JP2605568B2 - Stepladder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepladder, and more particularly, to a stepladder having a front leg and a rear leg which can be freely opened and closed by hinges.

[0002]

2. Description of the Related Art FIG. 11 is an exploded perspective view showing the vicinity of a hinge of a conventional stepladder disclosed in Japanese Unexamined Utility Model Publication No. 3-46700. The stepladder includes a pair of left and right front supports 101, a pair of left and right rear supports 102, and a front support 101 and a rear support 1.
02 is provided with a pair of left and right hinges 103 for opening and closing freely (only the right side is shown in FIG. 11). The pair of left and right front support legs 101 are arranged substantially parallel to each other. Similarly, the pair of left and right rear support legs 102 are arranged substantially in parallel with each other. The front leg 101 in the front of the opening direction 130 and the rear leg 102 in the rear of the opening direction 130
Both are formed by extruded shapes made of aluminum or the like.

[0003] The hinge 103 is connected to the housings 105 and 10.
6, including the rivet 104 and the lid 115. Front leg 1
The upper end of 01 is fixedly supported by the housing 106 of the hinge 103. The upper end of the rear support leg 102 is fixedly supported by the housing 105. One housing 10
Reference numeral 5 denotes a cylindrical annular portion 109, a bearing 110 formed substantially at the center of the annular portion 109, a pair of stopper pieces 111, and a pair of holes 132, which are integrally formed in a substantially cylindrical shape with a bottom with resin such as ABS. Etc. A sliding surface 133 is formed at the edge of the annular portion 109. The bearing 110 has an insertion hole 134 through which the rivet 104 is inserted. The pair of stopper pieces 111 are arranged at a position on a straight line reaching the bearing 110 from a position facing the annular portion 109. To reinforce the stopper piece 111, a rib is formed on the back surface of the stopper piece 111. A pair of holes 132
Are arranged in a position on a straight line reaching the bearing 110 from a position facing the annular portion 109.

The other housing 106 is a housing 1
It is integrally molded with resin such as ABS almost as same as 05.
Annular portion 112, bearing 113 and pair of stopper pieces 1
14 and so on. The edge of the annular portion 112 is in contact with the sliding surface 133 of the housing 105 and the sliding surface 1
A sliding surface 135 that slides with the slide 33 is formed. Bearing 113
Communicates with the insertion hole 134 of the bearing 110,
04 is formed. The stopper piece 114 is arranged at a position where it can be locked with the stopper piece 111.

The rivet 104 is inserted through the insertion hole 136 of the housing 106 and the insertion hole 134 of the housing 105, and the tip of the rivet 104 is caulked. Thus, a contact force acts between the sliding surfaces 133 and 135, and the sliding surfaces 133 and 135 slide with each other. Therefore, the housing 105 and the housing 1
Reference numeral 06 is connected to rotate about the rivet 104 as a center axis. A pair of locking claws 137 are formed on the lid 115. The locking claw 137 is connected to the hole 132 of the housing 105.
Is snap-engaged. As a result, the lid 115 is attached to the outside of the housing 105. In the stepladder configured as described above, the front support leg 101 and the rear support leg 102 can be freely opened and closed about the rivet 104 of the hinge 103 as a center axis.

[0006]

However, in the conventional stepladder, the two housings 105 and 106 of the hinge are connected with the rivet 1.
04, the two housings 105,
The contact force between the sliding surfaces 133 and 135 of 106 is weak. Therefore, the braking force between the two sliding surfaces 133 and 135 is weak. Further, since the sliding surfaces 133 and 135 are slid, the sliding surfaces 133 and 135 are worn in a short period of time. For this reason,
The braking force between the sliding surfaces 133 and 135 does not work in a short time. Therefore, in the conventional stepladder, the front support leg 10
Since the first and rear legs 102 open and close with a small force about the rivet 104 as a center axis, the door and the rear support leg 102 may suddenly close against the user's will. As a result, there is a great risk that a finger or the like is pinched between the front support leg 101 and the rear support leg 102.

[0007] An object of the present invention is to solve the above-mentioned technical problems and to provide a stepladder with improved safety.

