Checking Pre-Charge - JLG Lull 1044C-54 II Series Service Manual

Axles and Brakes

Checking Pre-charge

Gas Leaks
Checking Accumulator Recharge Pressure and Nitrogen Pre-Charge
9-16
10. Turn "T" handle all the way down. This will depress (open) the core in
the gas valve.
11. Crack open nitrogen bottle valve and slowly fill the accumulator. Close
the nitrogen bottle valve when gauge indicates desired pre-charge
pressure (400 psi).
12. Let the pre-charge set for 10–15 minutes. This will allow the gas
temperature to stabilize. If the desired pre-charge range (375–425) is
exceeded, close nitrogen bottle valve, then slowly open the bleed valve
(Item 4) until desired pressure is reached.
CAUTION: Do not reduce pre-charge by depressing valve core with a
foreign object. High pressure may rupture rubber valve seat.
13. When finished pre-charging accumulator, turn "T" handle all the way
out, then open (turn out) bleed valve.
14. While holding the gas valve to keep it from turning, loosen and remove
swivel nut on nitrogen hose (Item 7).
15. Install gauge cap on test valve. Remove test gauge and replace gas
cap on valve (Item 3). Torque gas cap to 10–15 in-lbs. (Gas cap acts
as a secondary seal.)
16. Install gas valve guard and two (2) capscrews on the accumulator gas
end cap. Torque capscrews to 35 ft-lbs.
If an external gas leak is suspected, apply soapy water to the gas valve
and seams of the gas end cap. If bubbles form, there is a leak.
If and internal gas leak is suspected, check for foaming oil in the hydraulic
reservoir and/or no accumulator action. These signs usually mean faulty
piston seals inside the accumulator.
1. Park the vehicle on a level surface, lower boom to the ground, and
engage park brake.
2. While the engine is off, pump brake pedal repeatedly until accumulator
is discharged. This will allow the "free-floating" piston to bottom against
the hydraulic end cap.
3. Connect a high pressure gauge to the test port marked "ACCUM."
located behind the cab step.
4. Start the engine and slowly pump the brake pedal while closely
watching the test gauge.
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