HI GUYS, JUST NEED TO KNOW HOW FAR ONE CAN TURN UP THE MAIN RELIEF PRESSURE ON A MINI EXCAVATOR WITH OUT DOING ANY HARM TO PUMP?
Have to ask, why would you do that?
Hi willie, well i would like a bit more digging force. The pump pressure on my yanmar vio 45-5 is 3130 psi and on the 55-5 its 3555 psi but both machines have the same motor and pump, the only difference is the 55-5 counter weight is 470 kg heaver then the 45-5 and the arm is 300 mm longer. When i drove the 55-5 it would lift it self easy as at idle but the 45- 5 won't. You can hear it opening the relief valve. It just seems than it needs a little more pressure. The 35-5 runs 3220 psi which is higher then the 45-5 and the 45-5 is a tonne heaver it just doesn't add up to me.
Whoa, information overload! Have to noodle this out. Let's see; models 35, 45, and 55. You're saying 45 and 55 is basically same machine, but 55 have heavier counterweight and 300mm longer dipper, and shares same engine and pump, but has a difference in main pressure relief setting. I assume you're wanting to turn up the relief pressure on a 45 to match the 55. If that's the case, why would you question if you would damage the pump doing so? Maybe I'm reading this wrong. The nuts and bolts of the matter; typically, the main relief setting is a pressure that not only protects the pump from excessive loads, but it's also relative to structural integrity of boom components, keep you from damaging boom or arm. But if the 45 and 55 are in fact comparable in structural integrity, I guess there would be little harm in increasing relief pressure. But I have to admit, I know nothing about these model machines and have to rely totally on info that you have offered.
sorry about that willie 59 haha. i was only going to turn it up about 10%, so that it will be at about 3400psi so that it doesn't hurt the boom/arm what do you think??
Well, again, I don't know the machines, so it's hard for me to be definitive about the discussion. But if the machines are as you have described, I don't see any issues of concern doing that. But if you are desiring to crank up a 45 to be near the hyd capacity (relief) of a 55, and the machines are comparable in structural integrity, keep in mind you will need be a more "seat of the pants" operator as the 45 is a lighter, and less counterweight, machine.
Max hydraulic pressure settings should not go more than the manufacturer's recommended specifications for a variety of reasons. First and foremost, if something happens that can be attributed to tampering with settings outside of specs, the owner is liable until he proves he isn't. Second item is that hoses and tubing may look the same but actually may not be. Say a standard two wire hose on the smaller machines and super two wire or four wire on the larger. Having said that, it is the owner's decision. I have been requested to make a machine hot both in speed and power. I've made a representative of the company sign a detailed service report and happily done the job and then watched and recorded whether it worked or not. The other issue that has not been brought up is that most piston pumps have cut out functions that destroke the pumps when the pressure hits a certain point in order to prevent over loading the engine. Both machines's max pressures may be the same but the cut outs on the smaller machine have cut the stroke back so that the flow is only enough to cover what is going over relief. You probably should find out more about your systems before boosting the max reliefs.
Thanks a lot guys I appreciate yr input, if I lift the pressure in piston pump 1 & 2 do i also lift the pressure of gear pump to the same pressure??
All the more reasons I asked "why would you do that?" Unless your machine is something far different than most any excavator system, the gear pump uses a pressure regulator to provide proper pilot pressure for control system, there should be no reason to make any changes to that system.
A lot of good reasons for not turning u the pressure, but one was left out...the smaller machine has less stick and counterweight than the larger machine. Maximum hydraulic pressure is also used to limit lift capacity. With less counterweight than the large machine, you may get yourself into a tipping situation if any of your load chart is stability limited. Most load charts do have some point where you are limited by stability. Need more power...get a larger machine
Absolutely. If you messed about with relief valve pressures and it resulted in the machine tipping over at some point you would be in deep **** with the Safety germs ........