VERTICAL SHAFT ROTATING IN A GUIDE BEARING (FIG. 23-5)

Figure 23-5: Vertical shaft rotating in a cylindrical bearing.

The surface velocity of shaft

The length of bearing in the direction of motion

The torque (Fig. 23-5)

Refer to Fig. 23-6 for projected area ( Ld).

Figure 23-6: Projected area of a bearing.

Petroffs equation for coefficient of friction (Fig. 23-5)

Design practice for journal bearing ³

Refer to Table 23-2.

Table 23-2: Journal bearing design practices
Machinery	Bearing	Maximum pressure, P	Diameter clearance ratio ? =	Ratio	Viscosity, ? ₁	Viscosity, ?	Bearing modulus (minimum)
kgf/mm ²	kpsi	MPa	cP	Pa s 10 ^?3	USCSU	SI Units, 10 9
Automobile	Main	0.56-1.19	0.8-1.7	5.50-11.70		0.1-1.8	7	7	15	36.3
and aircraft	Crankpin	1.06-2.47	1.5-3.5	10.40-24.40		0.7-1.4	to	10	10	24.2
engines	Wrist pin	1.62-3.62	2.3-5.0	15.00-34.80		1.5-2.2	8	8	8	19.3
Gas and oil	Main	0.49-0.85	0.7-1.2	4.85-8.35	0.001	0.6-2.0	20	20	20	48.4
engines (four ?	Crankpin	0.90-1.27	1.4-1.8	8.80-12.40	<0.001	0.6-1.5	to	10	10	24.2
stroke)	Wrist pin	1.27-1.55	1.8-2.2	12.40-15.20	<0.001	1.5-2.0	65	65	5	12.1
Gas and oil	Main	0.35-0.56	0.5-0.8	3.42-5.50	0.001	0.6-2.0	20	20	25	60.4
engines (two ?	Crankpin	0.70-1.06	1.0-1.5	6.85-10.40	<0.001	0.6-1.5	to	to	12	29.0
stroke)	Wrist pin	0.85-1.07	1.2-1.8	8.35-12.50	<0.001	1.5-2.0	65	65	10	24.2
Marine steam	Main	0.35	0.5	3.42	<0.001	0.7-1.5	30	30	20	48.4
engines	Crankpin	0.42	0.6	4.14	<0.001	0.7-1.2	40	40	15	36.3
	Wrist pin	1.06

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Machine Design Databook, Second Edition