(1) The center distance separability of a pair of involute spur cylindrical gears implies that a change in center distance does not affect the . Sp2<rI
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(2) The main failure form of the closed gear drives with soft tooth surfaces is the . lQ]8PR
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A. pitting of tooth surfaces B. breaking of gear tooth NQdz]o
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C. wear of tooth surfaces D. agglutination of tooth surfaces E;vF
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(3) The tooth form factor in calculation of the bending fatigue strength of tooth root is independent of the . ?e. Ge0&
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D. helix angle of helical gear D J:N
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(4) The contact fatigue strength of tooth surfaces can be improved by way of . 0YApaL+jt
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B. increasing the diameter of reference circle 9td[^EB#(h
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C. adding tooth number with not changing the diameter of reference circle @8;0p
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D. decreasing the diameter of reference circle D rMG{Yiu
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