Published 08-25-09, Control # 077-04 2-13
RT9130E SERVICE MANUAL HYDRAULIC SYSTEM
OIL COOLER
Description
An air cooled hydraulic oil cooler is the right rear portion of
the hydraulic/transmission oil cooler (Figure 2-5). When the
oil temperature reaches 120°F, the oil cooler solenoid valve
is de-energized, via a NC pressure switch, to allow
pressurized oil from pump No. 4 to the oil cooler motor which
drives the oil cooler fan.
The oil cooler fan pulls cool air through the cooling fins on the
cooler. Normally, most hydraulic oil from components is
routed through the oil cooler by way of a return line and on to
the filter in the reservoir. When several hydraulic functions
are being used at one time (i.e., hoisting, lifting, and
telescoping), more oil has to flow through this return line,
causing a pressure buildup. When this pressure reaches 100
kPa (15 psi), the normally closed check valve in the return
line (in parallel with the return line through the hydraulic oil
cooler) will open, letting some hydraulic oil bypass the
hydraulic oil cooler and flow directly into the reservoir filter.
When fewer functions are being used, the pressure in the
system will decrease below 100 kPa (15 psi) and the check
valve will close again.
Air Flow
FIGURE 2-5
7308
5
4
3
2
1
6
7
8
Item Description
1 Hydraulic Oil Cooler
2 Transmission Oil Cooler
3 Fan Shroud
4Fan
Item Description
5 Finger Guard
6Outlet Port
7 Motor
8 External Drain
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