tailieunhanh - Gas Turbine Engineering Handbook 2 Episode 12

Tham khảo tài liệu 'gas turbine engineering handbook 2 episode 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Gears 535 submarine gears where the ultimate in quietness is essential the hallmarks are moderate tooth loading fine pitch high-helix angle and low-pressure angle all diametrically opposite from the usual and necessary practice for single-helical hardened and ground gearing which have low-helix angle for minimum thrust very coarse pitch teeth to get adequate strength and high loading because of the carburized hardening . Some factors causing gear noise can be attributed to but not limited to the following 1. Tooth spacing or involute error 2. Contact ratio 3. Surface finish 4. Wear on tooth flanks or pitting 5. Excessive or too little backlash 6. Gear shaft or housing resonance 7. Tooth deflections 8. Pitch-line runout 9. Load intensity on gearing 10. Clutches and couplings 11. Lube oil pump and piping 12. Transmitted noise from driven or driving machinery Installation and Initial Operation The mounting of a gearbox into trains is a precision job and should be done carefully. Gear unit installation is one of the most important factors to be considered for long trouble-free operation. No matter how accurately the gear unit is manufactured it can be destroyed in a few hours of operation when improperly installed. The same care should be taken when installing a gearbox as with any high-speed machinery. The mounting surface should be a flat level single-plane surface of finished steel at a height that will permit the shimming necessary to align the gear unit properly to connecting shafts. The shims should be of a size at least equal to the width of the unit foot pad. Then the gear unit should be placed on the foundation in the approximate required position. Uneven supports can distort the gearbox and adversely affect the gear tooth contact. Shaft alignment is very important for long gear life. Poor alignment can cause unequal distribution of tooth loads and distortion of the gear elements from overhung moments. A shaft vibration level on the gear unit produced