically, the swing arm 56 is configured to be rotatable between a storage posture shown in FIG. 5 and an extended posture shown in FIGS. 6 and 7. The swing arm 56 includes a leg portion 57 and a head portion 65 that extend in directions intersecting each other. The storage posture is a posture of the swing arm 56 stored in the frame 21 of the lower traveling body 20. The projecting posture is a posture of the swing arm 56 projecting rightward from the frame 21 of the lower traveling body 20.

  The leg portion 57 includes a bottom plate 58 and a pair of side plates 59 and 60. The bottom plate 58 and the pair of side plates 59 and 60 are each formed of a long plate-shaped steel plate. The pair of side plates 59 and 60 are provided at both ends of the bottom plate 58 in the short direction. Thereby, the leg part 57 is formed in the elongate box shape. In other words, the cross-sectional shape of the leg portion 57 in the short direction is generally U-shaped.

  One end of the bottom plate 58 (the end on the side connected to the head portion 65 or the end on the rotating front end side) is gradually expanded in width toward the head portion 65 side, and is generally triangular. Is formed. One side of this triangle is brought into contact with the central portion of the head portion 65, whereby the leg portion 57 and the head portion 65 are firmly connected. A positioning member 61 is provided at the other end portion of the bottom plate 58 (the end portion on the side supported by the bracket 50 or the end portion on the rotation base end side). The positioning member 61 positions the swing arm 56 in the extended posture with respect to the bracket 50.

  The positioning member 61 includes a boss 62 provided on the bottom plate 58, a hexagon bolt 63 screwed to the boss 62, and a lock nut 64 that positions the hexagon bolt 63 with respect to the boss 62. The head of the hexagon bolt 63 is separated from the contact surface 54 when the swing arm 56 is in the retracted position, and contacts the contact surface 54 when the swing arm 56 is in the extended position. By changing the amount of protrusion of the hexagon bolt 63 from the boss 62, the angle formed by the bracket 50 and the swing arm 56 in the extended position can be adjusted.

  The pair of side plates 59 and 60 oppose each other in the front-rear direction. A triangular rib 66 is attached to one end of the pair of side plates 59, 60 (the end connected to the head portion 65) at a position where it abuts on the head portion 65. The rib 66 in contact with the head portion 65 strengthens the connection between the leg portion 57 and the head portion 65. Further, a support shaft 55 extending in the front-rear direction is inserted into the other side end portion (the end portion on the side supported by the bracket 50) of the pair of side plates 59 and 60. Further, the pair of side plates 59 and 60 support a piston rod 104 of a swing cylinder 101, which will be described later, so that the piston rod 104 can rotate at an intermediate portion in the longitudinal direction.

  The head portion 65 has a substantially central portion in the longitudinal direction fixed to the rotating tip of the leg portion 57 and extends in the front-rear direction. The head portion 65 is formed in a tubular shape having a substantially rectangular cross-sectional shape in the lateral direction. The head portion 65 supports the ladder body 70 so as to be rotatable. More specifically, the head portion 65 has a support shaft 67 that supports the ladder body 70 in a rotatable manner. The support shaft 67 protrudes rightward on the rear side of the head portion 65. The support shaft 67 is an example of a second rotation axis that intersects the support shaft 55. Moreover, the head part 65 is supporting the rotation cylinder 106 mentioned later on the outer surface so that rotation is possible. Further, the head portion 65 accommodates a positioning cylinder 111 to be described later.

[Ladder body 70]
As shown in FIGS. 4 to 7, the ladder main body 70 includes a pair of support pillars 71 and 72 and a plurality of (four in the present embodiment) step rails 73 passed between the support pillars 71 and 72. . The pair of struts 71 and 72 and the treadle 73 are formed of, for example, an aluminum alloy pipe member. In addition, the ladder body 70 includes a platform 74 attached to the upper ends of the pair of support columns 71 and 72. The step 74 has a substantially L-shaped cross-section so that an operator can easily step on the foot. The step 74 is made of, for example, metal or resin. The ladder body 70 is an example of a ladder.

  The ladder body 70 has a support member 75. The support member 75 is made of, for example, an aluminum alloy or a steel material. The support member 75 includes a substantially rectangular plate-shaped main body 76 and a pair of fixing plates 77 and 78. The pair of fixing plates 77 and 78 are fixed to the pair of support columns 71 and 72, respectively. The main body 76 is fixed to the columns 71 and 72 via a pair of fixing plates 77 and 78 between the adjacent step bars 73. Further, the support member 75 includes a cylinder connecting pin 79, a rotation restricting pin 80, and a positioning member 82 that are provided so as to protrude from the surface on which the swing arm 56 is attached.

