JP5784200B1 - Reach forklift and electric reach cylinder of the forklift - Google Patents

Abstract

A reach-type forklift capable of preventing a ball rolling surface of a ball screw from being damaged by an impact external force and an electric reach cylinder of the forklift are provided. An electric reach cylinder 100A includes an electric motor 20, a transmission belt 40, a ball screw 30 that moves a mast by linear motion, an elastic member, and a tension adjusting unit 10A that adjusts the tension of the transmission belt 40; The tension adjusting unit 10A normally adjusts the tension of the transmission belt 40 by pressing the transmission belt 40 using the return operation of the elastic member, and when an impact external force is applied to the ball screw 30, It is characterized in that the shocking external force is absorbed by relaxing the transmission belt 40 using the compression operation of the elastic member. [Selection] Figure 3

Description

  The present invention relates to a reach-type forklift and an electric reach cylinder of the forklift.

  2. Description of the Related Art Reach-type forklifts that move a mast that is movable in the front-rear direction along a pair of left and right straddle legs by an electric reach cylinder with a preset reach stroke are known (for example, Patent Documents). 1). According to the electric reach cylinder, the mast can be started / stopped smoothly at the front end and the rear end of the reach stroke, and power saving can be achieved.

  As shown in FIG. 10, there are electric reach cylinders for reach forklifts. An electric reach cylinder 100 </ b> C shown in FIG. 10 includes an electric motor 20, a ball screw 30, a transmission belt 40, a housing 50, a pair of bearings 60, and a tension adjusting unit 70.

  The electric motor 20 performs a rotational motion in response to an operation of a reach lever provided in a driver seat of the reach type forklift. The ball screw 30 includes a screw 30a that performs a linear motion, a nut 30b that includes a ball that rolls in a groove (ball rolling surface) of the screw 30a, and a nut 30b that is fixed to the nut 30b and responds to the linear motion of the screw 30a. A large pulley 30c (see FIG. 11) that rotates together with the nut 30b is provided, and the mast is moved in the front-rear direction by the linear motion of the screw 30a. The transmission belt 40 transmits the rotational motion of the electric motor 20 to the large pulley 30 c of the ball screw 30. The housing 50 integrally holds the electric motor 20 and the ball screw 30 arranged side by side in the left-right direction. The pair of bearings 60 supports a pair of left and right shafts provided in the housing 50 so as to be swingable. The tension adjusting unit 70 adjusts the tension of the transmission belt 40.

  As shown in FIG. 11, the tension adjusting unit 70 includes a tensioner link 71 composed of a pair of front and rear plate members, a fixing pin 72 for fixing one end of the tensioner link 71 to the housing 50, and the other end of the tensioner link 71. A roller 73 that presses the transmission belt 40 spanned between the small pulley 20a of the electric motor 20 and the large pulley 30c of the ball screw 30, a bolt and a nut, and a tensioner link 71 at the tip of the bolt. Are adjusted to adjust the position of the roller 73, and a fixing member 75 for fixing the nut of the adjusting screw 74 to the housing 50 is included.

  According to the electric reach cylinder 100 </ b> C, the roller 73 is held at a fixed position by the adjusting screw 74 of the tension adjusting unit 70, so that a constant tension can be applied to the transmission belt 40.

Japanese Utility Model Publication No. 62-121298

  By the way, in the reach type forklift, the tip of the fork frequently hits the load during traveling or reach operation, and an excessive force (hereinafter referred to as impact external force) is applied to the ball screw 30 each time.

  When the vehicle is running, the large pulley 30c of the ball screw 30 is not rotating, but the screw 30a of the ball screw 30 is linearly moved backward by impact external force, so that the large pulley 30c of the ball screw 30 tries to rotate. To do. However, since the small pulley 20a of the electric motor 20 is stopped and the roller 73 is held at a fixed position by the adjusting screw 74, even if the screw 30a of the ball screw 30 linearly moves backward, the ball screw The 30 large pulleys 30c cannot rotate. For this reason, in the conventional electric reach cylinder 100C, there is a risk that the ball rolling surface of the ball screw 30 may be damaged when an impact external force is applied during traveling.