[0008]

Means for Solving the Problems In order to solve the above technical problems, the present invention has the following arrangement. The stepladder according to the first aspect of the present invention is a pair of left and right front supports arranged substantially parallel to each other, a pair of right and left rear supports arranged substantially parallel to each other, and each of the front and rear supports is openably and closably connected. And a pair of left and right hinges, each hinge,
A first housing for fixedly supporting the front support leg, a second housing for fixedly supporting the rear support leg, and the first and second housings are connected, and the first and second housings are mutually connected. A connecting member rotatably supported and fixedly provided on one of the first and second housings, and integrally rotating with one of the housings and rotating about the connecting member as a central axis; A receiving member having a plurality of recesses arranged at predetermined angular intervals along the rotation direction, and fixedly provided on one of the first and second housings and integrated with one of the other housings; And at least one fitting means having a ball which is rotated about the connecting member as a central axis and which is spring-biased in a direction orthogonal to the direction of rotation of the receiving member, when opening and closing the front support leg and the rear support leg. There are, characterized in that the fitting means is fitted to sequentially into each recess of the ball receiving member by integrally rotating with the other one of the housing.

A stepladder according to a second aspect of the present invention is characterized in that, in the first aspect, each recess has a play fitting portion having a predetermined length along the rotation direction.

[0010]

In the stepladder of the first aspect, the receiving member is
The housing is fixedly provided on one of the first and second housings, is rotated integrally with one of the housings, and around a coupling member as a central axis, and at predetermined angular intervals along the rotation direction. It has a plurality of recesses arranged. The fitting means is fixedly provided on one of the other of the first and second housings, rotates integrally with the other one of the housings and around the coupling member as a central axis, and rotates in a direction of rotation of the receiving member. And a ball that is spring-biased in a direction perpendicular to the direction. When the front support leg and the rear support leg are opened and closed, the fitting means rotates integrally with one of the other housings, so that the balls are sequentially fitted into the respective recesses of the receiving member. Thus, when the ball escapes from each recess, a predetermined braking force acts between the first and second housings. The coupling member connects the first and second housings and pivotally supports the first and second housings so as to be rotatable relative to each other. Further, the first housing fixedly supports the front support leg, and the second housing fixedly supports the rear support leg. Therefore, a predetermined braking force acts between the front and rear legs which are opened and closed with the hinge connecting member as the central axis.

In the stepladder of the second aspect, since the concave portion of the receiving member has a play fitting portion having a predetermined length, when any one of the balls of the fitting means fits into one concave portion, the other fitting means can be used. This ball surely fits into the other recess.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing a configuration near a hinge of a stepladder according to an embodiment of the present invention, FIG. 2 is a perspective view showing an entire configuration when the stepladder shown in FIG. 1 is opened, and FIG. FIG. 3 is a right side view of the stepladder shown in FIG. 2 when the leg is closed.

The stepladder according to this embodiment includes a pair of left and right front supports 2, 4, a pair of left and right rear supports 6, 8, and front supports 2, 4.
And a pair of left and right hinges 10 and 12 for opening and closing the rear support legs 6 and 8 so as to be freely opened and closed (only the right side is shown in FIG. 1). As shown in FIG. 2, horizontal rails 14 and 16 having a predetermined length are provided between the front support legs 2 and 4. Crossbar 1
4 and 16 are screwed to the front supports 2 and 4 by screws 18. As a result, the front legs 2, 4 are arranged substantially parallel to each other. After screwing, the screw hole into which the screw 18 is inserted is sealed by the cap 20.
A slide groove 22 having a predetermined length is provided on the facing surface side of the front support legs 2 and 4.
Is formed.

A predetermined length of steps 24, 26 is provided between the pair of left and right rear support legs 6, 8. Engagement projections 28 are provided on the left and right end surfaces of the step 24. Engaging projection 28
Are screwed to the rear supports 6, 8 by screws 30.
At one end of each of the left and right side surfaces of the step board 26, an engagement protrusion 32 is provided. At the other end portions of the left and right side surfaces of the step board 26, engagement projections 34 are provided. The engagement projection 32 is screwed to the rear support legs 6, 8 by a screw 38. The engagement protrusion 34 is movably fitted in the slide groove 22 of the front support legs 2 and 4. As a result, the rear support legs 6, 8 are arranged substantially parallel to each other. The step 24 is rotatable around the engagement protrusion 28. In addition, the step 26 is rotatable around the engagement protrusion 32, and the engagement protrusion 34 of the step 26 slides between the top dead center and the bottom dead center of the slide groove 22.

