You should engage it while the tires are turning . You should only use it when traveling straight not turning . Once the wheels stop spinning and the tractor goes OK on it's own , it will disengage by itself . I'm not sure exactly how it works . You can test to see if it is engaged by pushing down on the pedal while the tire is spinning , other tire should grab , and than pedal should return on it's own once tire spin has stopped . If you engage it while turning it puts a lot of stress on the internal gears and can cause breakage .You can use it if tires are slipping while turning for traction but don't hold the pedal down with your foot . Just oil it real well and work it by hand untill it is free . It is very useful on slippery ground or uneven ground . The pedal doesn't travel very far , maybe 3/4" . If you look close , I think the pedal actually moves a seperate lever wich goes into the trans/diff. That is where it needs lubed extra good.