JP4539610B2 - Elevator drop prevention device - Google Patents

Description

  The present invention relates to a technique of a fall prevention device provided on a lifting platform such as a transport device or a transfer device.

  Conventionally, a transport device such as a stacker crane having a lifting platform, a transfer device, and the like have been provided with a lifting prevention device for the lifting platform. Inserting a pair of wedge-shaped fall prevention pieces between the sides of the mast and the lifting platform as a lifting prevention device for the lifting platform that is supported by a suspension member such as a chain or rope and moves up and down along the mast. Thus, an apparatus has been developed that prevents the lifting platform from falling (for example, see Patent Document 1).

The conventional elevator base drop prevention device is engaged with a pair of pivotable brake levers that support a pair of fall prevention pieces and the brake levers at all times, and rotates when the suspension member is abnormal. And a pair of toggle levers that allow each brake lever to rotate by being disengaged from the engagement position, and a biasing means that biases each brake lever so that each fall prevention piece moves upward. Yes. According to this fall prevention device, normally, each toggle lever engages with each brake lever and separates each fall prevention piece from between the both sides of the mast and the lifting platform. Sometimes, each toggle lever rotates to disengage from the brake lever engagement position, allowing each brake lever to rotate, and each brake lever rotates to prevent each fall between the mast and the platform Insert the piece and stop the elevator.
JP 2005-67839 A

  By the way, when the fall prevention pieces are inserted almost simultaneously on both sides of the mast, the fall prevention pieces are evenly inserted on both sides of the mast, but the fall prevention piece is inserted on both sides of the mast. When it deviates, the fall prevention piece inserted previously is inserted deeply, the fall prevention piece inserted later is inserted shallowly, and the fall prevention piece may not be inserted equally on both sides of the mast. If the fall prevention pieces are not evenly fitted on both sides of the mast as described above, the lift base may be inclined with respect to the mast, and the lift base may lose balance. Thus, the fall prevention function may not be fully exhibited. Therefore, it is necessary to insert the fall prevention pieces between the both sides of the mast and the lifting platform substantially simultaneously on both sides of the mast.

  When the conventional fall prevention device is a lifting platform in which the center line of the suspension member and the center line of the mast are combined, the fall prevention device has a substantially symmetrical structure with respect to the suspension member or the mast. In this case, the operation of the toggle lever when the suspension member is abnormal is left-right symmetric, the engagement with the brake lever is released substantially at the left and right, and the left and right brake levers are also rotated almost simultaneously. Therefore, the fall prevention piece can be fitted between the both sides of the mast and the lifting platform at almost the same time, and the lifting platform can be prevented from falling without any problem.

  However, since the conventional fall prevention device is a lifting platform in which the center line of the suspension member and the center line of the mast are shifted, it is necessary to change the shape of the toggle lever or the like on the left and right. Does not have a symmetrical structure with respect to the mast. In this case, the operation of the fall prevention device is not symmetrical, and the release of the engagement between the toggle lever and the brake lever is not performed substantially at the same time, and the fall prevention piece is placed between the both sides of the mast and the lifting platform at the same time. It becomes difficult to insert. Therefore, in the case of a lifting platform in which the center line of the suspension member and the center line of the mast are shifted, it is difficult to fit the fall prevention pieces between the both sides of the mast and the lifting platform substantially simultaneously. was there.

  In addition, for example, when the design of the conventional fall prevention device is adapted to be adapted to a lifting platform such as a transfer device or a transfer device having a different mast width, the shape and dimensions of a number of members must be changed. There is a problem that the design change is not easy.

