Patent Publication Number: US-2003230920-A1

Title: Seat apparatus for industrial vehicle

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the invention  
       [0002] The present invention relates to a seat apparatus for an industrial vehicle, such as fork lift. More particularly, the invention relates to a seat apparatus which can suppress reduction of the operationality of a traveling manipulating device in case of rotating a seat for the purpose of ensuring rearward visibility at the retreat of the industrial vehicle.  
       [0003] 2. Description of the Related Art  
       [0004] Japanese Patent Application Laid-open No. 2000-318498 discloses a conventional seat apparatus of this kind.  
       [0005] In this seat apparatus, for the purpose of preventing the reduction in operationality of various pedals since an operator&#39;s foot gets away from the pedals in rotating a rotatable seat in order to ensure rearward visibility with ease at a vehicle&#39;s retreating, the rotating center of the rotatable seat is positioned in front of a seat cushion. Thus, in order to facilitate an operator&#39;s manipulating of various pedals, the seat apparatus is constructed so as to reduce a movement of an operator&#39;s foot as possible even if rotating the seat at a predetermined angle.  
       SUMMARY OF THE INVENTION  
       [0006] In the above conventional device, however, there is a limitation to enlarge the rotating angle of the seat since the device is directed to ensure an operator&#39;s operationality of the pedals despite rotation of the seat, causing a possibility that it becomes difficult for an operator to take a manipulating amount to ensure rearward visibility at a vehicle&#39;s going back.  
       [0007] The present invention is provided to solve the above-mentioned problem. An object of the present invention is to provide a seat apparatus for an industrial vehicle, which can take a driving posture enabling an operator to ensure an operator&#39;s backward visibility when the industrial vehicle moves back.  
       [0008] According to the present invention, the above-mentioned object is accomplished by a seat apparatus for an industrial vehicle, the seat apparatus comprising:  
       [0009] an accelerator pedal for controlling a vehicle traveling unit;  
       [0010] a seat rotatably supported on a vehicle body through a rotating mechanism, for controlling a rotating position of the seat in relation to the vehicle body; and  
       [0011] an accelerator manipulating unit arranged about the seat, for allowing an operator to operate the vehicle traveling unit manually in place of the accelerator pedal. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012]FIG. 1 is a layout view showing a seat apparatus for an industrial vehicle in accordance with the first embodiment of the present invention;  
     [0013]FIG. 2 is a front view of the seat apparatus of FIG. 1;  
     [0014]FIG. 3 is a side view of the seat apparatus of FIG. 1;  
     [0015]FIG. 4 is a plan view of a rotating mechanism of the seat apparatus of FIG. 1;  
     [0016]FIG. 5 is a sectional view of the rotating mechanism of FIG. 4;  
     [0017]FIG. 6 is an exploded view of the seat apparatus;  
     [0018]FIG. 7 is an exploded perspective view of an accelerator interlocking unit;  
     [0019]FIG. 8 is a front view of the accelerator interlocking unit;  
     [0020]FIG. 9 is a perspective view of the rotating mechanism while the seat apparatus is in neutral;  
     [0021]FIG. 10 is a layout view showing the relationship in position between pedals and the seat apparatus in neutral;  
     [0022]FIG. 11 is perspective view of the rotating mechanism when the seat apparatus is in its backward rotational position;  
     [0023]FIG. 12 is a layout view showing the relationship in position between the pedals and the seat apparatus in its backward rotational position;  
     [0024]FIG. 13 is a layout view showing the relationship in position between the pedals and the seat apparatus in its position for an operator to get on and off;  
     [0025]FIG. 14 is a side view showing accelerator operating means of a seat apparatus for an industrial vehicle in a modification of the invention;  
     [0026]FIG. 15 is a side view showing an accelerator pedal of the seat apparatus of FIG. 14; and  
     [0027]FIG. 16 is a circuit diagram of the seat apparatus of FIGS. 14 and 15. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0028] Referring to accompanying drawings, an embodiment of the present invention will be described below.  
     [0029] FIGS.  1  to  8  show one example of a seat apparatus for an industrial vehicle on the application of the present invention. FIG. 1 is a layout view of the seat apparatus. FIG. 2 is a front view of the seat apparatus. FIG. 3 is a side view of the seat apparatus. FIG. 4 is a plan view of a rotating mechanism of the seat apparatus. FIG. 5 is a sectional view of the rotating mechanism of FIG. 4. FIG. 6 is an exploded view of the seat apparatus. FIG. 7 is an exploded perspective view of an accelerator interlocking unit. FIG. 8 is a front view of the accelerator interlocking unit.  
