Attachment_4_-_Submittal_Design_Analysis_With_Bid_Schedule.pdf

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Prepared By:

Hangar Door Wheel Replacement Building 837 100% Submittal – Design Analysis Travis Air Force Base, California

Prepared For:

Travis Air Force Base Contract Number FA4427-13-D-0104

XDAT 15-1126

06 April 2018

TranSystems Project No. P501170028

TranSystems 2000 Center Street Suite 303 Berkeley, CA 94704 Tel 510.835.2761 Fax 510.835.9839 www.transystems.com

This Page is Intentionally Blank

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Table of Contents

I. INTRODUCTION

II. EXISTING CONDITIONS

IV. FAILURE ANALYSIS

V. DATA COLLECTION AND SOLUTION REVIEW

APPLICABLE CRITERIA

LOADING ANALYSIS

CONSTRUCTION COST LIMITATION

VI. DESIGN DEVELOPMENT

COMPONENT SPECIFICATIONS

PROPOSED DEMOLITION

PROPOSED WORK

APPENDIX A – PHOTOGRAPHS

APPENDIX B – COST ESTIMATE AND BID SCHEDULE

APPENDIX C – SAMPLE PRODUCT DRAWING AND INFORMATION

APPENDIX D – REFERENCED SUPPORT MATERIAL AND CALCULATIONS

100% Submittal Hangar Door Wheel Replacement Building 837

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I. Introduction The project goal is to provide the design and specifications for the replacement of the failed wheels for the hangar doors at B837, the C-17 Two Bay Hangar. The base maintenance staff responsible for this building have indicated that the current wheels have shown a high failure rate since the building was constructed less than ten years ago. Failure-modes include wearing of wheel, bending of the wheel flange, and premature failure of bearings. This facility is designed to operate 24 hours a day and seven days a week, and downtime due to the frequent failure has an impact to the facility operations.

II. Existing Conditions The hangar aircraft doors consist of 10 door leaves, 5 in each direction of travel. Each leaf is approximately 38’-9” wide by 67’-6” tall and approximately 18” thick. Each leaf is built from a framework of steel channel and L shaped angle braces. The door leaves are faced with steel siding panel and translucent panels. They also insulated with R-19 fiberglass batts. The hangar aircraft door controls accommodate dual door control. Each sliding door panel weighs approximately 42,785 pounds and is supported on two 24” wheels rolling on embedded 60# rails with guide rails at the head of the door. The wheels are contained within a wheel assembly housing accessible from the interior side of the door leaf. These wheel assemblies are constructed of ASTM A36 Structural Steel and are welded to the web of the bottom wide flange member of each door. The assemblies vary slightly in size, but they average 33-3/4” long and 3-1/2” wide, and are welded to the lower web outboard of the web opening for the wheel. There are two door leaves, one on each side of the bay with electric motors attached to the two wheels for operating the doors. Other door leaves have two “idle” wheels that roll freely.

III. Project Approach The proposed work consists of three distinct Tasks: 1) Failure Analysis, 2) Data Collection and Solution Review, and 3) Design Development. The remainder of this Design Analysis breaks down each task, reviewing findings and transitioning statistical information into a fully developed proposed solution.

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IV. Failure Analysis Based on the information provided to us by the base, our field observations, and independent analysis by industry vendors, the following is list of causes that we believe contribute to the failure. Each cause is presented below with proposed solution.

Primary Cause #1. Improper Bearing Design. We believe and concur with the User that this is likely a primary cause of failure.

o Existing Conditions The original design involved tapered roller outer bearings with a center roller bearing. This configuration appears to be not optimal and has the potential for the load to be not distributed equally to each of the three bearing surfaces, which in turn can lead to early failure.

Failed bearings shows signs of unequitable loading due to lack of proper seating of the bearing.

Bearing seating design appears to be poor and appears to be ineffective to prevent bearing drift, resulting in bearing-to-bearing contact.

After recalculating the actual weight of the door leaf and lateral wind load and checking against the bearing capacity, it does not appear that bearing load capacity is a factor.

o Proposed Design The proposed design utilizes two tapered roller bearings for each wheel, removing the center roller bearing for better positioning and more equitable load distribution.

The proposed design relies on a more contained wheel solution, utilizing a solid steel casing with factory installed, pre-loaded bearings integrated within, ensuring proper seating at the factory stage and reducing the opportunity for installation variation between wheels as compared to wheels that are pre-loaded after being placed into the wheel assembly.

