SECTION 1111 — HIGH LOAD MULTI-ROTATIONAL BEARINGS

1111.01 DESCRIPTION — This work is the fabrication of high load multi-rotational bearings, as indicated.

1111.02 MATERIAL — Use new material at all times, with no reclaimed material incorporated in the finished bearing.

(a) Steel. Conform to AASHTO-M270 (ASTM-A709), Grades 36, 50 or 50W, except for steel for guide bars and shear restriction pins and sleeves. Furnish guide bars and shear restriction mechanisms as specified by the manufacturer, and approved by the Engineer.

(b) Elastomeric Disc.

1. Pot Bearings. Provide Shore A 50 Durometer and conform to AASHTO Section 18.3.3.1 of Division II where applicable. Use only virgin crystallization resistant polychloroprene (neoprene) or virgin natural polyisoprene (natural rubber) as the raw polymer. Use individually molded and one piece elastomers.

2. Disc Bearings. Provide polyether urethane conforming to AASHTO, Division II, Table 18.3.3.

(c) Sliding Surfaces. Furnish PTFE sliding surfaces conforming to the material requirements of AASHTO Section 18.8, Division II. Manufacture polytetrafluorethylene (PTFE) sheet and strip from pure virgin (not reprocessed) unfilled PTFE resin; from PTFE resin uniformly blended with either 15% glass fiber or 25% carbon (maximum filler, percent by weight); or from fabric containing PTFE fibers. Use heat cured, high temperature epoxy capable of withstanding temperatures of -320F to +500F when bonding the PTFE to its steel substrate, and conform to AASHTO Section 18.8.2, Division II.
Furnish stainless steel sliding surfaces conforming to ASTM-A167 or A240, Type 304 with a 20 micro-inch rms surface finish or less. Attach a stainless steel sheet by an approved welding procedure which keeps the sheet in contact with the substrate, or weld a stainless steel overlay using Type 309L electrodes. Use 0.05 inch minimum thickness stainless steel.

(d) Sealing Rings. Furnish sealing rings made of metal and conforming to the following requirements:

• Flat brass rings, ASTM-B36 half hard.
• Round cross section rings, Federal Specifications QQB626, composition 22, half hard.

(e) Bronze Elements. Furnish elements conforming to AASHTO, Section 18.6.1, Division II.

(f) Lubricant. Furnish solid lubricant consisting of a combination of solids having non-deteriorating characteristics as well as lubricating qualities and capable of withstanding long term atmospheric exposure, de-icing materials, and water. Do not use molybdenum disulfide and other ingredients which promote electolytic or chemical action between the bearing elements. Do not use shellac, tars and asphalts, or petroleum solvents as binders.

1111.03 FABRICATION —

(a) Rotational Elements. Furnish elements meeting the following requirements:

1. Pot Bearings. Manufacture from a solid plate by machining or fabricate by welding a flame cut shape to a plate. Have all welded areas tested by the magnetic particle method meeting AWS-D1.1, Section 6 requirements. Welding is to conform to Section 1105.03(m).
Machine inside diameter of pots to a tolerance of ±0.005 inch up to 20 inches ID and ±0.007 inch over 20 inches ID.
Pots machined parallel to the inside to a Class "A" tolerance.
Machined surfaces to a 125 micro-inch rms finish or better.
Elastomeric discs with tolerances as follows:

• Diameters up to 20 inches, ±1/16-inch
• Diameters greater than 20 inches, ±3/32-inch
• Total thickness of all pieces, -0 inch, +1/8-inch
• Discs may be made from up to 3 pieces, with the thinnest piece not less than 1/2-inch thick.

Pistons with tolerances as follows:

• Diameters up to 20 inches, ±0.005 inch
• Diameters greater than 20 inches, ±0.007 inch
• Upper side, Class "A" tolerance. Lower side, Class "B" tolerance.

2. Disc Bearings. Provide discs with tolerances as follows:

• Diameters up to 20 inches, ±1/16-inch
• Diameters greater than 20 inches, ±3/32-inch
• Thickness, -0 inch, +1/8-inch
• Make discs in one piece.


Furnish bearing plates for discs with tolerances as follows:

• Diameters up to 20 inches, ±0.005 inch
• Diameters greater than 20 inches, ±0.007 inch
• Inside surfaces facing disc Class "A" tolerance and minimum 125 micro-inch rms finish
• Outside surfaces, Class "A" tolerance and minimum 125 micro-inch rms finish

3. Spherical Bearings. Provide spherical bearings with tolerances as follows:

• Machined diameters, ±0.015 inch
• Convex radius dimensions, + 0.000 inch, -0.010 inch
• Concave radius dimensions, + 0.010 inch, -0.000 inch
• Mating surfaces to be as in the Design specifications, external edges may be "as cast" or flame-cut
• Lower surface of convex element Class "C" tolerance
(b) Non-Rotational Elements (All Bearings). Furnish elements meeting the following requirements: Furnish masonry and distribution plates with tolerances as follows: [
• Plan dimensions up to 30 inches, - 0 inch, +3/16-inch
• Plan dimensions over 30 inches, — 0 inch, +1/4-inch
• Thickness tolerance, — 0.030 inch, + 0.060 inch
• Masonry plates used with Pot, Disc, or Spherical Bearings, Class "C" tolerance for the underside and Class "A" tolerance for the upperside.

Provide PTFE sliding surfaces with tolerances as follows:

• Plan dimensions "total design area", +5%, -0%
• Substrate flatness: Class "A" tolerance for Pot and Disc Bearings, Class "B" tolerance for Spherical bearings.

