ARS | Publication request: DYNAMIC LOAD AND INFLATION PRESSURE EFFECTS ON CONTACT PRESSURES OF A FORESTRY FORWARDER TIRE

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 26, 2004
Publication Date: October 1, 2004
Citation: Jun, H., Way, T.R., Lofgren, B., Landstrom, M., Bailey, A.C., Burt, E.C., Mcdonald, T.P. 2004. Dynamic load and inflation pressure effects on contact pressures of a forestry forwarder tire. American Society of Agricultural Engineers Meetings Papers. 41(4):209-222.

Interpretive Summary: Forestry forwarders, machines that transport logs from forests to the roadsides, compact soil, form ruts in soil, and damage root mats in forest ecosystems. Deep rut formation reduces growth of residual trees, disrupts ecosystems, and increases fuel consumption of forwarders. Contact pressures of tires on soil influence soil compaction and rut formation. Contact pressures of a forwarder drive tire were measured on firm clay soil. Pressures on a lug at the edge of the tire increased as the weight supported by the tire increased. Average and peak pressures on the undertread, which is the tread area between lugs, generally were less than those on a lug. For a constant weight supported by the tire, the amount of pulling force generated by the tire and the efficiency with which the tire operated decreased as the tire air pressure increased. To minimize soil compaction and maximize efficiency without damaging tires, air pressures in forwarder tires should be set according to manufacturer specifications for the weight supported by the tire.

Technical Abstract: A Trelleborg Twin 421 Mark II 600/55-26.5 steel-reinforced bias-ply forwarder drive tire at inflation pressures of 100 and 240 kPa and dynamic loads of 23.9 and 40 kN at 5% travel reduction on a firm clay soil. Effects of dynamic load and inflation pressure on soil-tire contact pressures were determined using six pressure transducers mounted on the tire tread. Three were mounted on the face of a face and three corresponding locations on the undertread. Contact angles increased with increases in inflation pressure and dynamic load. Contact pressures on a lug at the edge of the tire increased as dynamic load increased. Mean and peak pressures on the undertread generally were less than those on a lug. The angular position of the peak pressures on the undertread occurred to the rear of the axle in most treatments. At constant dynamic load, net traction and tractive efficiency decreased as inflation pressure increased.