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Mount Vernon, WA | I just took a look at the hydraulic schematic in Service Advisor. It shows the high-flow pump as supplementing the main pump, but only for the auxiliary circuit, not the boom or bucket circuits. The PWM valve for the auxiliary circuit is not responsible for the routing of the high-flow circuit. That is done upstream by what I'll call the high-flow bypass valve. It either routes the high-flow pump oil to the aux valve, or it dumps it back to sump.
If the high-flow pump for whatever reason is cutting out (say a faulty/sticking high-flow bypass valve) , it would definitely reduce your flow at the couplers, but it shouldn't drop the flow to near zero if you have any kind of decent engine speed. The standard pump by itself is rated at 25GPM @ rated engine speed, and the high-flow option bumps the total to 41.
One possibility I can think of is that something upstream is taking all of your standard pump flow. Do the boom and bucket circuits function normally when the cutter slows down? What does the engine do if you bottom out a cylinder? Does it lug down or does the sound not change?
If that's not it, I'm suspecting something awry in the PWM control side of things. Either the HCU (hydraulic control unit) is limiting flow for some reason, or else the spool itself is sticking. This can easily be determined with a voltmeter. Having Service Advisor nearby helps to determine that the signal the joystick is delivering is correct. Alternatively, a second voltmeter and a wiring diagram can be used to confirm proper joystick signals. | |
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Any Deere 333G hydraulic experts here?
