Manitowoc National Crane NBT30H-2, Service Manual

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HYDRAULIC SYSTEM NBT30H-2 SERVICE MANUAL
2-6
03-20-2019 Control # 613-06
2. At the same service interval, visually inspect all other
hydraulic components and valves for the following:
- Leaking Ports
- Leaking valve sections or manifolds and valves
installed into cylinders or onto motors.
- Damaged or missing hose clamps, guard, or
shields.
- Excessive dirt and debris around the hose
assemblies.
If any of these conditions exist, address them appropriately.
3. Hydraulic hose assemblies operating in climate zone “C”
are recommended to be replaced after 8000 hours of
service life.
4. Hydraulic hose assemblies operating in climate zones
“A” or “B” with high ambient temperatures, could see
hose service life reduced by 40% - 50%. Therefore, it is
recommended to replace these hoses after 4000 - 5000
hours of service life.
5. Hydraulic hose assemblies operating in climate zones
“D” and “E” cold climates should expect a degrade of
mechanical properties such as elasticity. Therefore it is
recommended that these hoses be inspected and
address correctly.
Troubleshooting Aids
1. Hydraulic schematics - an exact illustration of the
arrangement of the system. The schematic shows all the
components in relation to the system. The ability to
understand the schematic is important to good
troubleshooting. The schematic can be found at the end
of this manual.
2. Flowmeter - an instrument that can be connected into
the system to measure the flow of the oil in the system.
The flow is measured in gallons per minute (gpm) or
liters per minute (Lpm). Normally, the flowmeter is used
to check the output of the pump. The flow meter can also
be used to find the location of leakage or restriction in
the system. Instructions for installation of the flow meter
and the use of the flowmeter are normally included with
the flowmeter.
3. Pressure Gauge - an instrument for measurement of
the pressure in the system. This indication is normally
given in pounds per square inch (psi) or kilopascals
(kPa). On this machine, quick couplers are installed in
the pressure lines from the pumps. Pressure taken at
these locations will give an indication of operating
pressure or relief pressure.
Troubleshooting Procedures
For good troubleshooting, a step by step analysis of the
problem and the possible cause is necessary. First, find the
symptoms.
1. Check with the operator. Learn if there was a loss of
power (machine did not move the load) or a loss of
speed (slow cycle time).
2. Learn if the problem is common to all circuits or is found
in one or two circuits.
3. Make a visual inspection. Look for a restriction in the
linkages, low level of hydraulic oil, bent tubes, collapsed
or ballooned hoses, leakage around the hydraulic
components, etc.
Second, make an analysis of symptoms. The function of
each component in the system must be known before a
correct analysis can be made.
Remember:
1. If a problem is common to all circuits, the component
which is causing the problem must also be common to
all circuits. Examples are: the engine, pump, hydraulic
tank and filters.
2. If the problem is common to only two or three circuits,
the component which is causing the problem must be
common to those two or three circuits. Examples are:
pump section, relief valve, hydraulic swivel, etc.
3. If a problem is in only one circuit, then the component
which is causing the problem must be in that circuit.
Examples are: valve section, cylinder, motor.
Again, use the schematic. Find which components are in the
circuit or circuits. What component can cause the problem
with these symptoms? Make a list of the possible causes.
Start at the source of the flow in that circuit. If the problem is
in all circuits, start at the pump. Know the direction of oil flow
through each circuit.
Use the flowmeter and pressure gauge to check your
diagnosis of the problem. Start at the source of the flow and
check each component in sequence until the exact location
of the problem is found.
Zone Classification
A
Tropical Moist: All months average above 18°C.
Latitude: 15° - 25 ° North & South
B
Dry or Arid: deficient precipitation most of the year.
Latitude: 20° - 35° North & South
C
Most Mid-Latitude: Temperate with mild winters.
Latitude: 30° - 50° North & South
D
Moist Mid-Latitude: Cold Winters. Latitude: 50° -
70° North & South
E
Polar: Extremely cold winters and summers.
Latitude: 60° - 75° North and South