  The present invention has been made in view of the above-described problems.Even if the lifting platform is arranged such that the center line of the suspension member and the center line of the mast are shifted, the fall prevention pieces are arranged on both sides of the mast and the lifting platform. It is an object of the present invention to provide a lifting table fall prevention device that can be fitted substantially simultaneously, and can be easily changed in design according to the lifting table such as a conveying device having a different mast width.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

That is, the invention according to claim 1 is a lift prevention device for a lift that is provided on a lift that moves up and down along the mast while being supported by a suspension member.
A plurality of fall prevention pieces inserted from below between both sides of the mast and the lifting platform to prevent the lifting platform from dropping;
The fall prevention piece is supported from the standby position where the fall prevention piece is separated from between the mast and the lifting platform, and the fall prevention piece is inserted between the mast and the lifting platform from below. A plurality of brake levers operably provided toward the operating position to be
Brake lever urging means for urging the brake lever in a direction to operate from the standby position to the operating position;
A locking member that engages with the brake lever in the standby position and prevents the operation of the brake lever is provided at the distal end, and the engagement between the brake lever and the locking member is released by rotating around the axis. A locking shaft that allows the operation of the brake lever,
A locking shaft urging means for urging the locking shaft in a direction to rotate around the axis from a position where the operation of the brake lever is prevented to a position where the operation of the brake lever is allowed;
Normally, it engages with the locking shaft at a position where the operation of the brake lever is blocked to prevent the rotation of the locking shaft, and when the suspension member is abnormal, the engagement with the locking shaft is released. An abnormality detecting means for allowing rotation of the locking shaft;
It was set as the fall prevention apparatus of the lifting platform characterized by having.

In the invention according to claim 2, in the invention according to claim 1,
The lifting platform is arranged with the center line of the suspension member shifted from the center line of the mast,
The locking shaft has a lift prevention device for a lifting platform characterized in that the length is asymmetric with respect to the center line of the suspension member.

In invention of Claim 3,
The suspension member is disposed along the mast;
The locking shaft is a single shaft disposed horizontally below the suspension member,
3. The lift-prevention device according to claim 1, wherein the brake lever sandwiches a side surface orthogonal to a side of the mast on which the suspension member is disposed.

  As effects of the present invention, the following effects can be obtained.

According to the first to third aspects of the present invention, when the locking shaft rotates around the shaft, the engagement with the brake lever at the standby position is released, and the operation of the brake lever is allowed. Since the rotation of the locking shaft around the shaft is constant regardless of the length of the locking shaft, the operations of a plurality of brake levers engaged with the locking shaft can be allowed substantially simultaneously. And the operation | movement of a some brake lever is performed substantially simultaneously, and the fall prevention piece supported by the brake lever can be inserted substantially simultaneously between the both sides of a mast and a raising / lowering stand. Therefore, even if the lifting platform is arranged such that the center line of the suspension member and the center line of the mast are shifted, the fall prevention piece can be fitted between the both sides of the mast and the lifting platform substantially simultaneously.
In addition, when the design is changed so as to be adapted to a lifting platform such as a transfer device or a transfer device having a different mast width, the length of the locking shaft may be changed, and other members are not changed. Therefore, it is possible to easily change the design according to the lifting platform such as a transfer device having a different mast width.

  According to the second aspect of the present invention, since the rotation of the locking shaft around the axis is constant regardless of the length of the locking shaft, the operations of the plurality of brake levers engaged with the locking shaft are performed. It is acceptable at almost the same time. Therefore, even if the length of the locking shaft is asymmetric with respect to the center line of the suspension member, the movement of the plurality of brake levers is performed almost simultaneously, so that the fall prevention pieces supported by the brake levers are attached to both sides of the mast. And can be fitted between the elevator and the lift.

  According to the invention described in claim 3, the device for preventing the fall of the lifting platform is configured to fit the fall prevention pieces supported by the brake lever between the both sides of the mast and the lifting platform at the same time and evenly. Can do. Therefore, it is possible to provide a highly safe automatic warehouse system in which the fall prevention function of the drop prevention device for the elevator platform is sufficiently exhibited.

  Next, embodiments of the invention will be described with reference to the drawings.