  The support member 75 is inserted through the support shaft 67 at a position close to the column 71 of the pair of columns 71 and 72. Thereby, the ladder main body 70 is supported by the swing arm 56 so as to be rotatable about the support shaft 67. More specifically, the ladder main body 70 is configured to be rotatable between a parallel posture shown in FIGS. 4 to 6 and an intersecting posture shown in FIG. The parallel posture is a posture of the ladder body 70 whose longitudinal direction is along the front-rear direction of the lower traveling body 20. The crossing posture is a posture of the ladder main body 70 in which the longitudinal direction intersects with the front-rear direction of the lower traveling body 20 and the worker can move up and down with respect to the upper working body 30.

  The cylinder connecting pin 79 rotatably supports the tip of a piston rod 109 of a rotating cylinder 106 described later. The support shaft 67 is disposed at a position shifted from the extension line of the piston rod 109 supported by the cylinder connecting pin 79. As a result, the rotational moment about the support shaft 67 acts on the ladder body 70 by expanding and contracting the rotating cylinder 106. The rotation restricting pin 80 has an abutment surface 81 that abuts on the tip of a piston rod 114 of a positioning cylinder 111 described later. Thereby, it is controlled that the crossing attitude ladder main body 70 rotates toward the parallel attitude.

  When the ladder main body 70 is in the parallel posture, the cylinder coupling pin 79 and the rotation restricting pin 80 are rotated by the swinging arm 56 from the extended posture to the retracted posture, so that the fitting groove 46 of the stabilizing member 41, Enter 47. Thereby, rotation of the ladder main body 70 is regulated. Further, the cylinder connecting pin 79 and the rotation restricting pin 80 are arranged so that the swinging arm 56 rotates from the retracted position to the extended position when the ladder body 70 is in the parallel position, so that the fitting groove of the stabilizing member 41 is fitted. Exit from 46 and 47. Thereby, rotation of the ladder main body 70 is permitted.

  The positioning member 82 positions the ladder main body 70 in the intersecting posture with respect to the head portion 65 of the swing arm 56. The positioning member 82 includes a boss 83 provided on the main body 76, a hexagon bolt 84 screwed to the boss 83, and a lock nut 85 that positions the hexagon bolt 84 with respect to the boss 83. The head of the hexagon bolt 84 is separated from the contact surface 68 of the head portion 65 when the ladder body 70 is in the parallel posture, and is in contact with the contact surface 68 when the ladder body 70 is in the crossing posture. By changing the protruding amount of the hexagon bolt 84 from the boss 83, the angle formed by the swing arm 56 in the overhanging posture and the ladder main body 70 in the crossing posture can be adjusted.

  The retracted posture of the ladder mechanism 40 is a posture when a swing arm 56 described later is in a retracted posture and a ladder main body 70 described later is in a parallel posture. The ladder main body 70 at this time is accommodated in a gap between the lower traveling body 20 and the upper working body 30. Thereby, the ladder mechanism 40 can be stored by effectively utilizing the space of the rough terrain crane 10. On the other hand, the raising / lowering posture of the ladder mechanism 40 is a posture when the swing arm 56 is in the extended posture and the ladder body 70 is in the crossing posture. At this time, the ladder main body 70 extends in the vertical direction below the cabin 35 in a state of protruding to the right side of the lower traveling body 20.

[Driving mechanism 100]
The drive mechanism 100 changes the posture of the ladder mechanism 40 between the retracted posture and the lifted posture, and positions the ladder mechanism 40 in each posture. As shown in FIG. 9, the drive mechanism 100 includes a swing cylinder 101 that rotates the swing arm 56, a rotation cylinder 106 that rotates the ladder body 70, and a positioning cylinder 111 that positions the ladder mechanism 40. Is mainly provided. The swing cylinder 101, the rotation cylinder 106, and the positioning cylinder 111 are pneumatic actuators that are expanded and contracted by compressed air supplied from the pneumatic system 120. The drive mechanism 100 is an example of an actuator.

[Oscillating cylinder 101]
As shown in FIGS. 7 and 9, the oscillating cylinder 101 includes a cylinder tube 102, a piston 103, and a piston rod 104. The base end of the cylinder tube 102 is rotatably supported by the bracket 50. The piston 103 is configured to reciprocate inside the cylinder tube 102. One end of the piston rod 104 is connected to the piston 103, and the other end protruding from the tip of the cylinder tube 102 is rotatably supported by the swing arm 56.

