JP2005082366A - Tilt structure of fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tilt structure of an elevating carriage without arranging a hydraulic piping, an electric wire, and the like around outside of the elevating carriage. <P>SOLUTION: This tilt structure of a fork 2 tilting the fork 2 turning around a vertical shaft 3 comprises a tilt means capable of reciprocating near a rear part of the fork 2, and a drive force transmission means reciprocating the tilt means by a drive force from an electric drive source. The drive force transmission means is accommodated in the vertical shaft 3, so as to tilt the fork according to the reciprocating movement of the tilt means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lift carriage for a forklift having a fork tilt function.

A forklift V shown in FIG. 5A has a sub mast M attached to a cab S that moves up and down along a main mast N so that the sub mast M can be shifted. A fork F is attached to C. The lift carriage C moves up and down while being guided by the mast M based on an operator's command, and the fork F is turned upright for rotation so that the fork F is lateral to the forklift V as shown in FIG. It is swiveled (rotated) around the axis R. Further, the elevating carriage C can tilt the fork F in the direction of arrow Y. If the elevating carriage C itself moves horizontally in the vehicle width direction of the forklift V, the fork F shifts accordingly. . Such a technique is disclosed in the following patent documents.
Japanese Utility Model Publication No. 55-172297 JP-A-5-254790

  The three-way stacker forklift V includes a tilting means H mainly composed of a hydraulic cylinder for tilting the fork F, and ensures a distance from the pivot point P for tilting the fork F to the operating point of the tilting means H. In order to achieve this, the tilt means H must be disposed below the upright shaft R for rotation, that is, outside the lifting carriage C. For this reason, it is inevitable that the hydraulic piping for supplying hydraulic pressure from the hydraulic pump (not shown in the figure) built in the lifting carriage C to the tilt means H is exposed to the outside of the lifting carriage C, and the hydraulic piping is lifted and lowered. There is a risk of being caught in a luggage or the like carelessly during the operation of Cage C. In addition, hydraulic oil may leak from the joints of the hydraulic piping.

  Furthermore, the portion of the hydraulic piping exposed from the lift carriage C needs to be loosened to some extent and bend gently so that the hydraulic piping can be freely bent or deformed. There is a problem that the hydraulic piping exposed in such a slack state obstructs the field of view of the operator who has entered the cab S at the rear of the mast M. The above problem is the same even when an electric motor is applied instead of the tilting means. That is, an electric wire that supplies electric power to the electric motor may be caught on a load or the like, or the electric wire may obstruct the operator's view.

  In view of the above problems, an object of the present invention is to provide a tilt structure of a fork that does not route hydraulic piping, electric wires, and the like outside the lifting carriage.

  The present invention relates to a tilt structure of a fork that tilts a fork that swings around an upright shaft, and includes tilting means that can move forward and backward in the vicinity of the rear portion of the fork and a driving force from an electric drive source. Drive force transmission means for moving the tilt means forward and backward, and the drive force transmission means is housed in the upright shaft, and the fork is tilted according to the forward and backward movement of the tilt means.

  The present invention relates to a rotating upright shaft that is supported in an upright posture on a lifting carriage, a tilt horizontal shaft that is connected to the upright shaft and protrudes at both ends in a horizontal direction from the upright shaft, and a rear end is supported by the horizontal shaft And a fork having a tip extending horizontally and a tilting means coupled to the upright shaft at a position spaced downward from the horizontal axis and extending and contracting in a direction intersecting the horizontal axis, the tilting means extending and contracting. According to an operation, the fork has a tilt structure for rotating the fork in a direction in which the tip moves up and down with the horizontal axis as a fulcrum, wherein the tilt means has one end pin-connected to the upright shaft. A first node whose other end is pivotable around the one end, a second node whose one end is close to the fork and the other end is pivotable around the one end, and the first and second nodes. Pin each other end An advancing / retreating rod connected to the joint and a driving device for moving the advancing / retreating rod back and forth, and moving the advancing / retreating rod back and forth to displace the slide; The distance from the one end of the second node is expanded and contracted.

