Tham khảo tài liệu 'handbook of lubrication episode 2 part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Volume II 579 e. High-torque high-misalignment applications are those where the centrifugal forces are lower than 220 G s misalignment is larger than 3 4 usually between and 3 and the shock loads exceed times the continuous torque. Many such applications also have high-ambient temperatures and only a few greases can perform satisfactorily. Besides the characteristics of a grease for normal applications the grease should also have antifriction and antiwear additives extreme pressure EP additives a Timken OK load greater than 40 lb and a minimum dropping point of 150 C. 4. Gear coupling oils should always be of high viscosity grade no less than 150 SSU at 100 C . Although the viscosity cannot be too high for satisfactory coupling operation oils with viscosities higher than 1000 SSU at 100 C should not be used since they cannot practically be poured into a coupling. Continuous oil flow lubrication uses the oil from the system which is seldom a high viscosity oil. To increase its viscosity the oil should be cooled before it enters the coupling. Relubrication Procedure If manufacturers recommendations are not available oil-filled couplings should be relubricated every six months and grease-filled couplings once a year. Coupling guards should be observed periodically for evidence of lubricant escaping from the couplings. The causes for this malfunction improper sealing should be found and corrected and the coupling refilled with lubricant before restarting. Unless the grease used has no oil separation under the centrifugal forces present in the coupling it is advisable to open and clean the coupling before relubrication. Without cleaning additional soap is introduced in the coupling and as indicated previously too much soap is detrimental to coupling performance. The quantity of lubricant that should be used depends on the internal volume of the coupling which varies not only with the size of the coupling but also with the coupling type and make. The lubricant .
