Multi Span

Adding Multi Span Supports

 

Multi Span Profiles require the user to nominate the Terrain Points at which Intermediate Supports are located. After placing the Tailhold the Select Multispan Supports form will be shown. The Terrain Points to add Intermediate Supports to can be selected by ticking the Multispan Support Point checkbox and entering the height of the support.

 

 

Supports can be modified on existing Profiles by clicking the Add Multispan Supports button on the Profile Settings panel of the Control Panel.

 

 

Note: The modeling of the cable system becomes more unreliable as the number of spans is increased. It is recommended that no more than three spans are used.

 

Assumptions:

•A Multispan skyline is a standing skyline system with intermediate supports included to provide clearance over difficult terrain points.  The carriage must pass over jacks at the intermediate supports and be capable of doing so.

•The skyline length is fixed, that is the line is neither lifted nor lowered during extraction.  The length of the line is based on the longest length that will just provide the minimum desired clearance (full or partial suspension) across the full yarding span.

•The length of the mainline is shortened so that the mainline is not on the ground

•A haulback line is assumed to be present for the main purpose of returning the carriage to the field.  For most situations the haulback line is assumed to provide no lift.

•Maximum allowable tensions in the skyline are used first in the calculations.  Tensions in the mainline and haulback line are then checked to see if maximum allowable tensions required in these lines to achieve static equilibrium are exceeded.  If mainline tensions are exceeded skyline tensions are reduced until all line tensions are within maximum allowable tensions.

•No checks have been made to determine if the skyline will lift off of one or more of the intermediate support jacks during load extraction.  This check will be included in a later version of CHPS.

 

http://cableharvesting.com/help//7-Yarding_System_Types.Multi_Span.htm                                                                                                                                        

 

Topic Last Updated: Tuesday, 13 September 2016