Alternatively, externally mounted Pillow Block Bearings could be used in this application, as suggested by the End User. However, the use of such bearings would involve additional forces being applied to the bearings, which could negatively affect performance. Additionally, such bearings would make for a very restricted fit in the existing door pocket, which would make installation and maintenance more difficult. For these reasons, we believe the integrated solution proposed is a better solution.

For more information on the proposed bearings, please see Appendix C.

Primary Cause #2. Improper Hardening of the Wheel Surface. We believe and concur with the User that this is likely another primary cause of failure.

o Existing Conditions The wheels were specified to be hardened but did not appear to have achieved the specified hardness. This is evident by the plastic flow of metal on the wear surface.

The premature wear of the wheel surface may have contributed to the shifting of the load to one side of the wheel as evident by the wear

Page | 5 pattern. This may further contribute to the abnormal loading of the bearings.

A36 steel was used, which, due to its low carbon content, requires carburization for proper case hardening. This may not have been done properly.

o Proposed Design Some replacement wheels (supplied by the original manufacturer) were made from ASTM 4140 steel. These wheels appear to have the proper hardening and appear to be performing well.

The strongest steel, with respect to economic feasibility, available for wheels of this size with this level of loading on a 60# rail is ASTM 1055 steel. Manufacturer recommendations specify a case hardening of 58-64 HRc on such wheels.

The recommended pin, which contains integral grease injection lines for bearing lubrication, should be made of ASTM 4140, with a hardness of 29-34 HRc.

Primary Cause #3. Improper Sizing of the Wheel and Wheel Housing. We believe that this is likely another primary cause of failure.

o Existing Conditions The embedded rails are standard, work-hardened, 60# rails, which are exhibiting up to a ¼” of deflection after 10 years of use. These rails have a nominal tread width of 2-3/8”.

The current wheels accommodate the nominal tread width of 2-3/8” with 3/8” flanges on either side. (For more notes of the Wheel Flange Width, see Secondary Cause #1.)

The existing wheel housings are only 3-1/2” wide for the idle wheels, which limits how thick the wheel, and most notably, the wheel flanges can be.

o Proposed Design Accounting for the nominal tread width and edge slope of a 60# rail, which are 2-3/8” and 80 degress respectively, and factoring in the recommended flange thickness of 1”, the minimum width of such wheels should be 4-3/4”.

The proposed design, which includes the steel integral bearing casing, requires a wheel housing that is approximately 6-1/4” wide. Ultimately, the width of the wheel housing will be driven by the size of the wheel assembly to be installed. The interior face of the wheel housing should be flush with the outer face of the thrust washer. In order to accommodate this, the current wheel housings will need to be demolished, a wider opening in the bottom framing member will need to be cut, and new wheel housings will need to be installed with modified supports to ensure the proper clearance.

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Secondary Cause #1. Improper Wheel Flange Design. We believe that this could be a significant contributing cause of failure.

o The purpose of the wheel flange is two-fold; 1) to keep the wheel from escaping the rail, and 2) transfer lateral force acting out-of-plane on the door to the rail and foundation.

o Existing Conditions Many of the existing wheel flanges show excessive bending deflection, suggesting that the wheel has been “climbing” on the deflected wheel flange. As the flange deflects further, the climbing tendency increases.

Such “climbing” can impose a significant unexpected load to the bearing.

This is likely the wheel’s response to the need for tolerances as discussed in Cause #3.

It is highly unlikely that the flange bending is a result of wind loading to the door. For further discussion on horizontal loading, please refer to the Loading Analysis Section below.

The existing original wheel flanges are 3/8” thick. The existing replacement wheels have a flange thickness of ½” and are made from a different steel. These replacement wheels have not shown flange deflection.

o Proposed Design As referenced in Primary Cause #2 and Primary Cause #3, the proposed design relies on both a higher yield strength steel and thicker flanges, which, in conjunction with more appropriate spacing, should provide the tolerances necessary to resist climbing, and the strength needed to prevent this deflection.

Possible Factor #1: Drive Motor Size. We do not believe that this is a contributing cause of failure.

o The existing drive wheels (4) are operated by electric motors (5 HP at 480V).

These motors appear to be sized sufficiently for the loading and have not exhibited any signs of early failure. For supporting calculations, please refer to Appendix D.

