Implements or apparatus for applying pushing or pulling force – Pipe or rod jack – Lifter
Reexamination Certificate
2000-11-30
2002-06-04
Watson, Robert C. (Department: 3723)
Implements or apparatus for applying pushing or pulling force
Pipe or rod jack
Lifter
Reexamination Certificate
active
06398188
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a post puller for pulling a post or a post anchor from the ground.
2. Description of the Related Art
Several devices are supported by one or more posts driven into the ground. Such devices include signs, mail boxes, fences, and the like. The post may be a one-piece post with the load carrying portion driven directly into the ground, or a two piece post with a post anchor driven into the ground, and the upper or load carrying portion of the post being driven or bolted to the post anchor. For purposes of the present application, the term “post” will be used to refer to either the one-piece or two piece assembly, and to either a post or post anchor. From time to time it may become necessary to remove or relocate the post. It then becomes necessary to remove the post and/or the post anchor.
It is sometimes possible to remove the post manually. This process is labor intensive, and may require striking the post from several different directions with a sledge hammer to loosen the ground about the post, and then leaning over and grabbing the post and yanking the post out of the ground. Not only is the process labor intensive, but the post may become damaged so that it cannot be reused, and the laborer can sustain a back injury in the process.
In order to obviate these problems, several machines or mechanical devices have been developed. U.S. Design Pat. No. 372,177, issued Jul. 30, 1996 to S.C. Hansen, shows a mechanical post puller with a single support post having a roller offset from the top of the post and what appears to be a ratchet mechanism with a C-shaped arm for gripping a post at the bottom of the support post.
Several devices are adapted for use with a tractor, front end loader, or other vehicle with a hydraulic system. U.S. Pat. No. 3,526,387, issued Sep. 1, 1970 to H. B. Fleming, describes a post puller having a metal plate base with a flared opening for straddling a post, a pair of uprights pivotally mounted on opposites side of the flared opening, a single hydraulic cylinder, pivotally mounted to the base and connected to a vehicle hydraulic system, a lever arm connected between the cylinder ram and the two uprights, and a chain with a post gripping fixture depending from the lever arm. U.S. Pat. No. 4,244,560, issued Jan. 13, 1981 to W. H. Hawkins, discloses a tree puller attached to a front end loader with a bifurcated wedging member for cutting into a tree trunk, a pair of parallel ground engaging members, each having a hydraulic cylinder mounted thereon with the cylinder rods being attached to an elevatable frame, the wedging member also be attached to the elevatable frame, so that the wedging member cuts into a tree trunk and the cylinder rods are extended to lift the tree out of the ground. U.S. Pat. No. 4,706,935, issued Nov. 17, 1987 to G. L. Thompson, teaches a post puller attached to a tractor three-point hitch, the puller including a stationary gripping plate and a pivotally mounted arcuate gripper, both grippers having teeth for clamping and gripping a post or tree therebetween.
Still other patents are primary concerned with the problem of post slippage in the post puller, several such patents dealing with T-shaped fence posts. U.S. Pat. No. 4,422,621, issued Dec. 27, 1983 to P. B. Ekern, shows a puller for pulling ranch fence posts having lugs extending from the flange of a T-shaped post, the puller having a pair of plated connected by a cross member, the plates having a slot defined therein for receiving a pin which lodges against a fence post lug. A chain is attached to the plates and the post is pulled by a hydraulic cylinder or jack. U.S. Pat. No. 5,011,117, issued Apr. 30, 1991 to Youngblood et al., describes a post puller having a plate with a hole in it so that the plate fits around the post. A chain pulls one side of the plate so that the plate tilts and grips the side of the post to pull it out.
U.S. Pat. No. 5,368,277, issued Nov. 29, 1994 to F. Moss, discloses a device for pulling a T-shaped fence post having bracket and a clevis which fits over the post and is pivotally attached to the bracket. A ring is placed through the bracket and a chain is looped through the ring. A lever is placed through the chain and braced against the ground to pull the post.
A more remote device having some features in common with the present invention is an apparatus for driving a pipe or other: elongated member horizontally through the ground, as described in U.S. Pat. No. 4,746,096, issued May 24, 1988 to Donnell et al. The apparatus uses a rectangular frame with a pair of parallel hydraulic cylinders having rods attached to a tray by a cradle bar. The tray has a plurality of pairs of spaced apart gussets which support a moveable end plate which is placed at an end of a pipe to be driven horizontally into the ground, the pipe being disposed between the hydraulic cylinders. The cylinders are extended to move the tray and pull the end plate against the pipe for the stroke distance of the rods, the end plate is moved forward in the tray, and the process is repeated to drive the pipe into the ground in stages. Optionally, jaws may be attached to the tray for gripping the pipe below collars placed on the pipe to pull the pipe out as the cylinder rods retract.
Another device for a dissimilar purpose but having some features in common with the present invention is a device for lifting the foundation of dwellings, buildings and other structures, described in U.S. Pat. No. 5,492,437, issued Feb. 20, 1996 to L. P. Ortiz. The device has a pier guide tube attached to a support plate which fits under a foundation footing and has two parallel hydraulic cylinders pivotally attached to the guide tube. The cylinder rams are pivotally attached to an articulating bar having a pier compression means between the two rams. A pier is placed into the guide tube and connected to the compression means. One or more piers are driven into the ground until they reach bedrock, after which further retraction of the rams raises the structure. The pier is then permanently affixed to the foundation and the hydraulic cylinders are detached.
There are several problems associated with the post pullers known in the art. Several of the devices are expensive or heavy devices which require attachment to a vehicle for operation. Many manual pullers require that the operator complete the operation in a bent position to extract the post, resulting in back strain and related back injuries. Many puller devices apply a load from the side of the post or utilize a pulling force with a large lateral component relative to the axis of the post, making the post difficult to extract. Consequently there is a need for a lightweight, portable, relatively inexpensive post puller which applies a pulling force primarily along the axis of the post.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a post puller solving the aforementioned problems is desired.
SUMMARY OF THE INVENTION
The post puller has an H-shaped base including a pair of parallel legs and a crossbeam normal to the legs, the crossbeam being offset from the midpoint of the legs and defining a shallow channel and a deep channel. A pair of rectangular blocks attached to the legs and crossbeam in the deep channel provide platforms on which a pair of single action hydraulic cylinders are mounted, and define a recess which straddles the post to be pulled. A cross member is pivotally mounted to each cylinder rod. A chain is suspended from the midpoint of the cross member. The chain may be wrapped directly around the post, or a post gripping structure may be attached to the free end of the chain. A pair of wheels may be mounted to the base for portability.
The base assembly is preferably made from aluminum. The entire post puller assembly is lightweight, permitting the post puller to be easily transported on the optional wheels by hand, without the need for a vehicle to transport the pul
Litman Richard C.
Watson Robert C.
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