Checking Depth Control Hydraulic System

The purpose of this procedure is to determine if total hydraulic depth control system is functioning properly. Based on results found at the conclusion of this test, it may be necessary to perform other diagnostic procedures in order to identify the specific area which is malfunctioning.

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CAUTION: Escaping fluid under pressure can penetrate skin, causing serious injury to you or others. Avoid hazard by relieving pressure before disconnecting hydraulic or other lines. Tighten all connections before applying pressure. Search for leaks with a piece of cardboard. Protect hands and body from high pressure fluids.

If an accident occurs, see a doctor immediately. Any fluid injected into skin must be surgically removed within a few hours or gangrene may result. Doctors unfamiliar with this type of injury may call Deere & Company Medical Department in Moline, Illinois, or other knowledgeable medical source.

IMPORTANT: To ensure accurate results, warm hydraulic oil to operating temperature before beginning tests.

Narrow FLEX-FOLD Machines: Make sure pressure bleed-off hose is attached to low pressure drain or open SCV connection on tractor.

1. With machine unfolded, check all hoses, hydraulic fittings, and cylinder rod seals for external leaks. Repair all external leaks before continuing procedure.

2. Turn single point crank so valve is not activated.

3. Cycle machine up and down three times.

NOTE: Hold tractor control lever in extend position for five seconds at end of each upward stroke to rephase cylinders.

4. Fully raise machine to transport position.

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NOTE: With test plunger stop extended, single point valve is closed, holding sweeps off ground so hydraulic cylinders can be tested for internal leakage.

5. Remove quick-lock pin and move test plunger stop (A) rearward until quick-lock pin can be installed in test position (B).

6. Lower machine until test plunger stop contacts poppet on single point valve.

7. Position tractor control lever(s) in "neutral" position.

8. Measure and record rod length of all depth control cylinders.

9. Allow machine to sit idle for 30 minutes.

10. Re-measure and record rod length on all depth control cylinders.

11. Compare your results below:

If none of the cylinders have retracted or extended more than 6.4 mm (1/4 in.), hydraulic system is operating correctly.

If all cylinders retracted uniformly, more than 6.4 mm (1/4 in.), repair single-point depth-control valve.

If any uneven retraction, more than 6.4 mm (1/4 in.), is measured between cylinders or if any cylinder(s) extended more than 6.4 mm (1/4 in.), see CYLINDER LEAKAGE TEST in this section.

A-Test Plunger Stop
B-Test Position

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A-Plunger Stop
B-Quick-Lock Pin

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