There are a number of assumptions that have been made when modeling Profile payloads they are outlined below:
•The maximum payload that can be brought to the landing given the ground profile, log to ground geometry, user defined payload clearances, and the physical limitations of the hauler and its operating lines is calculated
•Allowable maximum tensions in operating lines are based on user defined safe working loads (usually one third of the breaking strength) which allow for wear and tear on lines, shock loadings, and connections.
•For most systems it is assumed that the hauler power train does not limit the allowable maximum tensions in operating lines
•Payload analysis is based on two-dimensional problems only; all forces are assumed to be acting in a single vertical plane
•All systems are assumed to be in static equilibrium
•Payloads and line lengths are based on a rigid-link analysis. Although, lines actually follow a catenary path and a catenary analysis leads to more theoretically correct payloads it has been shown that the differences between catenary and rigid-link payloads are usually less than 0.5% for cable hauler operations
•With the exception of friction between the load and the ground during dragging, all systems are assumed to be frictionless. A coefficient of friction between the load and the ground in partial suspension situations is set at 0.9
•The terminal points, that is tower, tailholds and stumps, and intermediate supports, have sufficient strength to safely withstand the tensions generated by the operating lines.
•Systems with more than four line segments cannot be analysed. The exception is a system with a slackpulling line. In this case it is assumed that the slackpulling line provides no tension and the weight of the line is added to that of the mainline.
•Payloads are extracted towards the hauler, not away from the hauler
•Minimum clearances at each terrain point are set by the user
•Maximum payloads extracted to the landing from each terrain point are the minimum of the maximum payloads for all terrain points between the carriage and the landing. This assumption applies to both clamping and non-clamping carriages.
For further information on the Yarding System Types please see the subsections of this section
Topic Last Updated: Tuesday, 13 September 2016