TM 1-1520-238-23
3-252
3.63.
BRAKE CONTROL VALVES INTERNAL LEAKAGE REPAIR AND TEST (AVIM)
Table I. Spring Test Data
Part
No.
Free
Length
(INCHES)
Compressed
Length
(INCHES)
Load
(POUND)
5
--
2.000
9 to 11
11
2.19 to 2.25
0.500
1.14 to 1.34
Table II. Surface Finish Requirements
Part
No.
Nomenclature
Surface
Max. Surface
Roughness
(MICRO INCHES, RMS)
1
Cap
Valve seat
16
Packing groove
32
9
Poppet
Major OD
16
ID
8
6
Piston
Major OD
16
Packing grove
32
2
Valve body
ID
8
3.63.6. Repair
a. Repair transfer valve by polishing poppet. Use cloth (item 50, App F).
b. Repair transfer valve by lapping poppet to seating surface of cap. Use lapping and grinding compound
(item 107, App F) and lapping and grinding compound (item 108, App F). Clean cap and poppet after lapping
(para 1.47).
c. Replace poppet and seat which do not meet finish requirements after polishing or lapping (Table II).
d. Replace cap disk and packings each time brake control valve is disassembled.
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