  An elevator platform drop prevention device 12 according to a first embodiment of the present invention will be described with reference to the drawings. 1 to 5 show a state in which the brake lever 31 is in the standby position, and FIGS. 6 to 10 show a state in which the brake lever 31 is in the operating position.

  The elevator table fall prevention device 12 according to the first embodiment is provided, for example, in a stacker crane used as a transfer device in an automatic warehouse. As shown in FIGS. 1 to 10, the stacker crane includes a traveling cart (not shown) that travels on the floor of an automatic warehouse, a pair of masts 13 erected on the traveling cart, and the pair of masts 13. An elevator 11 supported between them and moving up and down along the mast 13; a transfer device (not shown) such as a slide fork and a scalar arm provided on the elevator 11 for transferring articles; It has a chain 14 as a suspension member for supporting a load, and drive means (not shown) for driving the chain 14. An end of the chain 14 is attached to the elevator 11 to support a load, and the elevator 11 moves up and down along the mast 13 when the chain 14 is driven by driving means. The lifting platform is not limited to that provided in a stacker crane used as a transfer device in an automatic warehouse, and may be any lifting platform that moves up and down along the mast while being supported by a suspension member. Further, the suspension member may be a belt, a rope, or the like in addition to the chain.

  As shown in FIGS. 1 and 4, a guide roller 23 for raising and lowering along the mast 13 is provided on the elevator 11 so as to hold both sides of the mast 13. It is attached to a guide roller shaft 24 provided on a lifting platform side plate 21 erected on the side portion.

  As shown in FIG. 1, a stop sliding contact portion 25 is provided at a position below the guide roller 23 and facing both side surfaces of the mast 13. The stop sliding contact portion 25 is provided so as to be symmetrical with respect to the mast 13 in the drawing. As shown in FIG. 4, the stop sliding contact portion 25 is supported by a fixing member 26 that extends from the lifting platform side plate 21 toward the mast 13. As shown in FIG. 1, a stop sliding contact surface 27 is formed on the side portion of the stop sliding contact portion 25 at a position facing the side surface of the mast 13. The stop sliding contact surface 27 secures a gap with respect to the side surface of the mast 13 and has a shape inclined at a certain angle with respect to the side surface of the mast 13. The space between the slidable contact surface 27 for stop and the side surface of the mast 13 is thereby formed with a substantially wedge-shaped space. In addition, a through hole 28 is formed at a substantially central portion of the stop sliding contact portion 25 for penetrating and swinging the rotation preventing portion 32 provided on the brake lever 31 described later.

  As shown in FIGS. 1 and 3, a fall prevention piece 34 is provided between both side surfaces of the mast 13 and the stop sliding contact surface 27. The fall prevention piece 34 is inserted between the both side surfaces of the mast 13 and the sliding contact surface 27 for stopping when the chain 14 is broken or the like, thereby sandwiching both sides of the mast 13 and raising and lowering the platform 11. It is a member which prevents fall of the. The fall prevention piece 34 is supported by a brake lever 31 to be described later, and is provided so as to be symmetrical with respect to the mast 13 in the drawing. The surface of the fall prevention piece 34 that contacts the stop sliding contact surface 27 is inclined at substantially the same inclination angle as the stop sliding contact surface 27, and the surface that contacts the side surface of the mast 13 is the side surface of the mast 13. And is formed in a substantially wedge shape. A long hole 35 is formed in the fall prevention piece 34 so as to be rotatably attached to the brake lever 31 described later. The fall prevention piece 34 is always supported in a state of being separated from the mast 13 and the elevator 11, and when there is an abnormality such as cutting of the chain 14, both sides of the mast 13 and the stop sliding contact surface 27 Is inserted from below and bites upward, generating a large clamping force for clamping both sides of the mast 13 to prevent the lifting platform 11 from falling.

