JP5305085B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a vehicle steering apparatus for a cargo handling vehicle.

Usually, in a forklift as a cargo handling device, a front wheel is a driving wheel whose direction is fixed, and a rear wheel is a steered wheel. A steering device such as a forklift performs steering by turning a rear wheel as the steered wheel in accordance with steering of a steering handle (steering member).
Further, in the forklift, a heavy object is loaded on the fork of the cargo handling device provided at the front of the vehicle body. In order to prevent the vehicle from falling forward when a heavy object is loaded on the fork in this way, the forklift is equipped with a “weight” called a counterweight at the rear of the vehicle body. This type of forklift is a counterweight forklift.

On the other hand, forklifts have been proposed in which the driver's seat is turned around a turning axis spaced from the driver's seat, specifically, around a turning axis arranged at the position of the foot pedal (for example, (See Patent Document 1).
Japanese Patent Laid-Open No. 10-7395

In a counterweight forklift, when a load is loaded on a fork, the load of the load generates a moment in a direction that reduces the ground load on the rear wheel with the front wheel as a fulcrum. For this reason, at the time of loading, the ground contact loads of the front wheels and the rear wheels are substantially balanced.
However, when no load is loaded on the fork, the above-mentioned moment is not generated by the load, and therefore the ground load on the rear wheel is significantly larger than the ground load on the front wheel. As a result, when the rear wheel is steered, the load on the steering actuator for applying the steered force (or the steering assist force) to the rear wheel is significantly increased. For this reason, the life of the steering actuator is shortened. In addition, a large steering actuator that can withstand a high load is required.

In addition, since the forklift in an unloaded state has a poor weight balance between the front and rear, there is a problem that the running stability is slightly inferior.
The present invention has been made in view of the above problems, and provides a vehicle steering apparatus that is excellent in durability and can contribute to running stability of the vehicle by reducing the steering load during empty load. The purpose is to do.

In order to achieve the above object, the present invention provides a vehicle for steering a cargo handling vehicle (1) having a cargo handling device (3) at the front portion of the vehicle body (2) and a counterweight (4) at the rear portion of the vehicle body. A steering member (24), a steering actuator (25) for generating a steering force for turning a rear wheel (6) as a steered wheel in response to an operation of the steering member, A unit (11) including a driver seat (10) and supported by the vehicle body so as to be slidable in a sliding direction (X1) along the front-rear direction of the vehicle, and a drive mechanism for moving the unit along the sliding direction and (12), a load sensor (80) for detecting a load which the handling device receives, when the detected load (W) is below a predetermined value (W1) by the load sensor, said unit As to slide the slide forward, characterized by comprising control unit for controlling the drive mechanism (13).

  According to the present invention, in a cargo handling vehicle having a counterweight at the rear of the vehicle, the weight balance between the front and rear of the vehicle can be adjusted by sliding the unit including the driver's seat back and forth. As a result, for example, it is possible to prevent the ground contact load of the rear wheel from being excessive when it is empty, and as a result, it is possible to reduce the driving force of the steering actuator when turning the rear wheel when empty. Therefore, the life of the steering actuator can be extended. In addition, a small steering actuator can be used. Furthermore, since the weight balance before and after the vehicle when empty is improved, the running stability of the vehicle when empty can be improved.

In addition, a load sensor (80) for detecting a load received by the cargo handling device is provided, and the control unit is configured to detect the unit when the load (W) detected by the load sensor is equal to or less than a predetermined value (W1). Since the drive mechanism is controlled so as to slide forward in the sliding direction, there are the following advantages. That is , an empty load is automatically detected and the unit is slid forward in the sliding direction. Therefore, it is possible to reliably reduce the ground contact load of the rear wheels when there is no load without troublesome operations for the driver.

Further, a lock mechanism (52) for locking the position of the unit may be provided (claim 2 ). In this case, since the position of the driver's seat and the like is fixed by locking the position of the unit, the posture of the driver is stabilized and it becomes easy to drive.
Further, the unit may include a cargo handling device (claim 3 ). In this case, it is possible to reduce the ground load on the rear wheel to a predetermined amount by simply sliding the unit forward for a short distance. Therefore, energy to be borne by the actuator when the unit is slid can be reduced, which is preferable in terms of energy saving.

