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3
National Crane
Published 8-01-2017 Control # 287-11
3-11
NBT40 SERVICE MANUAL ELECTRIC
SYSTEM
HYDRAULIC OIL COOLER
The hydraulic oil cooler (3, Figure 3-10) is mounted on the
boom rest. An electric fan in the cooler housing circulates air
through the cooling core when the hydraulic oil reaches 49°
C (120° F).
Not all return flow is routed through the oil cooler. A 206 kPa
(30 psi) check valve limits the flow through the cooler. Since
hydraulic oil is thicker when it is cold, less oil is routed
through the cooler when it is cold than when it is hot.
The cooler electrical system is made up of the electric fan (1,
Figure 3-10), temperature sensor (2) and fan relay.
The temperature sensor (2) is located in the cooling core and
energizes the fan relay when the hydraulic oil reaches 49° C
(120° F). The fan relay is in the VEC module (Figure 3-6) and
turns the fan on when energized. If the fan does not run
when the hydraulic oil is hot check the temperature sensor,
relay, and fan motor.
NOTE:
The fan runs constantly if the sensor fails.
HYDRAULIC TEMPERATURE SENSOR
WARNING LIGHT
A warning light on the crane cab console is illuminated when
the hydraulic oil has exceeded the maximum recommended
temperature. A sensor in the hydraulic swivel port #4
monitors the temperature of the return oil and turns the light
on when the hydraulic oil reaches 96° C (205° F). If the light
fails to illuminate, check the light and the temperature sensor
in swivel port #4.
FIGURE 3-10
1
2
3
Reference Only
Summary of Contents for National Crane NBT40 Series
Page 1: ...Service Manual National Crane NBT40 Series R e f e r e n c e O n l y ...
Page 2: ...R e f e r e n c e O n l y ...
Page 216: ...SCHEMATICS NBT40 SERVICE MANUAL 10 2 THIS PAGE BLANK R e f e r e n c e O n l y ...
Page 218: ...NBT40 SERVICE MANUAL APL 2 THIS PAGE BLANK R e f e r e n c e O n l y ...
Page 219: ...R e f e r e n c e O n l y ...
Page 220: ...R e f e r e n c e O n l y ...