  Further, in the tilt structure of the fork according to the present invention, the drive device of the tilt means includes a screw rod that vertically passes through the axis of the upright shaft, a drive source for rotating the screw rod, and the upright shaft. A nut inserted into the screw thread and screwed into the screw rod, connecting the advance / retreat rod to the nut, and rotating the screw rod with the drive source to move the interior of the upright shaft in the vertical direction. The forward / backward rod is moved forward and backward in accordance with the nut to be displaced.

  Further, in the tilt structure of the fork according to the present invention, the fork raises the rear end to form an upright piece having an upper end, and the upper end is supported between both ends of the horizontal shaft. The tilt bar is formed by connecting the upper end of each arm portion to the bearing portion and swinging pieces between the lower ends, and the bearing portion is pivotally connected to both ends of the horizontal shaft. A piece is suspended below the horizontal shaft, the swinging piece is brought close to the upright piece of the fork from the rear end side, and one end of the second section of the tilt means is pinned to the swinging piece of the tilt bar. It is characterized by being joined.

  The present invention also provides a rotating upright shaft that is supported by the elevating carriage in an upright posture, a tilt horizontal shaft that is connected to the upright shaft in a horizontal posture, a rear end supported by the horizontal shaft, and a front end horizontally. By extending the fork and pressing the fork in a direction intersecting the horizontal axis at a position spaced downward from the horizontal axis, the fork is moved up and down with the horizontal axis as a fulcrum. A tilt structure of a fork including a tilt means for rotating in a direction to rotate, wherein the tilt means rotates together with a worm rotated by a driving source, a worm wheel meshing with the worm, and the worm wheel. And a cam for pressing the fork in a direction intersecting the horizontal axis.

  Furthermore, the tilt structure of the fork according to the present invention is characterized in that the worm is connected to the drive source via a drive shaft that vertically penetrates the axis of the upright shaft.

  In the tilt structure of the fork according to the present invention, the tilting means can be moved forward and backward by transmitting the driving force generated by the electric drive source to the tilting means via the driving force transmitting means. Since such a tilting means is close to the rear part of the fork, the fork can be tilted by causing the rear part of the fork to follow the movement of the tilting means. Therefore, it is not necessary to supply hydraulic pressure from the hydraulic pump to the drive source for directly driving the fork as in the prior art, so that the hydraulic piping does not interfere with the cargo handling operation or disturb the operator's view. Moreover, by storing the driving force transmission means on the upright shaft, it is possible to achieve space saving of the tilt structure.

  According to the tilt structure of the fork according to the present invention, the distance between the one end of the first joint and the one end of the second joint is expanded and contracted by moving the forward / backward rod back and forth to displace the sliding joint, and according to this operation. Since the fork is tilted, there is no need to dispose a conventional drive source such as a hydraulic cylinder or the like outside the lift carriage, and the drive source can be stored in a proper position in the lift carriage.

  Accordingly, it is not necessary to expose the hydraulic piping for supplying hydraulic pressure from the hydraulic pump to the drive source and the electric wires for supplying electric power to the electric motor, etc. as in the prior art. The problem of inadvertently getting caught in luggage does not occur. In addition, the problem that hydraulic piping, electric wires, and the like obstruct the operator's field of view can be solved, and the operator's field of view can be secured satisfactorily. In addition, since it is not necessary to expose the hydraulic piping to the outside of the lifting carriage, the baggage is not damaged due to oil leakage from the joint of the hydraulic piping.

  Furthermore, according to the tilt structure of the fork according to the present invention, the nut inserted into the upright shaft is screwed into the screw rod that penetrates the shaft of the upright shaft in the vertical direction. When rotated by the power source, the advance / retreat rod moves forward and backward in the vertical direction together with the nut. Thereby, the space | interval of the end of 1st node and the end of 2nd node can be expanded-contracted, and a fork can be tilted according to this operation | movement. And since the above-mentioned screw rod and nut can be stored inside the existing upright shaft, it is not necessary to secure a space for storing the screw rod and nut inside the lifting carriage, which contributes to downsizing of the lifting carriage. There are advantages.

  Further, according to the tilt structure of the fork according to the present invention, the fork raises its rear end to form an upright piece having an upper end, and the upper end is supported between both ends of the horizontal shaft, Since the bearing part is pivotally connected to both ends of the horizontal shaft, and the swinging piece of the tilt bar suspended below the horizontal shaft is close to the upright piece of the fork from the rear end side, the fork As long as it is between both ends of the horizontal axis, the fork can be reliably tilted in accordance with the movement of the tilting means regardless of the position of the fork. In addition, the tilt bar hardly obstructs the operator's field of view and can ensure a good field of view of the operator.