  The internal space of the cylinder tube 102 is partitioned by the piston 103 into a first chamber 102A and a second chamber 102B. When air is supplied to the first chamber 102A and air is discharged from the second chamber 102B, the piston 103 moves in a direction that causes the piston rod 104 to be immersed (i.e., retracted) into the cylinder tube 102 ("cylinder contraction"). ”)”. As a result, the swing arm 56 rotates from the extended position to the stored position. On the other hand, when the air is discharged from the first chamber 102A and the air is supplied to the second chamber 102B, the piston 103 moves in a direction in which the piston rod 104 protrudes from the cylinder tube 102 ("cylinder extends" write.). As a result, the swing arm 56 rotates from the retracted position to the extended position. The position of the piston 103 in the cylinder tube 102 is detected by a sensor (not shown) provided in the swing cylinder 101, for example.

[Rotating cylinder 106]
As shown in FIGS. 6, 7, and 9, the rotating cylinder 106 includes a cylinder tube 107, a piston 108, and a piston rod 109. The base end portion of the cylinder tube 107 is rotatably supported by the head portion 65. The piston 108 is configured to reciprocate inside the cylinder tube 107. One end of the piston rod 109 is connected to the piston 108, and the other end protruding from the tip of the cylinder tube 107 is rotatably supported by the cylinder connecting pin 79 of the ladder body 70.

  The internal space of the cylinder tube 107 is partitioned into a first chamber 107A and a second chamber 107B by the piston 108. When the air is supplied to the first chamber 107A and the air is discharged from the second chamber 107B, the rotating cylinder 106 contracts. Thereby, the ladder main body 70 rotates from the crossing posture to the parallel posture. On the other hand, when the air is discharged from the first chamber 107A and the air is supplied to the second chamber 107B, the rotating cylinder 106 extends. Thereby, the ladder main body 70 rotates from the parallel posture to the cross posture. The position of the piston 108 in the cylinder tube 107 is detected by, for example, a sensor (not shown) provided in the rotating cylinder 106.

[Positioning cylinder 111]
As shown in FIGS. 7 and 9, the positioning cylinder 111 includes a cylinder tube 112, a piston 113, a piston rod 114, and a coil spring 115 that is an example of an urging member. The cylinder tube 112 is accommodated in the head portion 65 with the tip portion directed rearward. The piston 113 is configured to reciprocate inside the cylinder tube 112. The piston rod 114 can have one end connected to the piston 113 and the other end protruding from the tip of the cylinder tube 112.

  The internal space of the cylinder tube 112 is partitioned into a first chamber 112A and a second chamber 112B by the piston 113. The coil spring 115 is disposed in the second chamber 112B and biases the piston 113 toward the first chamber 112A. In other words, the piston rod 114 is urged by the coil spring 115 in the direction in which the positioning cylinder 111 extends. The piston rod 114 protruding from the cylinder tube 112 is inserted into the through hole 48 of the stabilizing member 41 when the ladder mechanism 40 is in the retracted posture. This restricts the rotation of the swing arm 56 in the storage position. Further, the piston rod 114 protruding from the cylinder tube 112 contacts the contact surface 81 of the rotation restricting pin 80 when the ladder mechanism 40 is in the up / down posture. Thereby, rotation of the ladder main body 70 in the intersecting posture is restricted.

  On the other hand, when the air is supplied to the first chamber 112A of the cylinder tube 112, the positioning cylinder 111 contracts. Accordingly, the piston rod 114 is removed from the through hole 48 when the ladder mechanism 40 is in the retracted position, and is separated from the contact surface 81 when the ladder mechanism 40 is in the up-and-down position. That is, the positioning cylinder 111 allows a change in the attitude of the ladder mechanism 40 in accordance with the supply of air from the pneumatic system 120. On the other hand, the positioning cylinder 111 regulates the posture change of the ladder mechanism 40 while the supply of air from the pneumatic system 120 is stopped.

  In this way, the tip portion of the piston rod 114 protruding from the cylinder tube 112 engages with the stabilizing member 41 or the ladder body 70 to regulate the posture change of the ladder mechanism 40 and the posture change of the ladder mechanism 40. It is an example of the engaging part of the lock member in which an attitude | position change is possible between the permissible non-lock attitude | positions. The locked posture is the posture of the piston rod 114 inserted through the through hole 48 and the posture of the piston rod 114 in contact with the contact surface 81. The non-locking posture is a posture of the piston rod 114 extracted from the through hole 48 and a posture of the piston rod 114 separated from the contact surface 81.

[Pneumatic system 120]
The lower traveling body 20 has a pneumatic system 120. The pneumatic system 120 supplies air to the parking brake 36, the swing cylinder 101, the rotation cylinder 106, and the positioning cylinder 111. As shown in FIG. 9, the pneumatic system 120 includes a pump 121, a tank 122, valves 123, 124, 125 and 126, and a pneumatic valve 127. Specific examples of the valves 123 to 126 are not particularly limited. For example, a mechanical valve such as a gate valve or a solenoid valve may be used. The valve 124 is an example of a first valve, the valves 125 and 126 are examples of a second valve, and the pneumatic valve 127 is an example of a third valve.