A hanger link 36 is provided between the left and right sides of the step 24 and the step 26. by this,
The steps 24 and 26 rotate around the engaging projections 28 and 32 integrally. An upper end of one front support leg 2 and a housing 40 as a first housing of the hinge 10 are integrally fixed by screws 42. The upper end of the other front support leg 4 and the housing 44 as the second housing of the hinge 12 are integrally fixed by screws 42. The upper end of one rear support leg 6 and the housing 44 of the hinge 10 are integrally fixed by screws 46. The upper end of the other rear support leg 8 and the housing 40 of the hinge 12 are integrally fixed by screws 46. When the screws 30, 38, and 46 have been screwed, the support cover 5 is inserted into the grooves 48 of the rear support legs 6, 8.
Zero is filled.

FIG. 4 is a sectional view of the hinges 10, 12.
FIG. 5 shows the housing 4 when the hinges 10 and 12 are disassembled.
FIG. 6 is a plan view of the housing 44 when the hinges 10 and 12 are disassembled, and FIG. 7 is a plan view of the plate 56. The hinges 10 and 12 include housings 40 and 44, bolts 52 as connecting members, plates 56 as receiving members, fitting members 58 as fitting means, and the like.

A cylindrical recess 74 is formed on the inner surface of one housing 40. A substantially elliptical column-shaped bearing 76 is formed substantially at the center of the concave portion 74. The bearing 76 is formed with a nut hole 54 into which the bolt 52 is screwed.
At substantially the center of the other housing 44, an insertion hole 68 for inserting the bolt 52 is formed. Housing 4
Nine screw holes 60 for screwing the fitting member 58 are formed in the vicinity of the outer periphery of 4. Each of the screw holes 60 is
It is formed in the same direction as the central axis of the bolt 52. Further, each screw hole 60 is formed on a circumference of a predetermined radius centered on the bolt 52 as a center axis, and the housing 4 having the bolt 52 as the center axis.
4 are arranged at a predetermined angular interval (for example, at an interval of 40 degrees) along the rotating direction. A pair of holes 70 are formed in the vicinity of the outer periphery of the rear surface of the housing 44, approximately 180 degrees around the insertion hole 68 and without the screw hole 60.

The plate 56 is provided in the recess 7 of the housing 40.
In order to be attached to the recess 4, it is formed in a disk shape having substantially the same diameter as the bottom surface of the recess 74. A substantially elliptical insertion hole 78 having substantially the same shape as the bearing 76 is provided substantially at the center of the plate 56 so as to be fitted to the bearing 76 of the housing 40. When the insertion hole 78 of the plate 56 is fitted to the bearing 76 of the housing 40, the insertion hole 78 and the bearing 76 have the same shape.
The housing 40 and the plate 56 do not rotate in different directions. Therefore, the housing 40 and the plate 56
Means to rotate around the bolt 52 fixedly and integrally. On the surface of the plate 56 on the side facing the housing 44, nine conical concave portions 72 having a vertical angle of 90 degrees, for example.
Is formed. Each recess 72 has a predetermined angular interval (for example, a 40-degree interval) along the rotation direction of the housing 40 about the bolt 52 as a central axis on the circumference of the bolt 52 as a central axis. It is arranged open. The radius of the circumference where the concave portions 72 are arranged is selected to be the same value as the radius of the circumference where the screw holes 60 are arranged.

The fitting member 58 is formed in a substantially cylindrical shape.
A screw is screwed on the outer peripheral surface of the fitting member 58. Therefore, each fitting member 58 can be fixed to the housing 44 by screwing the nine fitting members 58 into the respective screw holes 60 of the housing 44. Further, the fitting member 58
Rotates on a circumference of a predetermined radius centered on the bolt 52. The fitting member 58 has a ball 80 that can fit into the concave portion 72 of the plate 56. A seat 61 is formed at the top of the fitting member 58 to prevent the ball 80 from dropping outside. Inside the fitting member 58,
A spring 63 is provided. The elastic force of the spring 63 is
Is transmitted to the ball 80 via the. Therefore, the ball 80 is spring-biased in the same direction as the central axis of the bolt 52.

