DEC_Report_1518.103 _MTW_Brg_Loads_June_27 _2015_After_LSB_Adjust_.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 1518.103

VESSEL: USS MOUNT WHITNEY DEC REPORT NO: 1518.103

LOCATION: Victor Lenac Shipyard, Rijeka, Croatia

WORK ITEM: N/A

WORK DATE: 22 - 27 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

REPORT DATE: 28 June 2015

OWNER: US NAVY

CUSTOMER: Viktor Lenac Shipyard

CONTACT: Mr. Zoran Kosik TASK: Report Measured Main Propulsion Shaft Bearing Loads After 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. The current vertical load on lineshaft bearing 1 (LSB1) exceeds the allowable limit from Reference 3 by

35%.

3. DEC is recommending further adjustments to reduce the load on LSB1.

B. BACKGROUND

1. In Reference 4, DEC recommended adjusting the lineshaft bearing (LSB) 1, 2 & 3 heights by adding shims and then re-measuring the bearing loads to achieve more even bearing loading.

2. The following will serve as an interim report on the results of the LSB adjustments to date.

C BEARING ADJUSTMENTS & STRAIN GAGE TESTING

1. DEC utilized our previously constructed in-water digital shafting model.

2. 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. See Table 1 for a summary of the measurements.

3. DEC with the assistance of Victor Lenac machinists has added shims in two iterations to this point. See Table 2 for a summary of the shims added to date.

4. Strain data was measured on June 27 after completion of the current adjustments.

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

1.

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 1518.103

Vert Horiz Vert Horiz Vert Horiz Vert Horiz Vert Horiz Vert Horiz

Fwd Gear Brg lbs 78,000 16,555 436 9,674 436 32,048 436 25,848 436 33,625 436 27,065 436 (150psi) psi 150.0 31.8 0.8 18.6 0.8 61.6 0.8 49.7 0.8 64.7 0.8 52.0 0.8

Aft Gear Brg lbs 78,000 45,463 -739 55,208 -739 22,891 -739 31,671 -739 23,025 -739 31,805 -739 (150psi) psi 150.0 87.4 -1.4 106.2 -1.4 44.0 -1.4 60.9 -1.4 44.3 -1.4 61.2 -1.4 LSB 1 lbs 23,745 18,222 717 13,605 717 36,538 717 32,378 717 30,266 717 26,106 717 (45 psi) psi 45.0 34.5 1.4 25.8 1.4 69.3 1.4 61.4 1.4 57.4 1.4 49.5 1.4 LSB 2 lbs 23,745 32,517 717 34,572 717 17,515 717 19,367 717 23,127 717 24,978 717 (45 psi) psi 45.0 61.6 1.4 65.5 1.4 33.2 1.4 36.7 1.4 43.8 1.4 47.3 1.4 LSB 3 lbs 23,745 9,458 717 9,047 717 19,724 717 19,354 717 21,764 717 21,394 717 (45 psi) psi 45.0 17.9 1.4 17.1 1.4 37.4 1.4 36.7 1.4 41.3 1.4 40.5 1.4 LSB 4 lbs 23,745 32,127 717 32,260 717 24,682 717 24,802 717 21,414 717 21,534 717 (45 psi) psi 45.0 60.9 1.4 61.1 1.4 46.8 1.4 47.0 1.4 40.6 1.4 40.8 1.4 Total lbs n/a 154,404 2,566 154,432 2,566 153,431 2,566 153,457 2,566 153,265 2,566 152,929 2,566

Gr Brg Load Diff lbs n/a -28,908 1,175 -45,534 1,175 9,157 1,175 -5,823 1,175 10,600 1,175 -4,740 1,175 -46.6% 1.9% -70.2% 1.8% 16.7% 2.1% -10.1% 2.0% 18.7% 2.1% -8.1% 2.0%

Notes:

Table 1: USS MOUNT WHITNEY Measured Main Propulsion Shaft Bearing Loads, June 2015

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

Afloat & Fueled, 22 June 2015

As-Measured, Projected Hot

Operating

Current Alignment As-Of June 27, 2015

As-Measured, Projected Hot

Operating

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

Recommended Further Alignment

Raise LSB1 0.017", LSB 2 0.060, LSB 3

0.060", LSB 4 0.020"

Projected Hot Operating

D. DISCUSSION

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

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

3. DEC considers 45 psi very low for a disc lubricated bearing. Typically a self-aligning disc lubricated bearing would have a load limit of 75 psi.

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

5. The projected hot operating lineshaft bearing load on LSB1 exceeds the 45 psi limit by about 35%, while LSB4 exceeds the 45 psi limit by about 4%.

6. DEC is recommending further bearing adjustments be performed to reduce the load on LSB1, as shown in Table 1. This would allow LSB 1 to only exceed the 45 psi limit by about 12% and all other bearings to be within the limit.