Further, the mechanical connection between the steering member and the rear wheel as a steered wheel may be broken (claim 4 ). In this case, when the position of the unit is changed, the driver can easily operate the steering member. In addition, since the mechanical connection between the steering member and the steered wheels is broken, there is no difficulty in sliding the steering member together with the driver seat.
In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

A preferred embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic side view showing a schematic configuration of a forklift as a cargo handling vehicle according to an embodiment of the present invention.
Referring to FIG. 1, a forklift 1 includes a vehicle body 2, a cargo handling device 3 provided at a front portion of the vehicle body 2, a counterweight 4 provided at a rear portion of the vehicle body 2, and a driving wheel that supports the vehicle body 2. As a front wheel 5 and a rear wheel 6 as a steered wheel, a vehicle drive source 7 including, for example, an engine, a hydraulic pump 8 as a hydraulic source, and a vehicle steering device 9 for steering the rear wheel 6 I have.

  The forklift 1 includes at least a driver's seat 10 and is supported by the vehicle body 2 via a guide mechanism 40 so as to be slidable in a sliding direction X1 along the front-rear direction of the vehicle, and the unit 11 in the sliding direction X1. A unit drive mechanism 12 that slides to the rear position shown in FIG. 1 and the front position shown in FIG. 2 and an ECU (electronic control unit) 13 that controls the unit drive mechanism 12 are provided. . The ECU incorporates various interfaces and various drivers in addition to the CPU, ROM and RAM constituting the microcomputer.

Although not shown, the power of the drive source 7 such as an engine is transmitted to a transmission that performs forward / reverse switching and a shift operation via a torque converter, and further transmitted to left and right front wheels 5 (drive wheels) via a differential. It has become so. The transmission includes a forward clutch and a reverse clutch.
The cargo handling device 3 is lifted and lowered by a pair of left and right outer masts 14 supported by the vehicle body 2 so as to be tiltable about a lower end portion 14 a, an inner mast 15 supported by the outer mast 14 so as to be movable up and down, and the outer mast 14. The lift bracket 16 is supported so that it can be supported, and a pair of left and right forks 17 are attached to the lift bracket 16 and serve as a loading portion for loading a load.

  A tilt cylinder 18 is interposed between a predetermined portion of the outer mast 14 and a predetermined portion of the vehicle body 2. The tilt cylinder 18 includes a cylinder body 19 having one end that is swingably connected to a predetermined portion of the vehicle body 2, and a rod 20 that protrudes from the other end of the cylinder body 19. The tip of the rod 20 is slidably connected to a predetermined portion of the outer mast 14. As the rod 20 of the tilt cylinder 18 extends and contracts, the outer mast 14 is displaced into an upright posture and a tilted posture.

  Further, a lift cylinder 21 is provided for raising and lowering the inner mast 15 using the outer mast 14 as a guide. The lift cylinder 21 has a cylinder body 22 fixed to the outer mast 14 and a rod 23 protruding from the cylinder body 22. The tip of the rod 23 is fixed to a mounting portion 15 a provided at a predetermined portion of the inner mast 15. A load sensor 80 for detecting a load received by the cargo handling device 3 is attached to the lower portion of the cylinder body 22 of the lift cylinder 21.

  A unit slide position sensor 81 for detecting the position (slide position) of the unit 11 in the slide direction X1 with respect to the vehicle body 2 is provided. The unit slide position sensor 81 is disposed, for example, at the opposing portion of the vehicle body 2 and the unit main body 34. Specifically, the first and second fixing portions 82 and 83 fixed to the vehicle body 2 and the bottom frame 34A of the unit body 34 can be moved in the sliding direction X1 so as to be able to face the fixing portions 82 and 83. And a movable portion 84 attached thereto.

As the movable portion 84 faces the second fixed portion 83 as shown in FIG. 1, it is detected that the unit 11 is in the rear position, and the movable portion 84 is fixed to the first fixed portion as shown in FIG. By facing the portion 82, it is detected that the unit 11 is in the forward position.
The vehicle steering device 9 is configured as a so-called steer-by-wire vehicle steering device in which the mechanical connection between the steering member 24 that is a handwheel with a knob and the rear wheel 6 that is a steered wheel is broken. ing. As a steered wheel, a single rear wheel 6 may be provided at the center in the left-right direction of the vehicle body 2, or the rear wheels 6 may be provided on the left and right sides of the vehicle body 2, respectively.

  As shown in FIG. 1 and mainly in FIG. 3, the vehicle steering device 9 is composed of, for example, an electric motor for turning the rear wheel 6, and is steered by a steering actuator 25 controlled by the ECU 13 and a steering member 24. For example, a reaction force actuator 26 that is driven by the ECU 13 and is controlled by the ECU 13, a steering angle sensor 27 that detects the steering angle of the steering member 24, and a steering that detects the turning angle of the rear wheel 6. And an angle sensor 28.

