Lull 6K Service Manual - Manual (Page 578)

Brakes
9-4 Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
9. Open bleeder screw at left rear wheel (see Fig. 9-4) and slowly apply
brake pedal until air is bled out of the line. Then close the bleeder
screw by torquing it to 20 ft-lbs. Repeat this step at each wheel in the
following sequence: left rear, right rear, right front, left front.
Fig. 9-4: Brake Bleeding
10. For testing brake line pressure, apply pressure on the brake pedal and
hold. The gauge at the test port should read 310 to 350 psi. If pressure
is correct, release the brake pedal, remove gauge from port, put the
cap back on the port, and continue with Step 11. If pressure is
incorrect, contact the JLG Service Department.
11. Allow accumulator to reach full charge (high limit) pressure. The
accumulator test gauge must read between 1500 and 1600 psi. If
pressure is correct, proceed to Step 12. If pressure is incorrect, make
necessary adjustments (see “Service Brake Valve - Models with
Control Manifold Hydraulics” on page 9-6).
12. Repeatedly pump (push, hold, release) the brake pedal to allow
accumulator pressure to drop. While watching the accumulator test
gauge (Item 5), note the lowest pressure indicated before the
accumulator begins to recharge (pressure begins to rise).
13. Perform Step 12 two more times. Lowest pressure reading (low limit)
must be between 1100 and 1200 psi. If pressure is correct, proceed to
Step 14. If pressure is incorrect, shut off engine, replace the brake
valve, and return to Step 8.
14. Turn out “T” handle (Item 8) on accumulator test gauge (Item 5).
Release any remaining air in gauge through bleeding screw (Item 4)
and tighten. Remove gauge from accumulator and replace gas valve
cap (Item 3). Replace valve guard (Item 2) and two (2) capscrews
(Item 1). Torque capscrews to 35 ft-lbs.
Bleeder
Screw