  Furthermore, according to the tilt structure of the fork according to the present invention, the worm is meshed with the worm that is rotated by the drive source, and the fork is pressed in the direction intersecting the horizontal axis by the cam that rotates together with the worm wheel. Since tilting is performed, it is not necessary to dispose a drive source such as a hydraulic cylinder outside the lifting carriage as in the prior art, and it is possible to store the driving source in a proper position in the lifting carriage.

  Accordingly, it is not necessary to expose the hydraulic piping for supplying hydraulic pressure from the hydraulic pump to the drive source and the electric wires for supplying electric power to the electric motor, etc. as in the prior art. The problem of inadvertently getting caught in luggage does not occur. Further, it is possible to solve the problem that the hydraulic piping, electric wires, and the like obstruct the operator's view, and to ensure a good operator's view. In addition, when the cam has a long shape extending along the horizontal axis, if the fork is between both ends of the horizontal axis, the fork is securely pressed by such a cam regardless of the position of the fork. Can be tilted. Further, even if a load is applied to the fork and the worm wheel tries to rotate, the rotation is prevented by the worm. For this reason, even if a brake device or the like is not added, the fork is not tilted carelessly with a load placed on the fork.

  Furthermore, in the tilt structure of the fork according to the present invention, since the worm is connected to the drive source via the drive shaft that vertically penetrates the axis of the upright shaft, a space for storing the drive shaft is particularly provided in the lifting carriage. There is no need to ensure, and there is an advantage that it contributes to downsizing of the lifting carriage.

  The present embodiment relates to a tilt structure of a fork that tilts a fork that turns around an upright shaft. The tilt means is capable of moving forward and backward near the rear part of the fork, and the tilt means And a driving force transmitting means for transmitting a driving force generated by a general driving source, and the driving force transmitting means is housed in the upright shaft. Details will be described below with reference to the drawings.

  As shown in FIGS. 1 and 2, the tilt structure according to the present embodiment includes a fork 2 that extends from the lift carriage 1 and handles cargo, and an upright shaft 3 for rotation that is supported by the lift carriage 1 in an upright posture. The tilting horizontal shaft 4 is connected to the upright shaft 3 in a horizontal posture and supports the rear end 20 of the fork 2, and the tilt means 6 is coupled to the upright shaft 3 via a T-shaped bracket 5. ing.

  The main body of the lift carriage 1 is engaged with a mast 101 raised on a forklift chassis or the like via a plurality of rollers 102 so as to be movable in the vertical direction. The base portion 103 fixes a pair of horizontal rails 104 extending in the vehicle width direction, and further fixes two rack gears 105 extending in the vehicle width direction to the pair of horizontal rails 104, respectively. On the other hand, a plurality of groove portions 106 are formed in each of the pair of horizontal rails 104. Rollers (same reference numerals) are engaged in these groove portions 106, and the head portion 107 is attached to the base portion 103 through the rollers so as to be movable in the vehicle width direction.

  The head unit 107 includes a main shaft 109 provided with a pair of pinions 108 that mesh with the two rack gears 105, a first hydraulic motor 110 that engages an output shaft pinion 119 with one of the pair of pinions 108, and an upright shaft. 3 is provided with a second hydraulic motor 112 that applies a rotational force via a gear train 111. These first and second hydraulic motors 110 and 112 are driven in a timely manner by hydraulic pressure supplied from a hydraulic pressure generating unit that is on the left side in the figure and does not appear in the figure.

  As shown in FIG. 1, the upright shaft 3 is formed with a flat surface portion 30 at a portion directed to the fork 2 on its peripheral surface, and the flat surface portion 30 is formed into a T shape using a plurality of screws 31 shown in FIG. 2. The bracket 5 is fixed. The T-shaped bracket 5 is a substantially T-shaped structure in which a plurality of pieces of steel plates or steel strips are joined together by welding. The horizontal shaft 4 is inserted into a corresponding position between the end plates 51 at both ends of the horizontal extension portion 50 and the column portion 52 extending downward from the central portion in the longitudinal direction of the horizontal extension portion 50. Each bearing hole 53 is formed.