  On the other hand, during the reach operation, the large pulley 30c of the ball screw 30 is rotating. However, since the forward linear motion of the screw 30a is restricted by the impact external force, the rotation of the large pulley 30c is also restricted. However, since the small pulley 20a of the electric motor 20 is rotating and the roller 73 is held at a fixed position by the adjustment screw 74, even if the forward linear motion of the screw 30a is restricted, the ball screw 30 The large pulley 30c tries to rotate. For this reason, in the conventional electric reach cylinder 100C, there is a risk that the ball rolling surface of the ball screw 30 may be damaged even when an impact external force is applied during the reach operation.

  The present invention has been made in view of the above circumstances, and the problem is that a reach-type forklift capable of preventing a ball rolling surface of a ball screw from being damaged by an impact external force and the The object is to provide an electric reach cylinder for a forklift.

  In order to solve the above problems, a reach-type forklift according to the present invention includes a pair of left and right straddle legs provided at a front portion of a vehicle, and a mast provided so as to be movable in the front-rear direction of the vehicle along the straddle legs. A reach-type forklift comprising a fork provided to be movable up and down at the front of the mast, and an electric reach cylinder that moves the mast with a predetermined reach stroke, the electric reach cylinder comprising: an electric motor that performs rotational movement; It includes a transmission belt that transmits rotational motion, a ball screw that converts the rotational motion transmitted through the transmission belt into linear motion, and moves the mast by the linear motion, and an elastic member, and adjusts the tension of the transmission belt A tension adjusting section, and the tension adjusting section is normally transmitted by pressing the transmission belt using the return operation of the elastic member. And adjusting the tension of the belt, when the impact force is applied to the ball screw, characterized in that to absorb the impact force by relaxing the transmission belt by using the compression operation of the elastic member.

  The “normal time” in the present invention refers to, for example, when traveling or reaching, and no impact external force is applied to the ball screw. In addition, the “impact external force” in the present invention refers to, for example, directly or indirectly when the tip of the fork hits an obstacle such as a luggage or the obstacle is caught between the reach carriage and the vehicle. The power applied. The “impact external force” includes, for example, a force that hinders the linear motion of the ball screw, a force that causes the ball screw to perform a linear motion, and a force that attempts to rotate or stop the large pulley of the ball screw.

  In the reach forklift, the elastic member is a coil spring, and the coil spring preferably performs a return operation and a compression operation in the left-right direction of the vehicle.

  In the reach forklift, the tension adjusting unit can further include a roller that presses the transmission belt, and a link mechanism that displaces the roller in accordance with the return operation and compression operation of the coil spring.

  In the reach type forklift, the link mechanism has a first link member having one end as a fixed end and the other end as a free end, and a second link having one end connected to the other end of the first link member by a first connecting member. A member, a rod member having one end connected to the other end of the second link member by the second connecting member, and one end and the other end, and fixing the one end and the other end, the second connecting member, and the first link member A guide member for guiding the rod member so that the rod member linearly moves along a straight line connecting the ends, and the roller is rotatable to the first connecting member so that the first connecting member serves as a rotation axis. The coil spring is preferably provided between one end and the other end of the guide member so that the linear motion of the rod member is restricted by the return operation.

  In the reach type forklift, when the electric reach cylinder further includes an electric motor arranged side by side in the left-right direction of the vehicle and a housing that holds the ball screw, the one end of the first link member and the guide member are fixed to the housing. It is preferable that

  In the reach-type forklift, when the electric reach cylinder further includes a pair of left and right bearings for supporting the shafts provided on the left side surface and the right side surface of the housing, the electric reach cylinder is disposed in the vertical plane extending in the front-rear direction of the vehicle. It is preferable that a battery that can swing about an axis and that supplies power to the electric motor is disposed above the housing.

