JP2017036624A - Extendable leg device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extendable leg device with excellent safety which allows an extension leg member to be extended/contracted in a more comfortable posture, while preventing a ladder and the like from falling down during extending the leg member.SOLUTION: An extendable leg device 5 includes: extension leg members 6 mounted along a longitudinal direction of support pillars at lower parts of both support pillars of a ladder body 2B formed by fixing a plurality of rungs 4 between a pair of left and right support pillars 3 in a slidable manner, and having grounding members 60 at lower ends; and lock devices 7 for locking the tension leg members to the support pillars at a required slide position. The extension leg members are mounted on the lower parts on lateral outside surfaces of the support pillar in a slidable manner. An operation lever 74 for the lock device is provided at the extension leg member.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a telescopic leg device provided in a lower portion of a ladder body column in a ladder, a stepladder, a work table, or the like provided with a ladder body in which a plurality of step bars are secured between a pair of left and right columns.

In a ladder, a stepladder, a workbench, etc., a pair of left and right columns of the ladder function as legs that support the whole by grounding the lower ends thereof.
Here, the support | pillar of a general ladder body is comprised by single materials, such as an aluminum shape material, The length cannot be changed.
However, in the case of a ladder or the like provided with such a support, there is a problem that when it is installed on a stepped or inclined land, it is tilted or wobbled and becomes unstable, so that it cannot be used safely.

In view of this, a ladder or the like in which a telescopic leg device is provided at the lower part of the support of the ladder body has been proposed (for example, see Patent Document 1 below).
The telescopic leg device includes a telescopic leg member that is slidably inserted into the lower part of the hollow column of the ladder body and has a grounding portion at the lower end, and a lock device that locks the telescopic leg member to the column at a required slide position; It has.
The locking device is provided on the inner side surface of the telescopic leg member in the left-right direction and has a rack having a large number of teeth arranged along the length direction of the telescopic leg member, and a swing extending in the front-rear direction on the lowermost step rail of the ladder body. A lock claw that is incorporated so as to be swingable around the moving shaft and that has a tooth that meshes with the rack tooth at the tip, and that the lock claw is attached in the direction in which the tooth meshes with the rack tooth. The elastic member and the elastic force of the elastic member by pressing upward through an operation window provided so as to branch from the middle of the length of the lock claw inward in the left-right direction and formed on the lower surface of the step bar An operation lever is provided for oscillating the lock claw in a direction in which the teeth of the lock claw deviate from the teeth of the rack.
According to the ladder provided with the above-described telescopic leg device, the telescopic leg member under one or both struts of the ladder body is locked by the lock device at a required slide position even when installed on a stepped or inclined land. As a result, it can be used safely in a stable state standing almost vertically as in the case of installation on a horizontal plane.

JP 2003-193780 A

However, in the telescopic leg device described above, since the operation lever of the locking device is incorporated in the lowermost step bar of the ladder body, when the telescopic leg member is expanded and contracted, the operation lever is pushed upward with one hand. Then, while unlocking, it was necessary to hold the telescopic leg member with the other hand and slide it in the required direction.
For this reason, for example, when performing expansion / contraction work of the expansion / contraction leg member with the ladder etc. standing, the operator needs to squat deeply, and it is difficult to work, and both hands are blocked by the same operation, so the ladder etc. is unstable There was also a risk of falling.

  An object of the present invention is to provide a telescopic leg device that can easily perform the telescopic work of the telescopic leg member in a more comfortable posture, and that does not cause a ladder or the like to fall down during the telescopic work and has excellent safety. It is to provide.

  In order to achieve the above object, the present invention comprises the following aspects.

1) A ladder body in which a plurality of step bars are secured between a pair of left and right pillars. The ladder body is slidably attached along the length of the pillars at the bottom of at least one pillar, and a grounding portion is provided at the lower end. An extendable leg device comprising: an extendable leg member having a lock device that locks the extendable leg member to a support column at a required slide position;
The telescopic leg device, wherein the telescopic leg member is slidably attached to the lower part of the laterally outer side surface of the support column, and the operation unit of the locking device is provided on the telescopic leg member.

2) A guide rail is attached to the lower part of the outer side surface in the left-right direction of the support along the length of the support,
The guide rail has a base wall that faces the laterally outer side surface of the support column, and front and rear guide walls that protrude outward in the lateral direction from both front and rear edges of the base wall.
The telescopic leg member and the front and rear guide walls of the guide rail are provided with fitting portions that can be slidably fitted to each other in the length direction,
The locking device is centered on a rack provided on the outer side surface of the base wall of the guide rail in the left-right direction and having a large number of teeth arranged along the length direction of the guide rail, and a swing shaft extending in the front-rear direction on the telescopic leg member. As a rocking claw and having a tooth that engages with the teeth of the rack at the tip, and an elastic member that urges the locking claw in a direction in which the teeth engage with the teeth of the rack The elastic member is pressed inward in the left-right direction through an operation window that is provided so as to extend in the opposite direction to the lock claw and continues to the base end portion of the lock claw and formed on the left-right outer side surface of the telescopic leg member. The telescopic leg device according to 1), further comprising an operation lever that swings the lock claw in a direction in which the teeth of the lock claw deviate from the rack teeth against the elastic force.