  The tilt means 6 is composed of a mechanism portion that expands and contracts in a direction intersecting the horizontal axis 4 and its prime mover. Specifically, as shown in FIGS. 1 and 3, the tilting means 6 has a pair of first members that are joined to the lower end of the upright shaft 3 with one end 70 by a pin 71 and the other end 72 can pivot about the pin 71. The first joint 7 includes a pair of second joints 8 having one end 80 joined to the tilt bar 18 by a pin 81 and the other end 82 pivotable about the pin 81, an advancing / retracting rod 11, and a driving device 12. Has been.

  In the first joint 7 and the second joint 8, the other ends 72 and 82 are joined by a pin 90, thereby forming a V shape. The portion joined by the pin 90 is the smooth joint 9, and one end (lower end) 211 of the advance / retreat rod 11 is joined via the joint 91 in the vicinity of the smooth joint 9. The pin 71 is fixed to a stay 710 suspended from the lower end of the upright shaft 3. In the above description, an example in which the first joint 7 and the second joint 8 are respectively paired is shown, but these may be provided one by one as long as a desired rigidity can be ensured.

  The drive device 12 is inserted into the upright shaft 3, a screw rod 120 that penetrates the axis of the upright shaft 3 in the vertical direction indicated by an arrow Z in the drawing, a drive source 121 that revolves the screw rod 120, and the upright shaft 3. A nut 13 screwed to the screw rod 120 is provided. The screw rod 120, the nut 13, and the advance / retreat rod 11 described here correspond to the driving force transmitting means described above. The nut 13 is composed of a female screw formed at the other end (upper end) of the advance / retreat rod 11. By inserting the pin 92 of the joint 91 into the lower end 211 of the advance / retreat rod 11, these are pin-joined. A pin 73 is attached in the vicinity of the smooth joint 9. By inserting the pin 73 into the pin insertion hole 93 of the joint 91, the joint 91 may be pin-joined to the first joint 7, but the pin 73 is omitted and the pin 90 is inserted into the pin insertion hole 93. The joint 9 may be directly pin-joined to the joint 91 by being inserted.

  As shown in FIG. 1, the drive source 121 is mainly composed of an electrical drive source such as an electric motor, and is provided on a drive pulley 123 provided on the output shaft 122 and a screw rod 120 protruding from the upper end of the upright shaft 3. The driven pulley 124 and an endless belt 125 that transmits the rotational force generated by the driving source 121 from the driving pulley 123 to the driven pulley 124 are provided. In addition, as the drive source 121, a hydraulic motor driven by the hydraulic pressure supplied from the above-described hydraulic pressure generation unit may be applied.

  The fork 2 has a rear end 20 formed to form an upright piece 22 and a load receiving portion 23 extending from the upright piece 22 to the front end 21 and has a substantially L-shape as a whole. A steel pipe (same symbol) is welded to the upper end portion of the rear end 20 of the fork 2, and the rear end 20 of the fork 2 is rotatably supported by the horizontal shaft 4 with the horizontal shaft 4 inserted through the steel pipe. Has been. Further, as shown in FIG. 2, the carriage structure has a pair of arm portions 180 as upper ends of bearings 181 that can be rotatably inserted at both ends of the horizontal shaft 4, and between the lower ends thereof. A tilt bar 18 is provided which is connected by a swing piece 182 extending in the vehicle width direction. A bracket 810 is welded to the surface of the swing piece 182 opposite to the fork 2.

  As described above, in a state where the upper ends of the pair of arm portions 180 are pivotally connected to both ends 40 of the horizontal shaft 4, the swing piece 182 is suspended below the horizontal shaft 4, The upright piece 22 is in contact with the load receiving portion 23 from the opposite side. Further, by fixing the pin 81 to the bracket 810, one end 80 of the second joint 8 is pin-connected to the swinging piece 182 of the tilt bar 18.

  Next, an operation related to the carriage structure will be described. First, when the drive source 121 is activated and the screw rod 120 is rotated forward, the nut 13 is displaced upward in the upright shaft 3. When the entire advance / retreat rod 11 rises according to the nut 13, the smooth joint 9 is displaced upward in the figure according to the advance / retreat rod 11, and the distance d between the one ends 70, 80 of the first joint 7 and the second joint 8 is set. Elongate. As a result, the one end 80 of the second joint 8 exerts a force in a direction in which the one end 80 of the second joint 8 is pressed against the upright piece 22 of the fork 2 via the pin 81, the bracket 810, and the swing piece 182 of the tilt bar 18. Therefore, the fork 2 has an inclined posture in which the tip 21 is raised with the horizontal shaft 4 as a fulcrum.