  In order to solve the above problems, an electric reach cylinder of a forklift according to the present invention is an electric reach cylinder for moving a mast provided in a reach-type forklift with a predetermined reach stroke, and an electric motor that performs a rotational motion Includes a transmission belt that transmits rotational motion, a ball screw that converts the rotational motion transmitted through the transmission belt into linear motion, and moves the mast by the linear motion, and an elastic member, and adjusts the tension of the transmission belt The tension adjusting unit adjusts the tension of the transmission belt by pressing the transmission belt using the return operation of the elastic member in a normal state, and an impact external force is applied to the ball screw. Sometimes, the shock absorbing external force is absorbed by relaxing the transmission belt using the compression operation of the elastic member.

  ADVANTAGE OF THE INVENTION According to this invention, the reach type forklift which can prevent that the ball rolling surface of a ball screw is damaged by impact external force and the electric reach cylinder of the said forklift can be provided.

It is a top view which shows the principal part of the reach type forklift provided with the electric reach cylinder which concerns on this invention. It is a side view which shows the principal part of the reach type forklift provided with the electric reach cylinder which concerns on this invention. It is a top view which shows the electric reach cylinder which concerns on this invention. It is a figure which shows the electric reach cylinder which concerns on this invention, Comprising: (A) is a side view, (B) is a front view. It is a figure which shows the tension | tensile_strength adjustment part of this invention, Comprising: (A) is a front view, (B) is sectional drawing in the A-A 'line of FIG. 4 (B). It is a figure for demonstrating operation | movement of the tension adjustment part of this invention in the normal time. It is a figure for demonstrating operation | movement of the tension adjustment part of this invention at the time of impact external force generation | occurrence | production. It is an enlarged view of the tension adjustment part in FIG. It is a figure which shows the modification of the tension adjustment part of this invention. It is a top view which shows the conventional electric reach cylinder. It is a figure for demonstrating operation | movement of the conventional tension adjustment part.

  Hereinafter, embodiments of a reach type forklift according to the present invention and an electric reach cylinder of the forklift will be described with reference to the accompanying drawings. Note that the front-rear, left-right, and up-down directions are based on a reach-type forklift vehicle unless otherwise specified. Further, in the accompanying drawings, in order to facilitate understanding of the invention, even if it is a plan view, it is not partially represented as a plan view, but even if it is a sectional view, it is not partially represented as a sectional view. Even if it is a figure, there is a place which is not partially expressed as a side view.

  As shown in FIGS. 1 and 2, a reach forklift 1 </ b> A according to an embodiment of the present invention includes a pair of left and right straddle legs 3 provided at the front of a vehicle 2, and a front and rear direction along the straddle legs 3. A mast 4 provided so as to be movable, a lift bracket 5 provided so as to be movable up and down on the mast 4, a pair of left and right forks 6 provided on the lift bracket 5, and the mast 4 are moved in the front-rear direction with a predetermined reach stroke. The electric reach cylinder 100A is mainly provided. A battery 7 is provided above the electric reach cylinder 100A.

  The mast 4 is connected to the distal end portion of the electric reach cylinder 100A and is provided so as to be movable in the front-rear direction along the straddle leg 3, and a pair of left and right erected on the front portion of the reach carriage 4a. An outer mast 4b and a pair of left and right inner masts 4c that move in the vertical direction along the outer mast 4b are mainly provided.

  As shown in FIGS. 3 and 4, the electric reach cylinder 100A mainly includes an electric motor 20, a ball screw 30, a transmission belt 40, a housing 50, a pair of left and right bearings 60, and a tension adjusting unit 10A. ing.

  The electric motor 20 performs a rotational motion in accordance with the operation of a reach lever provided in the driver's seat of the vehicle 2. A small pulley 20a is provided on the rotating shaft of the electric motor 20 (see FIG. 6). The electric power necessary for the electric motor 20 is supplied from the battery 7. A non-excitation operation type electromagnetic brake that also serves as a torque limiter is provided at the front portion of the electric motor 20.