Possible Factor #2: Track and Door Misalignment. We believe that this is not a contributing cause of failure.

o The existing two flange wheel system, when designed with the correct tolerances as discussed in Cause #3, is designed to accommodate large misalignment of track (+/- 1”). Field observations indicate current rail deflections of approximately ¼”, well within the expected norms for 60# embedded rail.

After reviewing what design documents have been made available from the original Hangar Door/Wheel Design to determine where the aforementioned traits, which have likely resulted in the failures noted to date, were introduced into the design, most of the concerning features were determined by the wheel manufacturer. The design documents included all the pertinent standards, including Section 08 34 16.10 – Steel Sliding Hangar Doors of the UFGS Guide Specifications. Unfortunately, while the Guide Specification provides a good overall design criteria, it does not include best practice in the detailed design level. For this type of specialized

Page | 7 door hardware design, it is often left to the assembly designer to provide a design that is effective and long lasting, and such a design would be reviewed as a part of the shop drawing review process. To ensure that detailed designs are properly implemented for this project, we have included best practice details in the design documents in addition to providing the required specification. Such an approach remains in compliance with the UFC while providing a guideline to make sure the detail shop drawings are in conformance of the design intent.

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V. DATA COLLECTION AND SOLUTION REVIEW

Applicable Criteria The design will conform to the latest edition of the Uniform Facility Guide and all applicable criteria including the following:

• UFC 4-211-01 Aircraft Maintenance Hangars

• UFGS Guide Specifications

• Uniform Federal Accessibility Standards (UFAS)

• ASTM, ANSI, OSHA, and UL Standards and Regulations

• International Building Code (IBC), 2015

• Travis Air Force Base Architectural Compatibility Plan

Since this project focuses on the replacement of wheels and wheel assemblies for the hangar aircraft doors, no changes to the site, site utilities, protection measures, or landscaping are anticipated as part of this project.

All materials, hardware, and equipment provided for this project shall be of institutional, commercial, or heavy-duty quality/grade. All provided components must be capable of withstanding heavy use and must require only minimal maintenance. Standard-type, readily available fasteners and attachments shall be provided for ease of maintenance and replacement.

Loading Analysis Below is a free-body diagram depicting the loading to which the wheels are exposed. All known values have been included. The vertical loading has been determined from the existing door assemblies, for which the calculations can be found on Page 10. The horizontal loading is specified in the UFGS Guide Spec (Section 08 34 16.10), and factors in Wind and Seismic Loads.

For wind loads, Section 08 34 16.10 assumes a minimum of 33 PSF, or a wind speed of approximately 88 MPH, which was factored in to the following calculation for the horizontal loading:

Door Height (F) x Door Width (F) = Size of Door Leaf (SF) Size of Door Leaf (SF) x Wind Load (PSF) = Horizontal Loading (P)

67.5 (F) x 38.75 (F) x 33 (PSF) = 86,315 (P)

When distributed over the four contact points per door leaf, two on top and two on bottom, the horizontal load based on wind comes out to approximately 21,600 pounds per contact point.

For the seismic loads, Section 08 34 16.10 assumes a minimum of ½ times the vertical load, which in this case comes out to approximately 10,700 pounds per contact point. Since this number is less than half of the minimum wind load assumption, the design is predicated only on the wind load, as indicated below.

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*Horizontal loading factors in the maximum forces that may be applied from wind or seismic activity at any single moment. Unlike the vertical loads, which are constant, the horizontal loads are momentary. UFC 4-211- 01, Aircraft Maintenance Hangars, Section 3- 10 prohibits the operation of hangar doors during seismic activity or overly windy conditions (15 PSF, or approximately 75 MPH winds), meaning this degree of loading will only be experienced when the doors are stationary.

As part of the failure-mode assessment above, an independent set of calculations were performed using industry guidelines and local data such as historical wind speeds and seismic force activity in order to ensure that the UFC and UFGS required minimums are sufficient to withstand the actual local conditions and building-specific requirements. Based on the design drawings for the original hangar, a consistent door weight of 42,785 pounds per leaf was derived, matching the previously determined vertical load. With regards to the lateral load an average storm wind speed of 40 MPH was assumed, which equates to just over 4 PSF, or 1/8 of the Government Standard. With this in mind, the design team is confident that the Government Standards are sufficient for this location and do not require amendment with regards to the loading specifications.

