DEC_Report_1518.104 _MTW_Cold__Brg_Loads_June_30 _2015.pdf

Diehl Engineering Company, PO Box 1573, Kingston, WA 98346 Phone: 360-297-8781 Fax: 360-297-8784 email: ediehl@diehlengineering.com

DIEHL ENGINEERING COMPANY

CONDITION FOUND REPORT 1518.104

VESSEL: USS MOUNT WHITNEY DEC REPORT NO: 1518.104

LOCATION: Victor Lenac Shipyard, Rijeka, Croatia

WORK ITEM: N/A

WORK DATE: 22 - 30 June, 2015 REFERENCES:

1. Lenac Contract 2015/513

2. GE LCC Main Reduction Technical Manual, Section 2-3-1

3. Waukesha Lineshaft Bearing Drawing for 20.75

Inch Dia. Shaft

4. DEC Report 1529.101, Rev A

5. DEC report 1529.103, Rev. A

6. DLI Engineering Report 4469.002, April 20, 2007

REPORT DATE: 1 July 2015

OWNER: US NAVY

CUSTOMER: Viktor Lenac Shipyard

CONTACT: Mr. Zoran Kosik TASK: Report Measured Main Propulsion Shaft Bearing Loads After Final Lineshaft Bearing Adjustment

DEC REP: Eric Diehl

A. SUMMARY

1. The current main reduction gear bearing loads meet all requirements of Reference 2 and are acceptable.

2. DEC recommends revising the LSB operating load limit to 55 psi (29,000 pounds).

3. The current vertical load on lineshaft bearing 1 (LSB1) exceeds the allowable limit from Reference 3 by

16, but meets DEC’s recommended 55 psi limit.

4. LSB 2, 3 & 4 meet or are less than the load requirements from Reference 3.

5. DEC considers the current alignment acceptable.

6. No further bearing adjustments are recommended at this time.

B. BACKGROUND

1. DEC adjusted the heights of lineshaft bearings (LSB) 1, 2, 3 & 4 by adding shims to achieve more even gear and lineshaft bearing loading between June 22 and June 29, 2015.

2. The following will serve as a report on the results of the final LSB adjustments.

C BEARING ADJUSTMENTS & STRAIN GAGE TESTING

1. Strain gage data was measured from the inboard strain gage locations while the vessel was pierside on June 22, 2015 prior to any bearing height adjustments.

2. DEC utilized our previously constructed in-water digital shafting model to convert the measured strains into bearing loads. See Table 1 for a summary of the measurements.

3. DEC, with the assistance of Victor Lenac machinists added shims in four iterations, with the final shims added on June 29, 2015. See Table 2 for a summary of the final shim changes under each chock of each bearing.

4. Strain data was measured on June 30 in both the ahead and astern directions after completion of the June 29 adjustments.

5. Projected hot operating bearing loads were calculated for each strain case and are included in Table 1.

DIEHL ENGINEERING COMPANY

CONDITION FOUND REPORT 1518.104

Vert Horiz Vert Horiz Vert Horiz Vert Horiz Vert Horiz

Fwd Gear Brg lbs 78,000 34,162 4,321 31,356 3,696 26,627 4,009 16,555 1,625 9,674 -2,872 (150psi) psi 150.0 65.7 8.3 60.3 7.1 51.2 7.7 31.8 3.1 18.6 -5.5

Aft Gear Brg lbs 78,000 21,662 -5,197 24,998 -4,934 32,014 -5,066 45,463 -1,802 55,208 4,566 (150psi) psi 150.0 41.7 -10.0 48.1 -9.5 61.6 -9.7 87.4 -3.5 106.2 8.8 LSB 1 lbs 23,745 31,968 3,186 31,454 2,600 27,597 2,893 18,222 -1,769 13,605 -4,786 (45 psi) psi 45.0 60.6 6.0 59.6 4.9 52.3 5.5 34.5 -3.4 25.8 -9.1 LSB 2 lbs 23,745 22,216 46 21,901 397 23,890 2,222 32,517 1,961 34,572 3,304 (45 psi) psi 45.0 42.1 0.1 41.5 0.8 45.3 4.2 61.6 3.7 65.5 6.3 LSB 3 lbs 23,745 21,140 690 21,194 828 20,901 759 9,458 2,168 9,047 1,900 (45 psi) psi 45.0 40.1 1.3 40.2 1.6 39.6 1.4 17.9 4.1 17.1 3.6 LSB 4 lbs 23,745 22,380 -2,051 22,677 -3,219 22,647 -2,635 32,127 -3,558 32,260 -3,471 (45 psi) psi 45.0 42.4 -3.9 43.0 -6.1 42.9 -5.0 60.9 -6.7 61.1 -6.6 Total lbs n/a 153,570 995 153,622 -631 153,721 2,186 154,404 -1,371 154,432 -1,353

