Page 274 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

256 Major Process Equipment Maintenance and Repair

Figure 6-28. Typical tooth contact patterns for double helical gearing under no load.
A. Perfect tooth contact, no modification.
6. Gear with end easeoff modification (slight crowning)-acceptable.
C. Gear with crowning modification-acceptable.
D. Gear shafts slightly out of parallel-acceptable.
E. Gear shafts out of parallel-not acceptable-must be corrected before operating gear
unit.
F. Gear shafts out of parallel-not acceptable-must be corrected before operating gear
unit.
G. If no lead modification, gear or pinion or both mlscut-not generally acceptable-one
or both oarts should be corrected before ooeratina aear unit. Will result in Dremature
r- -- - --- - --
- --.
wear and failure if not corrected. .,I
H. If no lead modification, gear or pinion or both miscut-not generally acceptable-one
or both parts should be corrected before operating gear unit. Will result in premature
wear and failure if not corrected.