Construction Cost Limitation The Construction Cost Limitation (CCL) for this project according to the Task Order is $400,000.

Refer to Appendix B for a detailed cost estimate for the proposed design.

Project: C17 Hangar By: K. Nguyen Date: Nov-17 Page

Door Leaf Geometry: NOTES:

Door Leaf Height 67.50 ft Door Leaf Width 38.75 ft Door Leaf Thickness 18.0 in

5 Door Leaves per Opening 2 Openings Total

Components:

[lb] [lb]

3547.50 14190.00

710.42 2131.25

2131.25 2131.25

2247.50 2247.50

111.85 223.70

61.05 122.10

156.98 5180.31

71.05 1136.80

59.21 177.63

2.55 15.31

1.28 5.10

10.21 102.08

7846.88 7846.88

1162.50 1162.50

36672.4 lb

Weight of Connections 1,834 lb (5% of Subtotal Weight) Contingencies 4,278 lb (10% of Total Weight)

42784.5 lb ‐> 21.4 Tons

Refer to HANGAR DOOR DRAWINGS FOR C17 MAINTENANCE HANGAR Plan Set dated

06/25/2008 REVISION #3

Number of Elements

Total Weight

HSS4x4x1/4 Posts @ Top Trolley 12.21 5.00

PL 1/4"x3"x6" Connection 2.55 0.50

C8x14G 13.75 11.42

Total WeightWeight

[Ea]

10.21 1.00

Subtotal Weight

L3x3x1/4 Long Brace 4.90 14.50

PL 1/4"x6"x6" Connection 5.10 0.50

PL 1/4"x12"x12" Connection Wall Panel (Ext) Wall Panel (Int)

L3x3x1/4 Short Brace

38.75

116.25 67.50Exterior Panel

116.25 10.00Interior Panel

4.90 12.08

Single Door Leaf Weight

Location

Columns Beam @ Top

Beam @ Top TrolleyMC18x58 58.00 38.75

Element Unit Weight Length [lb/ft] [ft]

W18x55 Beam @ Bottom 55.00

W18x55 55.00 64.50 W18x55 55.00 12.92

HSS5x5x3/8 22.37 5.00Posts @ Top Trolley

Girts

Door Leaf

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VI. Design Development Although many of the key design traits for the proposed replacement wheels are outlined above to provide the context for their relevance to the design, a full assessment of the proposed work is outlined below.

Component Specifications The work described below involves revisions to the wheel assemblies, drive motor platforms, and the lower wide-flange of the hangar door leaves, as well as replacing the wheels and pins with entirely new designs, and requires the services of qualified welders and steel workers in addition to the general contracting requirements. Modifications to the wheel assemblies and drive motor platforms should be made with ASTM A36 Structural Steel to match the existing steel in these components. The steel should be cleaned, primed, and painted in accordance with the specifications.

The new wheels should have a 24” tread diameter, a 2-3/8” tread width, an 80 degree slope on the flange interior to form to the existing 60# rail, and a 1” flange on either side, for a nominal width of 4-3/4”. The wheels are to be made of ASTM 1055 Steel and must be case hardened to 58-64 HRc. The wheels shall include a fully enclosed bearing casing made of ASTM 1020 Steel, housing two tapered roller bearings. To prevent excessive wearing of either the bearing casing or the wheel assembly, a washer made of SAE 841 Bronze shall be installed between the bearing casing and the wheel assembly on either side of the wheel. A self-lubricated bronze, SAE 841 will provide additional protection for both the ASTM A36 wheel assembly and the ASTM 1020 bearing casing, while sustaining the thrust loads applied along the pin. The bearings themselves shall be rated for the loading indicated above for a duration of at least 10,000 hours under normal operating conditions. The pins, which are 2” in diameter and include integral grease injection and relief paths, must be made of ASTM 4140 Steel and case hardened to 29-34 HRc. For the Drive Motor Wheels, an additional rim shall be included with the wheel design, on which an 18” steel gear wheel shall be bolted.

Proposed Demolition The contractor must use a paired wedge system to immobilize one wheel per door at a time for demolition, repair, and replacement. The proposed demolition requires the Contractor to properly disconnect the power source to the drive motors and then carefully remove the motor and motor platform, preloading mechanism, pin, and wheel, as applicable. Gas powered torches should be used to remove the existing wheel assemblies and widen the opening in the wide-flange web as specified. All drive motors, motor platforms, and fasteners are to be saved for reuse with the new wheels, while the old wheels, pins, and assembly parts are to be recycled as applicable. Once the demolition of the existing components is complete, the remaining components should be cleaned and prepared for the new components referenced below.