  On the contrary, when the drive source 121 is activated in the opposite direction to reverse the screw rod 120, the nut 13 is displaced downward in the upright shaft 3. When the entire advancing / retreating rod 11 is lowered according to the nut 13, the smooth joint 9 is displaced downward in the figure according to the advancing / retreating rod 11, and the distance d between the one ends 70, 80 of the first joint 7 and the second joint 8 is set. Shorten. As a result, the swinging piece 182 of the tilt bar 18 moves backward in the direction away from the upright piece 22 of the fork 2, and the pressing force is removed, so that the fork 2 has a tilted posture in which the tip 21 side is lowered by its own weight. Become. Along with this, the swing piece 182 of the tilt bar 18 is also pushed back.

  In the above description, the operating rod 61, the swinging piece 182 and the upright piece 22 are simply brought into contact, but these contacts may be pin-joined or the like. Thereby, even when the fork 2 rotates in any of the above directions, the fork 2 can be forcibly driven in accordance with the expansion / contraction amount of the interval d. FIG. 2 shows four forks 2, which suggests that the fork 2 can be slid along the horizontal axis 4 by removing the pin 24 from the upper part of the rear end 20. ing. By sliding the fork 2 in this way, the swing piece 182 always abuts against the upright piece 22 wherever the fork 2 is positioned between both ends 40 of the horizontal shaft 4, so that the distance d is expanded and contracted. Then, the fork 2 tilts accordingly.

  In order to perform the shift operation of the fork 2, the first hydraulic motor 110 is activated, and the head portion 107 of the lifting carriage 1 travels in the vehicle width direction. In order to rotate the fork 2, the second hydraulic motor 112 is activated to rotate the upright shaft 3, and the fork together with the T-shaped bracket 5 and the tilt bar 18 is rotated along with the rotation of the upright shaft 3. Turn 2 At this time, as the upright shaft 3 rotates, the first joint 7 and the second joint 8 also turn together. When the turning range reaches 180 °, the nut 13 rotates 180 ° relative to the screw rod 120, and the fork 2 is slightly tilted regardless of the will of the operator. . Therefore, it is desirable to rotate the screw rod 120 by the drive source 121 in the same direction as the fork 2 is turned.

  Next, a second embodiment will be described with reference to FIG. The components of the embodiments already described are not shown in the figure, but are given the same reference numerals in the following description. The tilt structure according to the second embodiment includes a rotating upright shaft 3 that is supported by the elevating carriage 1 in an upright posture, a tilting horizontal shaft 4 that is connected to the upright shaft 3 in a horizontal posture, and the horizontal shaft 4. The fork 2 is supported by the rear end 20 and the tip 21 extends horizontally, and the tilt means 14 is coupled to the upright shaft 3 at a position spaced downward from the horizontal shaft 4.

  The tilt means 14 rotates together with the worm 15, the worm wheel 16 that meshes with the worm 15, and presses the upright piece 22 of the fork 2 in a direction intersecting the horizontal axis 4, for example, toward the tip 21 of the fork 2. It consists of a body cam 17. The worm 15 is fixed to the lower part of the drive shaft 150 that penetrates the axis of the upright shaft 3 in the vertical direction. A driven pulley 124 for inputting a rotational force from the drive source 121 described above is fixed to the upper end of the drive shaft 150. One camshaft 170 extends on each side of the worm wheel 16, and one cam 17 is formed on each of the two camshafts 170. Although not shown, brackets for bearing appropriate positions of the two camshafts 170 are respectively provided at the lower part of the column portion 52 of the T-shaped bracket 5.

  It should be noted that the present invention can be implemented in a mode in which various improvements, modifications, or variations are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

  According to the present invention, when the lifting carriage mounted on the three-way stacker forklift includes a mechanism for tilting the fork, the lifting carriage can be reduced in size regardless of the size or standard of the mechanism. Moreover, the present invention can ensure good visibility of the operator and improve the safety of cargo handling work using a forklift.