     [0030] As shown in FIGS.  1  to  3 , a seat  1  of a fork lift is mounted on an upper surface of a top panel  3  (engine hood) forming part of a vehicle body  2 , through seat slides  4  and a rotating mechanism  5 . In a variation, a suspension  6  may be interposed between the rotating mechanism  5  and the seat  1 . The seat slide  5  fixes the rotating mechanism  5  and the seat  1  on the top panel  3  slidably in the fore-and-aft direction of the vehicle (fork lift). The seat  1  includes a seat cushion  1 A providing a seat face, a seat back  1 B and hip supports  1 C for supporting an operator&#39;s hip. The seat  1  is also equipped with an accelerator lever  10  as an accelerator operating unit. The accelerator lever  10  is connected with a not-shown throttle valve of an engine (not shown) through the intermediary of an accelerator wire  11  and an accelerator interlock  12 . As is well known, on a floor in front of the seat, there are generally arranged an accelerator pedal  7 , a brake pedal  8  and a clutch pedal (or an inching pedal)  9 , in order from the right side of the vehicle.  
     [0031] As shown in FIGS.  4  to  6 , the rotating mechanism  5  includes a base plate  15  connected with the seat slides  4 , a rotating plate  16  connected with the seat  1  and a bearing mechanism  17  formed by a taper roller bearing  17 A that supports the rotating plate  16  in relation to the base plate  15  rotatably. The bearing mechanism  17  interposes the taper roller bearing  17 A between a boss  15 A projecting from the base plate  15  and a hub  16 A of the rotating plate  16 . The taper roller bearing  17 A includes an inner race  17 B having a conical pitch face having its upper part of a small diameter, and an outer race  17 C. In assembly, the inner race  17   b  is fitted to the outer periphery of the boss  15 A, while the outer race  17 C is fitted to the inner periphery of the hub  16 A. In order to prevent the inner race  17 B and the outer race  17 C from slipping out, the bearing mechanism  17  further includes a fixing bolt  17 D and a nut  17 E. Between the base plate  15  and the rotating plate  16  around the bearing mechanism  17 , a low-friction sheet  18  is arranged to reduce frictional resistance when the plate  15  makes contact with the plate  16 . The rotating plate  16  and the seat  1  are rotatably supported on the base plate  15  owing to the bearing mechanism  17 . When an offset load is applied from the seat  1 , the rotating plate  16  comes into contact with the low-friction sheet  18  without contacting with base plate  15 , accomplishing the smooth rotation. Owing to the constitution of the base plate  15 , the rotating plate  16  rotatable by the bearing  17  and the low-friction sheet  18  between the plate  15  and the plate  16 , the so-constructed rotating mechanism  5  is provided with a reduced vertical dimension. In the illustrated example, the rotating center of the rotating mechanism  5  is arranged so as to pass through the center part of the seat cushion  1 A. Nevertheless, the rotating center of the rotating mechanism  5  is not always required to coincide with the center part of the seat cushion  1 A and may be shifted to a margin part of the seat cushion  1 A as an intended purpose demands.  
     [0032] For the purpose of suppressing the rotating plate  16  from oscillating in the vertical direction, an oscillation control unit  19  is arranged between the plate  16  and the base plate  15 . As for this oscillation control unit  19 , an arc guide opening  15 B is formed in the front part of the base plate  15  so as to center the bearing mechanism  17 . While, a hole  16 B is formed in the front part of the rotating plate  16 . The oscillation control unit  19  is formed by a bolt  19 A consisting of a shaft part  19 B and a head part  19 C and a nut  19 D. In assembly, the shaft part  19 B of the bolt  19 A is inserted into the guide opening  15 B of the base plate  15  from its underside. Penetrating the rotating plate  16  through the hole  16 B, the shaft part  19 B of the bolt  19 A is screwed into the nut  19 D. In operation, when the rotating plate  16  oscillates apart from the base plate  15 , the head part  19 C of the bolt  19  abuts on the base plate  15 , thereby restricting a further oscillation of the rotating plate  16 . Again, the oscillation control unit  19  has an additional function to define the rotational range of the rotating plate  16  (and the seat  1 ) since the shaft part  19 B of the bolt  19 A can abut on both ends of the guide opening  15 B. In the modification, the bolt  19 A may be replaced with an element having an engagement part similar to the head part  19 C although it is not shown in the figure.  
