Textron JACOBSEN GP400, Technical/Repair Manual

Page: 234 / 354

6-42 4252490-Rev A
HYDRAULICS
6
!
CAUTION
7. Lower the cutting units and hold the raise/lower lever
in the lower position.
8. Record pressure reading.
9. Stop engine.
Is relief pressure 1250 ± 10% psi (86 ± 10% bar)?
YES Lift relief valve is good. Proceed to step 10.
NO Test gear pump. (See “Gear Pump” on
page 6-43.) Test lift cylinders. (See “Lift
Cylinder Leakage Test” on page 6-28.)
Repair or replace relief valve. (See “Lift
Valve” on page 6-46.)
10. Disconnect and remove test equipment. Install all
hoses and fittings as noted prior to removal.
11. Install and connect all components as noted prior to
test.
12. Check hydraulic oil level. Add oil as needed. (Refer
to “Parts and Maintenance Manual” for correct oil
specifications.)
Repair
Hydraulic Oil Tank—Drain Procedure
See Figure 6-41.
1. Park the mower safely. (See “Park Mower Safely” on
page 1-6.)
2. Block each side of front wheels using suitable wheel
blocks.
Figure 6-41
NOTES
• Label all hydraulic hoses and tubes before
disconnecting to ensure correct installation.
• Close all openings with caps or plugs to prevent
contamination.
• Hydraulic system capacity is 5.3 gal (20 L). Have
suitable container(s) available that can hold up to 10
gal (38 L) of hydraulic oil.
3. Place a suitable container under the gear pump (1)
and hose (2).
4. Disconnect hose (2), and plug the 90° gear pump
fitting (3).
5. Loosen the hydraulic oil tank cap to provide a vent for
draining oil.
Do not run mower lift system relief valve over
relief longer than 10 seconds or damage may
occur to hydraulic system components.
TN3798
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