AU2002100322A4 - Combined star post driver and extractor - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT COMBINED STAR POST DRIVER AND EXTRACTOR The following statement is a full description of this invention, including the best method of performing it known to me: COMBINED STAR POST DRIVER AND EXTRACTOR For many years there have been Star Post Drivers in use consisting of a long pipe blanked off at the top with long vertical handles for the purpose of driving Star Posts in to the ground. Also, there is a variety of separate Star Post Extractors in use, using a lever and clamping principle to withdraw the posts out of the ground.

This invention combines three functions in one hand tool, using the traditional post driver principle and attaching the extractor, based on a slide hammer principle and adding further refinements to the post driver. The invention has been specifically devised in order to remove twisting and improve directional accuracy on initial driving and to remove the star post without damage, hence increasing the reusability of the star posts.

The invention is an application in the Technical Fields: Mechanics; and Physics.

The driver component has been designed using a square section for ease of manufacture, facilitating the ability to further drive the star post into the ground in a non-twisted form. This design eliminates a second major weakness of existing systems by providing more strength in the striker plate area. The striker plate area is reinforced with a steel strap welded over the striker plate and attached to the square section as shown on the drawing.

The extractor component has a dual application, starting the post in the ground with the downward thrust minimizing the twisting of the star post and removing the star post without damage. The extractor is two steel plates welded length ways to the flat section of the driver to form a triangular section slightly larger than the cross section of a star post but created to allow the star post slide inside. Two striker plates are fitted to each end of the triangular section. These striker plates correspond with the impact bracket when the impact bracket is fitted to the star post by means of a high tensile bolt. A further refinement is that the impact bracket and spare high tensile bolts are also contained on the lower end of the driver-extractor.

Application: To drive a star post into the ground place the square section over the star post, then with downward thrusting of the driver the post will be driven into the ground until the required depth is achieved.

To precisely locate the star post for specific applications such as signage, the triangular extractor section can be used in reverse, for downward thrusting of the star post. This removes the potential for the star post to rotate within the standard driver section, ensuring alignment of posts where this is essential for additional application eg holding signs.

To remove a star post from the ground, place the extractor triangular section over the post and lower it to the ground. Select a hole in the star post approximately 400 mm above the top of the extractor. Place the high tensile bolt provided through the striker plate and the selected hole. With continuous upward thrusting, the star post will be drawn out of the ground.

The application of a vertical thrust to the star post eliminates both the twisting momentum occurring with lever action extractors and the potential for damage by chain pressure on the star post. The result will be a considerable increase in the reusability of the star posts highly desirable in the large number of temporary applications for which star posts are used.

The driver-extractor should be constructed of high tensile steel. However, other forms of steel can be used for limited use applications. The retaining brackets for the high tensile bolts and impact bracket are constructed from industrial standard rubber, although some forms of plastic could be used.

The dimensions of the design, as shown in Figure 1, make the driver-extractor suitable for rural fencing. A larger or smaller version can be constructed to the same design to be used in varying applications such as signage, support for parawebbing and temporary barricades, etc The invention may be better understood with reference to the illustrations of the embodiments of the invention.

Figure 1 is an elevation of the improved invention showing the relevant features of the driver-extractor.

Figure 2 illustrates the operation of the driver-extractor in the precise thrust mode and in the removal mode.

Figure 3 shows the individual components of the impact bracket.

Figure 4 shows contained impact bracket and bolts.

The driver-extractor is a square tube with two handles with an overall length of 1200mm and an integrated triangular steel section 600mm in length. The length is used as the measure for the exposed section of star post once in position, ensuring an even height distribution without recourse to separate measurement. The handles enable the driver-extractor to be lifted and to add additional thrust by increasing the driving thrust.

In addition, the top of the square section is reinforced with a high tensile strap to enable the effective transfer of the weight of the driver-extractor under thrust momentum to the star post.

For precise starting, the star post is located within the triangular extractor section and the impact bracket is located below the extractor so that the downward momentum of the driver-extractor is transferred to the star post through the impact bracket This maintains the star post in the correct twodimensional plane, with the triangular section controlling directional movement and twist of the star post.

For removal of the star post, the impact bracket is positioned on the second to top hole of the star post by the high tensile bolt and the driverextractor moved in an upward momentum to transfer the thrust to the star post To complete the driver-extractor, the impact bracket and the high tensile bolt(s) are located within a rubber moulding to ensure all parts of the driver-extractor are self contained.

Claims (4)

1. A combined driver-extractor comprising a post driver section in two forms and an integrated extractor relying on the use of reverse thrust.

2. The formation of the extractor in triangular shape to match the form of star posts to enable accurate thrust sliding.

3. The triangular striker plates that are used to transform the thrust to the star post for extraction or precision driving.

4. The integration of claims 1,2 and 3 into a single compact driver-extractor. The driver-extractor can be substantially described with reference to figures 1-4 of the accompanying drawings. Donald Grant 9, April 2002