Shafts bending

Shaft wobble/vibration impeller speed too dose to the first critical speed/shaft runout at the impeller and impeller eccentridty too large/insufficient support. Excessive gear-reducer maintenance excessive load/high shock loads/excessive shaft bending/excessive temperature of gearbox lubricant/incorrect lube oil selection and oil changing. 

As a rule of thumb, a power shaft running under no load at the MOR can be expected to have a useful life in excess of 10 revolutions. Such factors as service temperature, number of shaft bends, torque output, speed, shock loading, and operating radius can reduce shaft life. 

Belts should not be tightened more than necessary, otherwise the drive and the driven shafts will come under torsion and excessive bending moment. The bearings would also be subjected to excessive stresses. 

Bending moment at the motor shaft due to pulley and load... 

A typical screwdriver has a shaft and blade made of a high-carbon steel, a metal. Steel is chosen because its modulus is high. The modulus measures the resistance of the material to elastic deflection or bending. If you made the shaft out of a polymer like polyethylene instead, it would twist far too much. A high modulus is one criterion in... 

Flere M 4 is the couple which must be applied at the mid span of the shaft to make (di//dx) o= 0 and Mg is the couple that is needed to cause the out-of-plane deflection of the end discs. Using the standard beam-bending formula of... 

A deflection of the shaft due to the weight of the rotor, causing further distance between the center of mass and the center of rotation. Additional discrepancies can occur if the shaft has a bend or a bow in it. 

The eyelie bending stress imposed on a gear eoupling-equipped shaft ean be eomputed from... 

The eyele bending stress seen by the diaphragm eoupling-equipped shaft ean be obtained by a rapid ratio ealeulation... 

The stress eoneentration faetor kf results from the keyway and must be used in torsional stress ealeulations. Faetor /c takes into aeeount the shaft step it must be used in the bending stress ealeulation. 

Note When putting packing rings around the shaft, use an S twist. Do not bend open. See Figure 56.9. 

Peak tension is the dominant factor that determines belt drive performance and service life. It should be noted that only the working tension components, Tp and Ts, have a direct impact on the pulley, shafts, and bearings of the drive train. Bending and centrifugal tension affects the belt, but should not transmit tension to the drive-train system. 

Torsional stresses are developed when power is transmitted through shafts. In addition, the tooth loads of gears mounted on shafts create bending stresses. Shaft design, therefore, is based on safe limits of torsion and bending. 

Example 10.2 compares data of Table 10.4 with calculations based on Figures 10.6 and 10.7 for all-liquid mixing. Power and rpm requirements at a given superficial liquid velocity are seen to be very sensitive to impeller diameter. When alternate combinations of HP/rpm are shown in the table for a particular performance, the design of the agitator shaft may be a discriminant between them. The shaft must allow for the torque and bending moment caused by the hydraulic forces acting on the impeller and shaft. Also, the... 

It is concluded that the conveyor drive shaft failed as a result of corrosion fatigue in bending. The use of protective coatings or some other means of shielding the shaft from the corrosive medium could prolong the life of the drive shaft. 

The imbalanced forces result in a bending moment M on the shaft. Such moments must be summed for hydraulic loads at each shaft extension Ln where an impeller is located and must be adjusted for the impeller diameter Dn ... 

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