Dissertation/Thesis Abstract

Force and moment analysis of stacked counter rotating eccentric mass tree shaker energy-wheel system
by Snell, Lloyd Dale, M.S., Iowa State University, 2008, 77; 1454712
Abstract (Summary)

The tree shaker is a high throughput hydro-mechanical systems used in nut and fruit harvest. Many commercial tree shakers use stacked counter rotating eccentric mass energy-wheels to dislodge the crop from the tree by attaching and shaking the trunk. Tree shakers are known to cause tree trunk damage by approach impact, barking, and bruising of the tree trunk. Tree trunk damage, catastrophic or accumulative, could account for a 4% lifetime production loss, 1408 kg/hectare.

The energy-wheels are commonly known to create planer pulse forces. The pulse is created by the rotation of eccentric mass about a fixed common shaft. The frequency and magnitude of the force is determined by the weight, angular velocity, and center of gravity location of each energy wheel. The industry has developed pads and slings to conform to the tree trunk and transmit the force while minimizing the potential for trunk damage. Lubrication of the slings reduces the coefficient of friction and allows unwanted force dissipation. Lubrication of the slings reduce the transfer of non-normal forces.

This research discloses the presence of moments and extends the planer equations to allow analysis of moment magnitudes and the introduction of planer losses in the y-axis. Moments and planer forces are always present in stacked counter rotating eccentric mass energy-wheel systems. Moments are non-normal forces and are dissipated in the slings, pads, shaker head suspension system. Moments and y-axis losses reduce the efficiency of the system and require additional hardware and systems to control adverse effects on the tree trunk.

Understanding the magnitude of moments will allow development of new systems to extend the application of mechanical shakers to other crops and applications.

Indexing (document details)
Advisor: Birrell, Stuart J.
Commitee: Mickelson, Steven, Steward, Brian
School: Iowa State University
Department: Agricultural and Biosystems Engineering
School Location: United States -- Iowa
Source: MAI 47/01M, Masters Abstracts International
Subjects: Agricultural engineering
Publication Number: 1454712
ISBN: 978-0-549-68888-4
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