The rear wheel 6 as a steered wheel is rotatably supported by a substantially vertical support member 29. The support member 29 is supported through a bearing 30 held by the vehicle body 2 so as to be rotatable about a substantially vertical rotation axis C2.
The rotation of the output shaft of the steering actuator 25 is decelerated via the transmission mechanism 31 and transmitted to the support member 29. The transmission mechanism 31 is provided such that a drive member 32 made of, for example, a drive gear that rotates along with the output shaft of the steering actuator 25, and a support member 29 that can rotate along the rotation axis C2, and meshes with the drive gear. For example, it has the driven member 33 which consists of driven gears.

  As shown in FIG. 1, the unit 11 includes a unit body 34 placed on the vehicle body 2. The unit body 34 includes a bottom frame 34A and a pair of left and right side frames 34B. An operation stand 35 is provided on the bottom frame 34A in the front part of the unit body 34, and the driver seat 10 is fixed on the bottom frame 34A in the rear part of the unit body 34. The driver's seat 10 has a seat portion 10a and a backrest portion 10b.

  The operation stand 35 includes a plurality of operation elements 24 for a driver to operate by hand, the operation member 24, an elevating operation lever 36 for elevating the fork 17, and a tilt for swinging the outer mast 14. An operation lever 37 and a forward / reverse switching lever 38 are provided. In addition, a confirmation mirror 39 for mainly confirming the rear side is fixed to the operation stand 35. The operation stand 35 is provided with various switches not shown.

  In the vicinity of the base of the operation stand 35, an accelerator pedal 41, a brake pedal 42, and a clutch pedal 43 are provided on the bottom frame 34A of the unit body 34 as a plurality of operation elements for the driver to operate with his / her feet. ing. The accelerator pedal 41, the brake pedal 42, and the clutch pedal 43 are actually arranged side by side in a direction perpendicular to the paper surface (corresponding to the left-right direction of the vehicle), but are schematically shown in FIG.

As shown in FIG. 4, a guide rail 44 as a guide member having a pair of left and right inward grooves is fixed to the upper portion of the vehicle body 2. The guide rail 44 includes an upper flange 44a, a lower flange 44b, and a web 44c.
On the other hand, a plurality of rolling members 46 as guided members are rotatably supported on the side surfaces of the pair of side portions of the bottom frame 34 </ b> A of the unit main body 34 via the support shaft 45. As shown in FIG. 5, these rolling members 46 are arranged in a zigzag shape so as to be able to make rolling contact with the upper flange 44a and the lower flange 44b of the guide rail 44 alternately in the sliding direction X1.

A guide mechanism 40 that guides the unit 11 in the slide direction X1 is configured by the guide rail 44 as the guide member and the rolling member 46 as the guided member guided by the guide rail 44. The guide mechanism 40 also functions as a support mechanism that supports the unit 11 so as to be slidable in the slide direction X1.
The unit drive mechanism 12 for slidingly driving the unit 11 in the slide direction X1 decelerates the rotation of the unit slide actuator 47, which is an electric motor, and the output shaft of the unit slide actuator 47, and transmits it to the unit 11. And a transmission mechanism 48. A main body 47 a of the unit slide actuator 47 is fixed to the vehicle body 2.

  The transmission mechanism 48 meshes with a drive gear 49 provided so as to be able to rotate along with the output shaft 47 b of the unit slide actuator 47, a pinion 50 driven by the drive gear 49, and the pinion 50. And a rack 51 movably attached to the bottom frame 34A. The rack 51 extends longitudinally along the slide direction X1 (in FIG. 4, a direction orthogonal to the paper surface).

When the pinion 50 is rotationally driven by the unit slide actuator 47 via the drive gear 49, the rotation of the pinion 50 is converted into a linear motion of the rack 51. As a result, the rack 51 and the unit 11 are moved in the sliding direction X1. Slide.
Due to the function of the unit driving mechanism 12, the unit 11 is displaced to the front position shown in FIG. 1 and the rear position shown in FIG.