Proposed Work The new wheel assemblies should be factory produced based on field measurements and installed on-site, welded outboard of the opening in the wide-flange web as designed. Once finished, and the new wheels and pins are installed and secured, the motor platforms and

Page | 12 motors can be re-installed in the modified position as indicated on the drawings, and the door can be lowered back into place by removing the wedges.

APPENDIX A

PHOTOGRAPHS

Hangar Door Wheel Replacement B837 Appendix A Travis Air Force Base, California

Hangar Door Panel – Door 2, South Bay

Drive Wheel/Assembly with Motor Note: Motor Not in Scope

Idle Wheel/Assembly Note: Wider Wheel Will Require Expanding Wheel Assembly

Pre-Loading Mechanism Note: Expanding Wheel Assembly Will Require Adjusting Welded Supports

Replaced Wheel Note Flange Deflection and Plastic Flow

Embedded Rail Note: Point of Maximum Rail Deflection

Embedded Rails Note: Repetitive Uneven Wear Pattern, Consistent with Wheel Circumference

APPENDIX B

BID SCHEDULE

Bid Schedule

Travis AFB, CA Prepared by: TranSystems Date: 06 April 2018

Base Bid A. Site Preparations Wheel Isolation 20 EA B. Demolition Wheels 20 EA Wheel Assemblies 20 EA C. Manufactured Parts and Equipment Rental Wheels, Pins, and Assemblies 22 EA Equipment Rental 1 LS C. Installation and Commissioning Wheel Assemblies 20 EA Wheels 20 EA Drive Wheel Connections 4 EA Commissioning 1 LS

Subtotal $

General Conditions 35% $ Subtotal $

General Contractor Overhead 65% $ Subtotal $

Bonds and Insurance 95% $ Subtotal $

General Contractor Profit 100% $

Base Bid Total $

Line TotalDescription Quantity Unit

APPENDIX C

SAMPLE PRODUCT DRAWING AND INFORMATION

A

EXISTING HOUSING

(HANGAR DOOR)

EXISTING HOUSING

(HANGAR DOOR)

EXISTING SET SCREW EXISTING SET SCREW

24" WHEEL

MAT'L: AISI 1055

HARDNESS: 58-64 HRc

GREASE FITTING

SHAFT (PIN)

MAT'L: AISI 4140

HARDNESS: 280-320 BHN

BEARING, TRB, TS BEARING, TRB, TS

BEARING RETAINER

MAT'L: AISI 1020

BEARING RETAINER

MAT'L: AISI 1020

WIRE LOCKED

HHCS

WIRE LOCKED

HHCS

RELIEF FITTING

DESIGNED FOR 60# RAIL

THRUST WASHER

MAT'L: SAE 841 BRONZE

OIL IMPREGNATED

THRUST WASHER

MAT'L: SAE 841 BRONZE

OIL IMPREGNATED

NOTE:

IN THE EVENT OF AN ORDER, CUSTOMER IS RESPONSIBLE FOR

VERIFYING EXISTING HOUSING (HANGAR DOOR) DIMENSIONS

REQUIRED TO FINALIZE WHEEL ASSEMBLY DESIGN.

THIS INCLUDES INSIDE WALL DIMENSIONS, OUTSIDE COLLAR

TO COLLAR DIMENSIONS, SET SCREWS SIZE AND LOCATION &

EXISTING BORE DIAMETER.

IN THE EVENT OF AN ORDER, XTEK WILL SUPPLY GREASE

CAVITY VOLUME.

A

A

REV. DATE BY S.O. DESCRIPTION

REVISIONS

A 3/28/18 ACD Q-035250

OIL IMPREGNATED BRONZE WASHERS ADDED

BETWEEN A36 HOUSING AND BEARING RETAINERS;

BEARING RETAINER MATERIAL CHANGED FROM SAE

430A BRONZE TO AISI 1020 STEEL;

- 11/16/17 ACD Q-035250 RELEASED FOR CUSTOMER REVIEW.