  The ball screw 30 converts the rotational motion of the electric motor 20 into a linear motion, and moves the mast 4 in the front-rear direction by the linear motion. Specifically, the ball screw 30 includes a screw 30a that performs linear motion, a nut 30b that includes a ball that rolls in a groove (ball rolling surface) of the screw 30a, a nut 30b, and a screw 30a. A large pulley 30c (see FIG. 6) that rotates together with the nut 30b according to the linear motion is mainly provided.

  The transmission belt 40 is stretched over the small pulley 20 a of the electric motor 20 and the large pulley 30 c of the ball screw 30, and transmits the rotational motion of the small pulley 20 a of the electric motor 20 to the large pulley 30 c of the ball screw 30. Similarly, the transmission belt 40 transmits the rotational motion of the large pulley 30 c of the ball screw 30 to the small pulley 20 a of the electric motor 20. The transmission belt 40 is given a predetermined tension by the tension adjusting unit 10A.

  The housing 50 integrally holds the electric motor 20 and the ball screw 30 arranged side by side in the left-right direction. A pair of shafts are provided on the right side surface and the left side surface of the housing 50. The pair of left and right shafts are swingably supported by a pair of left and right bearings 60. For this reason, the electric reach cylinder 100A can swing around a pair of left and right axes of the housing 50 in a vertical plane extending in the front-rear direction of the vehicle 2 as shown in FIG.

  5A and 5B show details of the tension adjusting unit 10A. In FIG. 5A, the left side of the B-B ′ line is a front view, and the right side of the B-B ′ line is a cross-sectional view. FIG. 5B is a cross-sectional view taken along line A-A ′ of FIG.

  As shown in FIGS. 5A and 5B, the tension adjusting unit 10A includes a coil spring 11 corresponding to the “elastic member” of the present invention, a roller 12 that presses the transmission belt 40, and a state of the coil spring 11. And a link mechanism for displacing the roller 12 according to the above.

  The coil spring 11 is subjected to a “returning operation” that attempts to return to the natural length from the compressed state (the state of FIGS. 5 and 6 in the present embodiment), and a force is applied in the direction of compression in the compressed state. The “compression operation” to be performed is performed. Although details will be described later, the tension adjusting unit 10A adjusts the tension of the transmission belt 40 by pressing the transmission belt 40 using the “returning operation” of the coil spring 11 at normal times, and when an impact external force is generated, By utilizing the “compression operation” of the coil spring 11 to relax the transmission belt 40, the shocking external force is absorbed.

  The link mechanism mainly includes a fixing pin 13, a first link member 14, a first connecting member 15, a second link member 16, a second connecting member 17, a rod member 18, and a guide member 19. It is out.

  The fixing pin 13 fixes one end of the first link member 14 to the housing 50.

  The first link member 14 is composed of a pair of front and rear plate members. One end of the first link member 14 is a fixed end, and the other end is a free end. The other end of the first link member 14 moves on an arc centered on one end.

  The first connecting member 15 is made of a rod-like member, and connects the other end of the first link member 14 and one end of the second link member 16. The 1st connection member 15 becomes a rotating shaft of the roller 12 which consists of three bearings piled up in the front-back direction.

  Similar to the first link member 14, the second link member 16 includes a pair of front and rear plate members. As shown in FIG. 5A, the other end of the second link member 16 is positioned at the same height as one end of the first link member 14 when viewed from the front, and passes through one end of the first link member 14. Slide on a straight line.

  The second connecting member 17 is connected to the other end of the second link member 16 at both ends in the front-rear direction, and is connected to one end of the rod member 18 in the middle in the front-rear direction.

  The rod member 18 includes a rod 18a and a presser 18b. The rod 18a mainly includes a connecting portion connected to the second connecting member 17, and a rod-like portion extending leftward from the connecting portion. The presser 18b is a cylindrical member mounted on the rod-shaped portion of the rod 18a, and a flange is formed at the other end. One end of the presser 18b is in contact with the connecting portion of the rod 18a. For this reason, when the rod 18a moves to the left, the presser 18b also moves to the left, and when the presser 18b moves to the right, the rod 18a also moves to the right.