  The pump 121 is a compressor that compresses air and supplies the compressed air to the tank 122. The pump 121 is driven by, for example, electric energy charged in the battery 12. The tank 122 stores the compressed air supplied from the pump 121. As shown in FIG. 9, the tank 122 is partitioned into a first storage chamber 122 </ b> A that stores air supplied to the parking brake 36 and a second storage chamber 122 </ b> B that stores air supplied to the drive mechanism 100. ing. From the tank 122, a flow path 128 extending from the first storage chamber 122A to the parking brake 36 and a flow path 129 extending from the second storage chamber 122B to the drive mechanism 100 are extended. However, the number of storage chambers in the tank 122 may be one.

  The valve 123 is provided on the flow path 128 from the tank 122 to the parking brake 36. When the valve 123 opens the flow path 128, air is supplied to the parking brake 36, and when the valve 123 closes the flow path 128, supply of air to the parking brake 36 is stopped. Further, the parking brake 36 is released when air is supplied from the tank 122, and is restricted when air supply from the tank 122 is stopped. The parking brake 36 in the released state allows the lower traveling body 20 to travel. On the other hand, the parking brake 36 in the restricted state restricts the traveling of the lower traveling body 20.

  The valve 124 is provided on the flow path 129 from the tank 122 to the drive mechanism 100. Further, the flow path 129 is downstream of the valve 124, and includes a flow path 129 </ b> A from the valve 124 to the swing cylinder 101, a flow path 129 </ b> B from the valve 124 to the rotating cylinder 106, and from the valve 124 to the positioning cylinder 111. Branches to the flow path 129C. The valve 125 is provided on the flow path 129A. The valve 126 is provided on the flow path 129B.

  The valve 125 includes a first valve 125A that allows air to flow into and out of the first chamber 102A of the swing cylinder 101, and a second valve 125B that allows air to flow into and out of the second chamber 102B. The first valve 125A includes a shut-off state that blocks air flow into and out of the first chamber 102A, a supply state that allows the first chamber 102A to communicate with the flow path 129A, and a discharge state that opens the first chamber 102A to the atmosphere. Can be switched to. The second valve 125B includes a shut-off state that shuts off the inflow and outflow of air into the second chamber 102B, a supply state that allows the second chamber 102B to communicate with the flow path 129A, and a discharge state that opens the second chamber 102B to the atmosphere. Can be switched to.

  The valve 126 includes a first valve 126A that allows air to flow into and out of the first chamber 107A of the rotating cylinder 106, and a second valve 126B that allows air to flow into and out of the second chamber 107B. The first valve 126A includes a shut-off state that shuts off the inflow and outflow of air into the first chamber 107A, a supply state that allows the first chamber 107A to communicate with the flow path 129B, and a discharge state that opens the first chamber 107A to the atmosphere. Can be switched to. The second valve 126B includes a shut-off state that shuts off the inflow and outflow of air into the second chamber 107B, a supply state that allows the second chamber 107B to communicate with the flow path 129B, and a discharge state that opens the second chamber 107B to the atmosphere. Can be switched to.

  The pneumatic valve 127 is provided between the valve 124 and the branch positions of the flow paths 129A to 129C. Further, from the flow path 128, a flow path 128 </ b> A that reaches the pneumatic valve 127 is branched downstream from the valve 123. The pneumatic valve 127 closes the flow path 129 while air is supplied from the tank 122 through the flow paths 128 and 128A. In other words, the pneumatic valve 127 closes the flow path 129 while the parking brake 36 is in the released state. On the other hand, the pneumatic valve 127 opens the flow path 129 while the supply of air through the flow paths 128 and 128A is stopped. In other words, the pneumatic valve 127 opens the flow path 129 while the parking brake 36 is in a restricted state. That is, the attitude change of the ladder mechanism 40 by the drive mechanism 100 is possible only when the parking brake 36 is in a restricted state.

[Control unit 140]
As shown in FIG. 10, the rough terrain crane 10 includes a control unit 140. In addition, the lower traveling body 20 includes a lower operation switch 141, a power cutoff unit 142, a sensor 143, and a lower multiple power transmission unit 144. Furthermore, the upper work body 30 includes an upper operation switch 145, an ignition switch 146, an indicator lamp 147, an alarm buzzer 148, and an upper multiple power transmission unit 149. The control unit 140 acquires various signals output from each unit of the rough terrain crane 10 and outputs control signals to the valves 123 to 126, the indicator lamp 147, and the alarm buzzer 148. The control unit 140 may be realized by a relay circuit or an integrated circuit, or may be realized by a CPU that executes a program.

