Patent Application
20120267586
The present invention relates generally to stake removal, and more specifically, but not exclusively, to removing concrete-form-retaining stakes from the ground.
Stakes are used extensively in the concrete construction trade. The stakes are commonly cylindrical in shape and made from metal, although other materials like wood or plastic may be used. When concrete is poured, it is in a semi-liquid state and forms are required to constrain the concrete to a desired boundary. The stakes, which are driven into the ground with a sledgehammer, hold the forms in place while the concrete dries.
Once the concrete has hardened, the stakes must be pulled from the ground so the forms may be removed. Currently, this is a very laborious and time consuming task caused, primarily, by four factors. First, the stakes are driven deep into hard-packed soil, often to a depth of 12+inches. A great deal of physical effort is required to free the stake from the ground and, with the primitive tools currently available, it is often easier to simply abandon the stake by cutting it off at the ground's surface. The loss of stakes in this manner adds an additional penalty to an already costly process. Second, pouring the concrete into the form necessarily results in the form being pressed hard against the stake. After hardening, the concrete holds the form tightly against the stake completely obstructing access to the stake except from opposite the form. Third, the stakes are usually round and rigid, further decreasing an ability of a tool to engage the stake. Fourth, the large quantity of stakes required for the average construction project amplifies the stake removal problem. Even a small improvement over existing methods adds up to a significant time savings when several hundred stakes must be pulled.
There have been many different solutions to the problems of stake removal in general as well as removal of concrete form retaining stakes. There are deficiencies when using a general purpose post removal solution for this type of concrete form stake and tools for removing concrete form stakes are not as optimally efficient in time or as versatile as desired when locating the puller for certain stake positions. Challenges have been conveniently and quickly (re)locating the tool, efficiently and quickly engaging the stake with the tool, and efficiently extracting the stake with the tool.
What is needed is an improved stake puller that overcomes the limitations of the existing devices.
Disclosed is an improved stake puller that overcomes the limitations of the existing devices. The following summary of the invention is provided to facilitate an understanding of some of technical features related to stake pulling in the context of retaining stakes for concrete forms, and is not intended to be a full description of the present invention. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
A stake puller for extracting a stake from a portion of a substrate (e.g., earth, soil, or the like) wherein the stake is abutted against a perpendicular wall that thereby exposes a side portion of the stake opposite of the perpendicular wall between the portion of the substrate and an exposed top of the stake, the puller including: a shaft having a distal end and a proximal end; a cross-handle coupled to the proximal end; and a stake-engaging head, coupled to the distal end, engaging the exposed side portion of the stake between the portion of the substrate and the exposed top from a direction opposite of the perpendicular wall wherein a longitudinal axis of the shaft is generally parallel to a longitudinal axis of the stake when the stake-engaging head engages the exposed side portion of the stake.
A method for extracting a stake from a portion of the substrate wherein the stake is abutted against a perpendicular wall that thereby exposes a side portion of the stake opposite of the perpendicular wall between the portion of the substrate and an exposed top of the stake, the method including: a) engaging the exposed side portion of the stake between the portion of the substrate and the exposed top from a direction opposite of the perpendicular wall with an engagement head coupled to a distal end of a shaft with a longitudinal axis of the shaft generally parallel to a longitudinal axis of the stake; b) applying a longitudinal force to the shaft directed away from the portion of the substrate; and c) transferring the longitudinal force to the stake through the coupling of the engagement head to the shaft.
The preferred embodiments disclosed herein are described in the context of a extracting form-retaining stakes, particularly stakes holding concrete forms in position. There are two principle mechanical implementations, a “manual” model and a “pressure-driven” model. The manual model is efficient in terms of being able to locate a stake engagement head in virtually any location as it does not use or require any base or contact to leverage against (it is completely suspended above the ground by the user). For some stakes, the grip of the engagement head mechanically advantaged by the length of the shaft permits some stakes to be extracted simply by pulling, rocking and the like on the handle (which longitudinally pulls the stakes as well, improving its efficiency). Some stakes require additional extraction force and that is provided by operation of a slide hammer or the like coupled to the shaft. The user operates the slide hammer with the engagement head engaged to forcibly drive out the stake. The engagement head includes an exposed open channel for gripping an exposed side of a stake abutted against a form or other perpendicular wall. The construction is such that the harder one pulls at the stake, the stronger the engagement head grips the stake. The channel is open and permits a very long stake to be extracted by pulling a stake out part way and then re-engaging the stake closer to the ground and extracting more of the stake by similar operation.
