SHOP MANUAL
Ch 5 page 58
HYDRAULIC SYSTEM
Description of the Accumulators
The 2,15Litre parking brake accumulator is placed on the left side
of the cab front wall along with the 3,3Litre front service brake ac-
cumulator.
The two 3,3Litre rear service brake accumulators are placed on the
right side of the cab front wall.
The accumulators are from DOOSAN factory loaded with Nitrogen
(N
2
)
Pre-Charge
Wet disc brake: Pressure: 58,0 bar
Park brake: Pressure: 112,5 bar:
Read the loading instruction marked on each of the accumulators.
Accumulators
Checking and Adjusting Precharge Pressure
The precharge pressure of the accumulator may
be checked, and nitrogen filled or vented, using the UCA
Universal Charging & Gauging kit. (See view of the kit at next page)
The UCA assembly is screwed onto the accumulator’s gas
valve, allowing the precharge pressure to be checked or reduced.
If the precharge pressure is to be increased, the UCA can be
connected to the nitrogen source with the hose supplied. The UCA
kit is supplied with two pressure gauges, reading 0-25 bar and
0-250 bar; where a different pressure range is required, a
Commercially-available pressure gauge may be used.
Safety
Charging must be carried out by qualified personnel.
Before taking any readings or pressurizing with nitrogen,
the accumulator must be isolated from the hydraulic system
and the fluid side discharged in order to depressurize it.
Use only nitrogen (N2) to pressurize the accumulator.
Danger of Explosion – Never Charge with Oxygen
The types of nitrogen permitted are: type S (99.8% pure); type R (99.99% pure); type U (99.993% pure).
If the pressure of the gas contained in the nitrogen bottle is greater than the maximum permissible operating
pressure of the accumulator, a pressure regulator must be fitted to the nitrogen bottle.
Doosan recommends that the precharge should be checked during the first week following commissioning of
the system.
Thereafter, it should be checked every three months, or at intervals determined by the system builder.
The Effect of Temperature on Precharge Pressure
In order to compensate for the difference in pressure at
ambient and operating temperatures, it is recommended that the precharge pressure po should be adjusted to
reflect the operating temperature of the system, using the correction factor equations and table on page 11.
Warning – Stabilization
The process of charging or discharging an accumulator with nitrogen causes a temperature change which is
transmitted to the surrounding air as the temperature of the accumulator stabilizes.
To allow for the effects of temperature transfer, the accumulator should be allowed to stand for a minimum of 15
minutes before a final reading of the precharge pressure is taken.
NOTE
DANGER
On new models ac-
cumulator test points is
located on the test block
Figure 52
Figure 53
To Next Page
Loading...