GB2102870A

GB2102870A - Drop head unit

Info

Publication number: GB2102870A
Application number: GB08123116A
Authority: GB
Inventors: Richard Herbert Willia Lindsay
Original assignee: PALMERS SCAFFOLDING Ltd
Current assignee: PALMERS SCAFFOLDING Ltd
Priority date: 1981-07-27
Filing date: 1981-07-27
Publication date: 1983-02-09

Abstract

A drop head unit for mounting on a prop for supporting shuttering or formwork beams (18), comprises a stem (11) having means (12) for engaging a cast concrete slab (19) at its upper end, means (13) for connecting it to the upper end of a prop or support (14) at its lower end, and a supporting collar (15) for supporting the ends of the formwork beams (18) mounted so as to be free to move vertically on the stem (11) above a winged nut (16) engageable with a threaded portion (17) of the stem (11) for supporting the collar (15) the stem having a lower portion (20) of reduced diameter over which the nut (16) is free to move vertically when wound off the threaded portion (17) to permit the ends of the formwork beams (18) to fall to a lower level to permit their removal whilst the unit is still providing support for the slab (19). <IMAGE>

Description

SPECIFICATION Drop head unit This invention relates to a drop head unit for use when mounted on top of a prop or support for supporting shuttering or formwork beams during the casting of concrete slabs or beams such as floors and ceilings.

Until such time as the slab or beam becomes self-supporting, the props must remain in position, perhaps for several weeks, but as soon as the concrete has hardened, for example after a few days, much of the shuttering or formwork can be removed for use elsewhere to permit maximum utilization of the equipment.

For this reason the drop head unit is provided with a vertically movable collar or support upon which the ends or margins of the shuttering or formwork are supported and which may be lowered sufficiently to facilitate the removal of the shuttering or formwork whilst leaving the drop head unit and the prop or support upon which it is mounted still supporting the hardened but as yet uncured cast slab or beam.

It is an object of the present invention to provide an improved drop head unit.

The present invention consists in a drop head unit comprising a stem having at its upper end in use means for engaging a cast concrete slab or beam and at its lower end means for connecting it to the upper end of a prop or support, wherein a supporting collar is mounted so as to be free to move vertically on the stem above a nut engageable with a threaded portion of the stem for supporting the collar, the stem having a lower portion of reduced diameter over which the nut is free to move vertically when wound off the threaded portion.

In the accompanying drawings: Figure 1 is a vertical section through one form of drop head unit according to the present invention with its supporting collar in the raised position; Figure 2 shows the unit of Figure 1 with the supporting collar in the lowered position; Figure 3 is a horizontal section taken on line 3-3ofFigure 1, and Figure 4 shows an attachment to the bottom of the drop head unit.

In carrying the invention into effect according to one convenient mode by way of example, Figure 1 shows a drop head unit which includes a central solid or hollow stem 11 having at its upper end a support plate 12 and at its lower end a connecting plate 1 3 bolted to a connecting plate fixed to a prop 14.

A supporting collar 1 5 is free to move vertically on the stem 11 and the collar 1 5 is supported by a winged threaded nut 1 6 engaging a threaded portion 1 7 of the stem 11.

As shown in Figure 1 , the nut 1 6 supports the collar 1 5 which in turn supports the ends of formwork beams 1 8 which support shuttering panels (not shown) upon which concrete has been poured to effect the casting of a concrete floor 1 9.

The collar 1 5 has a flange 1 spa to provide positive location of the ends of bems 1 8, and it will be appreciated that before casting, the nut 1 6 may be rotated to achieve fine adjustment of the level of the beams 1 8 and shuttering panels.

As soon as the concrete of floor 1 9 begins to harden, the floor 1 9 is also supported directly by the central stem 11 and prior 14 by its engagement with support plate 1 2.

As soon as the concrete of the floor 1 9 has hardened sufficiently, the nut 1 6 may be unwound first of all to break the seal between the shuttering panels and the floor 1 9 slowly. Thereafter when the nut is wound off the threaded portion 17 onto an unthreaded portion 20 of smaller diameter than the nut thread, the nut 16 and the supporting collar 1 5 fall rapidly to the bottom of the unit to the position shown in Figure 2, thus providing a "crash strike" of the formwork beams 1 8 and shuttering panels which fall to a lower level whilst still leaving the floor 1 9 propped by stem 11 and prop 14. The formwork beams 18 and shuttering panels may then be removed in safety for re-use elsewhere.

Figure 4 shows the connecting plate 1 3 connected to an adapter 21 in the form of a spigot which fits in the open end of a scaffolding tube 22 serving as a prop.

1. A drop head unit comprising a stem having at its upper end in use means for engaging a cast concrete slab or beam and at its lower end means for connecting it to the upper end of a prop or support, wherein a supporting collar is mounted so as to be free to move vertically on the stem above a nut engageable with a threaded portion of the stem for supporting the collar, the stem having a lower portion of reduced diameter over which the nut is free to move vertically when wound off the threaded portion.