In FIGS. 1 and 2, the layout of the lift operation lever 36, the tilt operation lever 37, the forward / reverse switching lever 38, the accelerator pedal 41, the brake pedal 42, and the clutch pedal 43 as operation elements is schematically shown. It is.
Further, as shown in FIG. 6, the forklift 1 includes a lock mechanism 52 for locking the unit main body 34 to the front position and the rear position with respect to the vehicle body 2. The lock mechanism 52 includes a lock member 53. The lock member 53 includes a main body 53a fixed to the vehicle body 2, and a lock shaft 53b that expands and contracts by the action of a solenoid for a lock mechanism built in the main body 53a. I have.

  The lock mechanism 52 has a first lock hole 54 and a second lock hole 55 on the lower surface of the bottom frame 34 </ b> A of the unit main body 34 to engage with the lock shaft 53 b. When the lock shaft 53b is fitted into the first lock hole 54, the unit 11 is locked at the front position, and when the lock shaft 53b is fitted into the second lock hole 55, the unit 11 is at the rear position. Locked to.

  Referring to FIG. 7 which conceptually shows the principle of the operation of raising and lowering the fork 17, a sprocket 56 is rotatably supported on the upper portion of the inner mast 15, and a chain 57 is wound around the sprocket 56. It has been. One end 57 a of the chain 57 is fixed to a fixing portion 14 b provided on the outer mast 14, and the other end 57 b of the chain 57 is fixed to the lift bracket 16. Thereby, the lift bracket 16 and the fork 17 are suspended using the chain 57.

  When the inner mast 15 rises with the extension of the rod 23 of the lift cylinder 21, the sprocket 56 rises with respect to the fixed portion 14 b of the outer mast 14, and the lift bracket 16 and the fork as the loading portion are connected via the chain 57. Raise 17 The amount of rise of the fork 17 relative to the ground surface is twice the amount of extension of the rod 23 of the lift cylinder 21.

  FIG. 8 is a block diagram showing the main electrical configuration of the forklift 1. Referring to FIG. 8, the ECU 13 detects the positions of the steering angle sensor 27, the turning angle sensor 28, the vehicle speed sensor 58, the load sensor 80, the unit slide position sensor 81, the release operation switch 85, and the lifting operation lever 36. Signals are respectively input from a lift operation lever position sensor 59, a tilt operation lever position sensor 60 that detects the position of the tilt operation lever 37, and a forward / reverse switch 61 that operates in response to switching of the forward / reverse switching lever 38. It has become so.

The release operation switch 85 is a switch that is manually operated by the driver in order to return the unit 11 that has been moved to the front position when empty to the rear position as a pre-operation for the next loading. Although not shown in FIG. 1, the operation stand 35 is provided.
The ECU 13 includes a steering actuator 25, a reaction force actuator 26, a unit slide actuator 47, a lock mechanism solenoid 62, and an electromagnetic proportional control valve that controls the supply of hydraulic oil from the hydraulic pump 8 to the lift cylinder 21. The lift control valve 63, the tilt control valve 64 comprising an electromagnetic proportional control valve for controlling the supply of hydraulic oil from the hydraulic pump 8 to the tilt cylinder 18, and the hydraulic cylinder for engaging / disengaging the forward clutch. A forward clutch control valve 65 comprising an electromagnetic proportional control valve for controlling the supply of oil, and a reverse clutch comprising an electromagnetic proportional control valve for controlling the supply of hydraulic oil to a hydraulic cylinder for engaging / disengaging the reverse clutch A signal is output to each of the control valves 66 for use.

The ECU 13 executes various controls. For example, the ECU 13 determines a target turning angle based on the steering angle input from the steering angle sensor 27 and the vehicle speed input from the vehicle speed sensor 58, and uses the turning angle input from the turning angle sensor 28 as the target turning angle. The steering actuator 25 is drive-controlled (that is, steering control is performed) so that
Further, the ECU 13 is inputted from the steering angle and vehicle speed sensor 58 inputted from the steering angle sensor 27 so that the reaction force actuator 26 generates torque for giving the steering reaction force corresponding to the road surface reaction force to the steering member 24. The reaction force actuator 26 is driven and controlled based on the vehicle speed (that is, reaction force control is performed).

Further, the ECU 13 sends a control signal to the lift control valve 63 that controls the supply of hydraulic oil from the hydraulic pump 8 to the lift cylinder 21 in accordance with the position of the lift control lever 36 input from the lift control lever position sensor 59. Output.
Further, the ECU 13 sends a control signal to the tilt control valve 64 that controls the supply of hydraulic oil from the hydraulic pump 8 to the tilt cylinder 18 in accordance with the position of the tilt operation lever 37 input from the tilt operation lever position sensor 60. Output.

