A light weight, simple, effective, hydraulically operated device for dislodging and extracting poles or similar structures from the ground. In one embodiment, a hydraulically operated piston pulls directly upward on a chain or strap directly attached to the post or pole to be dislodged while an arm attached to both the chain and piston and a frame allowing the arm to pivot as the post is pulled upward operate to minimize side forces on the piston arm. An adapter, for pulling long poles that have holes only near the top is also disclosed.
BRIEF DESCRIPTION OF THE PRIOR ART AND SUMMARY OF THE INVENTION
Posts, poles and other similar structures are often mounted partially within the ground. Such poles and especially poles supporting signs and barriers along the highways necessarily are fixed securely and are often surrounded by concrete or other similar material to insure that the poles will not be removed by climatic occurrences or theft. However, such poles while indeed remaining securely in place often prove very difficult to extract when replacement, maintenance or change is necessary. Particularly, since such signs are often located in remote and relatively inaccessible places where sources of electrical or other power are not readily available, in the past such extraction has been accomplished by means of back-breaking muscle power supplied by workers. Thus, besides being difficult, such removal was usually slow and expensive.
A number of devices in the prior art have been employed to assist workers in dislodging posts. For example, the patent to Benchley, 3,103,343, shows a typical one of these post pulling implements whereby muscle power is applied by a worker through a lever to dislodge a post. Of course, such arrangements, while of great assistance to the workers delegated to extract the post did not wholly solve the problem since muscle power was still necessary and post removal was still slow and difficult.
The present invention seeks to solve this problem by employing hydraulic power to quickly and simply remove posts, poles and similar structures. Since hydraulic pressure can be easily taken to the inaccessible locations at which such posts are often found by means of specially constructed vehicles or carts which the workmen ride, or take to the pole sights, such pressure then provides an excellent source of energy for extracting the poles. Moreover, the hydraulically operated piston which applies an upward force on the post to extract the sign pulls substantially directly upward on the post or pole rather than acting through a lever arm as do many other hydraulically operated cranes or jacks such as the jack described in the U.S. Pat. to Buckeye, No. 3,059,785. Since sufficient strength is available in a suitable hydraulic system to pull almost any post, it is not necessary to increase that force by means of a lever. Further, since such a lever is subject to great stress and thus provides a weak point in the assembly it is necessary to provide a lever which will not break, thereby, increasing considerably the cost of the device. Pulling directly on the post both decreases the expense of manufacturing this invention and increases reliability. The arm in this invention, to which is attached the hydraulic piston at approximately the same location as the chain or other device which attaches to the post simply serves as a part of the frame and acts to minimize side forces on the piston arm.
Other objects and purposes of this invention will become clear after reading the following detailed description of the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a post extracting device of the present invention in position ready to pull a post supporting a guard rail;
FIG. 2 shows the extracting device of FIG. 1 in the extreme position after pulling a post or similar structure; and
FIG. 3 shows an adapter which can be employed with this invention to pull long poles which have holes only near the top,
DETAILED DESCRIPTION OF THE DRAWINGS
Reference is now made to FIG. 1 which shows a post extractor 18 attached to a post 20 which supports a guard rail and which is about to be pulled from the ground. The extractor 18 includes two horizontal legs 22 and 24 which are attached permanently at one end to a frame member 26, for example, by welding, and hold the extractor 18 firmly on the ground. These two legs 22 and 24 form a V angling outward from the place of attachment to the member 26. If desired, a single wheel or a number of wheels (not shown) can be mounted on the device 18 to permit easy movement. The post to be pulled, in FIG. 1 the post 20, can then be disposed between the outer ends of the legs 22 and 24 so that a piston and cylinder unit 28, or ram, can exert an approximately straight upward pull on the pole 20. Two inclined strut members 31 and 32 are attached permanently at their ends to the frame member 26 and to the legs 22 and 24, for example, by welding and serve to structurally strengthen the device. The legs 22 and 24 as well as the frame member 26 may be simply pieces of channel iron of conventional construction.