  As shown in FIG. 1, a brake lever 31 is provided in the stop sliding contact portion 25. The brake lever 31 supports the fall prevention piece 34. The brake lever 31 is a substantially L-shaped bell crank. As shown in FIG. 3, a pair of brake levers 31 are coaxially attached to one stop sliding contact portion 25 so as to sandwich the stop sliding contact portion 25. As shown in FIG. 1, the pair of brake levers 31 are provided for the left and right stop sliding contact portions 25 shown in the figure, and the brake lever 31 is provided so as to be symmetrical with respect to the mast 13. The fall prevention piece 34 is rotatably attached to an end portion on the long side of the brake lever 31. The fall prevention piece 34 is attached by passing a shaft through the elongated hole 35 formed in the fall prevention piece 34, and laying the shaft on the ends of the pair of brake levers 31. As shown in FIGS. 1, 3, and 4, a rotation prevention portion 32 that penetrates the through hole 28 of the stop sliding contact portion 25 is provided at a substantially central portion on the long side of the brake lever 31. The brake lever 31 is attached integrally. As shown in FIG. 2, the lifting plate side plate 21 is also formed with a through hole 22 having the same shape as the through hole 28 formed in the stopping sliding contact portion 25, and the lifting platform side plate 21 and the stopping sliding contact portion. The rotation preventing portion 32 is passed through the through holes 22 and 28 respectively formed in 25. As shown in FIG. 6, the brake lever 31 is moved from a standby position in which the fall prevention piece 34 is separated from between the side surface of the mast 13 and the stop sliding contact surface 27 as shown in FIG. The fall prevention piece 34 is rotatable toward an operating position where the fall prevention piece 34 is fitted between the side surface of the mast 13 and the stop sliding contact surface 27 from below. As the brake lever 31 rotates, the rotation preventing portion 32 swings in through holes 22 and 28 formed in the elevator platform side plate 21 and the stop sliding contact portion 25, respectively.

  As shown in FIG. 1, one end of a coil spring 33 as a brake lever urging means is attached to the short side of the brake lever 31. The other end is attached to the lower end of the sliding contact portion 25 for stopping. A coil spring 33 as a brake lever urging means is attached in an extended state, and the brake lever 31 is urged by the coil spring 33 in a direction to rotate from the standby position to the operating position. At the same time, the rotation preventing portion 32 integral with the brake lever 31 is also urged upward in the figure by the coil spring 33.

  As shown in FIG. 2, a locking shaft 41 is attached to the back side of the elevator board side plate 21 shown in FIG. 1. The locking shaft 41 engages with the rotation preventing portion 32 that is integrally fixed to the brake lever 31 to prevent the rotation of the brake lever 31 and engages with the rotation preventing portion 32. It is a member that is released and allows the brake lever 31 to rotate. The locking shaft 41 is supported by a bracket 42 attached to the lifting platform side plate 21 so as to be rotatable around the shaft, and a locking member 43 is provided at the tip of the locking shaft 41. The distance from the center line of the chain 14 to the locking member 43 is different on the left and right in the drawing and is asymmetric.

  As shown in FIG. 2, a protruding portion 43 a that protrudes laterally is formed on the upper portion of the locking member 43. As shown in FIGS. 3 and 4, the tip of the rotation preventing portion 32 of the brake lever 31 protrudes through the through hole 22 of the lifting platform side plate 21, and the brake lever 31 is in the standby position ( 1), as shown in FIGS. 2, 3, and 4, the protrusion 43 a of the locking member 43 is engaged with the upper portion of the tip of the rotation preventing portion 32. A brake lever attached integrally with the rotation preventing portion 32 by engaging the protrusion 43a of the locking member 43 with the rotation preventing portion 32 and preventing the rotation preventing portion 32 from moving upward in the figure. The rotation of 31 is prevented. Further, as shown in FIGS. 4 and 9, by engaging the locking shaft 41 in the right direction in the figure, the engagement between the protruding portion 43a of the locking member 43 and the rotation preventing portion 32 is released. As shown in FIGS. 8 and 9, the rotation prevention unit 32 is allowed to move upward in the figure, and the brake lever 31 attached integrally with the rotation prevention unit 32 is allowed to rotate.

