John Deere — Adjusting Centrifugal Pump Output - Open Center Systems
Adjustments · Bypass adjustment screw
From a John Deere service manual — check it applies to your exact model before use.
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Procedure
- Open the Bypass Adjustment Screw 2-1/2 turns from fully closed; turn in to achieve the flow for the desired gpm and psi.
- Start the tractor; allow hydraulic oil to circulate approximately 10 to 15 minutes or until adequately warmed.
- Prime the centrifugal pump with all valves open.
- Close the Agitation Line Valve and keep the Control Valve and Boom Shut-Off Valve open; note the spray pressure.
- Open the agitation line valve to desired circulation; recheck pressure and adjust control or agitation valves as needed.
Specs & values
- HM1C motors have a Bypass Screw set 1-1/2 turns from fully closed at the factory.
- HM4C motors have the Bypass Screw fully closed from the factory.
Source: John Deere service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.