JD 4020 hydraulics. This is news to me but I have never owned a JD as late a model as a 4020. This question and answer is from the Aug. issue of the Progressive Farmer. Writer said after turning off his 4020 to fuel it, the starter would spin slowly and then spin faster. Answer was that the 4020 has a closed center hydraulic system which maintains 2000 pounds of standby pressure. When there is no hydraulic demand, the pump does not pump oil and so requires very little hp to turn. When tractor was cut off for fueling, the tractor is at standby pressure. During the time spent fueling, the pressure leaks down some. When the starter is engaged, the pump tries to restore the lost pressure. Before the tractor starts, standby pressure is reached and the pump stops pumping(going out of stroke it is called) and the starter can spin the tractor faster. Some people jerk the steering wheel back and forth when starting which dumps hydraulic pressure making the tractor easier to start.
Question on another subject: I have been told that those rattle devices with a flat plastic container on the end of a handle work better at driving cattle than a hot shot. What is the reason given by for them working to drive cattle?
KEH