NSTM Chapter 243, Propulsion Shafting

Question 1

The primary purpose of propulsion shafting

Answer 1

Transfer torque generated by the main engine to the propeller and to transmit thrust developed by the propeller to the thrust bearings in the ship

Question 2

Sections of shafting outside the skin of the ship are usually supported by bearings located in ___

Answer 2

Struts, skegs, and stern tubes

Question 3

Sections of shafting inside the skin of the ship are usually supported on ___

Answer 3

Line shaft spring bearings

Question 4

Shafting seal is usually a ___

Answer 4

Split inflatable seal installed aft of a stuffing box and gland

Question 5

When propellers are unshipped due to a possible propulsion shafting or propeller related vibration problem, measure ___ for a fixed pitch propeller or the ___ for a controlled pitch propeller

Answer 5

Shaft taper runout

Aft facial runout of the after-most shaft flange

Question 6

Whenever a magnetic particle inspection is accomplished, the shaft shall be demagnetized to ___

Answer 6

7.0 gauss maximum

Question 7

Minor pitting can be removed up to ___ in depth

Answer 7

1/16”

Question 8

The shaft outside diameter shall not be reduced more than ___ below the minimum design diameter

Answer 8

1/8”

Question 9

Cracks associated with pitting shall be ___

Answer 9

Completely removed and repaired by welding

Question 10

Cracks or pits detected in keyways that will result in less than ___ contact between the key and keyway throughout the entire keyway length shall be removed by machining not to exceed ___ on the width and depth

Answer 10

90%

1/8”

Question 11

For ships possessing rotating coupling covers, prior to filling with corrosion preventive compound, verify the watertight integrity by ___

Answer 11

Pressurizing with air at 10 +/- 1 psi for a minimum of 10 minutes

Question 12

Type of coupling used to connect nontapered ends of shafts without keyways, flanges, or bolts

Answer 12

Oil-pressure-fitted shaft couplings (SKF or OK couplings)

Question 13

Consist of a thin inner sleeve, tapered on its outside diameter, and a thicker outer sleeve tapered on its inside diameter to match. The sleeves are positioned over the ends of the two shafts to be coupled, and oil is injected under pressure between the two sleeves to facilitate alignment and compressive friction fit over the shaft ends

Answer 13

Oil-pressure-fitted shaft couplings (SKF or OK couplings)

Question 14

Sleeves which have pitting and/or cracking exceeding ___ in way of the shaft sleeve should be replaced

Answer 14

5/32” depth

Question 15

Prior to machining the sleeve diameter, the refurbishing activity shall measure the current diameter of the sleeve in ___ radial increments and ___ locations

Answer 15

45 degree

3 axial

Question 16

If the anticipated sleeve diameter at the end of the next ten year cycle winds up being less than ___ below the nominal design diameter, the sleeve shall be replaced

Answer 16

0.310”

Question 17

If waterborne bearing sleeves are worn, pitted, otherwise damaged and rough to a depth less than or equal to ___ from the original design size, the roughness may be hand smoothed

Answer 17

0.030”

Question 18

Heating sleeves to fit to shaft, should not exceed ___ and the heating rate shall not exceed ___

Answer 18

900 degrees F

200 degrees F per hour

Question 19

When shrink fitting a sleeve, no ___ is allowed for installing the sleeve onto the shaft

Answer 19

Lubricant

Question 20

The tolerance for the axial positioning of each end of a sleeve is ___ from its design location

Answer 20

+/- 1/2”

Question 21

When installing sleeves on a shaft, they should be maintained at ___ for at least 24 hours

Answer 21

60 to 80 degrees F

Question 22

The strain in the sleeve shall not exceed ___

Answer 22

16000 psi

Question 23

Propeller shaft keyways are designed to have one be ___ bigger than the other to ensure correct orientation

Answer 23

1/16”

Question 24

When in the drydock position, the ___ propeller key is at the top

Answer 24

Smaller

Question 25

The final alignment of the main propulsion shafting should always be accomplished when the vessel is ___

Answer 25

Waterborne