TM 9-1829A, April 1944
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2021-07-07
f.
Test magnet strength to determine proper hair spring:
Pry split field ring out of frame. Place magnet
strength tester (408165) on frame and magnet assembly. Place assembly on calibrating machine (fig. 69), run
master at 60 miles per hour (chapter 13) and take reading on tester. Replace field ring. Determine pointer
deflection (in degrees) at 60 miles per hour of speedometer being repaired from following list. If the model
number of speedometer being repaired does not appear in this list, the angle of pointer travel from zero to 60
miles per hour on the dial may be easily determined with a protractor. Then refer to “Hair Spring Chart” on
page 82 to determine proper tension hair spring to use and select hair spring from kit (408082).
Speedometer model no.
Pointer deflection (in
degrees) at 60 mph (1000
rpm)
Speedometer model no.
Pointer deflection (in
degrees) at 60 mph (1000
rpm)
579-P
108
589-Z
245
579-R
180
589-AL
253
579-V
196
590-X
232
579-X
180
590-AB
235
579-Y
108
590-AD
235
579-Z
84
590-AE
235
579-AA
159
590-AF
197
579-AB
161
590-AJ
234
581-B
65
590-AM
235
589-D
245
Figure 69: Magnet strength tester (408165, on frame and magnet assembly) attached to calibrating machine (T-170645)
Pointer deflection
(in degrees) at 60
mph (1000 rpm)
Magnet strength tester reading at 60 mph or 1000 rpm
1
2
3
4
5
6
7
8
9
10
11
60-70
110
110
110
112
11
114
114
114
-
-
-
70-80
110
110
110
110
112
112
114
114
-
-
-
80-90
108
108
110
110
110
112
112
114
114
-
-
90-100
106
108
108
108
110
110
112
112
14
-
-
100-110
106
106
108
108
108
110
110
112
114
114
-
110-120
104
104
106
106
108
110
110
112
112
114
-
120-130
104
104
106
106
108
108
110
110
112
114
-
130-140
102
104
104
104
106
108
108
110
112
112
114
140-150
100
102
104
104
106
108
108
110
110
112
114
150-160
100
100
102
104
104
106
108
108
110
112
114
160-170
98
100
102
102
104
106
106
108
110
110
112
170-180
98
98
100
102
104
104
106
108
110
110
112
180-190
96
98
100
100
102
104
106
106
108
110
112
190-200
96
98
98
100
102
104
104
106
108
110
112
200-210
94
96
98
98
100
104
104
106
108
110
110
210-220
94
96
96
98
100
102
104
104
108
108
110
220-230
92
94
96
98
100
102
104
104
106
108
110
230-240
92
94
96
96
98
100
102
104
106
108
110
240-250
90
92
94
96
98
100
102
104
106
108
110
250-260
90
92
94
96
98
100
102
104
106
108
110