3) The guide rail is attached to the lower part of the left and right outer side of the column via a spacer so that it does not interfere with the end of the hollow tread that passes through the column and is crimped to the outer side of the column. The telescopic leg device of 2) above.

4) A straight line in which the engagement surfaces of the rack teeth and the lock claw teeth, which are engaged with each other when an external force is applied in the extending direction of the telescopic leg member, extends from the engagement surface toward the swing center of the lock claw. 2. The telescopic leg device according to 2) or 3), wherein the telescopic leg device is formed so as to be inclined to the rack side at an angle of 10 ° or less with respect to the perpendicular of the engaging surface.

In the telescopic leg device of 1) above, when the telescopic leg member is expanded and contracted, the member may be slid in a required direction while holding the member with one hand and operating the operating portion of the locking device.
Therefore, according to the telescopic leg device of the above 1), for example, the telescopic work of the telescopic leg member can be easily performed with one hand even when the ladder or the like is standing upright, and the ladder or the like is supported with the other hand. Since it can be prevented from falling down, it is possible to work safely.
The operation unit of the locking device is more preferably provided on the upper surface of the telescopic leg member. In this way, it is not necessary to squat deeply when the telescopic leg member is expanded and contracted, and the work can be performed in a more comfortable posture.

According to the telescopic leg device of 2), since the telescopic leg member is attached to the lower part of the outer side surface in the left-right direction of the support via the guide rail, it is not necessary to provide a complicated mounting structure for the support. A typical one can be used, and the extension leg member can be easily attached.
Further, according to the telescopic leg device of 2), the lock device can be easily unlocked by pressing the operation lever with a finger through the operation window formed on the laterally outer side surface of the telescopic leg member. In addition, since the telescopic leg member can be easily slid while performing the unlocking, excellent operability can be obtained.

  According to the telescopic leg device of the above 3), even if the ladder is provided with a ladder body in which the end portion of the hollow step bar is crimped to the column, the guide rail is placed on the lower part of the outer side in the horizontal direction of the column. It can be easily installed without hindrance, and the range of applications can be expanded.

According to the telescopic leg device of the above 4), the following problems can be avoided.
In other words, when an external force is applied in the direction in which the telescopic leg member extends, the engagement surface of the rack teeth and the lock claw teeth that are engaged with each other extends straight from the engagement surface toward the center of the lock claw. Is inclined at an angle exceeding 10 ° to the rack side with respect to the normal of the engagement surface, and when an external force acts in the direction in which the telescopic leg member extends, the lock claw is urged in the locking direction. The force that causes the lock claw to swing in the unlocking direction more easily than the elastic force of the elastic member is generated. Then, for example, when the ladder or the like is lifted and transported, the lock device may be carelessly unlocked, and the telescopic leg member may be extended.
On the other hand, when the engagement surface is formed such that a straight line extending from the engagement surface toward the rocking center of the lock claw is inclined to the lock claw side with respect to the normal of the engagement surface, the telescopic leg member When an external force is applied in the direction in which the lock extends, a force that swings the lock claw in the lock direction is generated, so there is no risk of the lock device being unlocked unexpectedly. It is necessary to press, and the operability may be impaired.

It is a perspective view of the ladder concerning a 1st embodiment of this invention. It is a front view which expands and shows the expansion-contraction leg apparatus provided in the lower part of the said ladder. It is an expanded sectional view which follows the III-III line of FIG. It is the IV-IV arrow line view of FIG. It is a partial expanded sectional view which follows the VV line of FIG. It is a disassembled perspective view of the said expansion-contraction leg apparatus. (A) is an exploded perspective view of units, such as a lock claw of a locking device in the above-mentioned telescopic leg device, and (b) is a perspective view showing an assembly state of the unit. FIG. 2 shows a locked state of the locking device, wherein (a) is a vertical sectional view showing an engaged state between the lock claw and the rack teeth when an external force in the direction in which the telescopic leg member contracts acts. (B) is a vertical sectional view showing the engagement state of the lock claw and the rack teeth when an external force in the direction in which the telescopic leg member extends is applied. FIG. 5 shows the force acting on the locking device in the locked state, wherein (a) shows the engagement surface between the locking claw and the rack teeth when an external force acting in the direction in which the telescopic leg member contracts is applied. FIG. 5B and FIG. 5C show the force generated on the engaging surfaces of the locking claws and the rack teeth when an external force in the direction in which the telescopic leg member extends is applied. FIG. It is a left view of the stepladder which concerns on 2nd Embodiment of this invention. It is a partial expanded horizontal sectional view which follows the XI-XI line of FIG.

