A stake or post puller is an engineering control that reduces repetitive bending, twisting, and pulling. When performed repeatedly, especially from a stooped posture, these movements put laborers at an increased risk for musculoskeletal disorders (MSDs). A stake or post puller reduces these risks by allowing the rebar, stake, or post to be removed from an upright position by pushing down on the handle, which provides an upward force.
Stake or post pullers consist of a handle connected to a central shaft and two pull shafts. At the end of the shafts are two gripping pieces and a baseplate. Stake or post pullers are made from heavy gauge steel plate and tubing with zinc and clear chromate plating to resist corrosion.
Stake or post pullers are operated by lifting the handle, which pulls on the pull shafts to open the gripping piece. Once open, the rebar, stake, or post is positioned inside the gripping piece. The object is lifted out of the ground by placing the foot on the base and pushing down on the handle. These steps are repeated until the post is completely removed.
With uneven ground, blocks can be placed beneath the base of the stake or post puller so that the central shaft and gripping device is parallel to the rebar, stake, or post. With soft ground, a wooden block can be screwed into two holes in the 4" by 8" base plate to increase the base of support.
There are numerous models of stake or post pullers for five categories of rebar, stake, and post removal (construction and concrete, T-post fencing and farming, tents and inflatables, sign posts, and utility grounding rods). The models range from a 9:1 to a 16:1 mechanical advantage, producing 900 to 2,800 lb of upward force. The different models vary to accommodate the various size and shapes of the objects being removed.
Exposure to repetitive bending, twisting, and pulling can cause multiple MSDs. Bending can put excessive loads on the spine, resulting in a low back disc injury. Overworking back muscles can also result in strains. Shoulder and wrist tendonitis may occur with repetitive twisting or pulling. Tendonitis is caused from overuse and is inflammation of a tendon that results in pain. A stake or post puller reduces the risks of MSDs associated with repetitive bending, twisting, and pulling because they are operated by pushing down on a handle from an upright position.
Musculoskeletal disorders associated with lifting, stooped postures, stressful hand and wrist activity, and fatigue.
Stake or post pullers minimize the duration of stooped posture because once in place, the tool can be operated from a standing position. A brief stooped posture is required to align the rebar, stake or post into the gripping piece. Additionally, stake or post pullers eliminate pulling, lifting, and twisting of the forearm and wrist, which is required in traditional rebar removal. Instead, pushing down on the handle while standing is sufficient to pull out the rebar, stake, or post.
There is ample evidence that low-back disorders are associated with lifting, stooping, and forceful movements (Bernard, 2007). Research has shown that workers who spend more time in stooped or other awkward back postures are at a higher risk for developing low back problems. Studies have reported a decrease in low back pain and stress among those working with materials kept at or near waist height (Hoogendoorn et al., 2000). Additionally, research has shown that forceful elbow and/or hand and wrist movements increase the likelihood of tendinitis in the associated joint and/or carpal tunnel syndrome.
Safety and health experts, as well as the manufacturer, believe that using stake or post pullers require less demand on the laborer because it eliminates strain on the operator's back. The manufacturer states, “pulling straight up [with the stake or post puller] is easier, because it eliminates side loading, and resulting strain on the operator's back.” Also, using stake or post pullers is safer than using a hammer and striking the metal stakes or posts to loosen them.
Stake or post pullers increase productivity on the worksite.
Manufacturers report that stake or post pullers are the “fast, easy and safe way to extract…” rebar, stakes, and/or posts faster and easier than the traditional technique. Stake or post pullers put laborers in less stressful positions, resulting in less fatigue and more efficient work. Therefore, productivity is likely to be improved.
The correct stake or post puller model must be chosen based on the object being removed. The frequency of use of stake or post pullers should be considered prior to purchase because the benefit may not outweigh the price if only used occasionally. In addition, stake or post pullers are safer than using a hammer and striking the metal stakes or posts to loosen them.
Dan Anton, PT, PhD, ATC; and Kevin Wright, SPT – Eastern Washington University