Improving Machinery Reliability 3 Episode 5 ppt

[...]... (L/D) given in Table 3- 21 is not exceeded on proposed gears Table 3- 19 Gear Tooth Strength "J" Factor ~ No o b Teeth ~ Ground or Shaved 14 .5" P.A 20" P.A ~ ~~ Full Round Bottom 14 .5" P.A 20" P.A Single Helical 20 30 60 I50 50 0 Double Helical 20 30 60 I50 50 0 39 43 47 50 5 1 41 50 55 56 58 44 49 56 58 60 5 I 55 60 6 I 63 31 39 42 43 44 47 SO 5 1 52 43 46 50 52 53 49 52 55 56 51 45 Note: Vnlttes (ire... Hardness Minimum Material Index Number Double Helical Single Helical 2 23 Bhn 262 Bhn 30 2 Bhn 35 2 Bhn 50 Rc (Nitrided) SSR, (Carburized) 58 Rc (Carburized) 2 65 Bhn 30 2 Bhn 34 1 Bhn 50 R, (Nitrided) 50 R, (Nitrided) 55 Rc (Carburized) 58 Rc (Carburized) 130 160 200 260 30 0 410 440 2.4 2 .3 2.2 2.0 1.9 1.7 1.6 I 7 1.6 1 .5 1.4s I 4 1 . 35 1 3 Note: L = Net jbce width plus gap d = Pinion pitch diariieter The sample calculation... service except as listed below) Centrifugal-Boiler feed Centrifugal-Hot oil High-speed Centrifugal (Over 3, 600 rpm) Centrifugal-Water supply Rotary-Axial Flow-All types Rotary-Gear Reciprocating 1.1 1.1 1 .3 I 3 1 .3 I 7 I 5 2.0 1.7 2.0 1.7 2.0 1.7 1.7 I 5 1 .5 1 .5 2.0 1 .5 1 .5 2.0 2.0 1.8 I 8 2 .3 Step 3: Calculate actual tooth pitting index, K' K'= 126,000x P,, n,xd2xF X - mG + 1 mG Verify that actual K'... Pump Co.) 166 Improving Machinery Reliubilify Figure 3- 55 Oil droplets flung against the top of a bearing housing have a chance of falling back on the shaft and migrating toward the bearing internals T 3 E 2 L - a Shaft Speed -t Figure 3- 56 Oil delivery vs shaft speed for different oil rings oil temperatures purposely induced to range from 65 F to 220°F at speeds from 880 rpm to 3, 55 0 rpm This company... typically 50 0°F and higher, a shaft-mounted fan is often used We found some of these fans thoroughly engineered for low noise and high efficiency Figure 3- 62 depicts a typical example of an intelligently engineered fan In contrast, the “fan” offered by another manufacturer (Figure 3- 65, item 37 5) leaves much to be desired bed Figure 3- 65 “Bearing cooling fan” on a centrifugal pump 174 Improving Machinery Reliability. .. Figure 3- 59 for oil ring containment, Goulds established a satisfactory working window for the design using IS0 Grade 68 lube oils and shaft diameters in the 2 .5- in range Adequate oil flow existed with Machinery Reliabiliv Audits and Reviews 1 65 Figure 3- 53 Oil rings inserted in trapezoidal ramps allow lube oil to move freely toward the bearing internals (Courtesy Byron Jackson Pump Co.) I Figure 3- 54 ... attendant increase in bearing life Machirrery Reliability Audits and Reviews 167 Figure 3- 57 Oil ring and shaft sleeve outer contours are in line with bearing inner ring surface This facilitates oil flow toward bearing interior Figure 3- 58 Cupped flinger design found in some older pumps (Courtesy Goulds Pumps.) 168 Improving Machinery Reliability Figure 3- 59 Optimum design for Goulds pumps A single flinger... susceptibility of a given design to scoring damage in service can be checked by calculating a so-called scoring index: 50 0 400 30 0 200 150 F 00 220 240 260 280 900 32 0 34 0 36 0 BRINELL GEARHARDNESS 50 52 54 56 AOCKWELL C Figure 3- 75 Material index numbers 58 ... with ball bearings 170 Improving Machinery Reliability Figure 3- 61 Roller bearing on inboard side of a centrifugal pump (Courtesy SulzerWeise, Bruchsal, Germany.) Figure 3- 62 Fan and tapered roller bearing on thrust end (Courtesy Sulzer- Weise, Bruchsal, Germany.) Machinery Reliability Audits arid Reviews io,ooo 12,000 14.000 16,000 Axial Force ia,aoo + 171 20,000 Figure 3- 63 Tapered roller bearing... in Figures 3- 50 and 3- 55 , is not available The Goulds Pump Company has experimented with different executions and found that keeping the oil level below the rotating elements results in lower bearing temperatures than would be achieved if lube oil were to reach to the center of the lowermost ball Goulds explained that their optimum design, Figure 3- 59 , evolved from the one shown in Figure 3- 58 , which . permitted. Figures 3- 55 and 3- 57 show executions that facilitate lube oil flow toward the bearings. However, oil rings as shown in Figures 3- 53 , 3- 54 , and 3- 57 to 3- 59 have a ten- dency. been virtually certain. Machinery Reliability Audits and Reviews 161 C B 20,000 EA 15, 000 6 c 6 3, 000 1 ,50 0 2,000 1.000 750 50 0 I 250 3 1 ,50 0 50 0 e - 2 1,000 A Figure 3- 47 will prove very enlightening. It shows that for a given bearing (FAG 731 4, 70 mm bore diameter) a shaft interference fit of 0.00 03 in. will 158 Improving Machinery Reliability