Operating Depth ConsistencyHigh-pressure oil on return side of depth control system (smallest depth control cylinder rod end port) can be detrimental to consistent operating depth and system rephasing. To keep return side pressure low, a pressure bleed-off circuit is added to depth control circuit. Bleed-off circuit consists of T-fitting (A) that is installed in circuit return line (B) (from smallest depth control cylinder rod end port), by-pass hose (C), restrictor (orifice) fitting (D), and SCV coupler (E). IMPORTANT: When pressure by-pass hose is connected to open SCV, place SCV lever in FLOAT position for precise depth control. FLOAT position opens a low pressure drain path to relieve pressure build-up off depth control circuit. Circuit bleeds high-pressure oil from depth control system return side. Bleed-off circuit or by-pass line is plumbed in open SCV or low pressure return port. (See ATTACHING MACHINE TO TRACTOR in Attaching and Detaching section). NOTE: Additionally, a thermal relief valve is added to depth control circuit to prevent circuit component damage during storage. Consistent low pressure on return side allows cylinders to settle back uniformly after rephase and maintain same operating depth on both wings and center frame. Bleed-off circuit also prevents tractor's stand-by pressure from being trapped on depth control hydraulic system return side, causing cylinders to extend unequally with inaccurate and uneven cultivating. |
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NX,980FH98,A5C -19-04AUG98-1/2 |
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By-pass line provides escape path for stand-by pressure, which is trapped when single point valve closes at operating depth. If not relieved through by-pass line, trapped stand-by pressure will cause hoses to expand. As pressure dissipates through internal SCV leakage or by raising machine off single point valve, uneven cylinder extension and uneven cultivating depth results. |
NX,980FH98,A5C -19-04AUG98-2/2 |