Seal weld the stainless steel sheet around the entire perimeter using techniques which ensure it will remain in contact with the backing plate.
Provide a 20 micro-inch rms finish or better. Flatness to Class "A' tolerance. Furnish sole plates with tolerances as follows:

• Plan dimensions up to 30 inches, -0 inch, + 3/16-inch
• Plan dimensions over 30 inches, -0 inch, + 1/4-inch
• Center line thickness, -1/32-inch, + 1/8-inch
• Flatness of surface in contact with steel beams, Class "B" tolerance; in contact with fresh concrete, none; in contact with stainless steel sliding surface, Class "A" tolerance; in contact with another steel plate, Class "B" tolerance.
• Minimum edge thickness, 3/4-inch
• Machined bevels to an angular tolerance of ±0.002 radians.
• Flatness of bevelled surfaces, Class "A" tolerance

Provide Guide bar with tolerances as follows:

• Length, unless integral with plate, ±1/8-inch
• Section dimensions, ±1/16-inch
• Flatness where it bears on another plate, Class "A" tolerance
• Bar-to-bar, nominal dimension ±1/32-inch
• Not more than 1/32-inch out of parallel

Overall bearing height not more than 1/8-inch or less than 0-inch from nominal dimension. Chamfer all edges.

(c) Determination Of Flatness and Tolerances. Furnish bearings with flatness determined by the following method:
Place a precision straightedge, longer than the nominal dimension to be measured, in contact with the surface to be measured or as parallel to it as possible.
Select a feeler gage having a tolerance of ±0.001-inch and attempt to insert it under the straightedge using the least number of blades.
Flatness is acceptable if the feeler gage does not pass under the straightedge.
Flatness tolerances are arranged in the following classes:

Class "A" = 0.0005 inch x "Nominal Dimension"
Class "B" = 0.001 inch x "Nominal Dimension"
Class "C" = 0.002 inch x "Nominal Dimension"

"Nominal Dimension" is defined as the actual dimension of the plate, in inches, under the straightedge.
In determining flatness, the straightedge may be located in any position on the surface being evaluated and not necessarily at 90 degrees to the edges.
Ignore a 1-inch wide border around the plate in determining flatness.

(d) Painting. Do not paint prior to completion of welding.
If the time of exposure before welding is to exceed three months, provide metal surfaces with a protective coating of clear lacquer or other approved coating.
Paint all steel surfaces as indicated and in accordance with recommendations of the coating manufacturer.

(e) Testing. Have the following tests conducted prior to installation of the bearings, and in the presence of the Engineer.

1. Sampling. Select one sample, for testing purposes, at random from each "lot" of completed bearings at the manufacturer's plant.
A "lot" consists of one of the following:

• No more than 25 fixed bearings of one "load category"
• No more than 25 expansion bearings of one "load category"

One "load category" may consist of bearings of differing vertical load capacity but the bearings may not exceed a range of capacity differing by more than 300 hps.

2. Friction Test. Test only those bearings actually fabricated for the project.
Test a sample from each lot of expansion bearings. Perform test as specified in AASHTO, Division II, Section 18.3.5.3.2.

3. Proof Load Test. Test one bearing from each production "lot" of fixed and expansion bearings. Perform test as specified in AASHTO, Division II, Section 18.3.5.3.1.

4. Material Tests. Submit one sample of elastomer and one sample of PTFE from each "lot" to MTD for material testing to assure compliance with appropriate material specifications.

(f) Packing and Shipping.

1. Packaging and Handling. Have bearings securely banded together as units by fabricator, shipped to the job site, and stored without relative movement of the bearing parts or disassembly at any time. Wrap bearings in moisture resistant and dust resistant material to protect against shipping and job site conditions. Have the bearings match marked to indicate normal position of each bearing.
Take care to ensure that bearings are stored at the job site in a dry sheltered area free from dirt or dust until installation.
Inspect bearings within one week after arriving on the project. Do not disassemble unless the fabricator's representative is present. Following inspection, rewrap the bearings to keep them dean until installation.
Do not remove the sole and top plates of bearings for separate attachment to the structure except under the direct supervision of the fabricator.
With each shipment enclose a copy of the materials, fabrication, and testing compliance certifications.

(g) Shop Drawings. Submit in accordance with Section 105.02(d) and include the following information:

• The total quantity of each kind of bearing required (fixed, guided-expansion, or non-guided expansion), grouped first according to type (load range) and then by actual design capacity.
• Plan view and section elevation including all relative dimensions.
• Details of all components and sections showing all materials incorporated into the bearing.
• All ASTM, AASHTO, and other material designations.
• The maximum design coefficient of friction as noted on the contract plans.
• Clearly describe and detail any welding process used in the bearing manufacture that does not conform to the approved processes of the AWS code.
• Vertical, horizontal, rotation, movement, and load capacity.
• A schedule of all bearing offsets, if required by the project.
• Alignment plans.
• Paint or coating requirements.
• Installation scheme.
• Complete design calculations verifying conformance with the provisions of this specification. Stress analysis and the mechanics of standard bearing details are not required.
• Anchorage details.
• Bearing pre-set details.
• Location of the fabrication plant.
• The manufacturer's name and the name of his representative responsible for coordinating production, sampling, and testing.

(h) Certification. Have the fabricator provide a certification package in accordance with Section 106.03(b)3. and containing the following:

• Material test reports for all steels used except AISI C1018 and C1020 for which a mill conformance certificate is acceptable.
• Certificate of Compliance for all non-ferrous metals.
• Material test reports for any elastomeric components.
• Certificate of Compliance for PTFE and any adhesive used.
• A Certificate of Compliance for the bearings, executed by an officer of the manufacturing company.
• Certificate of Compliance for any dowels or bolts supplied.
• Test reports for the performance tests.

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