In addition, the ECU 13 outputs a control signal to the forward clutch control valve 65 in response to the forward / reverse switching switch 61 being switched to forward, and the hydraulic pump for operating the forward clutch is operated from the hydraulic pump 8. Allow oil to be supplied.
Further, the ECU 13 outputs a control signal to the reverse clutch control valve 66 in response to the forward / reverse switching switch 61 being switched to the reverse, and the hydraulic cylinder for operating the reverse clutch is operated from the hydraulic pump 8. Allow oil to be supplied.

  FIG. 9 is a flowchart showing the main operation of the ECU 13. Referring to FIG. 9, in step S1, it is confirmed whether or not release operation switch 85 is turned on. If it is not turned on (NO in step S1), load sensor 80 in step S2. The load W applied to the cargo handling device 3 is detected on the basis of the signal from, and in step S3, the detected load W is equal to or less than the predetermined value W1 (W ≦ W1), and the fork 17 is loaded with the load. It is determined whether or not it is in an empty state.

  If it is determined as YES (empty) in step S3, it is determined in step S4 whether or not the unit 11 is in the rear position based on a signal from the unit slide position sensor 81. On the condition that 11 is determined to be in the rear position (YES in step S4), the unit 11 is moved to the front position. Specifically, after the lock of the unit 11 by the lock mechanism 52 is released in step S5, the unit slide actuator 47 is driven to move the unit 11 to the front position in step S6. Thereafter, in step S7, the unit 11 is locked at the forward position.

  On the other hand, if it is determined in step S1 that the release operation switch 85 is turned on (YES in step S1), it is determined in step S8 whether the unit 11 is in the forward position. In step S8, the unit 11 is moved to the rear position on the condition that the unit 11 is determined to be in the front position (YES in step S8). Specifically, after releasing the lock on the unit 11 by the lock mechanism 52 in step S9, the unit slide actuator 47 is driven to move the unit 11 to the rear position in step S10. Thereafter, in step S11, the unit 11 is locked at the rear position.

  According to the present embodiment, in the forklift 1 having the counterweight 4 at the rear portion, the weight balance between the front and rear of the vehicle can be adjusted by sliding the unit 11 including the driver seat 10 back and forth. Thereby, for example, it is possible to prevent the ground load of the rear wheel 6 from being excessive when it is empty, and as a result, it is possible to reduce the driving force of the steering actuator 25 when the rear wheel 6 is steered when empty. . Therefore, the life of the steering actuator 25 can be extended. In addition, a small steering actuator 25 can be used. Furthermore, since the weight balance before and after the vehicle when empty is improved, the running stability of the vehicle when empty can be improved.

Moreover, it detects that it is an empty load based on the load W detected by the load sensor 80, detects an empty load automatically, and slides the unit 11 ahead of the slide direction X1. Therefore, it is possible to reliably reduce the ground contact load of the rear wheel 6 when there is no load without troublesome operation for the driver.
Further, the unit 11 can be locked at the front position and the rear position by the lock mechanism 52. Since the driver's seat 10 is fixed by locking the position of the unit 11, the posture of the driver is stabilized, and it becomes easy to operate and drive the vehicle.

  The unit 11 includes a plurality of operation elements and a confirmation mirror 39 for the driver to operate with hands or feet. Specifically, a steering member 24, a lift operation lever 36, a tilt operation lever 37, a forward / reverse switching lever 38, an accelerator pedal 41, a brake pedal 42, a clutch pedal 43, and a confirmation mirror 39 are included. Therefore, since these operation elements and the like are slid and displaced together with the driver's seat 10, the ease of driving by the driver is remarkably improved.

Further, since the unit 11 includes the cargo handling device 3, the ground load of the rear wheel 6 at the time of empty load can be reduced to a predetermined amount by merely sliding the unit 11 a little distance forward of the vehicle. Therefore, energy to be borne by the unit slide actuator 47 when the unit 11 is slid can be reduced, which is preferable in terms of energy saving.
Further, as the vehicle steering device 9, a steer-by-wire vehicle steering device in which the mechanical connection between the steering member 24 and the rear wheel 6 as the steered wheel is broken is adopted. When the position is changed, the driver can easily operate the steering member 24. Further, since the mechanical connection between the steering member 24 and the rear wheel 6 as the steered wheel is broken, there is no difficulty in sliding the steering member 24 together with the driver seat 10.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the unit 11 includes the steering member 24, the lift operation lever 36, the tilt operation lever 37, the forward / reverse switching lever 38, the accelerator pedal. 41, the brake pedal 42, the clutch pedal 43, and the confirmation mirror 39 are included. However, the present invention is not limited to this, and the unit 11 only needs to include at least the driver's seat 10.

