Hello!
I'm sorry that I can't speak Swedish and I am not entirely sure that this is the right topic to ask also. But anyway, I have a similar harvester Valmet 862 as in the pictures in the beginning of the topic and I would like to ask some technical questions about this type of machine. My machine has Keto 150 harvester head and it is controlled by Epec 4W30 computer.
How big
hydraulic pumps should be used with this machine? My machine has one pump mounted on gearbox and one under the
radiator in front, driven by engine's
crankshaft. One pump used to feed one
valve of the
crane and second pump the other valve. Pumps are fixed displacement. Since both pumps seem to be very worn I got one used
gear pump with two sections (44+44 L/min at 1000 rpm) in good condition and mounted it on the gearbox. Initially i connected both pump sections together and put it to feed one crane valve since I thought 44 l/min to be too little
flow to feed one valve bank. But this type of connection was very harsh on the engine, it was always deadening the engine when I tryed to move the crane. It seemed that the valve bank is too small for the hydraulic flow. I thought that maybe the main
pressure valve in the valve bank is faulty and changed sides so that the gearbox pump will feed the other valve bank and front-mounted pump this valve bank. But it gave no results, as I could still not use the crane, it deadened the engine as soon as I moved the joystick. Both valve banks seem to be Monsun-Tison HV09, although I am not entirely sure. I thought that HV09 is enough for flow up to about 150 litres per minute. But then I realised that maybe the
transmission ratio for the gearbox-mounted pump under the
cab is not 1:1. I mean that when the engine does 1000 rpm the pump may do for example 1300 rpm? Does anybody know, what is the ratio for the gearbox pump?
Then I decided to connect one section of the new pump to feed one valve bank and the second pump section the other valve bank (that means 44 l/min per bank). And disconnected the front pump completely from the crankshaft. Now the engine is running good, but the crane movements seem to be slow. Also this
oil flow is far from enough for the Keto head-unit (it requires 220 l/min).
And now I have another question. How should the hydraulic flow to the harvester head be solved? The Keto valve is closed
circuit and my pumps are constant-displacement. At the moment on one crane valve there is a big 1" connection
flow divider valve that divides the flow to the crane valve bank and the harvester head valve. This flow divider is controlled by one section of the other crane's valve bank. And the interesting thing is that this other crane valve has no flow divider to the head unit, there is just a simple 3-way T-joint, where flow comes from the pump, and then one way goes to the valve bank and the other to the head unit. I suspect that the flow to the head is created this way: when i want to use the head and push some button, for example head up, the computer gives
output to one of the section of the crane valve. But this section's ports are "blind", so the oil cannot go anywhere. This way the valve's flow is restricted and oil can flow to the head unit. I'm not sure if this is the right way to
control the flow nor if the connection on my machine is actually solved this way. But I just can't imagine any other way since it has just a simple 3-way T-joint to feed crane's valve and head unit.
Long story short: is the gearbox pump output faster than the engine output? How is the hydraulic flow to the head unit solved originally on this machine? I suppose that the old head valves were also closed-circuit? At the moment I think that I should let one new pump's section feed one crane valve bank and second section the other bank and the front-mounted pump should only feed the head unit when it gets command from the computer. But still would like to read what you suggest.
Greetings from Estonia
Kristjan
