National Crane Published 4-23-2018 Control # 239-11 6-9
NBT40 SERIES OPERATOR MANUAL MAINTENANCE CHECKLIST
TIRE LOAD AND INFLATION TABLE
Definite tire inflation pressures are established for each tire
size depending upon the load imposed on the tires. For
greater stability, riding comfort and prolonged tire life, tires
should be inflated for the loads carried. The “Load and
inflation Table” shown below indicates the proper inflation
pressure.
NOTE: The values in the tables below are as published by
the Tire and Rim Association 2005. Your vehicle
may be equipped with other tire sized or the same
size tires rated differently. Always check the tire
sidewalls to verify the maximum capacity and
inflation. Inflation pressure and loading must not
exceed the values shown on the wheel or rim.
System is in a state of
constant cut-out.
Blown fuse.
Check fuse at crane cab console. Replace if
necessary.
ATB switch open. Ensure that ATB switch is closed.
System cuts out too early or
too late.
RCL programmed wrong. Reprogram RCL with correct lift values.
Jib Jack Troubleshooting
Will not lift load.
No oil in system.
Release valve not closed.
Add oil to reservoir.
Turn handle clockwise tightly.
Will lift load only part way. Oil level low. Add oil to reservoir tank.
Will lift load but will not
hold.
The following valve or valves leaking.
a. Suction valve
b. Delivery valve
c. Release valve
Replace jack
Packings worn or damaged. Replace jack
Jack will not lower.
Release valve stuck, probably dirt or
foreign matter.
Transfer load then replace dirty oil, flush oil
reservoir with non-flammable solvent.
Poor lifting.
Dirty oil.
Air in hydraulic system.
Change oil.
Purge air from system.
Poor pumping action.
Oil seal for pump unit worn in out or
damaged.
Replace jack.
Condition Possible Cause Possible Solution
Tire and Load Inflation Tables
Letters in parenthesis denote the load range for which the bold face loads are a maximum.
International load index numbers are shown after the load range. The load range letters and
corresponding ply rating are shown below.
D = 8 ply • E = 10 ply • F = 12 ply • G = 14 ply
H = 16 ply • J = 18 ply • L = 20 ply • M = 22 ply • N = 24 ply
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