D

C

B

A

B

C

D

12345678

8 7 6 5 4 3 2 1

E

F

E

F

AMAT'L FORM/BLANK#/ITEM#

00204476

TRAVIS AFB (TRANSYSTEMS)CUSTOMER:

HDNS:

CARB:

QTY

TH

IS

D R A W

IN

G

W A S O

R

IG

IN

A

TE

D B

Y A N

D I

S T

H E

EX

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PR

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ASSEMBLY [PROPOSAL]

DATA:

SIMILAR TO:

USED ON:

POS SO#:

NAME

DRAWN BY ACD

CHECKED BY

11/16/17

DATE

PART

NAME:

TOLERANCES:

FRACTIONAL 1/64

ANGULAR: 30'

RADII: +0.000 -0.015

X.XX 0.01

X.XXX 0.005

ITEM#

REV:

548 LBS

SHEET

HANGAR 837 DOOR

DESIGNED BY ACD 11/15/17

PROJECT:

UNLESS OTHERWISE SPECIFIED:

ALL OVER

TRACK WHEEL

PRD #:

LEGACY BP:

MATERIAL DATA

MAT'L:

FURNACE WEIGHT:

FINISHED WEIGHT:

RAW MATERIAL WEIGHT:

Q-035250

Timken Part Number 65200 - 65500-B, Tapered Roller Bearings - TSF (Tapered Single with

Flange) Imperial

RELATED PRODUCTS

RELATED PRODUCTS

Like the TS bearing design, the TSF design consists of two main separable parts: the cone (inner ring) assembly and the cup (outer ring). It is typically mounted in opposing pairs on a shaft. TSF bearings have anged cups to facilitate axial location and accurately align seals in through-bored housings.

Series 65000

Cone Part Number 65200

Cup Part Number 65500-B

Design Units Imperial

Bearing Weight

6.50 lb

3.000 Kg

Speci cations | Dimensions | Abutment and Fillet Dimensions | Basic Load Ratings | Factors

The Timken Company 4500 Mt Pleasant St. NW N. Canton, OH 44720 Phone: (234) 262-3000 E-Mail: CustomerCAD@timken.com • Web site: www.timken.com

Speci cations

2/9/2018 | Page 1 of 4 mailto:CustomerCAD@timken.com http://www.timken.com/

Cage Type Stamped Steel d - Bore 2 in

50.8 mm

D - Cup Outer Diameter 5 in 127 mm

D1 - Flange Outer Diameter

5.2772 in

134.041 mm

B - Cone Width

1.75 in

44.45 mm

C - Cup Width

1.3750 in

34.925 mm

C1 - Cup Flange Width

0.2813 in

7.145 mm

T1 - Bearing Width

1.7500 in

44.450 mm

T - Bearing Width to Flange

0.6563 in

16.670 mm

R - Cone Backface "To Clear"

Radius1

0.14 in

3.600 mm r - Cup Backface "To Clear"

Radius2

0.130 in

3.30 mm da - Cone Frontface Backing Diameter

2.72 in

69.10 mm db - Cone Backface Backing Diameter

2.95 in

74.90 mm

Da - Cup Frontface Backing 4.75 in

Dimensions

Abutment and Fillet Dimensions

2/9/2018 | Page 2 of 4

Diameter 120.65 mm

Ab - Cage-Cone Frontface Clearance

0.08 in 2 mm

Aa - Cage-Cone Backface Clearance

0.13 in

3.3 mm a - Effective Center Location3 -0.37 in -9.4 mm

C90 - Dynamic Radial Rating (90 million revolutions)4 14200 lbf 63100 N

C1 - Dynamic Radial Rating (1 million revolutions)5 54700 lbf 243000 N

C0 - Static Radial Rating 66700 lbf 297000 N

Ca90 - Dynamic Thrust Rating

(90 million revolutions)6 11800 lbf 52700 N

K - Factor7 1.2 e - ISO Factor8 0.49

Y - ISO Factor9 1.23

G1 - Heat Generation Factor

(Roller-Raceway)10 83.2

G2 - Heat Generation Factor (Rib-Roller End)

17.2

Cg - Geometry Factor11 0.0827

Basic Load Ratings

Factors

2/9/2018 | Page 3 of 4

1 These maximum llet radii will be cleared by the bearing corners.

2 These maximum llet radii will be cleared by the bearing corners.

3 Negative value indicates effective center inside cone backface.

4 Based on 90 x 106 revolutions L10 life, for The Timken Company life calculation method. C90 and Ca90 are radial and thrust values.