  The guide member 19 has at least one end (right end), the other end (left end), and a rear end, and connects the one end and the other end, the second connecting member 17, and the fixed end (fixing pin 13) of the first link member 14. The rod member 18 is guided so that the rod member 18 linearly moves along the straight line. One end of the guide member 19 has a through hole larger than one end of the presser 18b and smaller than the flange of the presser 18b, and is disposed on the right side of the flange of the presser 18b. The other end of the guide member 19 has a through hole larger than the other end of the rod 18a, and is disposed on the left side of the flange of the presser 18b so that the other end of the rod 18a always protrudes. Furthermore, one end and the other end of the guide member 19 are coiled when the coil spring 11 attached to the rod 18a is disposed between the flange of the holding member 18b in contact with the one end and the other end of the guide member 19. The springs 11 are arranged at intervals such that the springs 11 are compressed and perform a return operation to return to the natural length. Therefore, the presser 18 b and the rod 18 a are urged rightward by the return operation of the coil spring 11. The rear end of the guide member 19 is fixed to the housing 50.

  Next, the operation of the tension adjusting unit 10A will be described with reference to FIGS. FIG. 6 is a view showing the electric reach cylinder 100A in a normal state, and FIG. 7 is a view showing the electric reach cylinder 100A in a case where an impact external force is generated. FIG. 8 is a diagram showing the tension adjusting unit 10A when a shocking external force is generated. 7 and 8, it is assumed that the front end of the fork 6 hits the load and a shocking external force is applied to the ball screw 30 while traveling forward (when the reach operation is not performed).

  In the normal state, as shown in FIG. 6, the presser 18 b and the rod 18 a are urged rightward by the return operation of the coil spring 11. As a result, the roller 12 moves in an obliquely downward right direction on the arc centered on the fixed pin 13 and presses the transmission belt 40 to apply tension to the transmission belt 40. Since the coil spring 11 corresponds to the maximum tension of the transmission belt 40 assumed in normal times, the coil spring 11 does not perform compression operation in normal times.

  When the presser 18b and the rod 18a are urged to the right, the flange of the presser 18b comes into contact with one end of the guide member 19, so that the rod 18a is held at a fixed position and the roller 12 is also held at a fixed position. . For this reason, the roller 12 does not apply excessive tension to the transmission belt 40.

  When the impact external force is generated, the screw 30a of the ball screw 30 linearly moves backward due to the impact external force, so that the nut 30b of the ball screw 30 has a large pulley 30c of the ball screw 30 as shown in FIG. A torque T1 is generated to rotate the motor. Since this torque T1 is transmitted to the small pulley 20a of the electric motor 20 via the transmission belt 40, an inertia torque T2 that prevents the small pulley 20a from rotating by a rotor, a non-excitation actuating electromagnetic brake, or the like. Will occur.

  Due to the torque T1 and the inertia torque T2, the tension applied to the transmission belt 40 greatly exceeds the maximum tension assumed in normal times, and an excessive repulsive force F is generated in the direction opposite to the pressing direction of the roller 12. Due to the repulsive force F, the roller 12 is strongly pushed diagonally to the left on the arc centered on the fixed pin 13 and the rod member 18 is strongly pushed to the left via the second link member 16. The spring 11 performs a compression operation.

  When the coil spring 11 performs a compression operation, the rod member 18 slides leftward, and the roller 12 moves obliquely upward leftward on an arc centered on the fixed pin 13, so that the transmission belt 40 is relaxed. The As a result, the large pulley 30c of the ball screw 30 rotates without the small pulley 20a of the electric motor 20 rotating. That is, in the electric reach cylinder 100A, the large pulley 30c can be rotated in accordance with the linear motion of the screw 30a, so that the ball rolling surface of the ball screw 30 can be prevented from being damaged.

  Next, the case where the front end of the fork 6 hits the load during the forward reach operation and an impact external force is applied in the axial direction of the ball screw 30 will be described.

  In this case, the forward linear motion of the screw 30a is restricted by the impact external force. When the forward linear movement of the screw 30a is restricted, the rotation of the large pulley 30c of the ball screw 30 is also restricted.