The inner surfaces of the housings 40 and 44 are aligned, the bolt 52 is inserted into the insertion hole 68 of the housing 44, and the bolt 52 is tightened into the nut hole 54 of the housing 40. As a result, the plate 56 is
8 is pressed in the same direction as the central axis of the bolt 52 from the ball 80 and is fixed to the bottom surface of the concave portion 74 of the housing 40. A pair of locking claws 86 are formed on the cap 84. The locking claw 86 is snapped into the hole 70 of the housing 44. As a result, the cap 84 is attached to the outside of the housing 44. As a result, bolt 5
Exposure such as 2 can be prevented.

Here, the plate 56 is fixedly provided on the housing 40, and the fitting member 58 is
4 is fixed. Also, each recess 72 of the plate 56
Is a plane perpendicular to the central axis of the bolt 52,
Since the direction in which each fitting member 58 is biased by the spring of the ball 80 is the same as the center axis of the bolt 52, the direction of rotation of each recess 72 is orthogonal to the direction in which the spring of the ball 80 is biased. I have. Therefore, the housing 40 and the housing 4
When a force around the bolt 52 is applied between the four, the force acts between the plate 56 and the fitting member 58 via the ball 80. Therefore, the ball 80 of each fitting member 58 rotates while being fitted into each recess 72 along the circumference including the recess 72 of the plate 56 having a predetermined radius centered on the bolt 52. Therefore, the housing 40 and the housing 44 are connected to rotate about the bolt 52 as a center axis. Also, the front legs 2 and 4 are
, And the rear support legs 6 and 8 are fixed to the housing 44. Therefore, the front supports 2, 4 and the rear supports 6, 8 can be freely opened and closed about the bolt 52 of the hinges 10, 12 as a central axis.

In the case of changing from the closed state shown in FIG. 3 to the open state shown in FIG. 2, one of the front legs 2, 4 and one of the rear legs 6, 8 are held. 12
The front legs 2, 4 and the rear legs 6, 8 are opened with the bolt 52 as a central axis. As the front legs 2, 4 and the rear legs 6, 8 are opened, the engagement projections 34 of the step board 26 slide from the top dead center to the bottom dead center of the slide groove 22 and stop. Therefore, the platform 26 rotates around the engagement protrusion 32, and stops with the upper surface thereof being horizontal with the stop of the engagement protrusion 34.
In addition, the step 24 is rotated by the rotation of the step
It rotates around eight times and stops with the top surface horizontal as the step 26 stops.

In the case of changing from the open leg state shown in FIG. 2 to the closed leg state shown in FIG. 3, one of the front legs 2, 4 and one of the rear legs 6, 8 are held. 12
The front legs 2, 4 and the rear legs 6, 8 are closed with the bolt 52 as a central axis. With the closing of the front legs 2, 4 and the rear legs 6, 8, the engagement protrusion 34 of the step board 26 slides from the bottom dead center to the top dead center of the slide groove 22, and stops. Therefore, the platform 26 rotates around the engagement protrusion 32, and stops with the upper surface thereof being parallel to the rear support legs 6 and 8 with the stop of the engagement protrusion 34. Further, the step 24 rotates around the engaging projection 28 with the rotation of the step 26, and stops with the upper surface thereof parallel to the rear support legs 6 and 8 as the step 26 stops.

On the other hand, at the time of opening and closing the legs, when the ball 80 of each fitting member 58 that has fit into each of the recesses 72 of the plate 56 escapes from each of the recesses 72, the ball 80 has one angle from the slope of the recess 72. One component force is a force in the direction of pushing the ball 80 into the fitting member 58, and the other component force is a braking force for suppressing movement around the bolt 52. Therefore, at this time, the plate 56 and the fitting member 58
A braking force around the bolt 52 acts between the housing 40 and the housing 40,
A braking force acts between 44 and a predetermined braking force acts between the front support legs 2 and 4 and the rear support legs 6 and 8 with the bolt 52 as a central axis.
Therefore, there is no longer any free opening or closing of the front support legs 2, 4 and the rear support legs 6, 8 around the bolt 52 as a central axis, and the danger of pinching a finger or the like is eliminated. Note that even if the braking force when the ball 80 of the fitting member 58 escapes from the concave portion 72 of the plate 56 is large, the leg opening force and the leg closing force operate according to the leverage principle. Absent.