5 Based on 1 x 106 revolutions L10 life, for the ISO life calculation method.

6 Based on 90 x 106 revolutions L10 life, for The Timken Company life calculation method. C90 and Ca90 are radial and thrust values for a single-row, C90(2) is the two-row radial value.

7 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.

8 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.

9 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.

10 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.

11 Geometry constant for Lubrication Life Adjustment Factor a3l.

2/9/2018 | Page 4 of 4 https://cad.timken.com/plp/htm/ibot.htm

IMPERIAL UNITS

65200 - 65500-B

THE TIMKEN COMPANY

NORTH CANTON, OHIO USA

TSF BEARING ASSEMBLY

Every reasonable effort has been made to ensure the accuracy of the information contained in this writing, but no liability is accepted for errors, omissions or for any other reason. FOR DISCUSSION ONLY

ISO Factor - e 0.49 ISO Factor - Y 1.23 Bearing Weight 6.5 lb Number of Rollers Per Row 16 Effective Center Location -0.37 inch

Dynamic Radial Rating - C1 54700 lbf Static Radial Rating - C0 66700 lbf Dynamic Thrust Rating - Ca90 11800 lbf Dynamic Radial Rating - C90 14200 lbf K Factor 1.2

1.7500

5.

2.

1.3750

5.

2.

2.

4.

-0.37

0.08

0.13

To clear 0.13 max

Fillet Radius

To clear 0.14 max

Fillet Radius

0.2813

0.6563

APPENDIX D

REF. SUPPORT MATERIAL AND CALCULATIONS

16 Journal of Failure Analysis and PreventionVolume 4(5) October 2004

Premature Failure of Steel Gantry Crane Wheels (continued)

Premature Failure of Steel Gantry Crane Wheels E.E. Vernon, M.E. Stevenson, and J.L. McDougall

(Submitted August 5, 2004; in revised form August 31, 2004)

A metallurgical failure analysis was performed on a set of carbon steel gantry crane wheels following observation of excessive damage to the central tread surfaces. Rolling contact fatigue was considered as a possible failure mechanism due to the presence of what appeared to be spalling. Metallographic evaluation and hardness testing revealed that portions of the wheel tread surface had not reached the specified case hardness during heat treatment, leaving the tread surface edges in a near normalized condition. Continual contact with the rail during service allowed for plastic flow of the softer materials across the surface, resulting in the observed damage.

Keywords:

JFAPBC (2004) 5:16-18 © ASM International

DOI: 10.1361/15477020420783 1547-7029 / $19.00

Introduction/ Scope of Analysis

This paper outlines the failure analysis conducted on a set of carbon steel gantry crane wheels that exhibited signs of severe wear after a relatively short service period.

Within six months of the original installa-tion, wear was noted on the tread surfaces of all four wheels (Fig. 1). Prior to the metallurgical failure analysis, rolling contact fatigue (RCF) caused by misalignment of the runway I-beams had been suspected as the most likely cause of wear. In an effort to alleviate this mechanical condition, a complete realignment of the wheel/rail system was completed; however, the wear persisted, prompting the subsequent metal-lurgical failure analysis.

The wheels were manufactured from normalized 1045 carbon steel. Manufacturing specifications re-quired that the tread surface of each wheel be case hardened, via flame hardening, within the range of 212 to 240 Brinell hardness (HB). No specifications were provided for the wheel flanges, which were as-sumed to remain in the normalized condition.

Metallographic Evaluation Two of the four affected wheels were submitted for investigation. Both wheels appeared visually similar, with a clear delineation at the location of apparent wear on the tread surfaces (Fig. 2-4). Roll-ing contact fatigue was considered as a possible mechanism of failure, because light microscopy of the worn surface revealed what appeared to be spalling. Note that RCF is a type of wear but is referred to as fatigue, because cyclic mechanical stresses are induced by the wear processes, and these stresses are required to generate the spalled condition.

