NZ247835A - Post driver hydraulic lifting rig for removing pilot hole spike: rig rotatable about driver tower - Google Patents

Description

n Patents Form 5 iTjrl" PATENTS ACT 1953 COMPLETE SPECIFICATION After Provisional No. 247835 10 June 1993 A LIFTING RIG ATTACHMENT FOR A POST DRIVER I, STUART STOKES of Sinai, Pointz Road, Oxford, Canterbury, New Zealand being a New Zealand Citizen, 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 This invention relates to. a hydraulic lifting rig that can be attached to a post driver. This rig is useful for the extraction of metal spikes that are used for the formation of pilot holes for the driving of posts.

The driving of posts with a post driver into alluvial gravelly soils can be made difficult by the presence of large boulders and stones. Essentially while driving the post they physically damage posts or cause them to veer off line. Obviously when constructing a fence line these two effects are j^i+icularly troublesome. These problems are generally overcome by driving, prior to the post, a metal spike into the ground which has the effect of forming a pilot hole for the post. The spike because of its hardness has the effect of breaking up the boulders and stones in the soil or moving them out of the line of the post hole. As can be appreciated, however, once the spike has been driven into the soil the problem of extracting it again so that the post can be driven is faced. Common practice hitherto has involved attaching a rope or chain to the spike and using for example, the monkey of the post driver or hydraulic arms of a tractor to lift it out. Invariably these procedures are time consuming and can lead to damage to machinery, particularly the post driver. Firstly if the tractor's hydraulic arms are used, then the post driver has to be moved to bring the hydraulic arms of the tractor close to the spike to perform the lift. If the lifting rope is attached to the monkey of the post driver then damage may be caused to the driver as the 247 83 monkey is raised. Most post drivers raise the monkey by a cable and drum system which is not designed to lift heavy loads as would occur when lifting a spike from the ground.

There have been some attempts to provide attachments to overcome the lifting problem associated with pilot hole spikes. An example of one of these is disclosed in New Zealand patent specification No. 145495.

However, the attachment disclosed is not hydrauiically powered. Further, this attachment is not designed so that it can be easily swung into a transport position when not in use and easily returned to an operating position whenever it is required.

Accordingly it is an object of this invention to provide a hydraulic lifting rig for attachment to post drivers which rig can be used for the extraction of post hole forming spikes from the ground.

This invention provides a hydraulic lifting rig that can be attached to a post driver, the rig comprising: a frame constructed such that it supports a hydraulic ram which in turn is attached to a lifting arm.

Preferably the rig is attached to a tower of the post driver so the rig can rotate through 90 degrees relative to the tower.

Preferably the hydraulic ram is a double acting hydraulic ram and the movement of the rig relative to the tower is a pivoting movement.

It will be appreciated that as the ram moves up and down the lifting arm moves as well to thereby maintain its alignment (perpendicular to the orientation of the ram). One end of the arm has a sleeve which slides up and down a vertical column which forms part of the aforementioned frame and tower.

Conveniently the rig is able to be swung through 90 degrees to position the lifting arm and spike directly below the driving monkey of the post driver. The ram is then extended and simultaneously the lifting arm sleeve slides down the vertical column and a lifting arm collar slides down the length of the spike. The lifting arm is lowered to a defined position just below where the top of the spike will be positioned once it has been driven to the required depth. Following extraction of the spike from the ground the rig can be swung back 90 degrees and hence the lifting arm is rotated together with the spike out of the way of normal post driving operations.

It will be appreciated that because the lifting arm is moved up and down by the hydraulic ram the attachment has the ability to generally remove firmly stuck spikes from the ground. Further, because the lifting rig is conveniently attached to the post driver tower, the lifting forces are always substantially vertical thereby minimising the chances of twisting the rig or the post driver tower.

An embodiment of the invention will now be described, by way of example only, with reference to the drawings accompanying the provisional specification in which; ft783 Figures 1(a) and 1(b) are a front view of the lifting rig in its lifting position, and a front view of the lifting rig together with a metal spike in its transport position; and Figure 2 is an enlarged view of a swivelling means for the rig.