  The lower operation switch 141 outputs an operation signal indicating the instruction to the control unit 140 in response to receiving the instruction of the worker who changes the posture of the ladder mechanism 40. The lower operation switch 141 is provided at a position where it can be operated from the outside of the lower traveling body 20. The specific arrangement of the lower operation switch 141 is not particularly limited. For example, the lower operation switch 141 is a side surface (that is, the right side surface) of the lower traveling body 20 on the side where the ladder mechanism 40 is provided, and It is preferable to arrange on the outside.

  The power shutoff unit 142 supplies power from the battery 12 to the lower operation switch 141 in response to the engine 27 being stopped. That is, the lower operation switch 141 outputs an operation signal corresponding to an instruction received from the operator to the control unit 140 in response to the engine 27 being stopped. On the other hand, the power cut-off unit 142 cuts off the power supply from the battery 12 to the lower operation switch 141 in response to the engine 27 being started. That is, the lower operation switch 141 does not output an operation signal even if an instruction is received from the operator while the engine 27 is started.

  The sensor 143 outputs a detection signal corresponding to the attitude of the ladder mechanism 40 to the control unit 140. The sensor 143 has, for example, a mechanical switch (not shown) that outputs a detection signal when pressed. Then, the mechanical switch is pressed by the components of the rough terrain crane 10 in response to the ladder mechanism 40 being in the retracted posture and the lifted posture. On the other hand, the press of the mechanical switch is released when the position of the ladder mechanism 40 is different from the retracted position and the lifted position. Further, the control unit 140 determines the attitude of the ladder mechanism 40 based on, for example, a combination of a detection signal output from the sensor 143 and a detection signal output from a sensor that detects the position of each piston 103, 108, 113. .

  The upper operation switch 145 outputs an operation signal indicating the instruction to the control unit 140 through the upper multiplex transmission unit 149 and the lower multiplex transmission unit 144 in response to receiving an instruction from the worker who changes the posture of the ladder mechanism 40. To do. The ignition switch 146 receives an instruction from a work vehicle that starts or stops the engine 27. The indicator lamp 147 lights up in response to the attitude of the ladder mechanism 40 being different from the retracted attitude. The alarm buzzer 148 sounds an alarm sound when the position of the ladder mechanism 40 is different from the retracted position and the parking brake 36 is released.

  The ignition switch 146 supplies power from the battery 12 to the upper operation switch 145 in response to the engine 27 being started. That is, the upper operation switch 145 outputs an operation signal corresponding to an instruction received from the operator to the control unit 140 in response to the engine 27 being started. On the other hand, the ignition switch 146 cuts off the power supply from the battery 12 to the upper operation switch 145 in response to the engine 27 being stopped. That is, the upper operation switch 145 does not output an operation signal even if an instruction is received from an operator while the engine 27 is stopped.

[Ladder mechanism control processing]
Next, the ladder mechanism control process will be described with reference to FIG. The ladder mechanism control process is a process for changing the posture of the ladder mechanism 40 in accordance with an instruction from the operator. The ladder mechanism control process is executed by the control unit 140. The control unit 140 executes the ladder mechanism control process shown in FIG. 11 while the operation signal is continuously output from the lower operation switch 141 or the upper operation switch 145. On the other hand, the control unit 140 executes the ladder mechanism control process shown in FIG. 11 in response to the stop of the output of the operation signal from the lower operation switch 141 or the upper operation switch 145.

  First, the control unit 140 receives an operation signal output from the lower operation switch 141 or the upper operation switch 145 in response to an instruction to change the ladder mechanism 40 to an up / down posture (hereinafter referred to as an “extension instruction”). It is determined whether there is an instruction to change the attitude of the ladder mechanism 40 to the retracted attitude (hereinafter referred to as “storage instruction”) (S11). The lower operation switch 141 and the upper operation switch 145 continuously output an operation signal while being operated by the operator, and stop outputting the operation signal when the operator stops the operation.

  Next, in response to the acquisition of the overhang instruction (S11: overhang instruction), the control unit 140 determines whether or not the transmission shift position is parking (S12). In response to the shift position being parking (S12: Yes), the control unit 140 opens the valve 124 (S13). On the other hand, in response to the fact that the shift position is not parking (S12: No), the control unit 140 notifies the operator of an error and ends the ladder mechanism control process (S22). However, the shift position in step S12 is not limited to parking.

  For example, the process of step S13 may be executed in response to the shift position being neutral. Alternatively, the process of step S13 may be executed in response to the shift position being parking or neutral. In other words, the process of step S22 may be executed according to the fact that the shift position is not neutral. Alternatively, the process of step S22 may be executed in response to the shift position being neither parking nor neutral.