The side view which shows the structure inside the raising / lowering carriage which concerns on 1st Example of this invention. 1 is a front view showing a tilt structure of a fork according to a first embodiment of the present invention. The perspective view of the principal part of the tilt structure of the fork which concerns on 1st Example of this invention. The perspective view of the principal part of the tilt structure of the fork which concerns on 2nd Example of this invention. (A) is a side view of a forklift to which a tilt structure of a conventional fork is applied, and (b) is a perspective view of an essential part thereof.

Explanation of symbols

1: Lifting carriage 2: Fork 3: Upright shaft 4: Horizontal shaft 6: Tilt means 7: First section 8: Second section 9: Sliding joint 11: Retracting rod 12: Drive device 13: Nut 14: Tilt means 15: Worm 16: Worm wheel 17: Cam 18: Tilt bar 20: Rear end 21: Front end 22: Upright piece 23: Load receiving part 40: Both ends 120: Screw rod 121: Drive source 180: Arm part 181: Bearing part 182: Swing Fragment

Claims (6)

  A tilt structure of a fork that tilts a fork that swings around an upright shaft, the tilt means being capable of moving back and forth close to the rear of the fork, and the tilting means moving forward and backward with a driving force from an electric drive source A tilting structure for the fork, wherein the driving force transmitting means is housed in the upright shaft, and the fork is tilted according to the forward and backward movement of the tilting means. Rotating upright shaft that is supported in an upright posture on the lift carriage, a tilt horizontal shaft that is connected to the upright shaft and protrudes from the upright shaft in the horizontal direction, a rear end supported by the horizontal shaft, and a front end horizontally And a fork extending from the horizontal axis at a position spaced downward from the horizontal axis and extending and contracting in a direction intersecting the horizontal axis. A tilt structure of the fork for rotating the fork in a direction in which the tip moves up and down with the horizontal axis as a fulcrum,
The tilt means has a first joint pinned at one end to the upright shaft and the other end pivotable around the one end, and a second node pivotable around the one end with the other end pivoted around the one end. And a forward / backward rod connected to a smooth joint formed by pin-joining the other ends of the first and second clauses, and a drive device for moving the forward / backward rod back and forth. A fork tilt structure characterized in that the distance between the one end of the first joint and the one end of the second joint is expanded and contracted by moving the joint to move.   A drive device for the tilt means includes a screw rod that passes through the axis of the upright shaft in the vertical direction, a drive source for rotating the screw rod, and a screw inserted into the upright shaft and screwed into the screw rod. A nut, and the advance / retreat rod is connected to the nut, and the screw rod is rotated by the drive source, so that the inside of the upright shaft is moved in accordance with the nut vertically displaced, and the advance / retreat rod is The tilt structure of a fork according to claim 2, wherein the tilt structure is moved back and forth in the vertical direction. The fork raises the rear end to form an upright piece having an upper end, and the upper end is supported between both ends of the horizontal shaft,
Tilt bars formed by connecting the upper ends of the pair of arm portions with the bearing portions and connecting the lower ends with swinging pieces respectively connect the bearing portions to both ends of the horizontal shaft so as to be rotatable. The moving piece is suspended below the horizontal shaft, the swinging piece is brought close to the upright piece of the fork from the rear end side,
The tilt structure of the fork according to claim 2 or 3, wherein one end of the second node of the tilt means is pin-joined to a swing piece of the tilt bar. An upright shaft for rotation supported in an upright posture on the lifting carriage, a horizontal shaft for tilt connected in a horizontal posture to the upright shaft, a fork having a rear end supported horizontally on the horizontal shaft and a tip extending horizontally; By pushing the fork in a direction that is coupled to the upright shaft at a position spaced downward from the horizontal axis and intersects the horizontal axis, the fork is rotated in the direction in which the tip moves up and down with the horizontal axis as a fulcrum. A fork tilt structure comprising a tilt means,
The fork includes a worm that is rotated by a driving source, a worm wheel that meshes with the worm, and a cam that rotates together with the worm wheel and presses the fork in a direction intersecting the horizontal axis. Tilt structure.   6. The tilt structure of a fork according to claim 5, wherein the worm is connected to the drive source via a drive shaft that vertically passes through the axis of the upright shaft.

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