Question

(5) The gear reduction unit shown has a gear that is press fit onto a cylindrical sleeve that rotates around a stationary shaft. The helical gear transmits an axial thrust load of 300 Ibf as shown in the figure. Tangential and radial loads (not shown) are also transmitted through the gear, producing radial ground reaction forces at the bearings of 900 lbf for bearing A and 650 lbf for bearing B. The desired life for each bearing is 90 kh at a speed of 175 rev/min with a 90 percent reliability. The first iteration of the shaft design indicates approximate diameters of 1 1/8-in at A and 1-in at B. Select suitable tapered roller bearings from Fig. 11-15. T A B

Answer 1

Ang- Giren that, Let us Assurne that KAKB=115. Calculate the induced load in bearing A from equation (U-15 fin 0.47 (na) RA Dubstitute voolbf for fora and 1.5 for la fia 0.47(900) 423 28206F (11-15) fig Calculate the induced coad in beoring B from equation 0,47 Cf2B) KB Bubstitute 6500bf for favor and 1.5 0.47(650) fie s for the 3055 = 204 bf Oaserrie whether the induced toad is less than & eater than the sum of induced Load on the other bearing and axial Chorust lood. equal to con to & greate

Calculate the bearing B as the induced load would by wing equations CU-16) & (1441) whickexer is applicable Sige of ffect bearing A but not offected by the induced load from bearinga By deservation fia =( fistfad 282 lbf (204+300) Thus afply equation (11-16) fes - Faz - 6501bf. Calculate the rated load for the beoring Bwing equation (11-3) 13/10 FRB = affo (FR) 14 Blobstitute I fee of, 6500 1 H&e @f, 6500bt for fo, Go00ohn)x (176 rpm)XC60), 6, and 901106) for for Le (90000)(175)(60) 2009 FRB 3110 ei (650) 90 C106) 3lio = (650) () 3110 ¿ 650 0.3 650(105) c 650(20246) = 1316b

Select cone. 07100, Cup 07196, with linbore, rate at 1570 666 with factor, K.: 145 Calculate the induced wad after escaluation fie= 0,47FB KB Substitute 650ub for ff and 1.45 for Kz. fißt (0.49 XG50) 1:45 30515 1145 - 210.600. Calculate the equivalent radial load file bearing As from equation Cll-16a). FEA = 0.4 FRA + CA (fist Fae). 2014(900)+(115)(211+300) € 360+(1:5)(SW) = 360+76615 =1,126.5.6bf. By observation, fea Sfera Calculate the nated lood the for beooring A wing equation (1-3) 1523110 FRA = affo Bubstitute I gør af; 1126Uf for fo, (90000h10x (1759pm) x C60), 60, and 90(105) for p

3110 R90000)(115)(60) FRA - (1126) 90(106) = (X1126) Byho =(1126) (3139 (1126)(10.5,03 - (126)(2.0246) = 2279:7 2280lbf. for the Therefore, any bearing with life in a 11250 in bele is adequate green looding conòitions, Belect the apt part numbers from figure 11-15 Belect cone 15590, Cep 15520, rated at 2430 6f with factor, k=1:69.