Mechanical stresses

1. Stresses applied by the physical action of objects that transmit force onto a surface, such as the feet of players on a playing field.

http://www.deere.com/en_US/ProductCatalog/GC/media/images/category/action/large/cwb/7h17_122515

Walk behind mowing units such as this help to alleviate mechanical stress to turf.

Source:http://www.deere.com/en_US/ProductCatalog/GC/category/printableversion/GC_CWBM_printableVersion.html