Metallographic evaluation of three samples from a sectioned wheel yielded similar results. Macro-flame hardening, heat treatment failure, rolling contact, spalling, wear

Fig. 1 Photograph illustrating the observed wear on the tread surface of one of the gantry crane wheels

E.E. Vernon, M.E. Stevenson, and J.L. McDougall, Metals and Materials Engineers LLC, 1039 Industrial Court, Suwanee, GA 30024. Contact e-mail: evernon@mmelab.com

Journal of Failure Analysis and Prevention Volume 4(5) October 2004 17 etching of metallographic cross sections revealed a clear distinction between the macrostructure of the case hardened tread surface and the remainder of the wheel section (Fig. 5). Microscopic inspection revealed that the microstructure of the wheel flanges was a matrix of equiaxed ferrite grains with colonies of pearlite distributed throughout, as anticipated for normalized steel. The microstructure of the steel at the center of the tread surface was predominantly tempered martensite, as anticipated for flame hardened 1045 steel. At the wear interface, however, it was apparent that the surface condition originally believed to be caused by spalling was, in fact, due to plastic deformation of normalized and/or par-tially hardened material from the tread surface edges. This phenomenon was evidenced by the visible plastic flow patterns toward the center of the tread surface. Additionally, it was observed that the microstructure in the deformed region was comprised of highly elongated grains of ferrite and pearlite (Fig. 6). Had wear occurred on the tread surface, the observed flow patterns would be aligned at 90° to the observed flow. Furthermore, the deformed microstructure would contain a signifi-cant amount of tempered martensite.

Hardness Testing Hardness measurements taken at multiple loca-tions along the tread surface and flange of one of the wheels corroborated the metallographic evalu-ation. The specified case hardness range, 212 to

Fig. 2 The two gantry crane wheels submitted for investigation

Fig. 3 Photograph outlining the three main areas of interest on the submitted wheels

Fig. 4 A close-up view representative of the delineation on the tread surface of the submitted gantry crane wheels

Fig. 5 A removed section of one of the wheels, following macro-etching

18 Journal of Failure Analysis and PreventionVolume 4(5) October 2004

Premature Failure of Steel Gantry Crane Wheels (continued)

240 HB, converts into a Rockwell “C” scale range of 18 to 23 HRC. The average measured hardness value at the center of the tread surface was approx-imately 22 HRC, within the specified case hard-ness range. Toward the outer edges of the tread surface, however, the average hardness value dropped to approximately 85 on the Rockwell “B” scale (HRB)—well below the specified range. The average hardness of the wheel flanges was approxi-mately 78 HRB. It should be noted that the edges of the tread surface retained a hardness value slightly higher than that of the flanges, indicating that they were at least partially hardened by either cold work or by the flame hardening process.

Conclusions/Recommendations Although the observed gantry crane wheel fail-ures had originally been attributed to improper rail alignment, the metallographic analysis and hardness measurements suggest that the root cause of failure was improper heat treatment of the crane wheels. Few details are known regarding the flame hardening process used for the wheels;

however, it likely involved the wheel being sup-ported and mechanically rotated while a stationary flame was applied to the tread surface. Microstructural evidence suggests that a uniform heat treatment of the tread surface was not accomplished. The full case hardness was achieved only at the center of the tread surface, while the outer edges of the tread surface remained in a near-normalized state (Fig. 7). Continual cyclic contact with the rail while in service resulted in plastic deformation of the softer edges, as exem-plified by the elongation of grain structure toward the center of the tread surface. The localized defor-mation and the cyclic nature of the applied stresses resulted in surface spallation in the region of micro-structural/hardness transition. Both the localized plastic deformation and spallation of the inner sur-faces of the flanges (which were observed to be in the normalized condition) contributed to the deposition of material debris on the central tread surface.

In order to avoid reoccurrence of this type of fail-ure, it was recommended that the flame hardening process be reviewed and/or revised in order to guar-antee a consistent case hardening across the total tread surface. In addition, it was recommended that any surface that may potentially contact the rail during service, such as the inner flange surfaces, should likewise be case hardened.

References

1. P.J. Blau: “Rolling Contact Wear,” Friction, Lubrication, and Wear, vol. 18, ASM Handbook, ASM International, 1992.

2. G.F. Vander Voort: Metallography: Principles and Practice, ASM International, 1999.

3. “Standard Hardness Conversion Tables for Metals,” Designation E 140-84, Annual Book of ASTM Standards, vol. 03.01, Metals—Mechanical Testing; Elevated and Low- Temperature Tests, ASTM, W. Conshohocken, PA, 1986.

Fig. 6 Composite micrograph image illustrating the plastic flow of elongated grains of ferrite and pearlite on the tread surface of one of the wheels

Fig. 7 Schematic drawing illustrating the condition of the wheels subsequent to heat treatment via flame hardening