A full journal bearing has a journal diameter of 25 mm, with a unilateral tolerance of −0.03 mm. The bushing bore has a diameter of 25.03 mm and a unilateral tolerance of 0.04 mm. The l/d ratio is 1/2. The load is 1.2 kN and the journal runs at 1100 rev/min. If the average viscosity is 55 mPa · s, find the minimum film thickness, the power loss, and the side flow for the minimum clearance assembly.
The minimum film thickness for the bearing.
The power loss for the bearing.
The side flow for the minimum clearance assembly.
Answer to Problem 1P
The minimum film thickness for the bearing is
The power loss for the bearing is
The side flow for the minimum clearance assembly is
Explanation of Solution
Write the expression for the minimum radial clearance.
Here, the minimum radial clearance is
Write the expression for the radius of the journal bearing.
Here, the radius of the journal bearing is
Write the expression for the radial clearance ratio of the bearing.
Here, the radial clearance ratio of the bearing is
Write the expression for the number of revolution per second.
Here, the number of revolution per second is
Write the expression for the characteristic pressure.
Here, the characteristic pressure of the bearing is
Write the expression for the bearing characteristic number.
Here, the bearing characteristic number is
Write the expression for the minimum thickness of the film.
Here, the minimum thickness of the film is
Write the expression for the coefficient of the friction.
Here, the coefficient of the friction is
Write the expression for the parasitic friction torque.
Here, the parasitic friction torque is
Write the expression for the heat loss of the journal bearing.
Here, the heat loss of the journal bearing is
Write the expression for the volumetric oil flow rate in to the bearing.
Here, the volumetric oil flow rate in to the bearing is
Write the expression for the volumetric side flow leakage out of the bearing.
Here, the volumetric side flow leakage out of the bearing is
Conclusion:
Substitute
Substitute
Substitute
Substitute
Substitute
Substitute
Substitute
Thus, the minimum film thickness for the bearing is
Substitute
Substitute
Substitute
Thus, the power loss for the bearing is
Substitute
Substitute
Thus, the side flow for the minimum clearance assembly is
Want to see more full solutions like this?
Chapter 12 Solutions
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
- You are asked to design a plain surface journal bearing to carry a steady radial load of 5.75 kN while the shaft rotates at 950 rpm. The shaft stress analysis determines that an acceptable nominal diameter of the journal is 62.5-mm and an l/d ratio is 1. The shaft is part of a machine requiring good precision. So a minimum radial clearance cmin= 0.040 mm seems appropriate. We shall use SAE 30 oil as a lubricant, at an inlet temperature of 45 oC. Analyze the hypothetical bearing,a) Determine the operating temperature Tave, and operating viscosity μave. b) Determine the minimum film thickness, ho, temperature rise of the lubricant, ΔTC, the total oil flow, Q, and side flow Qs in [mm3/s], the maximum film pressure Pmaxdeveloped in [MPa]. c) Determine the power loss, Hloss in [W], friction torque, Tf in [N-m] d) For minimum radial clearances, perform a design assessment using Trumpler’s criteria.arrow_forwardA full journal bearing has a nominal diameter of 60.0 mm, a bearing length of 30.0 mm and supports a load of 3200 N when running at the design speed of 3200 rpm. The radial clearance has been specified as 0.04 mm. An SAE 20 oil has been chosen and the lubricant supply system is capable of delivering the lubricant to the bearing at 60oC. Using the Raimondi and Body design charts;1.1 find the temperature rise of the lubricant, (19)1.2 the total flow rate required, (1)1.3 the torque required to overcome friction (3)1.4 and the power dissipated in the bearing.arrow_forwardThere is a PVC pipe, with an internal diameter of 28 mm. The Reynolds number for this system is 1500. The percentage of error that represents the accuracy in the estimation of the friction factor, by the Swamee-Jain and Colebrook-White method, is in a range of (4-5)% . Hint Use 7 decimal places in calculating the friction factor and remember that the best method to estimate the friction factor is Colebrook-White. True or false?arrow_forward
- FLUID MACHINERY A duplex, single-acting reciprocating power pump is driven by a 40-HP electric motor at a speed of 120 RPM and delivers water at a temperature of 150oF. The pump operates against a heat of 150 psig. The overall efficiency is 75%. If the estimated slip is 8%, determine the required bore and stroke for a bore – stroke ratio of 0.75. a. bore Answer : __________________ in.b. stroke Answer : __________________ in.arrow_forwardA duplex, single-acting reciprocating power pump is driven by a 40-HP electric motor at a speed of 120 RPM and delivers water at a temperature of 150F. The pump operates against a heat of 150 psig. The overall efficiency is 75%. If the estimated slip is 8%, determine the required bore and stroke, for a bore-stroke ratio of 0.75. a. bore in inches b. stroke in inchesarrow_forwardA pipe (f = 0.015) has a diameter of 250-mm and 150 m of length is connected in series with another pipe (f = 0.02) having a diameter of 200 mm and 200 m of length. Calculate the diameter of an equivalent single pipe of length 350 m and friction factor of 0.025arrow_forward
- fluid machineries A duplex, single-acting reciprocating power pump is driven by a 40-HP electric motor at a speed of 120 RPM and delivers water at a temperature of 150oF. The pump operates against a heat of 150 psig. The overall efficiency is 75%. If the estimated slip is 8%, determine the required bore and stroke for a bore – stroke ratio of 0.75. a. bore Answer : __________________ in.b. stroke Answer : __________________ in.arrow_forward15.)A full journal bearing has a journal diameter of 4.000in. with a unilateral tolerance of -0.004in. The bushing bore has a diameter of 4.004in and unilateral tolerance of +0.004in. the bearing is 3in long. The journal load is 3000 lbf and it runs at a speed of 400 rpm. What is the load per projected bearing area 9P) in psi? Choose answer below 75 100 125 250 16.)For the bearing in problem #15, if the lubricant average viscosity is 9 ureym, what is the Sommerfield number (assuming minimum clearance) Choose answer below Between 0.6 and 0.7 Between 0.5 and 0.6 Between 0.3 and 0.4 Between 0.2 and 0.3arrow_forwardThe mean effective pressure of an engine running at 450 rpm is 550 kPa. What is the indicated power if the enginehas a bore of 250 mm x 450 mm.arrow_forward
- 8. A shaft 70 mm diameter is pushed at a speed of 450 mm/s through a bearing sleeve 73 mm in diameter and 252 mm long. The clearance , assumed uniform, is filled with at 20OC with v= 0.005 m2/ s ang s.g. = 0.9. find the force exerted by the oil on the shaft. (3 DECIMAL PLACES IN FINAL ANSWER PLS)arrow_forwardQ 2. A journal bearing has a shaft diameter of 75.00 mm with a unilateral tolerance of −0.02 mm. The bushing bore has a diameter of 75.10 mm with a unilateral tolerance of 0.06 mm. The bushing is 36 mm long and supports a load of 2 kN. The journal speed is 700 rev/min. For the minimum clearance assembly find the minimum film thickness, the heat loss rate, and the maximum lubricant pressure for SAE 30, SAE 40 and SAE 50 lubricants operating at an average film temperature of 60 °C.arrow_forwardThe values given for a radial plain bearing are:Shaft diameter = 40 mm, bearing width = 30 mm, Pem = 6 N / mm2, Radial force = 2 KN, Ty = 45 C, oil: ISO VG 15, bearing clearance = 35 µm, dynamic viscosity for given oil and temperature = 12 m Pa. sRequired:a) What is the working cycle of the shaft?b) Find the Sommerfeld number.arrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY