IE54455B1

IE54455B1 - Improvements in and relating to builders' props

Info

Publication number: IE54455B1
Application number: IE2005/83A
Authority: IE
Original assignee: Leada Acrow Ltd
Priority date: 1982-09-21
Filing date: 1983-08-26
Publication date: 1989-10-11
Also published as: GB2127886A; GB2127886B; IE832005L

Abstract

The prop has a head plate 11 connected to a prop body 13 having an outer tube 12 with a screwthread 14 thereon, an inner tube 18 telescopically engaged in outer tube 12 and having a pin 22 engaging a slot 20 formed in outer tube 12, a nut 16 engaged on the screwthread, and a stripping device 24, e.g. a cam, positioned between the pin and nut. Rotation of stripping device 24 relative to the nut gradually lowers pin 22, and hence the head plate, to strip formwork supported by the prop or the prop itself, from cast and set concrete. Stripping device 24 also acts as a load relieving means.

Description

This invention relates to supports for shuttering elements used during the setting of concrete (or the like) to form roofs, floors and ceilings or similar soffits.

Normally shuttering in the form of formwork panels are 5 supported by extensible props. On these formwork panels the concrete is cast and when the concrete is set the props and panels are stripped and taken away for re-use.

A builder's prop or fitment for a prop in 10 accordance with the invention comprises a head plate connected to a prop body, the prop body comprising an outer tube with a screwthread thereon, an inner tube telescopically engaged within the outer tube and having a transversely projecting pin engaging a slot formed in the outer tube, a nut screw15 threadedly engaged on the screwthread, and stripping means positioned between the pin and nut, the arrangement being such that rotation of the stripping means or part thereof relative to the nut acts gradually to lower the head plate to strip either formwork supported by the prop or the prop itself, from cast and set concrete.

Preferably, the stripping means comprises a ring surrounding the screwthread with one or more cam surfaces on which the pin acts directly or indirectly. The cam surface(s) is arranged so that on rotation of the stripping means the head plate is moved gradually from an upper to a lower position. 4 4 5 5 The invention will now be described, by way of example, with reference to the accompanying drawings, in which:Figure 1 is a side view of a prop in accordance with 5 the invention; Figure 2 is a side view along arrow A of the stripping device shown in Figure 1; Figure 3 is a side view of an' alternative stripping device used with a prop in accordance with the invention; Figure 4 is a side view of the stripping device of Figure 3 in an alternative position, and Figure 5 is a plan view of the stripping device of Figure 4.

The adjustable builder's prop or fitment for a prop 15 10 shown in Figure 1 comprises a head plate 11 connected to a prop body 13 comprising a lower outer tube 12 provided with a screwthread 14 and an upper inner tube 18 which can be telescoped in the outer tube 12. The outer tube is slotted at 20 to receive a pin 22 which is integral with the inner tube 18 and proj'ects therefrom at right angles to the tube. A nut 16 is screwthreadedly engaged on the screwthread 14.

To raise the plate 11 and increase the overall length of the prop 10, the nut 16 is turned in one direction to act on the screwthread 14, while to lower the plate 11 and decrease the overall length of the prop 10, the nut 16 is turned in the other direction to act S 4 4 5 :· on the screwthread 14.

Positioned between the pin 22 and nut 16 a stripping device 24 is provided in the form of a ring surrounding the outer tube 12. The device 24 has an upper cam surface S on which the pin 22 acts, and a lower flat surface 28 on which the upper surface of the nut 16 acts. The upper surface 26 is so shaped that the pin can rest either in an upper position on the surface 26£ or in a lower position on the surface 26b. Between the surfaces 26a and b a sloped surface 26£ is provided.

The arrangement is such that when stripping of formwork (e.g. primary, secondary beams and/or casting panels) or simply the props themselves is required, a strike with a hammer on an appropriate handle 30 causes the device 24 to rotate about the longitudinal axis of the prop approximately 135° resulting in the pin 22 moving from the upper surface 26a, gradually down and along the surface 26c to finish on the lower surface 26b. The head plate 11 thus drops a short distance corresponding to the distance marked x on Figure 2.

Preferably, the slope of the surface 26c is in the range of 15 to 45° to the horizontal plane containing the lower surface 28. Preferably the surface 26c covers a range of 30 to 90° arc of the axis 32 of the device 24 while surface 26a covers a range of 15 to 45° of arc and surface 26c covers a range of 7 to 23° of arc.

In Figures 3 to 5 an alternative stripping device 50 is shown for use instead of the device 24 on the prop 10. The device 50 comprises two identical components 52 and 54 each having a flat surface 56 and a shaped alternate concave and convex surface 58. In use the two components 52 and 54 are placed with their shaped surfaces 58 touching each other such that the device can be moved between two extreme positions. In the extreme upper'' position the convex portions 60 o£ the two components 52 and 54 touch each other (see Figure 3) to position the pin 22 in an upper position, while in the extreme lower position the convex portions 60 of the components 52 and 54 mate with the concave portions 62 of components 52 and 54 (see Figure 4) to position the pin 22 in a lower stripped position. The distance the head plat 11 drops and accordingly beams and/or casting panels are stripped corresponds to the distance marked y in Figure 3.

The components 52 and 54 are provided with handles 64 which act against each other to position and correctly locate the device 50 in the extreme upper position.

The handle 64 also acts as a component that workman can strike with a hammer and so strip formwork or the prop itself. Preferably, the handles 64 are each provided with 4 4 5 ίa bore 6b so that a pin (not shown) can be inserted in the handles 64 of each pair of components 52 and 54 to lock the device SO when it is in the extreme upper” position.

Both stripping devices 24 and 50 have cammed (shaped) surfaces such that when the device 24 or 50 is rotated the head plate 11 or formwork supported by the plate 11 is initially gradually lowered from the cast concrete to prevent any shock to the cast concrete. To further lower the head plate 11 or formwork from the cast concrete, the nut 16 is rotated around the screw-thread 14 in the appropriate direction. The devices 24 and 50 thus act both as stripping means and as load relieving means.

Both devices 24 and 50 are simple in overall design and efficient in operation as they strip formwork IS or the prop itself quickly and simply.

Claims

1. A builder's prop or fitment for a prop comprising a head plate connected to a prep body, the prop body having an outer tube with a screwthread thereon, an inner tube telescopically engaged within the outer tube and having a transversely projecting pin engaging a slot formed in the outer tube, a nut screwthreadedly engaged on the screwthread, and stripping means positioned between the pin and nut, the arrangement being such that rotation of the stripping means or part thereof relative to the nut acts gradually to lower the head plate to strip either formwork supported by the prop or the prop itself, from cast and set concrete.

2. A builder's prop or fitment for a prop as claimed in Claim 1 wherein the stripping means comprises a ring surrounding the screwthread with one or more cam surfaces on which the pin acts directly or indirectly.

3. A builder's prop or fitment for a prop as claimed in Claim 2 wherein the cam surface(s) is arranged so that on rotation of the stripping means the head plate is moved gradually from an upper to a lower position.

4. A builder's prop or fitment prop as claimed in either Claim 2 or Claim 3 wherein at least part of the cam surface(s) slopes in the range of 15 to 45° to the horizontal plane. 5. 4 4 5'

5. A builder's prop or fitment prop as claimed in any one of Claims 2 to 4 wherein the cam surface has an upper 'supporting' surface and a lower 'stripped' surface between which the cam surface is sloped. 56. A builder's prop or fitment prop as claimed in any one of the preceding claims wherein means are provided to lock or retain the stripping means in an upper 'supporting' position.

6. 7. A builder's prop or fitment prop as claimed in any 10 preceding claim wherein the stripping means has one or more handles, striking of which causes the stripping means to rotate.

7.

8. A builder's prop or fitment for a prop according to Claim 1, substantially as described herein with reference 15 to the accompanying drawings.