Hyundai HL955 Manual page 502

2) RETURN OIL FILTER BYPASS VALVE
(1) When the filter is clogged
Bypass valve (1) is opened and the oil
returns directly to the tank without
passing through the filter.
·Bypass valve set pressure : 1.36 kg/cm
3) AIR BREATHER
The air breather is equipped with the
capacity to perform three functions
simultaneously-as an air filter, breathing
valve, and as a lubrication opening.
Preventing negative pressure inside the
(1)
tank
The tank is a pressurized sealed type, so
negative pressure is formed inside the
hydraulic tank when the oil level drops
during operations. When this happens,
the difference in pressure between the
tank and the outside atmospheric
pressure opens the poppet in the
breather, and air from the outside is let
into the tank or prevent negative pressure.
(2) Preventing excessive pressure inside
the tank
When the hydraulic cylinder is being
used, the oil level in the hydraulic system
increases and as temperature rises. If
the hydraulic pressure rises above the set
pressure, breather is actuated to release
the hydraulic pressure inside the tank.
2
(19.3 psi)
6-38
1
From MCV
770-3ATM (6-33)
Air breather
757F6WE22