(First embodiment)
1 to 9 show a first embodiment of the present invention.
In the first embodiment, the telescopic leg device according to the present invention is applied to a dual ladder.
In the following description, “left and right” refers to the left and right of FIG. 2, “front” refers to the right side of FIG. 4, and “rear” refers to the left side of FIG.

As shown in FIG. 1, the two-stage ladder (1) is formed by connecting two upper and lower ladder bodies (2A) and (2B) in a telescopic manner.
Each of the upper and lower ladder bodies (2A) (2B) includes two left and right support posts (3) and a plurality of step bars (4) secured between the support posts (3) at equal intervals in the vertical direction. I have.
The telescopic leg device (5) according to the present invention is provided below the left and right struts (3) of the lower ladder body (2B).

2-6 shows the detailed structure of the lower part of a lower ladder body (2B).
The left and right struts (3) of the lower ladder body (2B) are made of a shape material such as aluminum. The left column (3) has a substantially U-shaped cross section including a vertical left side wall (31) and a front and rear wall (32) extending rightward from the front and rear edges of the left side wall (31) (FIG. 3). reference). The right strut (3) is symmetrical with the left strut (3) and has a substantially U-shaped cross section with a right side wall (31) and front and rear walls (32).
Each step bar (4) of the lower ladder body (2B) is made of a shape material such as hollow aluminum, and the upper part thereof is flat and the remaining part is a downward convex arc. The left end of the step bar (4) is passed through an insertion hole (not shown) formed in the left side wall (31) of the left column (3) and bulged to the left side wall (31) of the left column (3). ) And the right end is passed through an insertion hole (not shown) in the right side wall (31) of the right column (3) and bulged to the right side wall (31) of the right column (3) It has been swaged. Therefore, the crimped left end (41) of the crosspiece (4) protrudes from the outer surface of the left wall (31) of the left column (3) (see FIG. 5), and the right end (41) It protrudes from the outer surface of the right side wall (31) of the column (3).
The bottom pedestal (4) is held between the left side wall (31) of the left column (3) and the right side wall (31) of the right column (3) with a distance slightly above the lower end. Yes. Between the lower surface of the lowermost step bar (4) and the left side wall (31) of the left column (3) and the lower end of the right side wall (31) of the right column (3), each consists of a metal plate piece. The reinforcing metal fitting (21) is held diagonally.

The telescopic leg device (5) provided at the lower part of the left and right struts (3) of the lower ladder body (2B) is completely left-right symmetric. Therefore, hereinafter, the telescopic leg device (5) provided in the lower part of the left column (3) will be described in detail based on the drawings, and the description of the other telescopic leg device (5) will be omitted.
The telescopic leg device (5) is slidably attached along the length of the left column (3) to the lower part of the left side wall (31) of the left column (3) and has a grounding part (60) at the lower end. And a telescopic leg member (6) and a locking device (7) for locking the telescopic leg member (6) at a required slide position.
A guide rail (8) is attached to the lower part of the left side wall (31) outer surface of the left column (3) along the length direction of the left column (3). The guide rail (8) is inserted into the left column (3) via the spacer (9) so that it does not interfere with the left end (41) of the step bar (4) protruding from the outer surface of the left column (31) of the left column (3). ) Is attached to the lower part of the outer surface of the left side wall (31). The extendable leg member (6) is attached to the guide rail (8) so as to be slidable in the length direction.