Referring to Figures 1 and 2, a lifting rig attachment for a post driver is shown. Figures 1(a) and 1(b) show the rig and rig plus metal spike, respectively, in the lifting or transport position, whilst Figure 2 shows the swivel means for the rig in relation to the post driver tower.

As illustrated in Figures 1(a) and 1(b) the lifting rig attachment is attached to the tower of a post driver 1. As is best illustrated in Figure 2 the main column beam 2 swivels on another beam 3 which is of a smaller diameter; i.e., 3 is inserted inside 2. This allows the lifting rig attachment to swing through 90 degrees. As can be seen in Figure 1(a) the attachment is in a lifting position with the double acting ram 4 at its most extended position with the lifting arm 5 just above ground level. A metal spike 6 has been driven into the ground to the extent that its collar 7 is positioned just above a sleeve 8 on the lifting arm 5. As can be appreciated before the spike 6 was driven into the ground it was held in position beneath the driving monkey 9 by the sleeve 8 that is attached to lifting arm 5. Following insertion the hydraulic ram 4 is retracted which effectively raises the lifting arm 5 up and thus brings sleeve 8 against 247835 collar 7 on the metal spike 6. As the ram 4 continues to retract the lifting arm 5 together with the spike 6 are raised. Once the ram 4 is completely retracted the spike 6 is completely clear of the ground and is held in position by sleeve 8 on the lifting arm. As shown in Figure 1(b), when the lifting attachment is not in use it can be swung or turned through 90 degrees by swivelling column 2 on column 3 (refer to Figure 2). As illustrated column 2 is supported vertically whilst being turned by sleeves 10 and 11. This turning action effectively rotates spike 6 and the lifting arm 5 into the transport position, out of the way of any normal post driving operations.

It will be appreciated that numerous variations and modification can be made to the embodiment described in this specification without departing from the scope of the invention. For example, the length of the hydraulic ram 4 may be increased such that a longer spike can be driven into and extracted from the ground. Similarly the lifting capacity of the ram 4 can be increased so thicker spikes can be extracted. Further, the sleeve 8 attached to the lifting arm 5 can be modified such that it can be used to lift old unwanted posts or such like objects from the ground, e.g. fence standards or warratahs.

Particular examples of the invention have been described herein by way of example and it is envisaged that improvements and modifications can take place without departing from the scope of the appended claims.

Claims (11)

247835 WHAT I CLAIM IS:

1. A hydraulic lifting rig which can be attached to a post driver, the rig comprising a frame, hydraulic ram and a lifting arm, wherein the frame -Aa- suppcrts the hydraulic ram and the ram is attached to^ lifting arm, wherein a sleeve on the lifting arm holds a spike on insertion into and removal from the ground, and wherein the rig can rotate about a tower of the post driver so the spike can be pivoted away from its original position once the spike is above the ground.

2. A rig as claimed in claim 1 wherein the ram is a double acting hydraulic ram.

3. A rig as claimed in claim 1 wherein the movement of the rig relative to the tower is a pivoting movement.

4. A rig as claimed in any one of the preceding claims wherein the lifting arm is perpendicular to said ram.

5. A rig as claimed in any one of the preceding claims wherein the lifting arm moves as the ram moves vertically.

6. A rig as claimed in any one of the preceding claims wherein the frame includes a vertical column.

7. A rig as claimed in claim 6 wherein the sleeve is able to slide up and down the vertical column.

8. A rig as claimed in any one of the preceding claims wherein the rig is constructed from metaL

9. A hydraulic lifting rig substantially as herein described with reference to the drawings accompanying the provisional specification. •-•fV ,0

10. A method of using a hydraulic lifting rig to insert and remove, into and from the ground comprising the steps of ( - 8 - 247835 * swinging the rig through 90° to position a lifting arm and spike directly below a driving monkey of a post driver; extending a ram to slide a sleeve down a vertical column and to slide a lifting arm collar down the spike, the ram being attached to W^\c. lowering the lifting arm to a position just below where the top of the spike will be positioned once the spike has been driven to the required depth ; retracting the ram, thus raising the lifting arm and the spike; swinging the rig through 90° once the spike is above the ground.

11. A method of using a hydraulic lifting rig substantially as herein described. aWifting arm; STUART STOKES By His Attorneys BALDWIN. SON & CAREY CSPEC87104