The pressure-driven model uses some fluid (e.g., hydraulic liquid or compressed gas) to drive a motor (e.g., a piston or the like) coupled to the engagement head. This embodiment includes a base for supporting the tool on the ground, the top of a form, or other stable foundation, and pulls the stake by operating against the base. In the preferred embodiment, this model uses an external reservoir of fluid (e.g., an air compressor or hydraulic system of a piece of construction equipment such as excavation machinery) coupled to the tool by a hose or tube. Preferably the tool is operable by a single user which means that at least one control valve is directly coupled to the tool. In some implementations, it may be efficient to have a pair of users extracting stakes—for example one sits in the cab of the machinery and controls the fluid flow to the tool and the other moves and positions the tool at each stake.
Other features, benefits, and advantages of the present invention will be apparent upon a review of the present disclosure, including the specification, drawings, and claims.
The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.
Embodiments of the present invention provide an improved stake puller that overcomes the limitations of the existing devices. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. In the following text, the terms stake, post, rod, peg, and the like, whether metal, wood, plastic or other material may be used interchangeably (unless the context indicates otherwise” and may refer to any of a variety of different retaining structures or marker driven into a substrate, such as the earth or the like.
Various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.
Shaft 305 is preferably made of hardened steel to resist deformation/destruction as used herein. Shaft 305 is preferably cylindrical though it may have a square, oval, or other cross-section (including a rectilinear elongated plate structure and the like). Handle 310 is preferably “T” shaped to enable the user to pull, and/or rock a stake engaged by stake-engagement head 315. Other implementations may employ a different handle style appropriate for its intended use.
Stake-engagement head 315 includes a plate 320 affixed to the distal end of shaft 305. A pair of opposing biased cammed structures 325 form jaws with a special gripping channel 330. Cammed structures 325 are pivotally coupled at pivots 335 and biased together with springs 340. Channel 330 is exposed and open permitting a stake to be easily gripping with only limited purchase available due to the stake being abutted against the perpendicular wall of the form.
Channel 330, which receives the stake to be extracted, engages lateral surfaces of the stake as it is disposed in the substrate. Cammed structures 325 provide a variable width to channel 330, the channel expanding to receive the stake and then closing on the lateral surface due to springs 340. Stake-engagement head 315 is configured so that the stake to be extracted has a longitudinal axis (the axis running a length of the stake) generally parallel to a longitudinal axis of shaft 305. (The axes are displaced by a thickness of plate 320.) Further, cammed structures 325 are configured so that a longitudinal force applied to the longitudinal axis of shaft 305 (such as, for example, pulling on handle 310 directly away from the distal end of shaft 305) communicates a similar longitudinal extracting force to any stake gripped within channel 330. This longitudinal force also operates to reduce the width of channel 330 which increases the lateral gripping force on the stake within the channel. In this way channel 330 self-adjusts for differing diameter stakes and increases gripping strength the more force needed to extract a stake.
In some instances, a user will benefit from application of a greater longitudinal force than can be readily applied by a user pulling on handle 310. Tool 300 includes a slide hammer enabling a user to drive difficult-to-remove stakes from the substrate. A slide hammer, or similar structure, is coupled to shaft 305 to enhance application of extracting longitudinal forces. For example, the slide hammer of the preferred embodiment is constructed of a hammer 345 slidingly engaged to shaft 305 in-between handle 310 and stake-engagement head 315. Hammer 345 slides smoothly along the shaft and may be implemented complementary to any cross-section for shaft 305. Coupled to shaft 305 near handle 310 is an anvil 350. Anvil 350 is fixed in location and resists relocation when struck with significant force by hammer 345. In this way, the hammering force applied by quickly moving hammer 345 to strike anvil 350 is communicated to shaft 305 as another longitudinal force. This longitudinal is, in turn, transferred/communicated to a stake engaged by stake-engagement head 315 and operates to longitudinally drive the stake from the substrate, freeing it for removal.
