TRAFFICABILITY TESTS WITH A RUBBER-TIRED LOG SKIDDER

TESTS WERE CONDUCTED WITH A TAYLOR LOG SKIDDER, MODEL S-112, TO DETERMINE THE APPLICABILITY OF THE U.S. ARMY ENGINEER WATERWAYS EXPERIMENT STATION (WES) MOBILITY INDEX FORMULA TO ARTICULATED, RUBBER-TIRED, FOUR WHEEL-DRIVE VEHICLES. SELF-PROPELLED TESTS WITH AN WITHOUT A 4000-LB ADDED REAR AXLE LOAD WERE CONDUCTED TO DETERMINE EXPERIMENTALLY THE MINIMUM SOIL STRENGTH, OR VEHICLE CONE INDEX FOR ONE-PASS AND 50-PASS STRAIGHT-LINE OPERATIONS. DRAWBAR PULL-SLIP AND MOTION RESISTANCE-SOIL STRENGTH RELATIONS FOR SOILS RANGING IN STRENGTH FROM 25 TO 104 RATING CONE INDEX WERE DETERMINED. BECAUSE TIME WAS SHORT AND TEST AREAS WERE LIMITED IN WHICH TEST LANES OF THE DESIRED SOIL STRENGTHS COULD BE SELECTED, THE STRAIGHT LINE OPERATIONS AND 50-PASS WERE NOT DETERMINED EXACTLY, BUT SEVERAL TESTS WERE MADE FROM WHICH ONE-PASS COULD APPROXIMATED. SELF-PROPELLED TESTS WERE PERFORMED ON SOILS CLASSIFIED AS HEAVY CLAY AND LEAN CLAY. RESULTS SHOW THAT EXPERIMENTAL STRAIGHT-LINE OPERATIONS WAS 33 WITHOUT A REAR AXLE LOAD AND 38 WITH A REAR AXLE LOAD, WHICH IS APPROXIMATELY 3 RCI UNTIS ON THE CONSERVATIVE SIDE. THE EXPERIMENTAL 50-PASS WAS 16 WITH LOAD AND 14 WITHOUT LOAD. SEVEN DRAWBAR PULL TESTS WITH LOAD AND FIVE DRAWBAR PULL TESTS WITHOUT LOAD WERE PERFORMED ON SOILS CLASSIFIED AS ORGANIC SILT (IN THE 0- TO 2-IN LAYER) AND FAT CLAY (IN THE 2- TO 30-IN. LAYER). RESULTS SHOW A GOOD CORRELATION EXISTS BETWEEN BOTH DRAWER PULL AT 40 PERCENT SLIP AND MAXIMUM DRAWBAR PULL AT PLUS OR MINUS 95 PERCENT SLIP AND CONE INDEX OF THE SURFACE LAYER, AT THE 3-IN. DEPTH, AND OF THE 0- TO 6-IN. LAYER, RESPECTIVELY. CORRELATIONS BETWEEN DRAWBAR PULL AND RATING CONE INDEX WERE NOT AS GOOD AS CORRELATIONS BETWEEN DRAWBAR PULL AND CONE INDEX. DRAWBAR PULL CORRELATED WELL WITH THE SURFACE SHEAR STRESS AND MEASURED WITH THE COHRON SHEARGRAPH. IN TERMS OF TRACTIVE COEFFICIENT, A MAXIMUM TC OF ABOUT 0.75 (40 PERCENT SLIP) WAS EXPERIENCED AT SURFACE TO 6-IN. CI OF ABOUT 80; MAXIMUM TC FOR ASPHALT PAVEMENT WAS 0.80. MOTION RESISTANCE COEFFICIENTS CORRELATED WELL WITH VALUES OF SOIL STRENGTH. THE WEBB FORMULA AND COMPUTATIONS FOR THE DETERMINATION OF VEHICLE CONE INDEX FOR THE LOG SKIDDER ARE PRESENTED IN APPENDIX A. /AUTHOR/

  • Supplemental Notes:
    • No M-69-1, 29 PP, 15 FIG, 3 TAB, 1 APP
  • Authors:
    • Robinson, J H
    • SMITH, R P
    • Richardson, B Y
  • Publication Date: 1969-1

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Filing Info

  • Accession Number: 00235817
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 3 1970 12:00AM