  On the other hand, since the small pulley 20a of the electric motor 20 is rotating, as in the case of FIG. 7, the tension applied to the transmission belt 40 greatly exceeds the maximum tension assumed at the normal time, and the pressing direction of the roller 12 is An excessive repulsive force F is generated in the reverse direction. Due to the repulsive force F, the roller 12 is strongly pushed diagonally to the left on the arc centered on the fixed pin 13 and the rod member 18 is strongly pushed to the left via the second link member 16. The spring 11 performs a compression operation.

  When the coil spring 11 performs a compression operation, the rod member 18 slides leftward, and the roller 12 moves obliquely upward leftward on an arc centered on the fixed pin 13, so that the transmission belt 40 is relaxed. The As a result, the small pulley 20a of the electric motor 20 rotates without the large pulley 30c of the ball screw 30 rotating. That is, in the electric reach cylinder 100A, the force to rotate the large pulley 30c can be absorbed by loosening the transmission belt 40, so that the ball rolling surface of the ball screw 30 is damaged. Can be prevented.

  After all, in the electric reach cylinder 100A, the shocking external force can be absorbed by relaxing the transmission belt 40 using the compression operation of the coil spring 11 when the shocking external force is generated. Therefore, according to the electric reach cylinder 100A and the reach forklift 1A including the electric reach cylinder 100A according to the present embodiment, it is possible to prevent the ball rolling surface of the ball screw 30 from being damaged by an impact external force. .

  Furthermore, according to the reach-type forklift 1A provided with the electric reach cylinder 100A and the electric reach cylinder 100A according to the present embodiment, the coil spring 11 performs the return operation and the compression operation in the left-right direction of the vehicle 2, and thus the electric reach cylinder 100A. The vertical dimension can be reduced, and space saving can be achieved.

  As mentioned above, although the embodiment of the reach type forklift according to the present invention and the electric reach cylinder of the forklift has been described, the present invention is not limited to the above embodiment.

  FIG. 9 shows an electric reach cylinder 100B according to a modification of the present invention. The electric reach cylinder 100 </ b> B includes a tension adjusting unit 10 </ b> B in which the roller 12 is provided at one end of the rod member 18. Similar to the above-described embodiment, the tension adjusting unit 10B can absorb the shocking external force by relaxing the transmission belt 40 using the compression operation of the coil spring 11 when the shocking external force is generated. Therefore, according to this electric reach cylinder 100B, it is possible to prevent the ball rolling surface of the ball screw 30 from being damaged by an impact external force. In this electric reach cylinder 100B, the configuration of the tension adjusting unit 10B itself is simpler than that of the tension adjusting unit 10A, but the tension adjusting unit is configured so that the coil spring 11 performs the returning operation and the compressing operation in the left-right direction of the vehicle 2. Since 10B cannot be arranged, it is necessary to use the housing 50 ′ having a larger vertical dimension than the housing 50. As a result, the vertical dimension is larger than that of the electric reach cylinder 100A.

  The electric reach cylinder 100A according to the embodiment includes only one tension adjusting unit 10A, but may include two. When two tension adjusting units 10A are provided, the second tension adjusting unit 10A is arranged so as to press the transmission belt 40 from below against the first tension adjusting unit 10A across the transmission belt 40. It is preferable. By disposing the second tension adjusting unit 10A in this way, for example, the impact external force generated directly or indirectly due to an obstacle sandwiched between the reach carriage 4a and the vehicle 2 is absorbed. Can do.

  In the electric reach cylinder 100A according to the above-described embodiment, the tension adjusting unit 10A is disposed so as to press the transmission belt 40 from the outside to the inside, but the transmission belt 40 is pressed from the inside to the outside. A tension adjusting unit 10A may be arranged.

  In the electric reach cylinder 100A according to the above embodiment, the coil spring 11 is used as the elastic member. However, the "returning operation" for returning to the natural length from the compressed state (the state shown in FIGS. 5 and 6) and the above compression are performed. If a force is applied in the direction of compression in this state and a “compression operation” for further compression is performed, the coil spring 11 can be used instead.

