A-A-52160A
tension as specified in table III. Lock the tension pulley location, remove the tension weights from the belts, then place the assembly in a cold chamber at a temperature of minus 40°F plus or minus 2°F for 12 hours. At the end of the 12 hour period while the assemble is still at minus 40°F plus or minus 2°F rotate the pulley until the belt has been rotated not less than two complete revolutions. Measure and record the torque required to start and the torque required to continue rotation, then remove the belt from the assembly and examine for evidence of cracking. Any evidence of cracking, or torque necessary to start
or continue rotation in excess of the amount specified in table lI shall constitute failure of this test.
TABLE II. Torque.
Cross section design |
Torque required to start |
Torque required to continue |
||
Ft-lbs |
Nm |
Ft-lbs |
Nm |
|
A, 13c B, 16c C, 22c |
26 30 45 |
35 40 61 |
13 15 30 |
17 20 40 |
driven pulley
45°
45°
tension pulley
weight
driver pulley
FIGURE 1. Pulley arrangement.
TABLE lIl. Pulley size.
Belt cross section |
Pulleys, driver & driven |
Tension pulley |
Tension weights |
|||
Inches |
cm |
Inches |
cm |
lbs |
newtons |
|
A, 13c |
5.0 |
13 |
3.5 |
9 |
35 |
155 |
B, 16c |
6.0 |
15 |
5.0 |
13 |
45 |
200 |
C, 22c |
7.0 |
18 |
7.0 |
18 |
115 |
510 |
3.3 Representative cross-section. The belts in A(13c), B(16c) and C(22c) cross-sections shall be representative of D(32c) cross-section for the temperature test provided they are manufactured with the same basic compounds and tensile members.
3.4 Oil resistant belts. For oil resistant belts the thickness shall increase no more than 20%, nor decrease more than 1% when immersed in IRM 901 and IRM 902 as cited in ASTM D471. The test shall consist of two 3 inch (7.6mm) long sections of belt being immersed in 150°F (70° C) oil bath for 22 hours. The average of three measurements, the center point and ½ inch (13mm) from each end, shall constitute the thickness. When required the age of the belts shall not be more than 12 months old from the time of manufacture to the date of acceptance by the government.
3.5 Marking. The V-belt supplied to this CID shall be marked with the manufacturer's (MFR's) standard commercial PIN. The PIN marked on the unit pack shall be the CID PIN.
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