Lets discuss Front End Loader operation Here. Operation with a geared tractor and a HST tractor are somewhat different With a geared machine you typically set a "baseline" with the hand throttle and use the foot throttle for more RPM like when pushing into the pile of material for instance for more power. Of course your gear choice may need to be varied from pushing into the pile to transporting the load, as well as directional changes. The hydraulic pump produces flow, with more RPM comes more flow rate. The pumps don't produce pressure they produce flow. The pressure rises when the flow is restricted, such as when you apply the fluid to a hydraulic cylinder. At low RPM the flow rate is less, so the pressure rises slower, so the hydraulic cylinder responds slower, but with the same theoretical lift power just slower. But there is a little more to it, as the pumps have blow-by, or a certain amount of leakage internally. So at low RPM's the maximum pressure may not be achieved by the restriction of the hydraulic cylinder because the flow rate is low enough that the internal leakage of the pump wont achieve the peak pressure. So if you increase the RPM some the flow rate will overcome the leakage and allow the pressure to spike up and push harder on the cylinder. But in general you can lift almost as much at idle as you can at red line with a new tractor pump. but you are going to lift it a lot slower. This can be very good when you are lifting something dangerous or delicate. With a geared tractor you will want to choose the drive gear that gives you enough torque to push into the pile without bogging down the engine and you will typically want to increase the foot throttle a bit for more power to keep the RPM's up. A hydro tractor does not have a foot throttle, only a hand throttle. You typically set it to a higher setting than a geared tractor, enough to not bog down the tractor when you are pushing and moving with the load, I run my tractor typically around 1800 1900 for most general tasks, but this depends on the tractor, its engine (smaller engines need to be run higher) the way it is loaded etc.. You just have to listen to what it is telling you. When I want the tractor hydraulics to be less responsive I decrease the RPM's, but when I want more response and power for driving and lifting I increase RPM's. Now of course when discussing the HST+ transmission of a Kubota Grand L. now you have several more options and conditions that I won't go into here, but suffice to say, it turns some of what I said on it's head. What I am trying to say and probably doing a poor job of doing it, is that this is a complicated subject, but actual operation is intuitive after a while on the machine!
James K0UA