The guide rail (8) includes a base wall (81) that faces the outer surface of the left side wall (31) of the left column (3), and a front and rear guide wall (82) that protrudes leftward from the front and rear edges of the base wall (81). It has a substantially U-shaped cross section. A fitting convex portion (83) bent outward in the front-rear direction is provided at the front end portion of the front-rear guide wall (82). In the middle of the left and right widths of the opposing surfaces of the front and rear guide walls (82), there are provided vertical ridges that protrude short so as to face each other, and an internal enlarged groove (84) is formed between these ridges and the base wall (81). Is formed. On the right side surface of the base wall (81), a vertical fitting convex portion (85) is formed in a portion near the front and rear edges thereof, extending in a short direction toward the right and bending the tip outward in the front and rear direction.
As shown in FIG. 6, a total of three spacers (9) are used, and the upper end, lower end, and intermediate length of the outer surface of the left wall (31) of the left column (3) to which the guide rail (8) is attached. In addition, it is arranged so as to avoid the left fixed end (41) of the step bar (4). These spacers (9) are made of vertical metal plate pieces, and the lower end spacer (9) is slightly longer than the other two spacers (9). Each spacer (9) has the same horizontal cross section, and is superimposed on the outer surface of the left side wall (31) of the left column (3), and its front and rear ends are bolts (B) and nuts (N). Is fixedly bonded to the left side wall (31). A raised portion (91) having a trapezoidal cross section is formed at an intermediate portion in the front-rear width of the outer surface (left side surface) of each spacer (9). Then, two vertical front and rear fitting recesses (92) into which the two front and rear fitting projections (84) of the guide rail (8) are slidably fitted in the vertical direction are formed on the raised portion (91). Has been.
The guide rail (8) is joined to the outer surface of the left wall (31) of the left column (3) with bolts (B) and nuts (N) with the spacer (9) sandwiched between the upper and lower ends. It is fixed (see FIG. 6).
A cap (11) is attached to the upper end portion of the guide rail (8) so as to cover the upper end surface and the upper end surface of the spacer (9). The cap (11) is made of, for example, a synthetic resin, and has a single-flow roof shape so as to release the force when contacting the obstacle.

The telescopic leg member (6) is made of a material such as aluminum, for example, and has a hollow base portion (61) having a substantially rectangular cross section that is long in the front and rear sides, and right and left edge portions of the right side wall of the base portion (61). Two front and rear projections (62) projecting and having a hollow shape with a substantially square cross section are provided.
The front wall of the base portion (61) and the front wall of the front convex portion (62) connected to the front portion extend obliquely forward toward the right as a whole. Similarly, the rear wall of the base part (61) and the rear wall of the rear convex part (62) connected to the rear part extend obliquely rearward toward the right as a whole.
The right side wall of the front convex part (62) extends obliquely rightward toward the rear, and the rear end edge part protrudes rearward from the rear wall. Then, the front fitting recess (63) is formed by the rear wall edge of the front convex portion (62) and the rear edge portion of the right side wall, and the right wall portion of the base portion (61) facing the rear edge portion. The front fitting concave portion (63) is fitted into the front fitting convex portion (83) of the guide rail (8) so as to be slidable in the length direction.
Similarly, the right side wall of the rear convex portion (62) extends obliquely rightward toward the front, and the front end edge portion projects forward from the front wall. Then, the rear fitting concave portion (63) is formed by the front wall of the rear convex portion (62), the front end edge of the right side wall, and the right side wall portion of the base portion (61) facing the front end edge. The fitting recess (63) is fitted into the rear fitting projection (83) of the guide rail (8) so as to be slidable in the longitudinal direction.
With the above fitting structure, the extensible leg member (6) is slidably attached to the guide rail (8) along its length direction.
An upper cap (64) is attached to the upper end of the telescopic leg member (6) so as to close the upper end openings of the base (61) and the two front and rear projections (62). The upper cap (64) is made of, for example, a synthetic resin, and has a gable roof shape so as to release the force when contacting the obstacle.
A lower cap (65) is attached to the lower end of the telescopic leg member (6). The lower cap (65) is made of, for example, a synthetic resin, and includes a horizontal plate portion (651) that closes a lower end opening of the base portion (61) of the telescopic leg member (6) and the two front and rear projections (62), and a horizontal plate A fitting portion (652) that protrudes upward from the portion (651) and is fitted into the base portion (61).
Also, a substantially disc-shaped grounding member (60) is attached to the lower end of the telescopic leg member (6) via a U-shaped bracket (66) so as to be swingable in the front-rear direction by bolts and nuts. ing. The grounding member (60) constitutes a grounding portion at the lower end of the telescopic leg member (6). For example, an anti-slip sheet made of rubber (60a) is attached to the lower surface of the grounding member (60).

