Hello people, I am again here with some problems with my CAT 320 Serial Nº A8F00985. When I run the test of the Power Shift it varies the pressure on the Dash, but when it is working the pressure stays stable at 3550kpa. I don´t know if this is causing the engine to stall when applying load. I am not finding information about the Power Shift. Does the pressure should change during normal operation and under full load? Thank you!
You may find the attached useful.
Thank you Nige for the information. Those diagrams are very useful. But still I am not finding there my doubt, should the pressure of the Power Shift change during operation?
I have VERY limited understanding of hydraulics...I found this at the top of page 3. Does this address your question? "Drive pump (32) and idler pump (26) are variable displacement piston pumps. The performance of both pumps is equal. Drive pump (32) is directly connected to the engine by a flexible coupling. The drive pump delivers oil to the right control valve body (43) of the main control valve. Idler pump (26) is mechanically connected to the drive pump through gears. The idler pump delivers oil to the left control valve body (44) of the main control valve. Pilot pump (33) supplies oil to the pilot hydraulic system. Pilot pump (33) is directly connected to drive pump (32) by a coupling. All engine output is used to drive these three pumps. As the load pressure increases during working conditions, the main pumps increase the delivery pressure and the pumps decrease the flow rate. The hydraulic horsepower remains constant even though the delivery pressure and the flow rates change. The hydraulic horsepower is approximately identical to the engine horsepower. When no work is being performed, pump oil flows through main control valve (12) and into hydraulic tank (40). The main control valve sends a negative flow control signal to each main pump regulator in order to destroke the pump to the minimum output flow. If an operation is being performed, main control valve (12) directs pump oil to the respective cylinders (boom, bucket, and stick) and/or motors (swing and travel). Main control valve (12) contains numerous valve stems, passages, check valves, and orifices in order to carry out a single operation or a combined operation. The working pressure of the main hydraulic system is regulated by main relief valve (18)."
Look inside the right armrest or possibly behind the seat on the right side and see if the backup switch was flipped to manual. You shouldn't have throttle control with the dial if it is, but it's worth looking at because it will run fixed powershift. Are you checking powershift manually with a gauge? Have you done a powershift calibration? FYI the pressure shown on the monitor or through ET is a calculated pressure taken primarily from the powershift calibration offsets. There is no pressure sensor. To answer your question directly, yes powershift should be constantly changing based mostly on engine rpm. If you have engine stalling with max powershift, you have other problems.
Thank you!
We checked that switch, it is ok. We checked the powershift manually with a gauge, and it is also always the same pressure. We ran a powershift calibration. What other problems could be?
Is the engine RPM being seen? It can't work out what powershift pressure to ask for if it doesn't know what revs the engine is doing.
Yes, the RPM can be seen in the display. And they drop as you load the machine.
What is the boost pressure on the engine at high idle with the boom and stick stalled? What is your pilot pressure? What is your left and right NFC at high idle with all controls in neutral? Do you have any NFC at high idle with the boom and stick both stalled? Did this problem just suddenly appear from nowhere, or has it been slowly getting worse? Has anyone adjusted any screws on the right or left pump regulators?
Yes. Example: When Hi idle (throttle 10) - work lever at neutral, Powershift pressure 24** Kpa -when boom up, Powershift pressure 12** Kpa -when relief condition, Powershift pressure 14** Kpa If your Powershift pressure always 35** Kpa but your engine stall when the hydraulic press high or relief, maybe there's error on your engine sensors.. check your primary engine speed sensor first.
Pan the Raba, is that you?
hahaha...yes, Lum Ber Jack!! I own 2 excavators now and I read/lurk these threads slowly learning how these things work. Lots of voodoo in excavators.