Shaft 305 is preferably made of hardened steel to resist deformation/destruction as used herein (because of the potentially large forces applied by the pressurized (e.g., hydraulic/pneumatic) system, shaft 605 is preferably an elongated plate, though it may have other cross-section. Handle 610 is preferably similar to handle 310 though its manner of coupling to shaft 605 differs. Handle 610 is “T” shaped to enable the user to pull, and/or rock a stake engaged by stake-engagement head 315. Other implementations may employ a different handle style appropriate for its intended use. Stake-engagement head 315 is preferably the same as shown in
Tool 600 includes a pressure-driven subsystem 615 that couples shaft 605 to stake-engagement head 315. Subsystem 615 includes a tube 620 for fluid flow between chambers of the pressure-motor, a control valve 625, a pressure-equalization valve 630, a base 635 and a piston 640. Subsystem 615 contemplates both hydraulic (the fluid is a liquid) and pneumatic (the fluid is a gas (e.g., air)) implementations. There are many ways to implement a pressure-driven “motor” that typically includes different chambers responsive to fluid flow to effectuate mechanical motion. Tool 600 is most preferably implemented using a hydraulic fluid communicated through tube 620 from valve 625. Fluid flow controls an extension/retraction of piston 640. By securing base 635 near the stake to be extracted (directly on the substrate, an edge of a perpendicular wall abutting the stake (e.g., form 105), or other stable foundation) and extending piston 640, stake-engagement head 315 is moved away from base 635 and thereby extracts the stake by application of a transferred longitudinal axial force.
To increase portability and maneuverability of tool 600, a fluid reservoir and pump are not integrated into tool 600. Tool 600 receives pressurized fluid through a hose or tube coupled to valve 625, with the pressurized fluid provided by an additional machine having such a reservoir and pump. Air compressors and excavation machinery is commonly available/accessible at worksites employing stakes as described herein. Many types of excavation machinery include externally accessible hydraulic lines. Such hydraulic systems are typically controlled by an operator located in a cab of the machinery. In one implementation, tool 600 would require two people for efficient extraction of a stake. One person locates a stake, positions tool 600 to engage the stake and properly secure the base, and the other person actuates the hydraulic system to drive the piston and extract the stake. In another implementation, a version of a control system includes manual operation of a control valve to enable a single user to not only locate and position the tool, but to also actuate the piston.
As noted herein, the system and process are most preferably implemented in manual and/or pressurized tools. Preferably longitudinal axial forces applied to a shaft of the tool are closed transferred to longitudinal axial extraction forces for the stake, essentially pulling it straight out (least resistance and maximum extractive force).
The system and methods above has been described in general terms as an aid to understanding details of preferred embodiments of the present invention. Other preferred embodiments of the present include the described application for stake extraction in other contexts. In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the present invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention.
Reference throughout this specification to “one embodiment”, “an embodiment”, or “a specific embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention and not necessarily in all embodiments. Thus, respective appearances of the phrases “in one embodiment”, “in an embodiment”, or “in a specific embodiment” in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the present invention may be combined in any suitable manner with one or more other embodiments. It is to be understood that other variations and modifications of the embodiments of the present invention described and illustrated herein are possible in light of the teachings herein and are to be considered as part of the spirit and scope of the present invention.
It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application.
Additionally, any signal arrows in the drawings/Figures should be considered only as exemplary, and not limiting, unless otherwise specifically noted. Furthermore, the term “or” as used herein is generally intended to mean “and/or” unless otherwise indicated. Combinations of components or steps will also be considered as being noted, where terminology is foreseen as rendering the ability to separate or combine is unclear.
As used in the description herein and throughout the claims that follow, “a”, “an”, and “the” includes plural references unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
The foregoing description of illustrated embodiments of the present invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the present invention in light of the foregoing description of illustrated embodiments of the present invention and are to be included within the spirit and scope of the present invention.
Thus, while the present invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances some features of embodiments of the invention will be employed without a corresponding use of other features without departing from the scope and spirit of the invention as set forth. Therefore, many modifications may be made to adapt a particular situation or material to the essential scope and spirit of the present invention. It is intended that the invention not be limited to the particular terms used in following claims and/or to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Thus, the scope of the invention is to be determined solely by the appended claims.
