Scaffolding

Abstract: A scaffolding system comprises a diagonal brace 6 with a transverse pin 13 for engaging an eye 8 of a ledger end fitting. To hold the pin in the eye, the pin has an internal snap-action latch 15, with a hooked projection end to engage a complementary configuration 21 on the eye. The latch is provided with an operating arm 18 projecting from the pin, for moving the latch to a position retracted within the pin to enable the pin to be removed from the eye.

Description: This invention relates to scaffolding. In recent years, scaffolding systems have been developed in which the scaffolding elements, usually metal tubes, are interconnected by captive fittings, rather than by separate clamps. These systems provide improved speed of erection and striking, improved safety, and increased life. An object of the present invention is to provide a simple, compact and reliable means of interconnecting scaffold elements, in particular for connecting elongate scaffold elements to other elements. Danish Patent Application DK-A-117987 describes a scaffolding element including top and bottom chords having end pins, each with a portion orientated transversely to the chords. Each end pin has an oblique aperture housing a rivet-shaped member which is spring biased to a position where the head protrudes from the pin. In use, each end pin is passed through an aperture in another scaffolding element and retained there by the protruding rivet. The rivet is pushed into the pin by direct manual pressure to release the end pin from the aperture. According to the present invention, an end fitting for a scaffolding element having a transverse pin for insertion in an aperture provided in another fitting, and, a latch housed within the pin and resiliently loaded such as to urge the latch to a first position in which at least a portion of the latch protrudes laterally from the pin adjacent the free end of the pin for retaining the pin in the aperture, the latch further having a second, retracted, position in which it is accommodated entirely or substantially entirely within the pin against its resilient loading, for permitting the pin to be inserted in and removed from the aperture, characterised in that the end fitting includes an operating member arranged to retract the latch, for enabling the pin to be removed from the aperture. A scaffolding element, in accordance with the invention, comprises at least one such end fitting. For convenience and safety, a distinct operating member is provided for retracting the latch, preferably located at or adjacent the end of the pin remote from the projecting portion of the latch. The invention is particularly applicable to the connection of diagonal braces to horizontal ledgers, but is also applicable to the interconnection of other elements of a scaffold structure, e.g. braces to adjustable base and head jacks; horizontal and inclined members to form cantilever brackets; plan braces, etc. Preferably, the latch has an oblique lead-in surface in its projecting portion, such that when the pin is inserted in the aperture, the aperture wall will push the latch into the pin, permitting the pin to be inserted without action by the user to retract the latch The means providing the resilient bias is preferably housed entirely within the pin or within an end fitting on which the pin is provided. The member in which the aperture is provided, adjacent the aperture, may have a configuration to enhance retention by the latch and reduce the risk of accidental movement of the latch to its retracted position. The invention is particularly but not exclusively applicable to coplanar scaffold systems, that is to say, systems in which uprights, ledgers and braces can all lie in common vertical planes. The invention will be further described with reference to the accompanying drawings, in which: Figure 1 is a side view showing a portion of a scaffolding structure in which the invention is used Figure 2 is a side view of a brace end fitting embodying the invention, and Figure 3 shows the brace end fitting, in a view at 90° to figure 2. Figure 1 shows part of a scaffolding structure comprising an upright 1, a horizontal ledger 3, and a diagonal brace 6, e.g. generally as in GB 2149046. The ledger has an end fitting 7, comprising upper and lower eyes 8 and upper and lower arms 9 in each of which is a vertical slot. The upright is provided with laterally projecting sockets 10 all at the same level. In use, the ledger is placed so that its upper and lower arms 9 embrace a socket 10 between them, and a wedge 2 accommodated in the slots of arms 9 is dropped through the socket 10 to retain the ledger. The wedge is held captive, when raised clear of the socket 10, by a nib 4 on the upper eye 8. The ledger and upright are in a common vertical plane, rather than being laterally offset as in scaffolding systems in which the corresponding members are attached to one another by screw clamps. The brace 6 is provided with an end fitting 5 by which it is attached to an eye 8 of the ledger end fitting. The brace end fitting 5 is shown in more detail in Figures 2 and 3. It comprises a weldable malleable cast iron body with a generally annular region or boss 11 for welding to the brace end. Offset to one side of the axis of the boss and therefore of the brace, is an integral bracket portion 12. This is so placed that when its side face abuts on a side of an eye 8, the brace will lie in the same vertical plane as the ledger. The bracket portion 12 has a circular aperture in which is firmly mounted a pin 13 which is perpendicular to and intersects the longitudinal axis of the brace. This pin is for example of drawn seamless steel tube, welded into the bracket portion 12. It fits closely in an eye 8 in order to couple the brace to the ledger, and it has a free end projecting through the eye. This free end is closed by a tapered plastics plug 14, which provides a lead-in surface to facilitate insertion of the pin in the eye, and prevents dirt from entering that end of the pin. In the interior of the pin is mounted a hook-like latch member 15 for example of sheet mild steel. At its end adjacent the free end of the pin, the latch member 15 has a hooked projecting nib 15a in a slot 17 provided in the wall of the pin. Within the pin, the latch member extends to the other end of the pin, adjacent which it is mounted on a transverse Bissell pin 16 seated in opposite walls of the brace end pin 13. The pin 16 acts as a pivot for the latch member 15, which can accordingly move between the position illustrated in Figure 2 in which the nib 15a projects from the side of the pin 13, and a retracted position in which the nib is completely within the pin 13. A torsion spring 17 is mounted on the pivot pin 16 and acts between an internal surface of the brace end pin 13 and the latch member 15, urging the latter to the position illustrated in Figure 2 with the nib 15a projecting. Adjacent the pivot pin 16, the latch has an integral operating arm 18 which projects laterally from the pin 13 through a slot in the wall of the latter as best shown in Figure 3. The arm 18 projects in the direction towards the brace 6, and is disposed between a pair of protective ribs or flanges 19 on the brace end fitting. These ribs or flanges are provided with matching holes 20, in which a split pin or the like may be inserted, to prevent the arm 18 from being moved from the position illustrated in Figure 2, i.e. to prevent accidental or malicious release of the pin 13 from the eye. Because of the torsion spring 17, the latch nib 15a normally projects from the side of the brace end pin 13. The nib 15a has a tapered lead-in surface, such that, when the pin 13 is pushed into an eye 8, the lead-in surface of the nib will engage the side of the eye and push the latch nib into the pin 13, without any action by the user other than inserting the pin 13 into the eye. When the pin 13 has been fully inserted, the nib 15a is now clear of the opposite side of the eye 8 and the spring 17 causes it to snap outwards so that the nib 16 projects from the pin and engages the surface of the eye as shown in Figure 2, positively retaining the pin 13 in the eye. It will be seen that the attaching and securing of the brace to the ledger requires only one hand. The sides of the ledger end fitting, adjacent the latch nib, may be dished or recessed as shown at 21, to provide a retaining surface at an angle of 90° or more to a line extending from the pivot pin 16 to the tip of the latch nib, to improve retention of the latch. It is also desirable that the surface of the latch nib which abuts or, the eye (the upper surface in Figure 2) is concave, centred on the pivot pin 16. To withdraw the brace end from the ledger, the arm 18 is pressed towards the brace tube (downwards in Figure 2) and this causes the latch nib 15a to be withdrawn into the pin 13 against the action of spring 17. The pin 13 can then be withdrawn from the eye 8. This operation can be carried out with one hand. It will be understood that the resilient bias for the latch can be provided in other ways, for example by a leaf spring, coil spring or a pad of rubber. The latch member itself may take any convenient form.