FIG. 8 shows a hinge 10 according to another embodiment of the present invention.
FIG. 9 is a plan view showing a plate 56 used in FIG. 12, and portions corresponding to FIG. 7 are denoted by the same reference numerals. It should be noted in this embodiment that a concave portion 73 is used as a receiving portion instead of the concave portion 72. Each of the recesses 73 is
A cross section V having a predetermined length on a circumference of a predetermined radius centered on the half cone conical braking portions 75 and 77 and the bolt 52.
It has a U-shaped loose fitting portion 79. In the case of the concave portion 72 in FIG.
Unless the accuracy of the arrangement position of the screw holes 60 of 4, etc., is sufficiently improved, some of the balls 80 of each fitting member 58 fit into the concave portions 72, but other balls 80 do not fit into the concave portions 72. Things happen. In this case, the spring 63 is compressed in the fitting member 58 in which the ball 80 does not fit in the recess 72. Therefore, if this state is maintained for a long time, the spring 63 is deteriorated. When the spring 63 is deteriorated, the ball 8 acting on the slope of the concave portion 72
One component force in the direction in which 0 can be pushed into the fitting member 58 is reduced. For this reason, the braking force for suppressing the movement around the bolt 52, which is another component, does not work sufficiently.

In this embodiment, a loose fitting portion 79 is provided in the concave portion 73. For this reason, even if the accuracy of the arrangement position of the recess 73, the arrangement position of the screw hole 60 of the housing 44, etc. is somewhat poor, the state in which the balls 80 of all the fitting members 58 fit into the loose fitting portions 79 of the respective recesses 73 will be described. Can be easily realized. Accordingly, since the spring 63 is sufficiently extended at the loose fitting portion 79, the spring 63 is not deteriorated, and the braking portions 75 and 77 can exert a sufficient braking force.

FIG. 9 shows a hinge 10 according to another embodiment of the present invention.
FIG. 10 is a plan view of the case where the housing 12 is disassembled into a housing 40 side and a housing 44 side, and portions corresponding to the embodiment of FIGS. 1 to 7 are denoted by the same reference numerals. It should be noted in this embodiment that an outer ring 81 is used as a receiving member instead of the plate 56. The outer ring 81 is fixed to the housing 40. A plurality of recesses 72 are provided on the inner peripheral surface of the outer ring 81. Each recess 72 is disposed on a plane perpendicular to the central axis of the bolt 52. A cylindrical fixing member 83 is fixed to the housing 44. Each fitting member 58 is screwed to the fixing member 83. The fitting member 58 is disposed on a plane perpendicular to the central axis of the bolt 52 and outward in the circumferential direction. For this reason, the direction of rotation of each recess 72 and the direction in which the ball 80 of the fitting member 58 is spring-biased are orthogonal to each other. As a result, the ball 80 of each fitting member 58 rotates while being fitted into each of the concave portions 72 along the circumference including the concave portions 72 of the outer ring 81 having a predetermined radius centered on the bolt 52. Therefore, when the ball 80 of each fitting member 58 that has fit into each recess 72 of the outer ring 81 escapes from each recess 72, a braking force is applied.

FIG. 10 shows a hinge 1 according to another embodiment of the present invention.
FIG. 10 is a plan view when the housings 0 and 12 are disassembled into a housing 40 side and a housing 44 side, and portions corresponding to the embodiment of FIGS. 1 to 7 and FIG. It should be noted in this embodiment that an inner ring 85 as a receiving member is used instead of the plate 56 and the outer ring 81. The inner ring 85 is fixed to the housing 40. A plurality of recesses 72 are provided on the outer peripheral surface of the inner ring 85. Each recess 72
The bolt 52 is disposed on a plane perpendicular to the central axis. A ring-shaped fixing member 87 is fixed to the housing 44.
Each fitting member 58 is screwed to the fixing member 87. The fitting member 58 is disposed on a plane perpendicular to the central axis of the bolt 52 and inward in the circumferential direction. For this reason, the direction of rotation of each recess 72 and the direction in which the ball 80 of the fitting member 58 is spring-biased are orthogonal to each other. As a result, the ball 80 of each fitting member 58 moves along the circumference of the inner ring 85 including the recess 72 of a predetermined radius centered on the bolt 52.
It rotates while moving into each recess 72. Therefore, when the ball 80 of each fitting member 58 that fits into each recess 72 of the inner ring 85 escapes from each recess 72, a braking force is applied.

