GB1570869A - Locking mechanisms for scaffolds - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO LOCKING MECHANISMS FOR SCAFFOLDS (71) 1, PER OLOF LISSMYR. a Swedish subject of Box 132, S-792 01 Mora, Sweden, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a locking mechanism for a scaffold comprising at least two relatively movable sections. at least one pawl or catch being arranged at one of said sections while the other section has a number of abutments adapted to be engaged one by one bv said pawl.

In scaffolds or like structures comprising two or more, preferably telescoped sections there must be a free space or play between the sections to allow relative movement thereof. However, when the scaffold sections have been moved to the desired relative position they must be interconnected in such a way that the play therebetween is reduced to the utmost minimum because otherwise the stabilitv of the scaffold would be jeopardised. The object of the invention is to realise a mechanism which automatically provides that the play required for the relative movement of the sections will remain during the displacement thereof, but which interconnects the sections rigidly. i.e. without play, when the desired position has been reached.

The essential characteristic of the mechanism according to the invention resides therein that the pawl is connected with one section bv means of an interconnecting unit which is movable to a limited extent in the direction of displacement of the sections and takes one of its positions of displacement as long as the pawl is in the operative position engaging the abutment but. when said engagement has been interrupted. is carried to its other position of displacement bv spring means or the like. and that the sliding movement of the interconnecting unit is adapted to actuate adjustable blocking means which are arranged in one section and which, in one position, block the free space or play between the relatively movable sections and, in the other position, unblock said free space.

An embodiment of the mechanism according to the invention will be described in greater detail hereinafter with reference to the accompanying drawing, in which: Figure 1 is a partial side view showing two scaffold sections with the interconnecting unit in one position of displacement: Figure 2 is a corresponding front view; and Figure 3 is a partial side view showing the same as Figure 1 and the pawl but in the other position displacement.

For the sake of simplicity only two-side pieces 8 and 11, respectively, of the two relatively movable scaffold sections are shown in the drawing. In the example shown it is presupposed that the side-piece 11 is stationary while the side-piece 8 is vertically movable.

Extending between the side-piece 8 and another side-piece, not shown, both included in the movable section, is a number of rods 9 defining set positions for said section. A pair of rods 5 extend between the side-piece 11 and another side-piece, not shown, which are included in said stationary section.

Each section consists as a rule of two parts of side-pieces 8 and 11. respectively, which are connected in such a way that each section will be of rectangular cross-section which is fitted within the section in which the side-piece 11 is included. The former section thus is vertically slidable within the latter section.

A box lodging the pawl and constituting an interconnecting unit, designated 1, consists of a pair of plates 12 which are connected with one another and between which a pivot pin 10 for a pawl 2 extends. At either end of the pawl box there are elongated slots 6 each having a recess 14 in one of their long sides.

A sleeve, generally designated 15. is rotatably mounted on each of the rods 5.

The sleeve includes a relatively small cylindrical portion 16 the diameter of which corresponds to the width of the slot 6 in the interconnecting unit 1. Extending along said portion 16 is a lug-like projection 7 which is adapted to engage the recess 14 in one of the long sides of the respecitve slot 6. The sleeve also includes a relatively thick portion 17 which is cylindrical along the major part of its periphery but includes a generally flat section 3 so that the sleeve portion in question forms an eccentric.

In mounted position the small sleeve portion 16 extends through the slots 6 in the plates of the intermediate unit. the projection 7 engaging the recess 14. The thick portion extends past the side-piece 8 of the slidable section which extends along the side-piece 11 in diagonally displaced position.

The pawl 2 is adapted to pivot between the shown position of engagement which is defined by a pin 18 engaging the end 13 of the pawl, and an inwardly displaced position, in which the projection of the pawl is situated inwardly of the edge of the pawl box 1.

Between the pawl and an attachment.

suitably arranged on the sleeve 15. a spring 4 is damped in such a way that it tends to swing the pawl outwardly towards the position of engagement and to turn the sleeve 15.

A blocking flap 19 is arranged on the pawl to facilitate the relative movement past such positions which are to be passed. The mechanism according to the invention functions in the following way. When the section including the side-piece 8 is lifted bv means of a winch. not shown, so that the pressure of the rod 9 engaging the pawl no longer is exerted on the latter, the spring 4 will move the pawl box 1 upwardlv to the position shown in Figure 1. During the upward movement of the pawl box the sleeves 15 will turn about 600, due to the engagement between the projection 7 and the recess 14 in the slots 6 at the ends of the box. As a result the thick portion 17 of each of said sleeves will take the position in which the flat portion thereof 3 will face the side-piece 8 of the section to be displaced.The desired play S will thus be created between said flat portion and said side-piece.

When the intended position has been reached and the pawl is again caused to engage the movable section and take up its load, the pawl 2 and. consequently, the pawl box 1 are pulled downwardly against the action of the spring 4. During this movement the recesses 14 and the lug-like projections 7 make the sleeve 15 turn back and the flat section 3 of the thick portion 17 is turned away so that the cylindrical section of said portion will bear against the side-piece 8. As is apparent from Figure 1 the play will thus be eliminated.

