Abstract

This work presents the design of a motorized tree climbing lift developed for pinecone farmers in Lebanon. The current process of harvesting pinecones in Lebanon consists of a two-person team; one person manually scales a sixty-foot-tall Pinus Pinea tree, using only a sling, to shear pinecones, while the other collects the fallen pinecones from the ground. While this technique is effective, the one-point contact between the sling and the tree can cause the user to slip on to the siliceous terrain, resulting in annual casualties. Furthermore, the sling is fixed to the tree by friction caused by the user’s weight, reducing mobility and reach. To provide a faster, safer, and more efficient method for harvesting pinecones, a motorized tree climbing lift was designed. The lift, with a mass of 55 kg, features a standing platform with safety rails for farmers to harness themselves to and provides a location to store harvested pinecones. The stand is fixed to a tree by three rollers: a drive roller and two guide rollers. The drive roller is directly connected to the front of the stand and is powered using a combustion engine, and the guide rollers are attached to the two retaining arms at the back side of the tree. A pneumatic actuator pushes the arms apart, pulling all three rollers and fixing the stand to the tree. The combustion engine drives a gearbox with a 15:1 gear ratio, allowing the stand to ascend and descend a 113 kg person at a maximum speed of 0.25 m/s. The retaining arms were modeled, out of Aluminum 6061-T4 Alloy, and analyzed in SolidWorks. The maximum Von Mises Stress in the arms occur where the pneumatic actuator anchors to the retaining arms and has a value of 4.214 × 107 N/m2. The yield strength of the selected aluminum alloy is 2.27 × 108 N/m2; therefore, the factor of safety is a value of 5.39. Additionally, an electrical equivalent circuit of the retaining arm is modeled in this work. This design allows the engineers to determine the maximum weight that the platform can hold and adjust the maximum speed accordingly. For a lighter person who stands on the platform, the simulation shows that the mechanical gear can be adjusted in a way that the maximum speed can be increased. This design promotes a safe alternative to the current methods of collecting pinecones in Lebanon and provides additional benefits of added storage while harvesting, reducing the need for having a two-person team.

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