  As shown in FIG. 2, a torsion spring 44 as a locking shaft urging means is attached to the locking shaft 41. The torsion spring 44 urges the locking shaft 41 to rotate about the axis. The urging direction is such that the protrusion 43a of the locking member 43 and the rotation preventing portion 32 are changed from the state shown in FIGS. 2, 3, and 4 to the state shown in FIGS. This is the direction in which the engagement is released. That is, the engagement between the protrusion 43a and the rotation prevention part 32 is released from the position where the protrusion 43a of the locking member 43 is engaged with the rotation prevention part 32 and prevents the brake lever 31 from rotating. This is a direction toward a position where the rotation of the brake lever 31 is allowed.

  As shown in FIG. 2, an abnormality detection means 51 for detecting an abnormality such as when the chain 14 as a suspension member is cut is provided on the surface of the elevator board side plate 21 to which the locking shaft 41 is attached. . The abnormality detection means 51 normally engages with the locking shaft 41 located at a position where the rotation of the brake lever 31 is prevented to prevent the locking shaft 41 from rotating. The engagement with the shaft 41 is released, and the rotation of the locking shaft 41 is allowed. As shown in FIGS. 2 and 4, a lifting member fixing portion 52 to which the end portion of the chain 14 is attached is extended on the lifting platform side plate 21. A chain shaft 15 is attached to an end portion of the chain 14, and the chain shaft 15 penetrates the suspension member fixing portion 52 so as to freely advance and retract. A coil spring 53 is fitted on the chain shaft 15 penetrating the suspension member fixing portion 52, and a collar 54, which is a metallic cylindrical body, is fitted on the outer side thereof.

  As shown in FIGS. 2 and 3, a detection member 55 is fixed to the end of the chain shaft 15. In a state in which a load is applied to the chain 14, the coil spring 53 is compressed by the detection member 55 and the suspension member fixing portion 52 fixed to the chain 14, but the collar 54 is interposed between the suspension member fixing portion 52 and the detection member 55. By being interposed, the compression of the coil spring 53 is limited, and the load of the lifting platform 11 is supported by the chain 14. A coil spring 53 having a sufficiently large spring elastic coefficient is used, and when the load applied to the chain 14 decreases due to the chain 14 being cut or the like, the coil spring 53 is quickly restored to move the detection member 55 downward. (See FIG. 7).

  As shown in FIGS. 2, 3, and 5, the locking shaft 41 is provided with a contact member 56 that contacts the detection member 55 of the abnormality detection means 51. The abutting member 56 is a plate-like member as shown in FIG. 5, and at one end, one end of the abutting member 56 abuts against the detection member 55 to prevent the locking shaft 41 from rotating, and the chain 14 At the time of abnormality, the contact with the detection member 55 is released, and the rotation of the locking shaft 41 is allowed. As shown in FIG. 4, the contact member 56 is in contact with the detection member 55 in a state where the load of the elevator 11 is applied to the chain 14 and the detection member 55 is on the upper side. In this state, since the locking shaft 41 is urged in the clockwise rotation direction in the figure by the torsion spring 44, the contact member 56 is also urged in the clockwise rotation direction in the figure. As shown in FIG. 9, when the load applied to the chain 14 is reduced due to the chain 14 being cut or the like and the detection member 55 is moved downward, it is rotated rightward in the figure by the urging force of the torsion spring 44. The contact with the detection member 55 is released.