  In step 13, air is supplied from the tank 122 to the first chamber 112 </ b> A of the positioning cylinder 111 through the flow paths 129 and 129 </ b> C by opening the valve 124. As a result, the locating positioning cylinder 111 changes the posture of the piston rod 114 from the locked posture to the non-locked posture. That is, the piston rod 114 is removed from the through hole 48. Thereby, the swing arm 56 is allowed to rotate.

  Next, the control unit 140 opens the valve 125 in response to the piston rod 114 (that is, the lock member) being in the unlocked posture (S14: Yes) (S15). The fact that the piston rod 114 is in the unlocked position is detected by a sensor provided in the positioning cylinder 111, for example. Further, the valve 124 is held in an open state.

  In step S15, the controller 140 puts the first valve 125A into a discharge state and puts the second valve 125B into a supply state. Thereby, air is supplied from the tank 122 to the second chamber 102B of the swing cylinder 101 through the flow paths 129 and 129A, and the air is discharged from the first chamber 102A. As a result, the extending swing cylinder 101 changes the swing arm 56 from the retracted position to the extended position.

  On the other hand, when the parking brake 36 is in the released state (in other words, when the valve 123 is opened), the pneumatic valve 127 closes the flow path 129. Therefore, even if the valve 124 is opened in step S13, the posture of the piston rod 114 does not change to the unlocked posture. Therefore, the control unit 140 notifies the operator of an error in response to the fact that the piston rod 114 does not enter the unlocked position even after a predetermined time has elapsed after opening the valve 124 (S14: No). The mechanism control process is terminated (S22).

  Next, the control unit 140 closes the valve 125 in response to the swing arm 56 being in the extended posture (S16: Yes) (S17). The fact that the swing arm 56 is in the extended posture is detected by, for example, a sensor provided on the swing cylinder 101. In step S17, the controller 140 puts the first valve 125A and the second valve 125B into a shut-off state. Further, the positioning member 61 is brought into contact with the contact surface 54, thereby holding the swing arm 56 in the extended posture. Note that the process of step S17 may be executed at the timing of step S20 described later.

  Further, the control unit 140 opens the valve 126 (S18). In step S18, the controller 140 puts the first valve 126A into a discharge state and puts the second valve 126B into a supply state. Accordingly, air is supplied from the tank 122 to the second chamber 107B of the rotating cylinder 106 through the flow paths 129 and 129B, and the air is discharged from the first chamber 107A. As a result, the extending rotation cylinder 106 changes the posture of the ladder body 70 from the parallel posture to the cross posture. Note that the execution order of steps S17 and S18 may be reversed or may be executed in parallel.

  Next, the control unit 140 closes the valves 124 and 126 in response to the fact that the ladder body 70 is in an intersecting posture (S19: Yes) (S20). Note that the fact that the ladder body 70 is in the crossing posture is detected by, for example, a sensor and a sensor 143 provided in the rotating cylinder 106. Further, the ladder main body 70 is held in an intersecting posture by the positioning member 82 being in contact with the contact surface 68.

  In step S20, the controller 140 puts the first valve 126A and the second valve 126B into a shut-off state. Further, the positioning cylinder 111 in which the supply of air to the first chamber 112A has been stopped changes the posture of the piston rod 114 from the non-locking posture to the locking posture by the biasing force of the coil spring 115. That is, the tip of the piston rod 114 is brought into contact with the contact surface 81 of the rotation restricting pin 80. Thereby, rotation of the ladder main body 70 is regulated.

  And the control part 140 complete | finishes a ladder mechanism control process according to the piston rod 114 having been in the locked posture (S21: Yes). The fact that the piston rod 114 is in the locked posture is detected by a sensor provided in the positioning cylinder 111, for example.

  On the other hand, in response to the acquisition of the storage instruction (S11: storage instruction), the control unit 140 opens the valve 124 (S23). Next, the control unit 140 opens the valve 126 in response to the piston rod 114 being in the unlocked posture (S24: Yes) (S25). The piston rod 114 in the unlocked position in step S24 is separated from the contact surface 81 of the rotation restricting pin 80. Thereby, rotation of the ladder main body 70 is permitted. Since the processes of steps S23 and S24 are common to steps S13 and S14, the description thereof will be omitted.

  In step S25, the control unit 140 sets the first valve 126A to the supply state and the second valve 126B to the discharge state. Accordingly, air is supplied to the first chamber 107A of the rotating cylinder 106 through the flow paths 129 and 129B, and the air is discharged from the second chamber 107B. As a result, the rotating cylinder 106 which contracts changes the posture of the ladder body 70 from the crossing posture to the parallel posture.

