Lull 944E-42 Service Manual - Manual (Page 459)

8.207 Model 644E-42/944E-42 Rev. 6/04
Hydraulic System
8.13.1 General Information
Each accumulator is a 3000 psi (207 bar) diaphragm type
accumulator. Each accumulator has a total volume of 1
liter (gas & oil combined).
The pneumatic accumulator is operated by compressed
gas. Gas and hydraulic oil occupy the same container.
When oil pressure rises, incoming oil compresses the
gas. When oil pressure drops, the gas expands, forcing
the oil out into the service brake system.
The gas is separated from the oil by a flexible diaphragm.
This diaphragm prevents the mixing of gas and oil and
keeps the gas out of the hydraulic system.
The accumulator must be “pre-charged” with gas before
use in the service brake system. This is done by filling the
gas chamber with dry nitrogen to a pressure of 450 ±35
psi (3103 ±241 kPa). The gas valve (7) located under the
protective cap (8) at the top of the accumulator. The gas
valve is used for pre-charging and testing the
accumulator.
Precharge Pressure/Temperature
Range
Operating
Temperature
Actual Precharge
Pressure
30° F (-1° C) 414 psi (2854 kPa)
40° F (4° C) 423 psi (2916 kPa)
50° F (10° C) 432 psi (2978 kPa)
60° F (16° C) 441 psi (3040 kPa)
70° F (21° C) 450 psi (3103 kPa)
80° F (27° C) 459 psi (3165 kPa)
90° F (32° C) 468 psi (3227 kPa)
100° F (38° C) 477 psi (3378 kPa)
110° F (43° C) 486 psi (3440 kPa)
120° F (49° C) 490 psi (3502 kPa)
130° F (54° C) 499 psi (3565 kPa)
140° F (60° C) 508 psi (3627kPa)
150° F (66° C) 517 psi (3565 kPa)
160° F (71° C) 526 psi (3826 kPa)
B
A
5
6
MU5950
MU1970
7
8