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Question for Link Belt/Case/Sumitomo gurus!
- Thread starter TVA
- Start date
excavator
Senior Member
Like TVA said, my father-in-law passed away on Friday right about the time I was working on this machine so I didn't get any updated information for you all. This past few days have been busy with funeral things ect. and now the excavator is out working again so I'm not sure when I will be back on it.
excavator
Senior Member
I was finally able to make it back to the machine and had another hydraulics guy with me. We did pressure and flow tests with and without the mower running. Some of our results may have been covered in this conversation before, I don't remember but at this point we are thinking that the mower now is running just on standby flow. I think both John C and TVA touched on this before but next time I'm at the machine I am planning to T into the NFC lines going to the pump regulators , with a line also going to tank through a flow control valve. Once I start the machine and have the mower running I will open the flow control valves thereby removing the NFC pressure from the regulator, dumping it to tank and that should stroke the pump. If that works we can look into different options on how to control the NFC pressure, probably will use something like a solenoid actuated pressure reducing valve for each pump. But we need to confirm that this is the problem first.
excavator
Senior Member
Then you are running little bit better then on stand by. You are running on stand by when you have pressure on NFC lines.
I think you need to make one of the pressure switches ( probably for auxiliary function) to let the ECM know that you running the legitimate load, and not just a really high stand by pressure.
Not sure about this machine, but ECM does reduce pumps flow through PRV in instances when stand by is more then 1000 psi and there’s no feedback from functions pressure sensors/switches.
Those pressure switches not only for idle down control. At least it is true for CAT 312C/315C.
Those pressure switches not only for idle down control. At least it is true for CAT 312C/315C.
John C.
Senior Member
Standby pressure is a function on a closed center hydraulic system. This system is open center parallel passage. It is also negative control in that it only switches the pump on and off in the earlier versions and may have limited ability to regulate on this model. This machine as I recall has an H, S and L setting that is controlled by the mode switch in the control panel. That control went through the computer but didn't change by loads on the engine. A PRV is a component on a Caterpillar hydraulic pump. Link-Belt always called theirs a Main Pump Proportional Solenoid. It wasn't proportional at all. It had three milliamp readings that you took, one for H mode, one for S mode and one for L mode. The pump went to full output whenever a function was operated, limited only by the main pump proportional solenoid.
So what you saying is that solenoid by the pumps have nothing to do with torque limiting and protecting engine from overloading by hydraulics?
Because as I understand it is it’s main function, and it must be proportionate to do that.
OK, I see what you mean: ECM does not infinitely regulates the current on PRV, it steps down to current value pre set for L mode when it reads that RPMs lower then they are supposed to be at current position of the throttle.
Got it!
Garry.
I will suggest, before buying and installing additional valves, test and see if it is even possible to run mower and have satisfactory machine movement.
For that just take the NFC lines off of the pumps regulators, plug/cap the hoses and leave the regulators ports unplugged. You can even do the same with line to PRV.
This way you will have pumps at full flow.
Start and run both mower and machine right away and simultaneously. It is possible to bog the engine down and heat up the hydraulics, but this way you will know weather you ( or machine owner) will like the performance.
I will suggest, before buying and installing additional valves, test and see if it is even possible to run mower and have satisfactory machine movement.
For that just take the NFC lines off of the pumps regulators, plug/cap the hoses and leave the regulators ports unplugged. You can even do the same with line to PRV.
This way you will have pumps at full flow.
Start and run both mower and machine right away and simultaneously. It is possible to bog the engine down and heat up the hydraulics, but this way you will know weather you ( or machine owner) will like the performance.
LACHAU
Senior Member
I wonder why not use the optional port while the main control valve is available?
Dual flow option is available. Dual flow solenoid (11) activates high flow logic element (41) which brings the flow from Right Pump to the parallel circuit of the Left Pumps side right before the Hammer spool.
Also the same solenoid brings the pilot pressure to a neutral cut spool of the Right Pump section of the Main Control Valve, cutting NFC and effectively throwing the Right Pump in to full displacement.
But the problem with this set up is that you have to use restriction only type of flow control, and not restriction/bypass type to still have flow for the rest of machine to use.
And then question still remains what kind of pressures you will be able to build up on the Right Pump side of the MCV, will the operation of the functions on that side be stable or unstable and intermittent, will the Right Side start to heat up and so on, so on...
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John C.
Senior Member
According to the drawing, the only way you can get two pump flow to a circuit is to have two spools feeding. Notice boom 1 and boom 2 spools and arm 1 and arm 2 spools. It doesn't matter if both pumps are feeding the valves in combined flow. That just lets more functions work at the same time. It's meant to combine flows when you are moving both tracks and operate another function at the same time. If you aren't traveling, it don't go into combined flow.
Red line from port PO ( connected to a parallel passage of the Right Pump), goes to port A of a Multipurpose Three Way valve 41*, when logic element opens up that flow goes through port B of the valve 41* to port OPT of the MCV, inside the MCV port OPT connects to parallel gallery feed of Hammer/Option spool.
The position of the check valves on this circuit show the direction of flow.
The position of the check valves on this circuit show the direction of flow.
LACHAU
Senior Member
The simple answer is that you cannot ask for too much.
When you need to use other operations, you have to disconnect right side pump (turn OFF "dual flow solenoid" No.11) , the lawn mower switches back to use left pump only.
Note that we already have a toggle switch for this function (to turn ON "dual flow solenoid" No.11 for combine flow of 2 pumps).
LACHAU
Senior Member
The other way, we change No.41 Valve by Flow control valve.
https://www.hydradynellc.com/produc...-8-inch-to-3-4-inch-ports-flow-control-valves
https://www.hydradynellc.com/produc...-8-inch-to-3-4-inch-ports-flow-control-valves
LACHAU
Senior Member
For more convenience, we can use 02 pressure switches No. 25 and No. 40 to turn ON or OFF "dual flow solenoid" No. 11 automatically. It's not too difficult to do that, right??