  Next, the control unit 140 closes the valve 126 in response to the fact that the ladder body 70 is in a parallel posture (S26: Yes) (S27). Note that the fact that the ladder mechanism 70 is in a parallel posture is detected by, for example, a sensor provided in the rotating cylinder 106. In step S27, the controller 140 puts the first valve 126A and the second valve 126B into a shut-off state. Note that the process of step S27 may be executed at the timing of step S30 described later.

  Further, the control unit 140 opens the valve 125 (S28). In step S28, the control unit 140 sets the first valve 125A to the supply state and sets the second valve 125B to the discharge state. Accordingly, air is supplied from the tank 122 to the first chamber 102A of the swing cylinder 101 through the flow paths 129 and 129A, and the air is discharged from the second chamber 102B. As a result, the swinging cylinder 101 that contracts changes the position of the swing arm 56 from the extended position to the retracted position. Note that the execution order of steps S27 and S28 may be reversed or may be executed in parallel.

  Next, the control unit 140 closes the valves 124 and 125 in response to the swing arm 56 being in the retracted position (S29: Yes) (S30). The fact that the swing arm 56 is in the retracted position is detected by, for example, a sensor and a sensor 143 provided in the swing cylinder 101. In step S30, the controller 140 puts the first valve 125A and the second valve 125B into a shut-off state. Further, the positioning cylinder 111 extended by the urging force of the coil spring 115 changes the posture of the piston rod 114 from the unlocked posture to the locked posture. In other words, the piston rod 114 in the locked posture enters the through hole 48. The stabilizing member 41 regulates the posture change of the ladder mechanism 70 by locking the piston rod that has entered the through hole 48 at the periphery of the through hole 48.

  And the control part 140 complete | finishes a ladder mechanism control process according to the piston rod 114 having been in the locked posture (S31: Yes). The fact that the piston rod 114 is in the locked posture is detected by a sensor provided in the positioning cylinder 111, for example.

[Notification processing]
Next, referring to FIG. 12, a notification process is executed. The notification process is a process for notifying the operator that the ladder mechanism 40 is not in the retracted position and that it is dangerous to cause the lower traveling body 20 to travel. The notification process is executed by the control unit 140. The control unit 140 repeatedly executes the notification process shown in FIG. 12 in response to the engine 27 being started.

  First, the control unit 140 turns on the indicator lamp 147 in response to that the engine 27 is started and the ladder mechanism 40 is in a posture different from the retracted posture (S41: No) (S42). On the other hand, the control unit 140 turns off the indicator lamp 147 in response to the fact that the ladder mechanism 40 is in the retracted position (S41: Yes) (S43). The indicator lamp 147 is turned on and off by a control signal transmitted from the control unit 140 through the upper multiplex transmission unit 149 and the lower multiplex transmission unit 144. Further, the indicator lamp 147 lit in step S42 is continuously lit until step S43 is executed. Further, when the indicator lamp 147 is already turned off, the process of step S43 is skipped.

  Further, the control unit 140 causes the alarm buzzer 148 to be heard (S45) in response to the fact that the ladder mechanism 40 is not in the retracted posture and the parking brake 36 is in the released state (S41: No & S44: Yes). On the other hand, in response to the parking brake 36 being in a restricted state (S44: No), the control unit 140 stops the alarm buzzer 148 from being heard (S46). Note that the alarm buzzer 148 is sounded and stopped by a control signal transmitted from the control unit 140 through the upper multiplex transmission unit 149 and the lower multiplex transmission unit 144. Further, the alarm buzzer 148 sounded in step S45 is continuously sounded until step S46 is executed. Furthermore, when the alarm buzzer 148 is not being heard, the process of step S46 is skipped.

[Operational effects of this embodiment]
According to the above embodiment, the valves 124, 125, and 126 are provided in the flow path 129 between the tank 122 and the swing cylinder 101 and the rotation cylinder 106. As a result, even if one of the valves 124 to 126 fails, air is not immediately supplied to the swing cylinder 101 and the rotation cylinder 106. As a result, an unintended change in the attitude of the ladder mechanism 40 can be suppressed.

  Further, according to the above embodiment, while the supply of air from the tank 122 is stopped, the piston rod 114 is in the locked posture by the urging force of the coil spring 115. Thereby, compared with the case where the locked posture of piston rod 114 is maintained using motive power, such as fluid pressure and electric power, for example, it can control that piston rod 114 will not be in a non-locking posture unintentionally.

  Further, as in the above embodiment, the attitude of the ladder mechanism 40 is changed by supplying air from the tank 122, and the attitude of the ladder mechanism 40 is maintained by stopping the supply of air from the tank 122. The Thus, by not using power to maintain the posture of the ladder mechanism 40, an unintended posture change of the ladder mechanism 40 can be suppressed.