In the above embodiment, the housing 40
The plate 56, the outer ring 81 or the inner ring 85 are provided on the housing 44, and the fitting member 58 is provided on the housing 44. However, the plate 56, the outer ring 81 or the inner ring 85 is provided on the housing 44, and the housing 44 is fitted on the housing 44. The joining member 58 may be provided. Further, the concave portion 72 is provided in the outer ring 81 and the inner ring 85,
Instead of the concave portion 72, a concave portion 73 having a loose fitting portion 79 may be provided. Further, although nine fitting members 58 are provided, a single member or another plurality may be provided. Although only one of the concave portion 72 and the concave portion 73 is provided in the plate 56, the outer ring 81, or the inner ring 85, the concave portion 72 and the concave portion 73 may be provided in combination. Further, the shapes of the concave portions 72 and 73 may be other shapes such as a semi-spherical shape, a quadrangular pyramid shape, a semi-elliptical shape, and a rectangular shape. The housing 40,
Reference numeral 44 designates fixedly supporting the upper ends of the front support legs 2, 4 and the rear support legs 6, 8, respectively.
Reference numeral 44 may fixedly support the portions between the upper and lower ends of the front legs 2, 4 and the rear legs 6, 8, respectively.

[0030]

As described above, according to the first aspect of the present invention, when the ball of the fitting means escapes from the concave portion of the receiving member, a braking force is applied in the rotating direction, so that the first member is connected between the fitting means and the receiving member.
Also, since a predetermined braking force is applied between the second housing and the front support leg and the rear support leg, rapid opening and closing operation by a slight force about the connecting member of the front support leg and the rear support leg as a central axis. Therefore, there is no danger of pinching a finger or the like, and safety is improved. According to the second aspect of the present invention, since the concave portion is provided with a play fitting portion having a predetermined length along the rotation direction, when any one of the balls of the fitting means fits into the concave portion,
The ball of the other fitting means also surely fits into the other recess,
It is possible to maintain the braking force for a long time without a decrease in the spring biasing force.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration near a hinge according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the overall configuration of the stepladder shown in FIG. 1 when the leg is opened.

FIG. 3 is a right side view when the stepladder shown in FIG. 2 is closed.

FIG. 4 is a sectional view of hinges 10 and 12;

FIG. 5 is a plan view of the housing 40 when the hinges 10 and 12 are disassembled.

FIG. 6 is a plan view of the housing 44 when the hinges 10 and 12 are disassembled.

FIG. 7 is a plan view of the plate 56. FIG.

FIG. 8 is a plan view showing a plate 56 used for hinges 10 and 12 according to another embodiment of the present invention.

FIG. 9 is a plan view of another embodiment of the present invention in which the hinges 10, 12 are disassembled into a housing 40 side and a housing 44 side.

FIG. 10 is a plan view of another embodiment of the present invention in which the hinges 10, 12 are disassembled into a housing 40 side and a housing 44 side.

FIG. 11 is an exploded perspective view showing the vicinity of a hinge of a conventional stepladder.

[Explanation of symbols]

 2, 4 front legs 6, 8 rear legs 10, 12 hinges 40, 44 housing 52 bolts 56 plate 58 fitting members 72 73 depressed portions 79 loose fitting portions 80 balls 81 outer rings 85… Inner ring

Claims (2)

(57) [Claims] 1. A pair of left and right front supports arranged substantially in parallel with each other, a pair of left and right rear supports arranged substantially in parallel with each other, and a pair of left and right connecting each of the front supports and each of the rear supports in an openable and closable manner. Wherein each hinge comprises: a first housing for fixedly supporting the front support leg; a second housing for fixedly supporting the rear support leg; While connecting the two housings,
A coupling member that rotatably supports the first and second housings with each other; and a fixed member that is fixedly provided on one of the first and second housings, and that is integrated with one of the housings. And a receiving member having a plurality of concave portions arranged at predetermined angular intervals along the rotating direction with the coupling member as a center axis, and fixed to one of the first and second housings. At least one ball that is integrally provided with the other housing and that rotates about the coupling member as a central axis and is spring-biased in a direction perpendicular to the rotation direction of the receiving member. A fitting means, wherein when the front support leg and the rear support leg are opened and closed, the fitting means rotates integrally with the other one of the housings so that the ball Re stepladder, characterized in that fitted into sequentially to each recess of the member. 2. The stepladder according to claim 1, wherein each of the concave portions has a play fitting portion having a predetermined length along the rotation direction.