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21 Cards in this Set
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1.) A 1 in horizontal shaft rotates at 500 rpm in a sleeve-type bearing. The coefficient of friction is 0.15. Calculate the horsepower lost in the bearing if the reaction betweem yhe shaft and the bearing is 800 lb? |
0.4759 hp |
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2.) A 2 in horizontal shaft rotates in a sleeve type bearing. The coefficient of friction is 0.10 and the shaft applies a load of 500 lb. find the friction resistance |
50 lbs |
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3.) A bearing sustains a load of 4450 N. The shaft diameter is 100mm, the coefficient of sliding friction is 0.01, and the shaft speed is 400 rpm. Find the horsepower lost in bearing. |
93.20 watts |
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4.) a 50 mm diameter shaft supported by two sleeve bearings carries a load of 13.3 MN. The shfat rotates at 150 rpm. If the coefficient of sliding friction between the shaft and bearings is 0.1, how much power is lost in friction? |
522.30 kW |
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5.) A 36 mm shaft uses a sleeve bearing that sustain a load of 4000N. if the allowable bearing pressure is 1.3 MN/m² . Find the length of the bearing. |
85.47 mm |
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6.) A 20 mm shaft uses sleeve bearings. The total load per bearing is 2000N. An L?D ratio of 2.5 is desired. What is the bearing pressure? |
2 Mpa |
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7.) A 22 mm diameter shaft is supported by sleeve bearing at a distance of 0.50 m. A load of 2.2 kN is applied at 0.2 m from the left end. The Sleeve bearings have an L/D ratio of 1.5. Find the max. bearing pressure. |
1.818 MN/mm² |
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8.) A sleeve bearing is to have an LD ratio of 1.0 and an allowable bearing pressure of 0.5 MN/m². Find the inside diameter and the length of the bearing if its is to sustain a load of 2250 N. |
71.41 mm |
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9.) A sleeve bearing has an outside diameter of 1.50 in and a length of 2 in. The wall thickness is 3/16 in. The bearing is subjected to a radial load of 450 lb. Find the bearing pressure. |
200 psi |
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10.) A thrust washer has an inside diameter of 12 mm and an outside of 75 mm. If the allowable bearing pressure is 0.6 Mpa, how much load can it sustain? |
2582.90 N |
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Units of Viscosity: |
1 reyn = 1 lb-sec/in² 1 poise = 1 dyne-sec / cm² |
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Formula of Silding bearings |
Cd = diametral clearance = D - d Cr = radial clearance = (D-d)/2 |
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Diametral CLearance ratio |
Dcr = Cd/D = (D-d)/D where: p = unit loading or bearing pressure p = F/LD e = eccentricity e = radial dustance between center of bearing and the displaced center of the journal D = diameter(bore) of the bearing d= diameter of the journal L = axial length of the journal inside the bearing F = radial load |
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formula of Bearing Modulus & with subjected to change in speed |
Bearing Modulus = un/p u= viscosity in reyns n = speed in rps p = unit loading, psi = un/p(n |
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Formula of Frictional torque in bearings |
Tb = (FfD)/2 f= coefficient of friction F = radial load D =bearing diameter |
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Formula of Petroff's equation for frictional torque( faires p 302) |
Tf = (4π²r³Lns)/ Cr where: Tf = frictional torque, in-lb u = viscosity reyns (fig AF 16, p 595) r = journal radius , in L = axial length of bearing, in Ns = journal speed, rps Cr = radial clearance, in |
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formula of Heat dissipation in journal bearings |
H = Ch L D / 778 where: H = heat dissipated in btu/min Ch = heat dissipation coefficient, projected area, ft-lbs/min-in² L = length of bearing , in D = diameter of bearing, in |
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Note for ball and roller bearings |
* bearing sizes and designation example of bearing designation: SAE or IS 314 is 300 series, no.14 *tabulated data on ball and roller bearings: VAllance: Table 9-2 p 206 |
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* beariing capacity based on stresses ( Vallance p 205) |
Fr = k1nD²/5 for ball bearings) Fr = k2nLD/5 ( for roller bearings) where: Fr = total radial load, lbs n = number of balls or rollers D = ball diameter or roller diameter, in L = length of rollers,in k1 = 550 for unhardened steel = 700 for hardened carbon steel = 1000 for hardened alloy steel on flat races =1500 for hardened carbon steel =2000 for hardened alloy steel on grooved races k2= 7000 for hardened carbon steel = 10,000 for hardened alloy steel |
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catalog capacities of ball and roller bearings: |
Fc = (kak1) Ko Kp Ks kf Fr where: Fc = catalog rating of bearing, lb Fr = actual radial load on the bearing, lb Ha = desired life of bearing, hrs of use Hc = catalog rated life of bearing, hr Ka = application factor taking into account the amount of schock(table 9-4) k1 = 3√(ha)/Hc K rel, the life factor where: ko = oscillation factor = 1.0 for constant rotational speed of the races = 0.67 for sinusoidal ocillations of the races kp = preloading factor = 1.0 for non-preloaded ball bearings and straight rolller bearings kr = rotational factor =1.0 for bearings with fixed outer spaces krel = reliability factor, table 9-3 ks = 3√(KrNa)/Nc , the speed factor Kf = thrust factor = 1.0 if there is no trust load component |
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formula of Bearing Modulus with subjected to change in speed |
given : D = 76 mm u = 0.70 poise N = 500rpm change speed = 600rpm P = 14 kg/cm² |
