TM 55-1680-320-23 & P
3-15. BOOM HEAD ASSEMBLY - REPAIR (cont)
Measure and adjust end play of spur gear shaft
(70) as follows;
Install machine key (73), spur gear (72)
and worm gear (71) on spur gear shaft
(70). Press fit bearings (69) onto spur
Measure distance between
outer faces of bearings (dimension A).
Measure thickness of main housing as-
sembly between flanges where side cover
assemblies make contact (dimension B).
Measure depth of side cover assemblies
from face to bottom of bearing bores
Add dimensions B and C. From this value,
subtract dimension A. The difference is
the end play between side cover as-
semblies and bearings on the spur gear
Install shims (33) in bearing bores of both
side cover assemblies so that total end
play is 0.002-0.005 in. (0.005-0.013 cm).
After completion of end play adjustment,
remove one bearing (69), worm gear (71)
and spur gear (72) from spur gear shaft
Install spur gear shaft (70) into main housing
Install worm gear (72) with hub facing out
onto exposed end of spur gear shaft (70).
Install spur gear (71 ) with hub facing in onto
exposed end of spur gear shaft (70).
Install remaining bearing (69) onto spur gear
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