Gr Brg Load Diff lbs n/a 12,500 9,518 6,358 8,630 -5,387 9,075 -28,908 3,427 -45,534 -7,438 22.4% 17.1% 11.3% 15.3% -9.2% 15.5% -46.6% 5.5% -70.2% -11.5%

Notes:

2) Positive horizontal bearing load means the shaft pushes to port on the bearing.

Max Loads From

Builder

Bearing Location & (allowable psi)

% GBLD of Vert Sum

As-Found, Afloat & Fueled, 22 June 2015

As-Measured, Ahead Direction

Projected Hot Operating

Current Cold Alignment, Measured June 30, 2015

1) Positive vertical bearing load means the shaft pushes down on the bearing.

Table 1: USS MOUNT WHITNEY Measured Main Propulsion Shaft Bearing Loads, June 2015, Before & After Bearing Adjuistment

Ahead Direction Average, Projected Hot

Operating Astern Direction

A B C D A B C D inches 0.085 0.087 0.091 0.093 0.062 0.064 0.068 0.070 mm 2.16 2.21 2.31 2.36 1.57 1.63 1.73 1.78 inches 0.090 0.090 0.090 0.090 0.090 0.090 0.090 0.090 mm 2.29 2.29 2.29 2.29 2.29 2.29 2.29 2.29 inches 0.106 0.098 0.082 0.074 0.126 0.118 0.102 0.094 mm 2.69 2.49 2.08 1.88 3.20 3.00 2.59 2.39 inches 0.028 0.024 0.016 0.012 0.028 0.024 0.016 0.012 mm 0.71 0.61 0.41 0.30 0.71 0.61 0.41 0.30 Note: The forward chock on each side of the bearing is "A, and chocks are lettered sequentially aft.

Units

LSB 1

LSB 2

LSB 3

LSB 4

Table 2: USS MOUNT WHITNEY Total Shims Added During June 2015 Shaft Realignment

Bearing Location

Chock Locations

Port Starboard

D. DISCUSSION

1. Reference 2 includes projected gear bearing offsets and load tolerances in the hot operating (dynamic) condition. From Reference 2, both the vertical and horizontal gear bearing load difference (GBLD) should be less than 10,000 pounds.

DIEHL ENGINEERING COMPANY

CONDITION FOUND REPORT 1518.104

2. The lineshaft bearings are disc lubricated, non-self-aligning Babbitt bearings. From Reference 3, the vertical load should be less than 23,740 pounds, which is equivalent to a projected unit load of 45 psi.

3. DEC considers the Reference 3 load limit of 45 psi to be very low for a disc lubricated bearing.

Historically, as indicated by Reference 6, these lineshaft bearings have been successfully operating in the 30,000 pound (57 psi) load range. Similar disc lubricated bearings that are self-aligning on the USS EMORY LAND and FRANK CABLE have a load limit of 75 psi.

4. Therefore DEC considers a limit of 55 psi (29,000 pounds f) to be more realistic, and recommends revising the LSB operating load limit accordingly.

5. The current vertical projected hot operating main reduction gear bearing loads are within the 10,000 pound difference criteria and are acceptable.

6. The projected hot operating lineshaft bearing load on LSB1 is 52.3 psi, and exceeds the 45 psi limit by about 16%, but is within DEC’s recommended 55 psi limit.

7. The projected hot bearing loads on LSB 2, 3 & 4 meet or are below the 45 psi limit. See Table 1.

8. Prior to adjustment, the projected hot operating maximum LSB load was 65.5 psi on LSB2, while at the same time the GBLD was over 4 times higher than the 10,000 pound limit.

9. DEC believes the current load balance on the lineshaft and reduction gear bearings is the best balance that can presently be achieved. Further reduction in LSB1 load, while still achieving satisfactory gear bearing loads, would require raising all four lineshaft bearings and would also raise the elevation at the thrust bearing further.

10. DEC therefore recommends the current alignment be considered acceptable.

11. No further bearing adjustments are recommended at this time.