  In the electric reach cylinder 100A according to the above-described embodiment, the link mechanism includes the fixing pin 13, the first link member 14, the first connecting member 15, the second link member 16, the second connecting member 17, and the rod member. 18 and the guide member 19, but can be appropriately changed as long as the roller 12 can be displaced according to the state of the elastic member such as the coil spring 11.

1A Reach type forklift 2 Vehicle 3 Straddle leg 4 Mast 4a Reach carriage 4b Outer mast 4c Inner mast 5 Lift bracket 6 Fork 7 Battery 10A, 10B Tension adjuster 11 Coil spring (pressing means)
12 roller 13 fixing pin 14 first link member 15 first connecting member 16 second link member 17 second connecting member 18 rod member 18a rod 18b holding member 19 guide member 20 electric motor 20a small pulley 30 ball screw 30a screw 30b nut 30c large pulley 40 Transmission belt 50, 50 'Housing 60 Bearing 100A, 100B Electric reach cylinder

Claims (7)

A pair of left and right straddle legs provided at the front of the vehicle, a mast provided to be movable in the front-rear direction of the vehicle along the straddle leg, and a fork provided to be movable up and down at the front of the mast; A reach-type forklift comprising an electric reach cylinder for moving the mast with a predetermined reach stroke;
The electric reach cylinder is
An electric motor for rotational movement;
A transmission belt for transmitting the rotational motion;
A ball screw that converts the rotational motion transmitted through the transmission belt into a linear motion, and moves the mast by the linear motion;
A tension adjusting section that includes an elastic member and adjusts the tension of the transmission belt,
The tension adjusting unit is
During normal operation, the tension of the transmission belt is adjusted by pressing the transmission belt using the return operation of the elastic member, and when the impact external force is applied to the ball screw, the compression operation of the elastic member is used. A reach-type forklift that absorbs the impact external force by relaxing the transmission belt. The elastic member is a coil spring;
The reach forklift according to claim 1, wherein the coil spring performs the return operation and the compression operation in a lateral direction of the vehicle. The tension adjusting unit is
A roller for pressing the transmission belt;
The reach forklift according to claim 2, further comprising a link mechanism that displaces the roller in accordance with the return operation and the compression operation of the coil spring. The link mechanism is
A first link member having one end as a fixed end and the other end as a free end;
A second link member having one end connected to the other end of the first link member by a first connecting member;
A rod member having one end connected to the other end of the second link member by a second connecting member;
The rod member is guided so that the rod member linearly moves along a straight line connecting the one end and the other end, the second connecting member, and the fixed end of the first link member. A guide member,
The roller is rotatably attached to the first connecting member so that the first connecting member serves as a rotation axis.
The reach according to claim 3, wherein the coil spring is provided between one end and the other end of the guide member so that linear movement of the rod member is restricted by the return operation. Forklift. The electric reach cylinder further includes a housing that holds the electric motor and the ball screw arranged side by side in the left-right direction of the vehicle,
The reach type forklift according to claim 4, wherein one end of the first link member and the guide member are fixed to the housing. A pair of left and right bearings for supporting shafts provided on the left side surface and the right side surface of the housing;
The electric reach cylinder is swingable around the axis of the housing in a vertical plane extending in the front-rear direction of the vehicle,
The reach forklift according to claim 5, wherein a battery for supplying electric power to the electric motor is disposed above the housing. An electric reach cylinder for moving a mast provided in a reach-type forklift with a predetermined reach stroke,
An electric motor for rotational movement;
A transmission belt for transmitting the rotational motion;
A ball screw that converts the rotational motion transmitted through the transmission belt into a linear motion, and moves the mast by the linear motion;
A tension adjusting section that includes an elastic member and adjusts the tension of the transmission belt,
The tension adjusting unit is
During normal operation, the tension of the transmission belt is adjusted by pressing the transmission belt using the return operation of the elastic member, and when the impact external force is applied to the ball screw, the compression operation of the elastic member is used. The electric reach cylinder absorbs the impact external force by relaxing the transmission belt.

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