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Mathieu Lamandé

Rubber tracks are still not good enough!

Research output: Contribution to conferenceConference abstract for conferenceResearch

Subsoil compaction is persistent. Elasticity theory and recent studies have confirmed the elasticity theory and established wheel load as the primary source of high stress in the subsoil. In contrast, stresses at the tire/soil interface are determined primarily by the tyre inflation pressure and the primary cause of direct damages to crops and topsoil compaction. However, very low contact stress without reduction of wheel load would also help reducing stress in the deep subsoil, and thereby the risk of subsoil compaction of relevance to plant growth. Using tracks instead of tires is a technical solution to increase contact area. However, how well are the stresses distributed across the contact area under tracks? We measured contact stress below a sugar beet harvester equipped
with either a large tire (1050/50R32) with low inflation pressure (150 kPa; load rated for 10 km h-1)
or equipped with a track (0.9 m width and 2.0 m long). The wheel load was 100 kN in both cases. The tests took place in November 2013 on an arable field with 20% clay and the soil water potential close to -10 kPa. Seventeen stress transducers were installed at 0.1 m depth and covered with loose soil. Measured stress distributions and the theoretical uniform stress distribution were used as input to calculate vertical stress in the soil profile using the analytical solution based on the elasticity theory. The results showed that the contact area was larger and the maximum stress was smaller below the track than below the tire. Nevertheless, the stress distribution below the track was far from uniform, presenting much higher stresses below the front, rear and the two mid-wheel rollers. Despite this, the calculated vertical soil stress was lower below the track than below the tire. The calculations using a theoretical uniform stress distribution under the track indicated that the contact area was too small to distribute the wheel load of 100 kN in order to prevent subsoil compaction. We conclude that there are still some technical issues to be solved to get a uniform stress distribution below tracks (positioning of mid-wheel rollers, spring stiffness at attachment points, track stiffness, dynamic weight transfer when under drawbar load, etc.). Also, the contact area should be considerably increased to prevent subsoil compaction if wheel loads as high as in this study are applied.
Original languageEnglish
Publication year2015
Number of pages1
Publication statusPublished - 2015
Event20th International Soil Tillage Research Organization Conference (ISTRO) 14-18th, September, 2015 Nanjing, P.R. CHINA - Kina, Nanjing, China
Duration: 14 Sep 201518 Sep 2015


Conference20th International Soil Tillage Research Organization Conference (ISTRO) 14-18th, September, 2015 Nanjing, P.R. CHINA

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