Terex TS14G, Maintenance Manual

Page: 250 / 376

Section 235-0070
Bowl Hydraulic System - Accumulator
2
SM 1791 Rev1 04-04
Testing Pre-charge Pressure
Numbers in parentheses refer to Fig. 2, unless
otherwise specified.
Note: The nitrogen pressure in an accumulator is
directly affected by changes in nitrogen temperature.
The cylinder pressure will increase or decrease
proportionally with temperature changes. An
accumulator pressure reading can vary about 4.3 bar
(62 lbf/in
2 ) with 22 o C (72 o F) temperature change.
Such temperature changes could easily occur
between noon and midnight of the same day. Refer to
the table at the end of this section for Nitrogen pressures
at ambient temperatures of other than 21
o C (70 o F).
To test accumulator pre-charge pressure or to charge
the accumulator, a charging assembly tool can be
used. See Fig. 2.
1. Position the vehicle in a level work area, apply the
parking brake and switch off the engine.
2. Operate the bowl hydraulic controls continuously to
discharge the bowl hydraulic accumulator. Block all
road wheels and place the battery master switch in the
'Off' position.
3. Check accumulator mounting to be sure the
accumulator is held tightly in position.
4. Remove cap (1A, Fig. 1) from accumulator charging
valve (1, Fig. 1). Attach charging line (1) to charging
valve by rotating 'T' handle of valve chuck (2)
anticlockwise until it stops. Screw the swivel nut down
on the valve until it seats. Loosen charging valve
locknut (1D, Fig. 1) by turning anticlockwise one to two
turns.
5. Turn 'T' handle clockwise until charging valve core
is depressed. Be sure bleeder valve (10) is tight and
does not leak, and valves (4 & 6) are closed.
6. To read accumulator precharge pressure, slowly
open accumulator valve (4). Pressure gauge (5) will
register pre-charge pressure, it should be 27.5 bar
(400 lbf/in
2
) at 21
o
C (70
o
F) ambient temperature. Refer
to the table at the end of this section for Nitrogen
pressures at ambient temperatures of other than 21
o
C
(70
o
F).
Fig. 2 - Charging Assembly
1 - Line
2 - Valve Chuck
3 - Valve Extension
4 - Accumulator Valve
5 - Pressure Gauge 6 - Tank Valve
7 - Gland Fitting
8 - Gland Nut
9 - Cylinder Adaptor
10 - Bleeder Valve
SM - 1273
7. Close accumulator valve (4) and open bleeder valve
(10) to dissipate gauge pressure. Close bleeder valve
(10) after pressure is relieved. If accumulator needs
charged, leave line and chuck attached to charging
valve and charge the accumulator as described under
'Charging The Accumulator'.
8. If precharge is 27.5 bar (400 lbf/in 2 ) at 21 o C (70 o F),
rotate 'T' handle anticlockwise until it stops, then
torque tighten locknut (1D, Fig. 1) on charging valve
(1, Fig. 1) to 11 Nm (100 lbf in). Loosen the swivel nut
and remove the gauging head.
9. Install valve cap (1A, Fig. 1) on charging valve
(1, Fig. 1) and tighten finger tight.
CHARGING THE ACCUMULATOR
Numbers in parentheses refer to Fig. 2, unless
otherwise specified.
Either oil or water pumped nitrogen can be used to
charge the accumulator. Both types are readily
available from a local compressed gas dealer.
Courtesy of Machine.Market