Specifications

December 2013
REQUEST FOR PROPOSALS FOR
PURCHASE AND DELIVERY OF HEAVY-DUTY BUSES
RFP SRTA-2014-01
TECHNICAL SPECIFICATIONS
PAGE-10
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9. BRAKES
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9.1 General
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a. The vehicle’s air brake system will be equipped with both service and emergency
brakes that conform with FMVSS 121 as applicable. An Anti-lock Brake System
operating in conjunction with the air brake system shall be standard with each
coach. Prior to delivery of the first coach, the Contractor shall supply
documentation certifying the air brake system conforms to FMVSS 121/. If
the contractor has no documentation certifying that the vehicles furnished
under this contract conforms with FMVSS 121, the SRTA shall require the
manufacturer to perform stopping tests on one (1) coach at full
G.V.W.R. and measure stopping distances, in accordance with FMVSS 121.
The test shall be completed prior to delivery of any coaches to the SRTA. If
the test vehicle fails any portion of the testing, the vehicle will be re-tested
after modifications until all tests are successfully completed.
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b. A dual brake system shall be provided in the coach which provides two totally
independent brake systems. This system features a dual brake valve in which
the top portion provides the primary service brake system. In the event of a loss
of air of one system, the other system will provide adequate braking to stop the
coach. A Bendix-Westinghouse "SR-1" spring brake control valve, or approved
equal, shall be provided to modulate rear spring brakes in the case of a primary
system failure. The service brakes shall consist of four (4) wheel air operated,
internal expanding S-Cam type.
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9.2 Brake Chambers
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a. Brake chambers shall be MGM type, or approved equal, with protective boot over the
push rod.
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b. Brake chambers shall be equipped with manufacturer's standard diaphragm and
spring. Brake system shall be balanced to provide safe stop operation.
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9.3 Service Brakes
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a. Coaches shall be equipped with brake systems which conform to the
requirements of all Federal regulations, designed so such conformance can be
maintained throughout the normal adjustment cycle. A supplemental brake
(transmission retarder) shall also be provided. The supplemental braking shall
not be used in meeting regulatory criteria. The braking system shall include
service brakes, a parking and emergency brake.
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b. The driver's brake pedal shall control the service brake and the supplemental
brake in a coordinated manner to give a total braking effort depending on the
position of the pedal up to the maximum capability of the braking system. Brake
valve shall be a Bendix-Westinghouse or approved equal, brake to minimize
brake fade and to achieve maximum brake lining lifetimes. Braking forces shall
be proportioned among the axles to assure balanced braking and equalize lining
life between axles.