The locking device (7) is a rack (71) having a number of teeth (711) provided on the left side surface of the base wall (81) of the guide rail (8) and arranged along the length direction of the guide rail (8). And a tooth (721) (722) which is incorporated in the telescopic leg member (6) so as to be swingable about a swinging shaft extending in the front-rear direction and meshed with the teeth (711) of the rack (71) at the tip. The lock claw (72) having the elastic claw (73) and the elastic member (73) for urging the lock claw (72) in a direction in which the teeth (721) and (722) mesh with the teeth (711) of the rack (71). ) And the base end of the lock claw (72), and is extended through the operation window (672) provided on the surface of the telescopic leg member (6) and extending in the opposite direction to the lock claw (72). Thus, the operating lever (74) swings the lock pawl (72) against the elastic force of the elastic member (73) in a direction in which the teeth (721) (722) are disengaged from the teeth (711) of the rack (71). ) (Operation unit).
The rack (71) is fitted into the internal enlarged groove (84) of the guide rail (8) so that the surface having the teeth (711) is directed to the left, and the upper and lower ends thereof are guided by the rivets or the like. The base wall (81) is joined and fixed.
As shown in FIGS. 5 and 7, the lock claw (71), the elastic member (73), and the operation lever (74) are incorporated in the bracket (75) to constitute one unit.
The bracket (75) is made of a bent metal piece having a substantially U-shaped horizontal cross section that opens to the left. The upper part of the right side wall (751) of the bracket (75) is cut out so as to expose the tip of the lock claw (72). A bottom wall portion (752) bent at a right angle toward the left is continuously provided at the lower end portion of the right side wall (751) of the bracket (75). An insertion hole (753a) is formed in the middle of the height of the front and rear walls (753) of the bracket (75) so as to face each other. At the upper end of the front wall (753) of the bracket (75), an upper mounting portion (754) bent at a right angle toward the rear wall (753) is continuously provided. A lower mounting portion (755) that is bent at a right angle toward the outside in the front-rear direction is connected to the lower end portion of the front-rear wall (753) of the bracket (75).
The lock claw (72) and the operation lever (74) are constituted by one swing piece (70). The oscillating piece (70) has an insertion hole (701) penetrating in the front-rear direction at the center of its length. Then, the swing piece (70) is inserted into the bracket (75) and straddles the insertion hole (701) of the swing piece (70) and the insertion hole (753a) of the front and rear walls (753) of the bracket (75). By inserting the pin (76), the swing piece (70) is swingably attached to the bracket (75) about the pin (76). The lock claw (72) is constituted by the upper part of the swing piece (70), and the operation lever (74) is constituted by the lower part of the swing piece (70).
At the tip of the lock claw (72), four teeth (721) and (722) lined up and down are formed so as to face the rack (71) side, that is, to the right.
Two bent portions (741) bent substantially at right angles toward the right are formed at the front end of the operation lever (74) with a slight gap therebetween.
The left side surface of the operation lever (74) constitutes a pressing portion (74a) that is pressed with a finger when unlocking. In the pressing portion (74a), a plurality of horizontal grooves (742) having a concave arc shape in the cross section are formed at equal intervals in the vertical direction in order to prevent the fingers from slipping.
The elastic member (73) is composed of a compression coil spring, and is interposed between the right side wall (751) of the bracket (75) and the operation lever (74) on the lower part of the swing piece (70) to swing. The piece (70) is urged toward the locking direction in which the teeth (721) and (722) of the lock claw (72) on the upper part thereof mesh with the teeth (711) of the rack (71).

The unit is accommodated in the telescopic leg member (6) through a substantially square hole (611) formed in the upper part of the left side wall of the base (61) in the telescopic leg member (6), and the unit of the bracket (75). The upper and lower mounting portions (754) and (755) are fixed to the telescopic leg member (6) by being joined to the left side wall of the base portion (61) by rivets or the like.
The right part of the bracket (75) and the tip of the locking claw (72) are extended through a vertically rectangular hole (612) formed in the upper part of the right side wall of the base (61) of the extendable leg member (6). It protrudes on the back side of the member (6).
The left side wall outer surface (left side surface) of the base portion (61) of the telescopic leg member (6) is covered with a substantially rectangular frame-shaped cover (67) so as to cover a part of the hole (611) and the unit. Yes. The upper edge of the cover (67) is formed with two front and rear hooks (671) that are engaged with the upper edge of the hole (611) in the inner surface of the left side wall of the base (61) of the telescopic leg member (6). Yes. The lower edge of the cover (67) is joined and fixed to the left side wall of the base (61) of the telescopic leg member (6) with a rivet or the like.
In the central opening (672) of the cover (67), the pressing part (74a) of the operating lever (74) of the swing piece (70) is arranged so as not to protrude from the surface side of the cover (67). The central opening constitutes an operation window (672). The cover (67) prevents the pressing portion (74a) of the operating lever (74) from being carelessly pressed and unlocked.

When the telescopic leg member (6) is slid in the extending direction, the bottom wall portion (752) of the bracket (75) secures the guide rail (8) to the lower end of the left column (3) ( It abuts against the head of B), thereby preventing the telescopic leg member (6) from coming out below the guide rail (8) (see FIG. 2). At this time, the telescopic leg member (6) is in the maximum stretched state where the downward projecting portion is the longest.
On the other hand, when the telescopic leg member (6) is slid in the contracting direction, the upper end of the fitting portion (652) of the lower cap (65) attached to the lower end of the telescopic leg member (6) is moved to the guide rail (8 ), Thereby preventing the telescopic leg member (6) from penetrating above the guide rail (8) (see FIG. 2). At this time, the expansion / contraction leg member (6) is in the minimum expansion / contraction state where the downward projecting portion is the shortest.

