Question

6. A journal bearing has shaft with a diameter of 75 mm. The bushing bore is 75.1 mm and the bushing is 37.5 mm long and supports a load of 2 kN. The journal Speed is 720 RPM. Find the minimum film thickness, the heat loss rate is SAE 20 oil and the operating temperature is 60 C.

Answer 1

For the given dimensions and operating conditions provided in the question for journal bearing, the complete step by step procedure for solution is provided below.

Soluion Diameter of shaft, dmax -75mm Bushing bosebmin in510 mm K load, Type of Oil, --) SAE 20 e minimum sadial cleaance -d max bmin min 2 2 Cos mm min 36- 0.5 (close enough) Then, d 5 ニ31.5mm 75 Radius, γ = d 2 31 5 So Then r6 0 65

i S Then, the Pressu γ e due to loa ld 2000 45x36 +OJI SAE 20oT, at operating temper perature -temperature chart" bsolute viscosity 5 Mea. S Nous, The Sommefield numbes (1S0)x Chart fol minimum film thi From fi g υγ e cImess vaiable and ecenticy Talio For, SO.169 Minimum m thiekness vasiable ho

figuve wow ,TJom chat for of coeff; ci e n ㅏ sriction variable coefficient of fricion yale 5 Now, F om figure '' cha γ t for dete r mining the lOUo maximumilm Pressue 3 vakio P -315 inimum fm Pressure raho a) mum m Thickness minimumm thickness, ho ho C : 0.29 x 0.05 CAnswer) Cb) teat loss rate the heat loss state equal to the sate of euoY m the fm

4H) loss 21T N cotere paaitie frichon Tr fニ coefficient of friction , : 5.I 50 f 0.0068 T= 0.0068 x (2) x ( 37.5) (12) -20×(0. SIJr tl 15% tted loss, l6ts 42.35 M Pa 0.31S (ex)

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