2. A drop head unit as claimed in claim 1, wherein the supporting collar is adapted to provide positive location of the ends of formwork beams.

3. A drop head unit substantially as described with reference to the accompanying drawings.

New claims or amendments to claims filed on 19 Nov 1981.

Superseded claims 1-3.

New or amended claims: 1. A drop head unit comprising a stem secured at its upper end to a support plate for engaging a concrete slab or beam when cast upon it and secured at its lower end to a connecting plate for connecting the stem to the upper end of a prop or support, wherein a supporting collar for supporting shuttering or formwork is mounted so as to be free to move vertically on the stem above a nut engageable with a threaded portion of the stem for supporting the collar, the stem having a lower portion of reduced diameter over which the nut, when wound off the threaded portion, is free to

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Drop head unit This invention relates to a drop head unit for use when mounted on top of a prop or support for supporting shuttering or formwork beams during the casting of concrete slabs or beams such as floors and ceilings. Until such time as the slab or beam becomes self-supporting, the props must remain in position, perhaps for several weeks, but as soon as the concrete has hardened, for example after a few days, much of the shuttering or formwork can be removed for use elsewhere to permit maximum utilization of the equipment. For this reason the drop head unit is provided with a vertically movable collar or support upon which the ends or margins of the shuttering or formwork are supported and which may be lowered sufficiently to facilitate the removal of the shuttering or formwork whilst leaving the drop head unit and the prop or support upon which it is mounted still supporting the hardened but as yet uncured cast slab or beam. It is an object of the present invention to provide an improved drop head unit. The present invention consists in a drop head unit comprising a stem having at its upper end in use means for engaging a cast concrete slab or beam and at its lower end means for connecting it to the upper end of a prop or support, wherein a supporting collar is mounted so as to be free to move vertically on the stem above a nut engageable with a threaded portion of the stem for supporting the collar, the stem having a lower portion of reduced diameter over which the nut is free to move vertically when wound off the threaded portion. In the accompanying drawings: Figure 1 is a vertical section through one form of drop head unit according to the present invention with its supporting collar in the raised position; Figure 2 shows the unit of Figure 1 with the supporting collar in the lowered position; Figure 3 is a horizontal section taken on line 3-3ofFigure 1, and Figure 4 shows an attachment to the bottom of the drop head unit. In carrying the invention into effect according to one convenient mode by way of example, Figure 1 shows a drop head unit which includes a central solid or hollow stem 11 having at its upper end a support plate 12 and at its lower end a connecting plate 1 3 bolted to a connecting plate fixed to a prop 14. A supporting collar 1 5 is free to move vertically on the stem 11 and the collar 1 5 is supported by a winged threaded nut 1 6 engaging a threaded portion 1 7 of the stem 11. As shown in Figure 1 , the nut 1 6 supports the collar 1 5 which in turn supports the ends of formwork beams 1 8 which support shuttering panels (not shown) upon which concrete has been poured to effect the casting of a concrete floor 1 9. The collar 1 5 has a flange 1 spa to provide positive location of the ends of bems 1 8, and it will be appreciated that before casting, the nut 1 6 may be rotated to achieve fine adjustment of the level of the beams 1 8 and shuttering panels. As soon as the concrete of floor 1 9 begins to harden, the floor 1 9 is also supported directly by the central stem 11 and prior 14 by its engagement with support plate 1 2. As soon as the concrete of the floor 1 9 has hardened sufficiently, the nut 1 6 may be unwound first of all to break the seal between the shuttering panels and the floor 1 9 slowly. Thereafter when the nut is wound off the threaded portion 17 onto an unthreaded portion 20 of smaller diameter than the nut thread, the nut 16 and the supporting collar 1 5 fall rapidly to the bottom of the unit to the position shown in Figure 2, thus providing a "crash strike" of the formwork beams 1 8 and shuttering panels which fall to a lower level whilst still leaving the floor 1 9 propped by stem 11 and prop 14. The formwork beams 18 and shuttering panels may then be removed in safety for re-use elsewhere. Figure 4 shows the connecting plate 1 3 connected to an adapter 21 in the form of a spigot which fits in the open end of a scaffolding tube 22 serving as a prop. CLAIMS

New claims or amendments to claims filed on 19 Nov 1981.

Superseded claims 1-3.

New or amended claims:

1. A drop head unit comprising a stem secured at its upper end to a support plate for engaging a concrete slab or beam when cast upon it and secured at its lower end to a connecting plate for connecting the stem to the upper end of a prop or support, wherein a supporting collar for supporting shuttering or formwork is mounted so as to be free to move vertically on the stem above a nut engageable with a threaded portion of the stem for supporting the collar, the stem having a lower portion of reduced diameter over which the nut, when wound off the threaded portion, is free to move vertically downwards until it engages the connecting plate serving as a lower stop, the shuttering orformwork having then been lowered sufficiently to permit its removal.