For example, as shown in FIG. 2, when the ladder (1) is installed in a stepped area where the right installation surface (G1) is higher than the left installation surface (G2), the left telescopic leg device ( By extending the telescopic leg member (6) of 5) by a required length, it can be used safely in a stable state standing almost vertically as in the case of being installed on a flat horizontal surface.
Here, when the telescopic leg member (6) is extended, while pressing the operation lever (74) of the locking device (7) provided on the upper surface of the telescopic leg member (6) with one finger, You can hold the telescopic leg member (6) with the same one hand and slide it in the extension direction, so you can work safely while supporting the column (3) and the step rail (4) of the ladder (1) with the other hand. It can be carried out.

FIG. 8 shows a locked state in which the teeth (721) and (722) of the locking claw (72) and the teeth (711) of the rack (71) mesh with each other in the locking device (7) of the telescopic leg device (5). It is.
A number of teeth (711) of the rack (71) are arranged in the vertical direction at a predetermined pitch. The teeth (711) are all the same shape and size, and have a substantially inverted isosceles trapezoidal cross section. More specifically, the top surface (711a) of the tooth (711) is a flat vertical surface. The upper and lower side surfaces of the tooth (711) are tapered such that the top half of the tooth (711) is a flat horizontal surface (711b) and the other half is gradually tapered toward the root. Surface (711c).
On the other hand, in the case of the lock claw (72), the shape and size of the upper two teeth (721) and the lower two teeth (722) are different.
The upper two teeth (721) of the locking claw (72) have a cross section of a substantially inverted unequal foot trapezoidal shape, and the top surface is a flat vertical surface (721a), and the upper side surface thereof Consists of a flat horizontal surface (721b) and a tapered surface (721c) inclined so that the half of the top surface of the lower surface gradually becomes narrower toward the root, and the rest of the lower surface The half of each is a flat horizontal surface (721d). The maximum thickness of the upper two teeth (721) is slightly smaller than the maximum thickness of the teeth (711) of the rack (711) so that it can be inserted between the teeth (711) of the rack (71). Yes.
The lower two teeth (722) of the lock claw (72) have a substantially rectangular cross section, and the top surface is a flat vertical surface (722a), and the upper and lower side surfaces are flat. It consists of a horizontal plane (722b). The thickness of the lower two teeth (722) is slightly smaller than the maximum thickness of the upper two teeth (721).

In the installation state in which the ladder (1) is leaned against a wall or a roof, an external force acts on the ladder (1) in a direction in which the telescopic leg member (6) contracts. In this case, as shown in FIG. 8A, the lock pawl (72) tends to move upward and the rack (71) tends to move downward. The upper surfaces (721b), (722b) (engagement surfaces) of the four teeth (721), (722) of the lock claw (72) are connected to the lower surfaces of the four teeth (711) of the corresponding rack (71). It is engaged with the horizontal surface portion (711b) (engagement surface).
FIG. 9 (a) shows the force generated on the engagement surface (721b) of the uppermost tooth (721) of the lock claw (72) in the installed state of the ladder (1). A radially outward force (P1) extending from the swing center (C) of the lock claw (72) through the engagement surface (721b) acts on the engagement surface (721b). This force (P1) is the force acting in the direction of swinging the locking claw (72), that is, the tangential force (P2) of the engaging surface (721b) and the tooth (721) of the locking claw (72). The engagement surface (721b) is divided into a force that pushes the engagement surface (711b) of the teeth (711) of the rack (71) vertically, that is, a force (P3) in the perpendicular direction of the engagement surface (721b). Then, the force (P2) in the tangential direction of the engagement surface (721b) tries to press the teeth (721) of the lock claw (72) further against the rack (71) in the clockwise direction of FIG. 9 (a). It turns out that it is facing the lock direction. Although not shown, a force in the same direction as described above also acts on the engagement surfaces (721b) and (722b) of the second and subsequent teeth (721) and (722) from the top of the lock claw (72). . Although not shown in FIG. 9, the elastic force of the elastic member (73) made of a compression coil spring acts on the engagement surfaces (721b) and (722b) in the locking direction. Therefore, in the installed state where the ladder (1) is leaned against a wall or the like, the locked state by the locking device (5) is reliably maintained, and there is no possibility that the lock is inadvertently released.