     [0033] On either side of the rear part of the rotating plate  16  (e.g. right side in the shown example), a bracket  20  having rising sides opposing each other is fixed to the plate  16 . A support shaft  21  having both sides supported by the rising sides of the bracket  20  is arranged in the left-and-right direction of the vehicle. A lock lever  22  is provided with a pair of collars  23  fixed thereto. The collars  23  are rotatably engaged with the support shaft  21 . Thus, the support shaft  21  supports the lock lever  22  rotatably about an axis extending in the left-and-right direction of the vehicle. The lock lever  22  is formed to extend forward along the lateral side of the seat  1  and also provided, at the tip of the lever  22 , with a manipulating grip  22 A. A coil spring  24  is arranged between the collars  23  and the support shaft  21  (or the bracket  20 ) to urge the lock lever  22  in a direction to rotate the grip  22 A downward. The other end of the lock lever  22  is bent so as to penetrate a notch  25  of the rotating plate  16  and project downward, providing a lock pin  27  for engagement with lock grooves  26  of the base plate  15 .  
     [0034] The lock grooves  26  of the base plate  15  are positioned so as to engage with the lock pin  27  of the lever  22  when the rotating seat  1  is in a neutral position, a retreat rotating position and a “passenger&#39;s getting on-and-off” position, respectively. The lock grooves  26  are formed in an circular margin  28  centering the bearing mechanism  17 . Due to urging force of the coil spring  24 , the lock pin  27  engages with a neutral lock groove  26 A when the seat  1  is in the neutral position. When the seat  1  is in the retreat rotating position, the lock pin  27  engages with a retreat lock groove  26 B. When the seat  1  is in the “passenger&#39;s getting on-and-off” position, the lock pin  27  engages with a “passenger&#39;s getting on-and-off” lock groove  26 C. With these engagements of the lock pin  27 , the seat  1  is prohibited from rotating freely. When the seat  1  is in the retreat rotating position, there is established one condition where the shaft part  19 B of the bolt  19 A abuts on one end of the guide opening  15 B of the oscillation control unit  19 . Further, when the seat  1  is in the “passenger&#39;s getting on-and-off” position, there is established another condition where the shaft part  19 B of the bolt  19 A abuts on the other end of the guide opening  15 B of the oscillation control unit  19 . The engagements of the lock pin  27  with the lock grooves  26 A to  26 C can be canceled by rotating the lock lever  22  in opposition to the coil spring  24  by means of the grip  22 A. When the seat  1  is rotated for any length subsequently to the above rotation of the lock lever  22 , the lock pin  27  of the lock lever  22  comes into contact with the circular margin  28 , allowing the seat  1  to be rotated to an operator&#39;s intended position.  
     [0035] As shown in FIG. 3, an accelerator lever  10  (as an accelerator manipulating unit) is pivotally arranged in the vicinity of the grip  22 A. The manipulation on the accelerator lever  10  is transmitted to a throttle lever  30  of an accelerator interlock  12  through an accelerator wire  11  in the form of a pull-cable or a push-pull cable. Together with a shaft  32 , a pedal lever  33  is rotatably supported on a bracket  31 . The accelerator pedal  7  allows this pedal lever  33  to be rotated corresponding to an operating span of the accelerator pedal  7  and also allows a throttle valve (not shown) of an engine to be opened or closed through a lever  34  fixed on the shaft  32  and a pull (or push-pull) wire  35 . The throttle lever  30  is rotatably supported on the shaft  32  of the pedal lever  33 . Since the throttle lever  30  is provided, at an intermediate part thereof, with a claw  30 A for engagement with the other end of the pedal lever  33 , the manipulation of the lever  33  allows the throttle valve of the engine to be operated. That is, according to the embodiment, the throttle valve of the engine can be controlled by both of the accelerator pedal  7  and the accelerator pedal  10 . Noted that although the accelerator lever  10  forms the accelerator manipulating unit in the above description, it may be formed by a rotary-type manipulator to rotate the grip  22 A or a joy-stick type manipulator both not shown in the figure. Further, as for the grip(rotary)-type manipulator or the joy-stick type manipulator, an operating span thereon may be converted to electrical signals to drive a not-shown motor etc. for actuating the accelerator interlock  12  mechanically.  
