Just got a PC200LC-3. What do each of the following do H, S, L when selected on the OLSS switch?? Thanks in advance.
Those are the mode settings for the pump. Basically they change the torque curve put on the engine by changing the amount of flow the pump puts out per operating pressure. The L mode allows fine control of the functions for doing things like fine grading or setting things like man holes and pipe. The S mode is supposed put out a little more flow while burning a little more fuel. It was supposed to be for everyday work. The H mode was high or heavy loading mode. Say you are hogging out a hole and side or full turn loading trucks as fast as the machine was able. It also used a lot more fuel. All these modes were meant to work with the engine at fuel throttle. This was the early version of load sensing hydraulics. Basically the pump would stroke up flow as you increased the amount that you moved the joy stick handle. It was a big departure from earlier excavators that used positive displacement pumps. The Japanese seemed to like the gadgets and bells and whistles as they did power modes like this and operational modes in the Dash 5 systems later on. The system gave incredible feel and great fuel usage. The Japanese loved the mode setting systems but in America, and most of the rest of the world as far as I can tell, the mode switch was just put on H and the operator could just run the machine on feel. If you needed real fine control you just turned down the throttle some. The down side to the system was adjusting the flow and pressure controls over time as the machine orifices wore open some the springs lost some of their tension. The process isn't hard to do but you have to have enough gauges to read the functions and be able to understand what is happening as you do adjustments. The Dash 3 and 5 open center load sensing systems went a little out of favor when the Dash 6 machines with closed center load sensing systems came into being. I have a video on YouTube showing the early Dash 6 controls if you are interested. https://youtu.be/XRO4fwDo1So
John, thanks for the info on the H S L function......and the link to the video which answered a couple of other questions I had.