  Next, the operation of the elevating table drop prevention device 12 according to the present embodiment at all times and in an abnormal state will be described. First, as shown in FIG. 1, in a normal state, the lifting platform 11 is supported by a chain 14 as a suspension member, and the load of the lifting platform 11 is applied to the chain 14. As shown in FIG. 2, the coil spring 53 is compressed by the chain 14 and the detection member 55, but the compression of the coil spring 53 is limited by the collar 54 being interposed between the suspension member fixing portion 52 and the detection member 55. Then, the load of the lifting platform 11 is supported by the chain 14.

  At all times, as shown in FIG. 1, the brake lever 31 is located at a standby position in a state in which the fall prevention piece 34 is separated from between the mast 13 and the lifting platform 11. The brake lever 31 is urged so as to rotate from the standby position to the operating position by a coil spring 33 as a brake lever urging means. However, as shown in FIG. The rotation preventing portion 32 is engaged with a protruding portion 43 a of a locking member 43 provided on the locking shaft 41. For this reason, the brake lever 31 is held at the standby position by the locking shaft 41.

  Further, the locking shaft 41 itself is also urged so as to rotate about the axis in a direction to release the engagement with the rotation preventing portion 32 by a torsion spring 44 as a locking shaft urging means. However, as shown in FIG. 2, the contact member 56 provided on the locking shaft 41 is in contact with the detection member 55, and the detection member 55 prevents the rotation of the locking shaft 41 around the axis. Has been. Thus, in a state where the load of the lifting platform 11 is applied to the chain 14, the fall prevention piece 34 is kept in a state of being separated from between the mast 13 and the lifting platform 11.

  Next, when the chain 14 is broken or the like, the load applied to the chain 14 is reduced, and the detection member 55 is quickly moved by the elastic force of the coil spring 53 fitted to the chain shaft 15 as shown in FIG. Move downward in the figure. When the detection member 55 moves downward in the drawing, as shown in FIGS. 7 and 9, the contact between the contact member 56 provided on the locking shaft 41 and the detection member 55 is released, and the rotation of the locking shaft 41. Is acceptable.

  When the rotation of the locking shaft 41 is allowed, the locking shaft 41 is rotated around the axis by the urging force of the torsion spring 44 as the locking shaft urging means, as shown in FIGS. The locking member 43 provided at the tip of the locking shaft 41 is also rotated together. When the locking member 43 rotates, the engagement between the protrusion 43a of the locking member 43 and the tip of the rotation preventing unit 32 is released, and the rotation of the brake lever 31 is allowed.

  When the rotation of the brake lever 31 is allowed as described above, the brake lever 31 is biased in the direction of rotating from the standby position to the operating position by the coil spring 33 as the brake lever biasing means. As shown in FIG. 4, the mast 13 is inserted from both sides of the mast 13 and the stop sliding contact surface 27 from below in the figure. The fall prevention piece 34 inserted between the both side surfaces of the mast 13 and the stop sliding contact surface 27 bites upward and generates a large clamping force for clamping both sides of the mast 13, thereby It will prevent falling.

  According to the elevator table fall prevention device 12 according to the present embodiment described above, the engagement with the brake lever 31 at the standby position is released by rotating the locking shaft 41 around the axis in the event of an abnormality. The brake lever 31 is allowed to rotate. Since the rotation of the locking shaft 41 around the shaft is constant regardless of the length of the locking shaft 41, the rotation of the plurality of brake levers 31 engaged with the locking shaft 41 can be released substantially simultaneously. it can. Therefore, even if the length of the locking shaft 41 is asymmetric with respect to the center line of the chain 14 as in this embodiment, the plurality of brake levers 31 are rotated substantially simultaneously and supported by the brake lever 31. The fall prevention piece 34 thus made can be fitted between the both sides of the mast 13 and the lifting platform 11 almost simultaneously.

  In addition, when the design is changed so as to be adapted to the lifting platform 11 such as a transfer device or a transfer device having a different mast width, the length of the locking shaft 41 may be changed, and other members are not changed. Since a common member can be used, design changes can be easily made in accordance with a lifting platform such as a transfer device having a different mast width.