Attached to the upper part of the frame member 26 and adapted to pivot in a vertical plane about the point of attachment 27 is a guide arm 30 which serves to minimize side forces on the piston and cylinder unit 28 during a post pulling operation. The upper end of the unit 28 is pivotally connected to the outer end portion of the arm 30, as by means of a bracket 33 fixed to the arm 30 and a bolt 29. The lower end of the unit 28 is attached to a baseplate which is pivotally connected between the legs 22 and 24 as by a bolt 50 located at about the midpoint of the legs.
Any suitable arrangement of attaching the post or sign to the arm 30 can be employed, and it is envisioned that the arm 30 may have a number of mounting holes or fixtures so that any of a number of different connecting devices, such as chains of various lengths and solid metal connectors, can be employed. In the illustrated embodiment a chain 36 is attached to the outer end of the arm 30, as by attachment to the bracket 33.
In order to releasably attach the chain 36 to the pole 20 there is provided an adapter plate 40 which carries a hook 38. The plate 40 is provided with at least one hole 41 through which a bolt 42 may be inserted so as to pass through one of the usual holes in the pole 20. Three sizes of holes 41 are located on the illustrated adapter 40 so that the adapter will match any of several sizes of holes conventionally found in poles supporting guard rails and signs.
The piston and cylinder unit 28 which is illustrated in the drawings is of the type which includes a hand-operated pump assembly and valve means for controlling the operation of the unit. As shown, the pump assembly is provided with a socket 44 into which the end of a handle 45 may be inserted, the pump being operated by manual up and down jacking movement of the handle 45. The valve means includes a rotatable knob 47 which may be manually rotated in one direction to apply pump pressure to the unit 28 and in the other direction to release the pressure. When the pump is operated, a piston arm 48 moves upwards to the position shown in FIG. 2 thereby applying tension to the chain 36. The arm 30 pivots upwardly about the bolt 27 during this operation, but no bending forces are applied to the arm 30 as a result of the connection of both the piston arm 48 and the chain 36 to generally the same location on the arm 30. At the same time the piston and cylinder unit 28 pivots in a vertical plane about the pivot point 50. As shown in FIG. 1 the unit 28 when in its retracted position is inclined slightly from the vertical toward the post 20, and as shown in FIG. 2 is inclined slightly away from the post 20 when in its extended position.
In the embodiment of the invention as set forth in FIG. 1 the extractor 18 is capable of developing a lifting capacity of about 6,000 lbs. while weighing about 70 lbs. in contrast to the 100 or more pounds of upward force which a human of ordinary strength can apply. When the device has pushed the piston arm 48 to its furtherest extent as shown in FIG. 2, the post or guard rail 20 has also been elevated to a considerable height above its original position. If the lower end of the post 20 is still embedded in the ground, the pulling operation may be repeated by reconnecting the adapter to a lower point on the post 20.
FIG. 3 shows an adapter 58 which finds special utility for extracting long poles 59 which have holes only near the top. This adapter 58 is made up of a channel iron member 60 which has a large number of holes 61 at spaced intervals together with a holding member 62 which may be simply a conventional piece of channel iron. The member 62 is permanently attached to the member 60 by a weld, a bolt, or any other suitable means. Jutting from member 62 is an extension 64 to which is attached a hook 66 which in turn can be attached to a chain, such as chain 36 in FIG. 1, to extract a post in the same manner as described above.
To attach the adapter 58 to the long pole 59 having holes only near the top, the pole 59 is slipped into the U-shaped interior of the member 62, so that the member 60 runs roughly parallel to the pole 59 and in contact with it. One of the holes 61 in the member 60 is then appropriately bolted to one of the holes in the upper part of the pole 59 and a bolt 68 is placed in the one of the several holes in the member 62 which brings the bolt 68 closest to the pole 59. The arm 30 is then connected to the hook 66, for example, by means of a chain and the hydraulic piston and cylinder unit 28 then is operated to pull the pole 59 in the same manner as described above in connection with FIGS. 1 and 2.
The embodiments described above are merely intended to be examples of the invention and many modifications and changes are possible without departing from the spirit of the invention.