User:SPL Tech/sandbox

The lineGrip is a mechanical-actuated friction clamp for 24-26mm wide slacklines. Most commonly, slackliners use the lineGrip to softpoint slacklines. Because the lineGrip can be placed on the slackline at any point along the slackline's length, and because the lineGrip allows for one-way feeding of the slackline webbing, it is especially well suited for softpointing. The lineGrip was invented by German inventor Andreas Riedrich in 2009. In 2010, Riedrich started mass producing the lineGrip through his slackline-equipment manufacturer slackPro!, which sold units to Gibbon Slacklines for distribution. The lineGrip is protected under German patent 102009044739, as well as patents in 38 other countries.

Operation and Use
The lineGrip essentially has four parts:
 * A pull tab, which is used to anchor the device that will be applying tension to the slackline;
 * four lever tabs which multiplies leveraging force onto the slackline webbing;
 * two rubber-coated plates which directly clamp the slackline webbing;
 * and a secondary attachment point on the rear of the lineGrip which allows two lineGrips to be placed in parallel to increase the safe working load of the lineGrip system.

When a load is applied to the pull tab, approximately 160% of the fundamental force is transferred into opposing clamping force through the rubber-coated plates and onto the slackline. Friction created from the opposing clamping force, and from the rubber, results in a condition in which the load on the slackline is less than the load required to cause the webbing to slip, allowing stable tensioning of the slackline webbing.

To install the lineGrip on a slackline, the user should first remove the loose plate, which is affixed to the lower plate by means of a steel cable to prevent loss of the loose plate. The pull tab should face toward the device used to tention the slackline. Upon applying tension to the lineGrip, the slackline will elongate, possibly eventually requiring the user to move the lineGrip further away from the tensioning system.

Limitations
slackPro! explicitly designed the lineGrip for use with 24-26mm wide, 1-5mm thick slackline webbing made of Nylon, Vectran® or polyester. The lineGrip is not suitable to be used with rope, wider-than or narrower-than-prescribed webbing, nor is it suitable to hold loads for extended periods of time, overhead lifting, securing cargo, or life-support applications. While using the lineGrip on threaded webbing is conditionally possible, slackPro! does not recommend users apply the lineGrip to threaded webbing.

Temperature Concerns
While the official safe working load of the line grip is 15kN for the 7075-T6 aluminum version and 12kN for the A2 stainless steel version, the actual safe working load may depreciate depending on the temperature of the rubber-plated plates. At a tension of 15kN, the operating temperature range of the rubber-coated plates is -7 to 34°C. Exposing the rubber-coated plates to temperatures outside the operating range will result in a lower safe working load.

Rubber-Coated Plates
The LineGrip uses a proprietary rubber compound that is vulcanized directly onto a stainless steel plate in a press. Because the rubber is vulcanized to a removable plate, the rubber can be replaced. slackPro! recommends users replace the rubber every 18 months under normal conditions, and every 12 months if the lineGrip is exposed to prolonged and frequent UV radiation. With time, accelerated by UV radiation, the rubber starts to harden and loose its friction properties. Without replacement, the friction provided by the rubber will eventually degrade, allowing the webbing to slip.

Variants
As of February 2014, slackPro! manufacturers the lineGrip in two versions: an A2 stainless steel version and a 7075-T651 aluminum version. The stainless steel version weighs 850g and has a safe working load of 12kN, and the aluminum version weighs 560g and has a safe working load of 15kN. Aside from an anodized coating on the aluminum version, and a modified arm on the aluminum version, the stainless steel versions and aluminum versions are fundamentally identical. The aluminum version has a higher safe working load than the stainless steel version because 7075-T651 has a higher yield strength than A2 stainless steel does. In the future, slackPro! intends to manufacturer a highlineGrip, designed for use on highlines, and a lineGrip designed for use with 51mm-wide slacklines.

Versions
Four lineGrip versions exist: G0, G1, G2 and G3, with G0 as the oldest. Versions G1, G2 and G3 contained numerous reversions, which include minor changes. Major versions include complete design reforms.


 * G3.7: Included a new fastening system for the loose plate. Shipped starting February 2013.
 * G3.6: The aluminum LineGrip includes a redesigned lever shape. Shipped from March 2012 to January 2013.
 * G3.5: Included small intermediate series, delivered from January to April 2012.
 * G3.4: The G3 series 4 marked the second major round of G3 lineGrips available to the public. It shipped from August 2011 until January 2012.
 * G3.3: This series included minor updates. It shipped from June to August 2011.
 * G3.2: The G3 series 2 was the first major production run available to the public of the G3 model.
 * G3.1: The G3 series 1 included major body design changes, but it was mostly used as a pre-production model and show model. It was manufactured from October 2010 until January 2011.
 * G2.2.1: The G2 series 2-2 included minor improvements to the lineGrip's mechanics. It shipped from June 2010 to October 2010.
 * G2.2.0: This series used a vulcanized rubber coating instead of a glued rubber coating. It was shipped from May 2010 to June 2010.
 * G2.1.0 and G2.1.1: These were the first mass-produced lineGrips that were sold to the public. They used glue to affix the rubber to the rubber-coated plates. The first G2 series one model was manufactured in May 2010.
 * G2 Beta: The G2 beta model was a pre-release model designed in in March 2010. It was distributed to beta testers for research purposes.
 * G1.1 through 26: These versions included various prototypes that were primarily used for internal research. The series spanned from October 2009 until January 2010.
 * G0: The very first functional prototype. The G0 held 10kN, and was manufactured in October, 2009.

References