CONTROLS AND OPERATING PROCEDURES OPERATOR MANUAL NBT50
3-16 Published 03-23-2018 Control # 243-14
Warm-up Procedures:
1. Without operating the hoist function, warm the hydraulic
oil (see Hydraulic Oil System, page 3-16).
2. Once the hydraulic system is warm, operate the
unloaded hoist, in both directions, at low speeds several
times to prime all hydraulic lines with warm hydraulic oil
and to circulate gear lubricant through the planetary
gear sets.
Swing Drive and Turntable Bearing
Warm-up Procedures for Temperatures Above -7°C
(20°F):
1. Setup the crane on fully extended outriggers, with the
boom fully retracted and near maximum lift angle with no
load applied.
2. Rotate the superstructure at a speed of less than one
RPM for at least one complete revolution in one
direction, then rotate the superstructure at a speed of
less than one RPM for at least one complete revolution
in the opposite direction.
Warm-up Procedures for Temperatures Below -7°C
(20°F):
1. Ensure the boom is fully retracted and near maximum lift
angle with no load applied.
2. Rotate the superstructure at a speed of less than one-
half RPM for at least two complete revolutions in one
direction, then rotate the superstructure at a speed of
less than one-half RPM for at least two complete
revolutions in the opposite direction.
Axles
NOTE: For National Crane axle warm-up procedures, refer
to chassis manufacturer’s manual.
Hydraulic Oil System
Operating Limits and Warm-up Procedures:
• From 4°C to -10°C (40°F to 15°F): Crane operation
without
a load is allowed with medium engine RPM and
medium function speed (joystick position) until the fluid
reaches at least 10°C (50°F). It is then recommended
that all crane functions be cycled to remove cold fluid
from all components and cylinders of the hydraulic
system. If there is any unusual sound coming from the
crane’s hydraulic pumps or motors, stop the operation
and engine immediately and contact a Manitowoc
distributor.
• From 10°C to 4°C (50°F to 40°F): Crane operation with
a load is allowed with medium engine RPM and medium
function speed (joystick position) until the fluid reaches
at least 10°C (50°F).
• From 95°C to 10°C (200°F to 50°F): Crane operation
with a load is allowed with no restrictions.
• Above 95°C (200°F): No crane operation is allowed. Let
the crane’s hydraulic oil cool by running the engine at
idle with no functions actuated.
Anti-two Block Check
Check the anti-two block alarm light and the audible alarm by
lifting the anti-two block weight until the switch is activated.
To check the anti-two block switch, do one of the following:
• manually lift the weight.
• slowly raise the hoist cable.
• slowly extend (telescope) the boom.
• with the load block close to the A2B switch weight and
the boom at 70° boom angle, slowly lower the boom.
If the crane is equipped with a jib that is deployed and rigged
for work, repeat the test procedure for the jib anti-two block
switch.
RCL Check
Perform the following checks to verify proper RCL operation.
• Check that the display of the main boom length agrees
with the actual boom length.
• Check that the display of the main boom angle agrees
with the actual boom angles.
• Check that the display of the operating radius of the
crane agrees with the actual radius.
Check the load display by lifting a load of known weight. The
accuracy of the load indication shall be within the tolerance
of SAE J159.
DANGER
The following tests must be performed with caution to
prevent damage to the machine or injury to personnel.
DANGER
If the light and audible alarm do not function and the hoist
does not stop, the system is not working properly and
must be corrected before operating the crane.
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