Hitachi John Deere 160LC final drive pressure

I am working with a hatachi zx160LC I need to find out the specifications for the final drive pressure and the pressure relief settings and how to set the pressures Relief valves on the drive itself
Thanks in advance to anybody can help me

I have seen that information not quite sure i understand is that for both valves on the final drive to be adjusted the same pressures with the drive stalled or is that at the main valve body
And thanks very much

LACHAU said:

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I have seen that information not quite sure i understand is that for both valves on the final drive to be adjusted the same pressures with the drive stalled or is that at the main valve body
And thanks very much

Travel pressure reliefs are set at the motors and with one track at a time and to the higher pressure. Each adjustment cartridge only adjusts on a single direction of the motor.

When both motors are in relief, I believe the pumps are in load sensing and the flows are reduced. One of the Deere/Hitachi guys might clarify that. I'm not sure how the main relief in the main control valve works.

Thank you very much that was very helpful now I know what to do again thanks you all for your help

@LACHAU

I thought the system relief had to be turned up a 1/2 turn before testing propel circuit reliefs on that machine. Yes, No??

mg2361 said:

@LACHAU

I thought the system relief had to be turned up a 1/2 turn before testing propels circuit reliefs on that machine. Yes, No??

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Sure my friend.
Due to the ports relief values ( Travel Propeller, Boom, Arm...) is always higher than the main relief system value.

I have to question that. If you look at the supplied page above it shows the travel relief pressure at 5,130 PSI on one pump at a time while the boom up and arm in is at 5,400 PSI and the boom down arm out is at 5,690 PSI. That would indicate to me that the main relief is already higher than the settings of the travel circuits.

John C. said:

I have to question that. If you look at the supplied page above it shows the travel relief pressure at 5,130 PSI on one pump at a time while the boom up and arm in is at 5,400 PSI and the boom down arm out is at 5,690 PSI. That would indicate to me that the main relief is already higher than the settings of the travel circuits.

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Hi Mr. John C,
It's an ambiguity of the Hitachi''s technical documentation!!
I would like to note that there are 03 kinds of "RELIEF" pressure (as you can see in the picture):
1/- MAIN RELIEF VALVE SET PRESSURE (02 MAIN relief valves on Main control valve): set for all actuators.
2/- RELIEF PRESSURE (usually named that PORT RELIEF VALVE, they are installed on hydraulic motors ): set for SWING & TRAVEL. Their values should be equal to or higher than main relief pressure values.
3/- OVER-LOAD RELIEF VALVE SET PRESSURE (usually named that PORT RELIEF VALVE, they are installed on main control valve also): set for BOOM _ ARM _ BUCKET. Their values should be higher than main relief pressure values.
You also can see that MAIN RELIEF PRESSURE MAX. is 4980 psi for BOOM & ARM and 5160 psi for BUCKET, is it right?
And TRAVEL pressure MAX. is 4980 psi for both travel and 5130 psi for 01 travel.
That means TRAVEL PRESSURE MAX. equal to MAIN PRESSURE RELIEF (5160 psi and 5130 psi is a negligible error ).

LACHAU said:

And TRAVEL pressure MAX. is 4980 psi for both travel and 5130 psi for 01 travel.

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Interesting the way the Hitachi manual lists their specs and procedures. Must be a translation thing..... For comparison, a ZX160LC is the Deere 160CLC. In the Deere manual it just states that propel pressure is 4980 - 5264 psi. It does not say one lever or two lever operation. Their procedure only has you activating one lever direction at a time.

What I've seen on other brands is that it depends on the type of pump system and the philosophy of the designer. Is it open center load sensing with negative control or is it closed center load sensing? On some systems I've worked on the main relief was lower and the circuit reliefs were to catch the hydraulic spikes in the individual circuits that were caused from an outside source. Say something falling the boom, stick or bucket. I saw that a lot with positive displacement pumps. On machines today I've seen the circuit reliefs set lower than the main and it makes sense to me in that they are closer to the load, can react quicker and they are usually a lot bigger in size and flow capacity. The closed center systems will only make pressure up to the setting of the pumps so main relief cartridges are usually pretty small.
Travel motor circuits as far back as I can remember always had the reliefs in the motors and it makes sense. People want more power to climb hills as well so the easy fix for more power is to turn the pressure and flow of the pump up to the same as the circuit reliefs in the travel motors.There are counterbalance valves and mechanical brakes also involved because of the possibility for the machine to travel down hill and possibly try to over run the amount of oil going into the motors.

Boy a lot to learn for a layman thank you all for all the information