Next, in a state where the ladder (1) is lifted while supporting a part other than the telescopic leg member (6) during transportation, for example, an external force is applied in the direction in which the telescopic leg member (6) extends with respect to the ladder (1). Works. In this case, as shown in FIG. 8B, the lock claw (72) tends to move downward and the rack (71) tends to move upward. Of the four teeth (721) and (722) of the lock claw (72), the tapered surface portion (721c) (engagement surface) on the lower surface of the upper two teeth (721) is the corresponding rack (71). The two teeth (711) are respectively associated with tapered surface portions (721c) (engagement surfaces) on the upper surface. However, the lower surface (722b) of the lower two teeth (722) is not engaged with the lower surfaces (721c) and (721d) of the two teeth (711) of the corresponding rack (71).
FIG. 9 (b) shows the force generated on the engagement surface (721c) of the uppermost tooth (721) of the lock claw (72) when the ladder (1) is lifted. A radially inward force (P1) extending from the swing center (C) of the lock claw (72) through the engagement surface (721c) acts on the engagement surface (721c). This force (P1) is the force acting in the direction of swinging the lock claw (72), that is, the tangential force (P2) of the engagement surface (721c) and the tooth (721) of the lock claw (72). The engagement surface (721c) is divided into a force that pushes the engagement surface (711c) of the teeth (711) of the rack (71) perpendicularly, that is, a force (P3) in the perpendicular direction of the engagement surface (721c). Then, the tangential force (P2) of the engagement surface (721c) is the counterclockwise direction of FIG. 9 (a), that is, the lock release in which the tooth (721) of the lock claw (72) is separated from the rack (71). Facing the direction. When this force (P2) becomes larger than the elastic force of the elastic member (73) acting in the locking direction, the engagement surface (721c) of the teeth (721) of the lock claw (72) and the teeth ( 711) is disengaged from the engagement surface (711c), and the tooth (721) of the lock claw (72) is released from the tooth (711) of the rack (71), and the telescopic leg member (6) is released. The situation that it grows carelessly occurs.
Therefore, in the telescopic leg device (5) according to the present invention, when the external force is applied in the extending direction of the telescopic leg member (6), the teeth (721) of the lock claw (72) and the rack (71) The engagement surface (721c) (711c) of the tooth (711) is associated with the straight line (L1) extending from the engagement surface (721c) (711c) toward the rocking center (C) of the lock claw (72). It is formed so as to coincide with the perpendicular (L2) of the mating surfaces (721c) and (722c) or to be inclined toward the rack (72) at an angle (A1) within 10 ° with respect to the perpendicular (L2).
In this embodiment, the tapered surface portion (721c) of the lower surface of the upper two teeth (721) of the lock claw (72), and the tapered surface portion (711c) of the upper surface of the teeth (711) of the rack (71). Corresponds to the engagement surface. In the case of the uppermost tooth (721) of the lock claw (72) and the engagement surface (721c) (711c) of the tooth (711) of the rack (71) corresponding thereto, as shown in FIG. The angle (A1) is about 3 °. Further, in the case of the second tooth (721) from the top of the lock claw (72) and the engaging surface (721c) (711c) of the tooth (711) of the rack (71) corresponding thereto, FIG. As shown, the angle (A1) is about 9.5 °. In any case, the force (P2) acting in the unlocking direction on the engaging surfaces (721c) and (711c) is sufficiently smaller than the elastic force of the elastic member (73) acting in the locking direction. In addition, the angle (A1) increases as the position of the teeth of the lock claw (72) is lowered, and accordingly, the force (P2) acting in the unlocking direction on the engagement surface also increases. However, as described above, the lower surface (722b) of the lower two teeth (722) of the locking claw (72) is engaged with the lower surfaces (711b) (711c) of the teeth (711) of the rack (71). There is no such thing.
With the above configuration, in the telescopic leg device (5) of this embodiment, even when an external force is applied in the direction in which the telescopic leg member (6) extends, a large force is exerted on the lock pawl (72) in the unlocking direction. Since it does not act, the locked state is reliably maintained by the elastic force of the elastic member (73), and the inconvenience that the telescopic leg member (6) extends carelessly does not occur.
Further, according to the telescopic leg device (5) of this embodiment, it is not necessary to use an elastic member (73) having a larger elastic force than necessary, so the lock device (5) is unlocked. Therefore, the force that presses the pressing portion (74a) of the operating lever (74) is not so great, and the operability is not impaired.

(Second Embodiment)
9 and 10 show a second embodiment of the present invention.
In the second embodiment, the telescopic leg device according to the present invention is applied to a stepladder.
In the following description, “front” refers to the right side of FIG. 9, “rear” refers to the left side of FIG. 9, and “left and right” refers to the left and right when viewed from the front.

As shown in FIG. 9, the stepladder (10) is formed by connecting the upper ends of the two front and rear ladder bodies (20A) and (20B) with a hinge fitting (201) so as to be freely opened and closed.
Each of the front and rear ladder bodies (20A, 20B) includes two left and right struts (30) and a plurality of step bars (not shown) secured between the two struts (30) at equal intervals in the vertical direction. It has.
The struts (30) and the step bars of the front and rear ladder bodies (20A, 20B) are the struts of the upper and lower ladder bodies (2A) (2B) in the ladder (1) of the first embodiment except for the following points. It is substantially the same as (3) and the treadle (4).
That is, the left and right ends of each step bar are fixed to the front and rear walls (32) of the left and right columns (30) by rivets (not shown), etc., and penetrate the side walls (31) of each column (30), It does not have a protruding part on its outer surface.

Telescopic leg devices (50) are respectively provided at the lower portions of the left and right struts (30) of the front and rear ladder bodies (20A) (20B).
The telescopic leg device (50) has substantially the same structure as the telescopic leg device (5) of the first embodiment except for the following points, and is substantially the same as the device (5). The effect of this is achieved.
That is, in the case of the telescopic leg device (5) of this embodiment, the guide rail (80) is directly attached to the outer surface of the side wall (31) of the column (30) without a spacer as shown in FIG. Yes. More specifically, a fitting convex portion is not formed on the inner surface in the left-right direction of the base wall (81) of the guide rail (80), and instead, the base wall (81) of the guide rail (80) is formed. A front / rear mounting portion (86) is formed that extends inward in the left-right direction from the front / rear edge of the front and rear ends and is bent at right angles outward in the front-rear direction. These front and rear mounting portions (86) are fixed to the side wall (31) of the support column (30) by bolts (B) and nuts (N).

  It should be noted that each of the above embodiments is merely an example, and it is of course possible to implement the present invention as a mode appropriately modified without departing from the gist described in the claims.

(1): Double ladder
(2A): Upper ladder body
(2B): Lower ladder body
(3): Prop
(4): Tread
(41): End of (tread bar)
(5): Telescopic leg device
(6): Telescopic leg member
(60): Grounding member (grounding part)
(63): Mating recess
(672): Control window
(7): Locking device
(71): Rack
(711): (rack) teeth
(711c): Tapered surface portion (engagement surface) of upper surface (of tooth)
(72): Lock claw
(721): Upper two teeth (of lock claw)
(721c): Tapered surface portion (engagement surface) of lower surface (of tooth)
(722): Lower two teeth (of lock claw)
(73): Elastic member
(74): Control lever (control unit)
(8): Guide rail
(83): Mating protrusion
(9): Spacer
(L1): A straight line extending from the engagement surface toward the center of swing of the lock claw
(L2): perpendicular to engagement surface
(10): Stepladder
(20A): Front ladder body
(20B): Rear ladder body
(30): Prop
(50): Telescopic leg device
(80): Guide rail

Claims (4)

A ladder body in which a plurality of step bars are secured between a pair of left and right struts, is attached to the lower part of at least one of the struts so as to be slidable along the length of the strut, and has a grounding portion at the lower end. A telescopic leg device comprising: a telescopic leg member, and a locking device that locks the telescopic leg member to the support column at a required slide position,
The telescopic leg device, wherein the telescopic leg member is slidably attached to the lower part of the laterally outer side surface of the support column, and the operation unit of the locking device is provided on the telescopic leg member. A guide rail is attached along the length direction of the column at the bottom of the left and right outer side of the column,
The guide rail has a base wall that faces the laterally outer side surface of the support column, and front and rear guide walls that protrude outward in the lateral direction from both front and rear edges of the base wall.
The telescopic leg member and the front and rear guide walls of the guide rail are provided with fitting portions that can be slidably fitted to each other in the length direction,
The locking device is centered on a rack provided on the outer side surface of the base wall of the guide rail in the left-right direction and having a large number of teeth arranged along the length direction of the guide rail, and a swing shaft extending in the front-rear direction on the telescopic leg member. As a rocking claw and having a tooth that engages with the teeth of the rack at the tip, and an elastic member that urges the locking claw in a direction in which the teeth engage with the teeth of the rack The elastic member is pressed inward in the left-right direction through an operation window that is provided so as to extend in the opposite direction to the lock claw and continues to the base end portion of the lock claw and formed on the left-right outer side surface of the telescopic leg member. The telescopic leg device according to claim 1, further comprising an operation lever that swings the lock claw in a direction in which the teeth of the lock claw deviate from the teeth of the rack against the elastic force.   The guide rail is attached to the lower part of the lateral outer side of the column via a spacer so that it does not interfere with the end of the hollow tread that passes through the column and is crimped to the lateral outer side of the column. The telescopic leg device according to claim 2. When the external force is applied in the direction in which the telescopic leg members extend, the engagement surfaces of the rack teeth and the lock claw teeth that are engaged with each other have the same straight line extending from the engagement surface toward the center of the lock claw. The telescopic leg device according to claim 2 or 3, wherein the telescopic leg device is formed so as to coincide with the perpendicular of the engaging surface or to be inclined toward the rack at an angle of 10 ° or less with respect to the perpendicular.

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