     [0036] As shown in FIGS. 7 and 8, the accelerator interlock  12  includes a vacuum actuator  36  having a rod  38 . When the vacuum actuator  36  is in an inactivated state, the rod  38  is urged by a built-in spring  37  to occupy its forward position. When the vacuum actuator  36  is activated, the rod  38  is moved to its backward position in opposition to the built-in spring  37 . In the forward position, the rod  38  intersects with a rotational track of the throttle lever  30  to engage with a hole  31 A formed in the bracket  31 , thereby preventing the throttle lever  30  from moving in a direction to open the throttle valve. The vacuum actuator  36  is driven by negative pressure supplied from a vacuum switching valve  39 .  
     [0037] The vacuum switching valve  39  includes an output port  39 A communicating with the actuator  36 , an atmospheric port  39 B communicating with atmospheric air and a vacuum port  39 C communicating with an intake manifold of the engine. When a solenoid  40  is inactivated, the atmospheric port  39 B communicates with the output port  39 A, so that the actuator  36  is brought into the inactivated state. When the solenoid  40  is activated, the vacuum port  39 C communicates with the output port  39 A, so that the actuator  36  is brought into the activated state. The solenoid  40  is connected with a battery  44  through the intermediary of a seat-rotating detecting switch  43 , a fuse  42  and a key switch  41 . The seat-rotating detecting switch  43  is turned on when the seat  1  is positioned in the retreat rotating position. The solenoid  40  is activated providing that the key switch  41  is turned on and the seat-rotating detecting switch  43  detects the seat  1  in the retreat rotating position. Then, the actuator  36  causes the rod  38  to be withdrawn to allow the rotation of the throttle lever  30 , thereby allowing the opening/closing action of the throttle valve by means of the accelerator lever  10 .  
     [0038] The above-constructed seat apparatus for an industrial vehicle operates as follows.  
     [0039] In the neutral state of the seat  1 , as shown in FIGS. 9 and 10, the lock pin  27  of the lock lever  22  engages in the neutral lock groove  26 A to lock the rotating mechanism  5 , so that an operator takes a seat in the normal posture directing ahead of the vehicle. Accordingly, the operator can manipulate the accelerator pedal  7 , the brake pedal  8 , the inching pedal  9 , etc. to travel the vehicle, as usual. Then, the seat-rotating detecting switch  43  is in OFF state and both of the vacuum switching valve  39  and the actuator  36  are together turned off. Thus, the rod  38  occupies its projecting position to obstruct the action of the throttle lever  30 , thereby establishing a condition disenabling manipulating the throttle valve despite an operator&#39;s manipulation of the accelerator lever  10 .  
     [0040] In case of manipulating the seat  1  from the above state to the retreat rotating position for reverse travel of the vehicle, as shown in FIGS. 11 and 12, an operator pulls up the lock lever  22  by an operator&#39;s right hand. Then, the lock lever  22  rotates about the support shaft  21 , so that the lock pin  27  disengages from the neutral lock groove  26 A and abuts on the bottom of the notch  25  in the rotating plate  16 , whereby the lock lever  22  is prevented from further rotating.  
     [0041] Successively, when an operator twists an operator&#39;s body to the right (in this case), the seat  1  rotates around the taper roller bearing  17 A of the rotating mechanism  5  as the rotating center, smoothly. In this state, since the lock pin  27  bears on the circular margin  28  with the rotation of the seat  1 , it can rotate even if stopping the pulling action of the lock lever  22 . Here, we describe a case of rotating the seat  1  while keeping on pulling up the lock lever  22 . With the rotation of the seat  1 , the bolt  19 A of the oscillation control unit  19  abuts on the end of the guide opening  15 B to obstruct a further rotation of the seat  1 , while the lock pin  27  faces the retreat lock groove  26 B. When stopping pulling up the lock lever  22  in the above state, the lock lever  22  rotates about the support shaft  21  by the coil spring  24  and the lock pin  27  engages in the retreat lock groove  26 B thereby locking the seat  1  in the retreat rotating position. If rotating the seat  1  while stopping pulling up the lock lever  22 , the lock pin  27  engages in the retreat lock groove  26 B at the same time of facing it.  
