The bearing is subjected to a radial load of 4000N. Expected life for 90% bearings is 9000h and shaft is rotating at 1500rpm. Calculate the dynamic load capacity.

Calculate the bearing life if expected life for 90% bearings is 9000h and shaft is rotating at 1500rpm.

A

850 million rev

B

810 million rev

C

810 h

D

850h

The dynamic load carrying capacity of a bearing is defined as the radial load in radial bearings that can be carried for a minimum life of 1000 revolutions.

A

True

B

False

Consider the following statements in connection with thrust bearings: 1) Cylindrical thrust bearings have higher coefficient of friction than ball thrust bearings. 2) Taper rollers cannot be employed for thrust bearings. 3) Double-row thrust ball bearing is not possible 4) Lower race, outer race and retainer are readily separable in thrust bearings. Which of the above statements are correct?

A

1 and 2

B

2 and 3

C

3 and 4

D

1 and 4

Consider the following statements: The basic reason why shafts are made of steel and its alloys is: 1. The shaft is subjected to normal stress. 2. The shaft stress alternates with respect to time. 3. The shaft is subjected to pure compressive stress. 4. The shaft is subjected to the stress of constant intensity. Which of these statements are correct?

A

1 and 2

B

2 and 3

C

3 and 4

D

4 and 1

A rotor which is balanced statically but not dynamically is supported on two bearings L apart and at high speed of the rotor, reaction on the left bearing is R. The right side of the bearing is shifted to a new position 2L apart from the left bearing. At the same rotor speed, dynamic reaction on the left bearing in the new arrangement will

A

Remain same as before

B

Become equal to 2R

C

Become equal to $$\frac{{\text{R}}}{2}$$

D

Become equal to $$\frac{{\text{R}}}{4}$$

The radius of a friction circle for a shaft rotating inside a bearing is (where r = Radius of shaft and $$\tan \varphi $$ = Coefficient of friction between the shaft and bearing)

A

$${\text{r}}\sin \varphi $$

B

$${\text{r}}\cos \varphi $$

C

$${\text{r}}\tan \varphi $$

D

$$\frac{{\text{r}}}{2}\cos \varphi $$

Consider that modern machines mostly use short bearings due the following reasons: 1) l/d of the most modern bearings is in the range of 1.4 to 2 2) No end leakage of oil from the bearing 3) Shaft deflection and misalignment do not affect the operation 4) Can be applied to both hydro-dynamic and hydrostatic cases Which of the above are correct?

A

1 and 4

B

3 and 3

C

1 and 3

D

2 and 4

A flange mounted shear pin is used on a shaft as a safety device. The steel shear pin has a diameter of 2.38 mm and is to be mounted on the flange of shaft rotating at 650 rpm. The maximum power transmitted by the shaft is 4.5 KW. If the shear strength of material of pin is 30 MPa, the radial distance of its mounting is ____

A

5.02 mm

B

11.98 mm

C

47.94 mm

D

301.20 mm

Consider two shafts connected with two gears as per the following options: 1. One on each shaft 2. Through an intermediate gear mounted on an intermediate shaft, and every shaft having one gear only 3. Through an intermediate gear mounted on an intermediate shaft, with the intermediate shaft having two gears, whereas the other shafts have one gear each Which of the above represent(s) a simple gear train?

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2 and 3

A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the maximum speed of the intermediate shaft if the driving shaft has a constant speed of 500 r.p.m.

A

532.1 r.p.m

B

469.85 r.p.m

C

566.25 r.p.m

D

441.5 r.p.m.

The bearing is subjected to a radial load of 4000N. Expected life for 90% bearings is 9000h and shaft is rotating at 1500rpm. Calculate the dynamic load capacity.

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