The invention should not be considered restricted to that which is described above and shown in the drawing but mav be modified in various ways within the scope of the appended claims.

WHAT I CLAIM IS: 1. Locking mechanism for a scaffold comprising at least two relatively movable sections, at least one pawl or catch being arranged at one of said sections while the other section has a number of abutments adapted to be engaged one by one by the said pawl, wherein the pawl is connected with one section by means of an interconnecting unit which is movable to a limited extend in the direction of displacement of the sections and takes one of its positions of displacement as long as the pawl is in the operative position engaging the abutment but. when said engagement has been inter erupted, is carried to its other position of displacement by spring means or the like, and that the sliding movement of the interconnecting unit is adapted to actuate adjustable blocking means which are arranged in one section and which, in one position, block the free space or play between the relatively movable sections and, in the other position, unblock said free space.

2. Locking mechanism as claimed in claim 1, wherein the blocking means are eccentric or cam-shaped means mounted at one section to pivot between a position where a projecting portion engages the other section, and a position where said portion is removed from said section.

3. Locking mechanism as claimed in claim 2. wherein the turning movement of the eccentric or cam-shaped means is effected in that the interconnecting unit acts upon a lug-like portion of said means.

4. Locking mechanism for scaffolds, substantiallv as herein described with reference to and as illustrated in the accompany ing drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. which a pivot pin 10 for a pawl 2 extends. At either end of the pawl box there are elongated slots 6 each having a recess 14 in one of their long sides. A sleeve, generally designated 15. is rotatably mounted on each of the rods 5. The sleeve includes a relatively small cylindrical portion 16 the diameter of which corresponds to the width of the slot 6 in the interconnecting unit 1. Extending along said portion 16 is a lug-like projection 7 which is adapted to engage the recess 14 in one of the long sides of the respecitve slot 6. The sleeve also includes a relatively thick portion 17 which is cylindrical along the major part of its periphery but includes a generally flat section 3 so that the sleeve portion in question forms an eccentric. In mounted position the small sleeve portion 16 extends through the slots 6 in the plates of the intermediate unit. the projection 7 engaging the recess 14. The thick portion extends past the side-piece 8 of the slidable section which extends along the side-piece 11 in diagonally displaced position. The pawl 2 is adapted to pivot between the shown position of engagement which is defined by a pin 18 engaging the end 13 of the pawl, and an inwardly displaced position, in which the projection of the pawl is situated inwardly of the edge of the pawl box 1. Between the pawl and an attachment. suitably arranged on the sleeve 15. a spring 4 is damped in such a way that it tends to swing the pawl outwardly towards the position of engagement and to turn the sleeve 15. A blocking flap 19 is arranged on the pawl to facilitate the relative movement past such positions which are to be passed. The mechanism according to the invention functions in the following way. When the section including the side-piece 8 is lifted bv means of a winch. not shown, so that the pressure of the rod 9 engaging the pawl no longer is exerted on the latter, the spring 4 will move the pawl box 1 upwardlv to the position shown in Figure 1. During the upward movement of the pawl box the sleeves 15 will turn about 600, due to the engagement between the projection 7 and the recess 14 in the slots 6 at the ends of the box. As a result the thick portion 17 of each of said sleeves will take the position in which the flat portion thereof 3 will face the side-piece 8 of the section to be displaced.The desired play S will thus be created between said flat portion and said side-piece. When the intended position has been reached and the pawl is again caused to engage the movable section and take up its load, the pawl 2 and. consequently, the pawl box 1 are pulled downwardly against the action of the spring 4. During this movement the recesses 14 and the lug-like projections 7 make the sleeve 15 turn back and the flat section 3 of the thick portion 17 is turned away so that the cylindrical section of said portion will bear against the side-piece 8. As is apparent from Figure 1 the play will thus be eliminated. The invention should not be considered restricted to that which is described above and shown in the drawing but mav be modified in various ways within the scope of the appended claims. WHAT I CLAIM IS:

1. Locking mechanism for a scaffold comprising at least two relatively movable sections, at least one pawl or catch being arranged at one of said sections while the other section has a number of abutments adapted to be engaged one by one by the said pawl, wherein the pawl is connected with one section by means of an interconnecting unit which is movable to a limited extend in the direction of displacement of the sections and takes one of its positions of displacement as long as the pawl is in the operative position engaging the abutment but. when said engagement has been inter erupted, is carried to its other position of displacement by spring means or the like, and that the sliding movement of the interconnecting unit is adapted to actuate adjustable blocking means which are arranged in one section and which, in one position, block the free space or play between the relatively movable sections and, in the other position, unblock said free space.

2. Locking mechanism as claimed in claim 1, wherein the blocking means are eccentric or cam-shaped means mounted at one section to pivot between a position where a projecting portion engages the other section, and a position where said portion is removed from said section.

3. Locking mechanism as claimed in claim 2. wherein the turning movement of the eccentric or cam-shaped means is effected in that the interconnecting unit acts upon a lug-like portion of said means.

4. Locking mechanism for scaffolds, substantiallv as herein described with reference to and as illustrated in the accompany ing drawing.