HYDRAULIC SYSTEM
NBT40 SERVICE MANUAL
2-22
Published 8-01-2017 Control # 287-11
TROUBLE DIAGNOSIS
The following chart lists malfunctions which may occur
during equipment operation, the possible cause, and the
possible solution. These are not all inclusive but are
designed to help isolate the problem and should be checked
before calling
Manitowoc Crane Care
.
O-RING FACE SEAL
O-RING BOSS
B
A
O-RING
FACE (REF)
O-RING
BOSS (REF)
A
B
O-RING FACE SEAL
FITTING SIZE
O-RING BOSS
THREAD
SIZE
B inches
(mm)
A inches
(mm)
TUBE
O. D.
MFGR’S
SIZE
CODE
A inches
(mm)
B inches
(mm)
THREAD
SIZE
9/16-18
.07 (1.78)
.301 (7.64)
.250
4
.351 (8.92)
.072 (1.83)
7/16-20
11/16-16
.07 (1.78)
.364 (9.24)
.375
6
.458 (11.63)
.078 (1.98)
9/16-18
13/16-16
.07 (1.78)
.489(12.42)
.500
8
.644 (16.36)
.087 (2.21)
3/4-16
1-14
.07 (1.78)
.614 (15.60)
.625
10
.755 (19.18)
.097 (2.46)
7/8-14
1 3/16-12
.07 (1.78)
.739 (18.77)
.750
12
.924 (23.47)
.116 (2.95)
1 1/16-12
1 7/16-12
.07 (1.78)
.926 (23.52)
1.000
16
1.171
(29.74)
.116 (2.95)
1 5/16-12
1 11/16-
12
.07 (1.78)
1.176
(29.87)
1.250
20
1.475
(37.46)
.118 (3.00)
1 5/8-12
2-12
.07 (1.78)
1.489
(37.82)
1.500
24
1.720
(43.69)
.118 (3.00)
1 7/8-12
NOTE:
Contact your National Crane Distributor or Manitowoc Crane Care for O-Ring boss seal kits.
CONDITION
POSSIBLE CAUSE
POSSIBLE SOLUTION
No hydraulic oil flows in
systems.
Low hydraulic oil level
Fill reservoir.
Reservoir-to-pump suction lines broken or
restricted. Air entering at suction lines.
Pump not priming.
Check that all connections are tight and there are
no cracks. Clean, tighten, repair, or replace parts as
necessary.
Pump shaft sheared or disengaged.
If drive shaft is damaged or sheared, remove and
repair or replace as necessary
Internal contamination.
Drain, flush with recommended oil mixture, then
drain and refill system with recommended hydraulic
oil.
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 ...
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