     [0042] The engagement between the lock pin  27  and the retreat lock groove  26   b  causes the seat-rotating detecting switch  43  to be turned on. As a result, the solenoid  40  of the vacuum switching valve  39  is activated to communicate the vacuum port  39 C with the output port  39 A, so that the vacuum actuator  36  is supplied with negative pressure of an intake manifold of an engine. Then, the vacuum actuator  36  moves the rod  38  back in opposition to the built-in spring  37 , allowing rotation of the throttle lever  30 . Therefore, when an operator manipulates the accelerator lever  10 , the movement is transmitted to the throttle lever of the engine through the accelerator wire  11 , the throttle lever  30 , the claw  30 A, the pedal lever  33 , the shaft  32 , the lever  34 , etc., thereby allowing a vehicle speed etc. to be controlled.  
     [0043] In this state, as shown in FIG. 12, since an operator makes an angle of 40 to 45 degrees with the forward traveling direction of the vehicle, an operator can identify obstacles etc. existing in the backward traveling direction without twisting an operator&#39;s body greatly. On the other hand, an operator&#39;s left foot approaches the brake pedal  8  to enable maintaining to manipulate it, while an operator&#39;s right foot leaves the accelerator pedal  7  greatly to disenable manipulating it. However, owing to the provision of the lock lever  22  accompanied with the accelerator lever  10 , the operator can control a traveling speed of the vehicle by means of the accelerator lever  10  while identifying the backside of the vehicle.  
     [0044] In order to return the seat  1  into the neutral state, it is performed to lower the lock lever  22  to make the lock pin  27  apart from the retreat lock groove  26 B and twist an operator&#39;s body to a neutral direction (left). Then, the operator releases an operator&#39;s hand from the lock lever  22  when the seat  1  begins to rotate. With a further rotation of the seat  1 , it rotates up to its straight state. When the lock pin  27  faces the neutral lock groove  26 A, an urging force of the coil spring  24  allows the lock pin  27  to engage in the neutral lock groove  26 A under lock automatically. As soon as the lock lever  22  is pulled up, the seat-rotating switch  43  is inactivated. Then, the excitation of the solenoid  40  is canceled to release the operation of the vacuum actuator  36 , so that the rod  38  goes ahead to obstruct the action of the throttle lever  30 . That is, in the neutral state of the seat  1 , it becomes possible to control the throttle valve by means of the accelerator pedal  7  only, thereby preventing wrong operation of an operator. In case of continuing the pulling-up operation of the lock lever  33  even after the rotation of the seat  1 , an operator has only to stop the pulling-up operation of the lock lever  22  after confirming the recovery of the seat  1  to the neutral state. Then, it is checked whether the seat  1  is in the neutral state or not. For example, if a detent mechanism is built in the rotating mechanism  5 , then it is possible to attain accurate operation of the lock lever  22 .  
     [0045] In order to change the seat  1  from the neutral state to the “passenger&#39;s getting on-and-off” position, it is performed to pull up the lock lever  22  to make the lock pin  27  apart from the neutral lock groove  26 A and twist an operator&#39;s body toward the “passenger&#39;s getting on-and-off” position. As a result, the seat  1  rotates about the taper roller bearing  17 A of the rotating mechanism  5  smoothly. Since the lock pin  27  faces the circular margin  28  with the rotation of the seat  1 , it can rotate in this state even if stopping the pulling-up operation of the lock lever  22 . Here, we describe a case of rotating the seat  1  while keeping on pulling up the lock lever  22 . With the rotation of the seat  1 , the bolt  19 A of the oscillation control unit  19  abuts on the other end of the guide opening  15 B to obstruct a further rotation of the seat  1 , while the lock pin  27  faces the “passenger&#39;s getting on-and-off” lock groove  26 C. When stopping pulling up the lock lever  22  in the above state, the lock lever  22  rotates about the support shaft  21  by the coil spring  24  and the lock pin  27  engages in the “passenger&#39;s getting on-and-off” lock groove  26 C thereby locking the seat  1  in the “passenger&#39;s getting on-and-off” rotating position. If rotating the seat  1  while stopping pulling up the lock lever  22 , the lock pin  27  engages in the “passenger&#39;s getting on-and-off” lock groove  26 C at the same time when the lock pin  27  faces the groove  26 C.  