  Further, when the elevator table fall prevention device 12 according to this embodiment is applied to an automatic warehouse system, the fall prevention pieces 34 supported by the brake lever 31 are inserted between the both sides of the mast 13 and the elevator table 11 almost simultaneously. Therefore, since it can be inserted evenly, it is possible to provide a highly safe automatic warehouse system that can sufficiently exhibit the fall prevention function of the fall prevention device 12 of the lifting platform.

  In the above description, the lifting platform with the center line of the suspension member shifted from the center line of the mast has been described, but the lifting platform with the center line of the suspension member aligned with the center line of the mast may be used. Can be provided.

The front view which looked at the fall prevention apparatus 12 of the lifting platform which concerns on the Example of this invention from the mast 13 side. The reverse view which looked at the fall prevention apparatus 12 of the lifting platform which concerns on the Example of this invention from the opposite side of FIG. Sectional drawing in the 3-3 line of FIG. The side view seen from the direction of the arrow 4 of FIG. Sectional drawing in the 5-5 line | wire of FIG. The front view which looked at the fall prevention apparatus 12 of the lifting platform which concerns on the Example of this invention from the mast 13 side. The reverse view which looked at the fall prevention apparatus 12 of the lifting platform which concerns on the Example of this invention from the opposite side of FIG. Sectional drawing in the 8-8 line of FIG. The side view seen from the direction of the arrow 9 of FIG. Sectional drawing in the 10-10 line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Lift stand 12 Lift prevention device 13 Mast 14 Chain as suspension member 15 Chain shaft 21 Lift plate side plate 22 Through hole 23 Guide roller 24 Guide roller shaft 25 Stop sliding contact portion 26 Fixing member 27 Stop sliding contact surface 28 Through-hole 31 Brake lever 32 Anti-rotation part 33 Coil spring as brake lever urging means 34 Fall prevention piece 35 Long hole 41 Locking shaft 42 Bracket 43 Locking member 43a Protruding part 44 Torsion as locking shaft urging means Spring 51 Anomaly detection means 52 Suspension member fixing part 53 Coil spring 54 Color 55 Detection member 56 Contact member

Claims (3)

A device for preventing the fall of the lifting platform, which is provided on the lifting platform that moves up and down along the mast while being supported by the suspension member,
A plurality of fall prevention pieces inserted from below between both sides of the mast and the lifting platform to prevent the lifting platform from dropping;
The fall prevention piece is supported from the standby position where the fall prevention piece is separated from between the mast and the lifting platform, and the fall prevention piece is inserted between the mast and the lifting platform from below. A plurality of brake levers operably provided toward the operating position to be
Brake lever urging means for urging the brake lever in a direction to operate from the standby position to the operating position;
A locking member that engages with the brake lever in the standby position and prevents the operation of the brake lever is provided at the tip, and the engagement between the brake lever and the locking member is released by rotating around the axis. A locking shaft that allows the operation of the brake lever,
A locking shaft urging means for urging the locking shaft in a direction to rotate around the axis from a position where the operation of the brake lever is blocked to a position where the operation of the brake lever is allowed;
Normally, it engages with the locking shaft at a position where the operation of the brake lever is blocked to prevent the rotation of the locking shaft. When the suspension member is abnormal, the engagement with the locking shaft is released. An abnormality detecting means for allowing rotation of the locking shaft;
A device for preventing a fall of the lifting platform. The lifting platform is arranged by shifting the center line of the suspension member and the center line of the mast,
The apparatus according to claim 1, wherein the length of the locking shaft is asymmetric with respect to the center line of the suspension member. The suspension member is disposed along the mast;
The locking shaft is a single shaft disposed horizontally below the suspension member,
The fall prevention device for an elevator platform according to claim 1 or 2, wherein the brake lever sandwiches a side surface of the mast perpendicular to a side where the suspension member is disposed.

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