  In addition, it may be prohibited to load the fork 17 and lift the fork 17 in a state where the unit 11 is moved to the front position when empty. Specifically, when the load W detected by the load sensor 80 exceeds the predetermined value W1 when it is detected that the lift operation lever position sensor 59 is in the lift operation position (when it is not empty). May control the elevating control valve 63 so as to prohibit the supply of hydraulic oil to the lift cylinder 21. In addition, various modifications can be made within the scope of the claims of the present invention.

1 is a schematic side view showing a schematic configuration of a forklift as a cargo handling vehicle including a vehicle steering apparatus according to an embodiment of the present invention, showing a state in which a unit including a driver's seat is in a rear position. It is a typical side view which shows schematic structure of a forklift, and has shown the state in which the unit containing a driver's seat exists in a front position. It is a typical side view showing the schematic structure of the steering device for vehicles constituted as steer-by-wire. It is typical sectional drawing which shows the principal part of a unit, a vehicle body, and a unit drive mechanism. It is a schematic sectional drawing of the mechanism which guides a unit. It is a schematic sectional drawing of the mechanism which locks the position of a unit. It is the schematic for demonstrating the principle of operation which raises / lowers a fork. It is a block diagram which shows the electric constitution of a forklift. It is a flowchart which shows the flow of the main control by ECU.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Forklift (cargo handling vehicle), 2 ... Vehicle body, 3 ... Cargo handling device, 4 ... Counterweight, 5 ... Front wheel (drive wheel), 6 ... Rear wheel (steered wheel), 7 ... Drive source, 8 ... Hydraulic pump, 9 DESCRIPTION OF SYMBOLS ... Steering device for vehicles, 10 ... Driving seat, 11 ... Unit, 12 ... Unit drive mechanism, 13 ... ECU (control part), 17 ... Fork (loading part), 18 ... Tilt cylinder, 21 ... Lift cylinder, 24 ... Steering 25, steering actuator, 26 ... reaction force actuator, 27 ... steering angle sensor, 28 ... steering angle sensor, 29 ... support member, 30 ... bearing, 31 ... transmission mechanism, 34 ... unit main body, 34A ... bottom frame, 34B ... side frame, 35 ... operation stand, 36 ... elevating operation lever (operation element), 37 ... tilt operation lever (operation element), 38 ... forward / reverse switching lever (operation element), 39 Confirmation mirror, 40 ... guide mechanism, 41 ... accelerator pedal (operation element), 42 ... brake pedal (operation element), 43 ... clutch pedal (operation element), 44 ... guide rail (guide member), 45 ... support shaft, 46 ... rolling members (guided members), 47 ... actuators for unit slides, 48 ... transmission mechanisms, 50 ... pinions, 51 ... racks, 52 ... lock mechanisms, 53 ... lock members, 53a ... main bodies, 53b ... lock shafts, 54 DESCRIPTION OF SYMBOLS 1st lock hole, 55 ... 2nd lock hole, 61 ... Forward / backward changeover switch (reverse detection means. Advance detection means), 62 ... Solenoid for lock mechanism, 80 ... Load sensor, 81 ... Unit slide position sensor 85 ... Release operation switch, X1 ... Slide direction

Claims (4)

In a vehicle steering apparatus for steering a cargo handling vehicle provided with a cargo handling device at the front of the vehicle body and with a counterweight at the rear of the vehicle body,
A steering member;
A steering actuator that generates a steering force for steering the rear wheel as a steered wheel in accordance with an operation of the steering member;
A unit including at least a driver's seat and supported by the vehicle body so as to be slidable in a sliding direction along a longitudinal direction of the vehicle;
A drive mechanism for moving the unit along the sliding direction;
A load sensor for detecting a load received by the cargo handling device;
When it is detected load less than a predetermined value by the load sensors, the unit so as to slide forward the sliding direction, the vehicle steering apparatus characterized by comprising a control unit for controlling the drive mechanism . Oite to claim 1, a vehicle steering system, characterized in that it comprises a locking mechanism for locking the position of the unit. The vehicle steering apparatus according to claim 1 or 2, wherein the unit includes a cargo handling apparatus. In any one of claims 1 to 3, the steering member and the vehicle steering apparatus characterized by mechanical connection is broken between the rear wheels as steered wheels.

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