Implements or apparatus for applying pushing or pulling force – Portable implements or apparatus for tensioning flexible... – Including either force transmitting – hand held and operated...
Reexamination Certificate
2000-02-03
2002-04-09
Matecki, Katherine A. (Department: 3653)
Implements or apparatus for applying pushing or pulling force
Portable implements or apparatus for tensioning flexible...
Including either force transmitting, hand held and operated...
C254S250000, C294S092000
Reexamination Certificate
active
06367779
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a mechanism for manually pulling posts from the ground.
Prior art post pullers typically include a stand that rests on and extends upwardly from the ground, and an arm that is pivotally connected to the stand. A rearward end of the arm can be grasped by the operator for pressing down on that end of the arm. This causes the front end of the arm on the opposite side of the pivotal connection with the stand to pivot upwardly. The front end of the arm is connected by some structure to the post to be pulled from the ground. As the operator presses down on the rear end of the arm, the front end of the arm pivots upwardly, thereby pulling the post out of the ground once sufficient force is applied.
One shortcoming of typical prior art post pulling devices is the structure that engages the post. Some prior art post pullers include a post engaging mechanism having a square opening that must be passed over the top of the post. This can be difficult with tall posts or if obstructions such as screws, or nails are fixed to the post or if the post has been knocked down and/or twisted. Other conventional devices provide a C-shaped bracket for engaging the post. These brackets include an opening in their side through which the post may pass, and therefore these brackets can be slipped around the side of a post. Because of the opening in the side of these brackets, some of these C-shaped brackets are relatively weak and are subject to failure by bending under the relatively large forces that develop during post pulling operations. Many prior art post engaging devices are also prone to slipping on the post. Many prior art post engaging devices have the disadvantage of being generally suited for only one type of post. Some devices are best suited for engaging square wooden posts, others for engaging metallic channel-type posts. Prior art post engaging devices are typically not adapted for adequately engaging various types and shapes of posts to hold the posts sufficiently as upward force is applied to the post during post pulling operations. Some prior art post engaging devices clamp down against the post with greater and greater force as the arm is pressed down with greater and greater force. These devices may cause damage to wooden and metal posts, and may be relatively difficult to get on and off the post.
Many prior art post pulling devices do not develop sufficient leverage or force for pulling a post from the ground in certain soil conditions. In the worst soil conditions where it is very difficult to pull a post from the ground, these prior art post pullers do not develop enough leverage or force to dislodge the post from the ground.
Furthermore, many prior art post pulling devices do not allow the amount of leverage to be easily adjusted. The operator can vary the amount of downforce he applies to the rear end portion of the arm, which will vary the amount of upward force applied to the post within a particular range, but many prior art post pulling devices do not have any other easy way of varying the amount of force or leverage applied to the post, or that will easily shift the range of upward force that can be operatively applied to the post. This can be disadvantageous since post pullers can be used in various soil conditions that may require different amounts of leverage for pulling a post from the ground.
Typical prior art post pullers are not easily transportable. The post pullers are topically carried by hand at various points during transport between their storage site and the job site. In other situations a line of posts must be pulled, for example from a fence-row, and an operator may wish to carry a post puller by hand between the posts to be pulled. Typical prior art post pullers are relatively awkward to carry by hand, and may even have loose parts which make transport by hand more difficult.
Many prior art post pulling devices undesirably allow an operators fingers or hands to be easily pinched between the arm and the stand as the arm pivots down close to the stand during post pulling operations.
A prior art post puller provides an extension that can be attached to the arm for effectively lengthening the arm and thereby increasing the distance between the point at which the operator presses own on the arm and the point of pivotal connection between the arm and the stand. This arm extension thereby increases the lever age applied for a given amount of downforce applied to the arm by the operator. Since these arm extensions are detachable parts they can be relatively clumsy or awkward to transport and attach and detach, and may inadvertently be lost or left behind and not brought to the job site.
Many prior art post pulling devices establish a relatively large effective lever arm or fulcrum which extends forwardly from the pivotal connection of the arm with the stand. This relatively large fulcrum created by the relatively long front portion of the arm can cause the post pulling device to be relatively unstable and subject to toppling over to the side under the large forces established during post pulling operations. Furthermore, a large fulcrum can decrease the amount of leverage or force imparted by the device for pulling the post upward.
SUMMARY OF THE INVENTION
The preferred embodiment of the present invention provides a post puller mechanism having a post pulling mode and a transport mode. The post puller includes a leg that extends upwardly from the ground surface during post pulling mode. A lever member is pivotably coupled with the leg and extends generally horizontally during the post pulling mode. The lever can be operatively grasped and pivoted by an operator during the post pulling mode for causing the post puller mechanism to pull a post from the ground. The lever can also be pivoted to a position proximate the leg during the transport mode, whereat the lever is operatively held in position proximate the leg and generally prevented from pivoting during the transport mode. During this transport mode the lever is graspable by an operator as a handle for carrying the post pulling mechanism. A base is coupled with the lower end portion of the leg, and the lever is received by an opening in the base for holding the lever in its position proximate the leg during the transport mode. The lever is extendable along a longitudinal axis of the lever and extends at least slightly to be received within the opening in the base. The lever is biased by a compression spring toward an extended position for maintaining the lever within the opening during the transport mode. Interference with a portion of the base which defines the opening blocks the lever from shifting out of the transport mode.
The lever member is pivotal with respect to the leg, and has a handle portion on one side of a pivotal connection of the lever member with the leg. A chain engaging portion is positioned on the other side of the pivotal connection. A chain is engaged with the chain engaging portion of the lever member, and in this position the chain extends downwardly and is operatively coupled via a hook and post holder to a post to be pulled from the ground. The post is pulled upwardly from the ground as the operator presses the handle portion downwardly. The chain engaging portion further comprises first and second chain engaging positions spaced from each other and whereas the chain is engagable with the chain engaging portion at different distances from the pivotal connection of the lever member with the leg. A longitudinal slot is formed in the chain engaging portion and receives a first chain link. At least one recess extends generally transverse to the longitudinal slot, said recess receives a second link of the chain directly above the first chain link when the first chain link is positioned within the longitudinal slot. The chain engaging portion abuts the second chain link for lifting the chain upwardly as the operator presses the handle portion of the lever member for pulling the post upwardly. The chain engaging portion according to the pre
Martin Robert B.
Tibbs David I.
Matecki Katherine A.
Rockey Milnamow & Katz Ltd.
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