     [0046] As shown in FIG. 13, the “passenger&#39;s getting on-and-off” rotating position is mainly utilized in getting on-and-off the vehicle, forming a seat-rotating position facilitating an operator&#39;s getting on-and-off the vehicle. Then, in the accelerator interlock  12 , the actuator  36  is so inactivated that the rod  38  occupies the forward position to obstruct rotating of the throttle lever  30 , disenabling manipulating of the accelerator lever  10 . In case of traveling the vehicle for any reason, since the pedals are not apart from the seat  1  so much, an operator can manipulate the accelerator pedal  7  by an operator&#39;s right foot and also the brake pedal  8  and the inching pedal  9  by an operator&#39;s left foot, allowing traveling of the vehicle.  
     [0047] FIGS.  14  to  16  show a modification of the seat apparatus for an industrial vehicle of the present invention. In the modification, the above-mentioned mechanical accelerator interlock is replaced with an electrical accelerator interlock. FIG. 14 shows the structure in the circumference of an accelerator lever, while FIG. 15 shows the structure in the circumference of an accelerator pedal. FIG. 16 shows the structure of an electrical circuit.  
     [0048] In FIG. 14, a manipulation amount about the accelerator lever  10  is inputted to a rotary encoder  51  through a rod  50 . Then, the rotary encoder  51  converts the manipulating amount about the accelerator lever  10  to an electric signal and further outputs the signal to a controller  52 .  
     [0049] In FIG. 15, a manipulation amount about the accelerator pedal  7  is inputted to a rotary encoder  54  through a rod  53 . Then, the rotary encoder  54  converts the manipulating amount about the accelerator pedal  7  to an electric signal and further outputs the signal to the controller  52 .  
     [0050] The rotary encoder  51  for the accelerator lever  10  is connected with the rotary encoder  54  for the accelerator pedal  7 , as shown in FIG. 16. The encoders  51 ,  54  include variable resistances  51 A,  54 A to which voltages are applied from the controller  52 , respectively. Output voltages from the variable resistances  51 A,  54 A are respectively inputted to a switching relay  55 . The switching relay  55  outputs an output of the rotary encoder  54 , which corresponds to the manipulating amount of the accelerator pedal  7 , to the controller  52  when a built-in solenoid  55 A is not excited. While, when the solenoid  55 A is excited, the switching relay  55  outputs an output of the rotary encoder  51 , which corresponds to the manipulating amount of the accelerator lever  10 , to the controller  52 . The solenoid  55 A of the switching relay  55  is connected to the seat-rotating switch  43  and therefore, the relay  55  is activated when the switch  43  operates. When the seat-rotating switch  43  is turned off, a signal corresponding to a manipulating amount of the accelerator pedal  7  is inputted to the controller  52 . While, when the seat-rotating switch  43  is turned on, a signal corresponding to a manipulating amount of the accelerator lever  10  is inputted to the controller  52 . Then, the controller  52  operates a traveling motor  56  or a brake  57  corresponding to the above signals, thereby controlling the traveling condition of the vehicle.  
     [0051] Also in this modification, since the switching relay  55  generates a signal corresponding to the manipulating amount of the accelerator lever  10  to the controller  52  when the seat-rotating switch  43  detects the seat  1  being rotated to the backward traveling position, an operator can manipulate the accelerator lever  10  on the lock lever  22  while identifying obstacles etc. existing in the backward traveling direction without collapsing an operator&#39;s driving posture, thereby allowing a vehicle&#39;s traveling condition to be controlled corresponding to an operator&#39;s manipulation.  
     [0052] Since the switching relay  55  generates a signal corresponding to the manipulating amount of the accelerator pedal  7  to the controller  52  when it is detected due to the inactivation of the seat-rotating switch  43  that the seat  1  is in the neutral rotating position or the “passenger&#39;s getting on-and-off” rotating position, an operator can control a vehicle&#39;s traveling condition corresponding to an operator&#39;s manipulation on the accelerator pedal  7  while identifying obstacles etc. existing in the forward traveling direction.  
     [0053] According to the embodiment of the invention, it is possible to bring about the following effects.  
     [0054] First, the seat  1  is equipped, in place of the accelerator pedal  7 , with the accelerator lever  10  (as the accelerator manipulating unit) allowing a vehicle traveling unit to be controlled manually. Therefore, even when an operator is getting on the seat  1 , the operator can control the vehicle traveling unit by the accelerator lever  10  manually, allowing a rotating angle of the seat  1  to be increased without taking operationality about the accelerator pedal  7  into consideration. Thus, it is possible to rotate the seat  1  up to an ideal angle required to ensure field of vision at a vehicle&#39;s backward traveling, whereby an operator&#39;s fatigue due to a strained driving posture can be reduced remarkably.  