  Moreover, according to said embodiment, it can suppress that the ladder mechanism 40 changes an attitude | position when the parking brake 36 is cancelled | released. That is, an unintended posture change of the ladder mechanism 40 can be suppressed while the lower traveling body 20 is traveling or when the lower traveling body 20 is traveling.

  Furthermore, according to the above embodiment, each cylinder 101, 106, 111 can be operated using compressed air that changes the state of the parking brake 36. That is, the compressed air in the tank 122 can be shared by the parking brake 36 and the drive mechanism 100. As a result, an increase in the number of parts of the rough terrain crane 10 can be suppressed.

  In the above embodiment, an example in which the cylinders 101, 106, and 111 are expanded and contracted by pneumatic pressure has been described. However, the method for expanding and contracting the cylinders 101, 106, and 111 is not limited to this. May be. That is, pneumatic pressure and hydraulic pressure are examples of fluid, and each cylinder 101, 106, 111 is an example of fluid pressure cylinder. More specifically, the swing cylinder 101 and the rotation cylinder 106 are examples of a step cylinder, and the positioning cylinder 111 is an example of a lock cylinder.

  In the above embodiment, the example in which the attitude of the ladder mechanism 40 is changed by the rotation of the swing arm 56 and the ladder body 70 has been described. However, if the posture can be changed between the retracted posture stored in the frame 21 and the raising / lowering posture in which the operator can move up and down with respect to the cabin 35, a specific configuration for changing the posture of the ladder mechanism 40 is as follows. It is not limited to this.

DESCRIPTION OF SYMBOLS 10 ... Rough terrain crane 20 ... Lower traveling body 30 ... Upper work body 36 ... Parking brake 40 ... Ladder mechanism 100 ... Drive mechanism 101 ... Swing cylinder 106 ... Rotating cylinder 111 ... Positioning cylinder 114 ... Piston rod 115 ... Coil spring 122 ... Tank 123, 124, 125, 126 ... Valve 127 ... Pneumatic valve 128, 129 ... Flow Path 141 ... Lower operation switch 145 ... Upper operation switch

Claims (6)

A lower traveling body,
An upper working body disposed on the upper part of the lower traveling body;
A ladder mechanism capable of changing its posture into a retracted posture stored in the lower traveling body and a lifting posture that protrudes to the side of the lower traveling body and assists an operator to lift and lower the upper working body;
A lock member capable of changing a posture to a locked posture that restricts a posture change of the ladder mechanism and a non-locking posture that allows a posture change of the ladder mechanism;
A tank for storing fluid;
An actuator that changes the posture of the ladder mechanism and the lock member using the fluid stored in the tank, and
The actuator is
A lock cylinder that changes the posture of the lock member by supplying a fluid;
A step cylinder for changing the posture of the ladder mechanism by supplying a fluid;
A first valve that opens and closes a fluid flow path from the tank to each cylinder;
A work vehicle having a second valve for opening and closing a fluid flow path from the first valve to the step cylinder. The locking member is attached to the ladder mechanism;
Engagement that projects from the ladder mechanism in the retracted position in the locked position and engages with the lower traveling body, and retreats toward the ladder mechanism in the unlocked position to disengage from the lower traveling body And
An urging member that urges the engaging portion in a protruding direction,
2. The work vehicle according to claim 1, wherein the lock cylinder retracts the engagement portion toward the ladder mechanism against a biasing force of the biasing member when a fluid stored in the tank is supplied. . A switch for receiving an instruction from an operator for changing the posture of the ladder mechanism;
A controller that opens and closes the first valve and the second valve;
The control unit
In response to the switch receiving an instruction from the operator to change the ladder mechanism to the up / down position, the first valve is opened,
In response to the locking member being in the unlocked position, the second valve is opened,
The work vehicle according to claim 2, wherein the first valve and the second valve are closed in response to the ladder mechanism being in the raising / lowering posture. The control unit
The first valve and the second valve are opened in response to the switch receiving an instruction from an operator to change the position of the ladder mechanism to the retracted position.
The work vehicle according to claim 3, wherein the first valve and the second valve are closed in response to the ladder mechanism being in the retracted posture. A parking brake capable of changing the state to a restricted state that restricts the traveling of the lower traveling body and a released state that permits the traveling of the lower traveling body;
The fluid stored in the tank is compressed air,
The parking brake is
The release state is achieved by supplying air stored in the tank,
The work vehicle according to any one of claims 1 to 4, wherein the restricted state is established when supply of air stored in the tank is stopped.   The actuator is disposed between the first valve and the second valve, is closed by the air supplied to the parking brake, and is released when the supply of air to the parking brake is stopped. The work vehicle according to claim 5, further comprising a third valve.

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