The invention relates to a group of novel triazine derivatives which are ligands for human adenosine-A3 receptors, as well as to pharmaceutical compositions containing a pharmacologically active amount of at least one of these compounds as an active ingredient. The guide system may include a cord guide operable to hold the starter cord to a non-interfering position such that a rear collection hopper can be easily removed from the lawn mower for dumping of collected grass clippings. The substrate is then cleaned to remove the organic compound layer. The ring gear has a ring gear axis that is in alignment with the drive sprocket axis. A rotation mechanism allows the U-shaped frame to rotate 180\xb0 allowing patients to reverse their direction of travel along the given path.