     [0055] Since the rotating mechanism  5  is formed by the bearing  17  that supports the rotating plate  16  to the base plate  15  rotatably and the low-friction sheet  18  disposed between the base plate  15  and the rotating plate  16  through a clearance while surrounding the bearing  17 , the rotating mechanism  5  can be thinned as a whole, whereby it is possible to suppress raising of a hip point about the seat  1  to the utmost. A load applied on the seat  1  is mostly born by the bearing  17 , while the low-friction sheet  18  bears the load only when the rotating plate  16  is bent. Therefore, the seat  1  can be rotated by only twisting an operator&#39;s body slightly, thereby requiring no motive energy to rotate the seat  1 .  
     [0056] Since an oscillation of the rotating plate  16  allowing it to apart from the base plate  15  is restricted by the oscillation control unit  19 , even if the seat back  1 B is subjected to a great input at breaking etc., it is possible to prevent the rotating plate  16  from lifting, thereby preventing a change in posture of an operator on the seat  1 .  
     [0057] The position of the rotating plate  16  in relation to the base plate  15  can be altered at least between the neutral position and the retreat rotating position and also locked up in each of the neutral position and the retreat rotating position. Furthermore, the lock lever  22  for releasing these locking states is equipped with the accelerator lever  10  as the accelerator manipulating unit. Therefore, it is possible for an operator to manipulate the accelerator lever  10  while gripping the lock lever  22  after the rotation of the seat  1  has been completed, whereby a smooth shifting to the backward traveling can be accomplished, thereby improving the operating efficiency of an operator.  
     [0058] Additionally, if allowing the releasing direction of the lock lever  22  to coincide with the rotating direction of the seat  1 , then an operator&#39;s twisting direction to rotate the seat  1  coincides with the manipulating direction of the lock lever  22 , thereby facilitating rotating of the seat  1  furthermore.  
     [0059] The position of the rotating plate  16  can be altered to the “passenger&#39;s getting on-and-off” rotating position on the opposite side of the retreat rotating position over the neutral position and also locked up in the “passenger&#39;s getting on-and-off” rotating position. Therefore, when the rotating plate  16  is in the “passenger&#39;s getting on-and-off” rotating position, the seat  1  faces in the “passenger&#39;s getting on-and-off” direction, whereby the passenger&#39;s boarding and alighting capability can be improved remarkably. Particularly, the seat apparatus of the embodiment is effective for the latest mainstream hip-support seat for holding an operator.  
     [0060] Since the rotating mechanism  5  is disposed between the seat slide mechanism  4  and the seat  1 , the relationship between a hip point of the seat  1  and its rotating center is usually fixed irrespective of the sliding position of the seat  1 , thereby producing no operator&#39;s sense of discomfort in rotating the seat  1  and also producing a constant power necessary for an operator to rotate the seat  1 .  
     [0061] Since the seat apparatus of the embodiment enables an operator to manually operate the vehicle traveling unit by means of the accelerator lever  10  as the accelerator manipulating unit when the seat  1  is positioned in the retreat rotating position, it is possible to prevent an operator&#39;s wrong operation at a vehicle&#39;s forward movement etc., thereby improving safety.  
     [0062] According to the embodiment of FIGS.  1  to  13 , since the seat apparatus is constructed so that an operator can control the traveling of an industrial vehicle with a throttle valve for drive control by means of the accelerator lever  10  (as the accelerator manipulating unit) communicated with the throttle valve through an accelerator wire  11 , the seat apparatus is suitable for an industrial vehicle, such as fork lift equipped with an engine, and is available at a popular price.  
     [0063] According to the modification of FIGS.  14  to  16 , for an industrial vehicle equipped with at least the electric motor  56  to be controlled by the controller  52 , since the seat apparatus is adapted so as to generate a signal corresponding to an operator&#39;s manipulating amount for accelerator lever  10  (as the accelerator manipulating unit) to the controller  52 . Accordingly, the seat apparatus of the modification is suitable for an electrically-operated industrial vehicle, such as battery-type fork lift. Furthermore, the seat apparatus is available at a popular price and also easy in layout.  
     [0064] Japanese Patent Application No. 2002-155202 is incorporated herein by reference in its entirety.  
     [0065] The scope of the invention is defined with reference to the following claims.