Claims: An end fitting (5) for a scaffolding element (6) having a transverse pin (13) for insertion in an aperture (8) provided in another fitting (7), and, a latch (15) housed within the pin (13) and resiliently loaded such as to urge the latch (15) to a first position in which at least a portion (15a) of the latch (15) protrudes laterally from the pin (13) adjacent the free end of the pin (13) for retaining the pin (13) in the aperture (8), the latch (15) further having a second, retracted, position in which it is accommodated entirely or substantially entirely within the pin (13) against its resilient loading, for permitting the pin (13) to be inserted in and removed from the aperture (8), characterised in that the end fitting (5) includes an operating member (18) arranged to retract the latch (15), for enabling the pin (13) to be removed from the aperture (8). An end fitting (5) as claimed in Claim 1, in which the latch (15) has an oblique lead-in surface in its projecting portion (15a), such that when the pin (13) is inserted in the aperture (8), the aperture wall will push the latch (15) into the pin (13), permitting the pin (13) to be inserted without action by the user to retract the latch (15). An end fitting (5) as claimed in either Claim 1 or Claim 2, in which the operating member (18) is located at or adjacent the end of the pin (13) remote from the projecting portion (15a) of the latch (15). An end fitting (5) as claimed in any preceding Claim, further including means (17) providing the resilient loading of the latch (15), housed within the pin (13). An end fitting (5) as claimed in any of Claims 1 to 3, further including means (17) providing the resilient loading of the latch (15), housed within an end fitting (5) on which the pin (13) is provided. A scaffolding element comprising at least one end fitting as claimed in any preceding Claim. A scaffolding system comprising at least one scaffolding element (6) as claimed in Claim 6, and at least one further scaffolding element (3) or end fitting (7) provided with a said aperture (8), the said further element (3) or end fitting (7) having, adjacent the aperture (8), a configuration (21) adapted to enhance retention of the latch (15).

Inventors: HANNAY DAVID JAMES, HANNAY, DAVID JAMES
Applicants: LEADA ACROW LTD, LEADA ACROW LIMITED (REG. N 891748)
Application year: 1990
Main classification: E04G7
IPC codes: E04G7