§ 3280.904 - Specific requirements for designing the transportation system.

§ 3280.904 Specific requirements for designing the transportation system.

Cross Reference

Link to an amendment published at 86 FR 2524, Jan. 12, 2021.

Cross Reference

Link to a delay published at 86 FR 13645, Mar. 10, 2021.

(a) General. The entire system (frame, drawbar and coupling mechanism, running gear assembly, and lights) shall transportation system must be designed and constructed as an integrated , balanced and durable unit which is safe and suitable for its specified use during the intended life of the manufactured home. In operation, the transportation system (supporting the manufactured home structure and its contents) shall must effectively respond to the control of the towing vehicle tracking and braking, while traveling at applicable towing vehicle in terms of tracking and highway speeds and in normal highway traffic conditions.

Note:

While the majority of manufactured homes utilize a fabricated steel frame assembly, upon which the manufactured home structure is constructed, it is not the intent of this standard to limit innovation. Therefore, other concepts, such as integrating the frame function into the manufactured home structure, are acceptable provided that such design meets the intent and requirements of this part).

(b) Specific requirements -

(1) Drawbar. The drawbar shall must be constructed of sufficient strength, rigidity, and durability to safely withstand those dynamic forces experienced during highway transportation. It shall must be securely fastened to the manufactured home frame by either a continuous weld or by boltingsubstructure.

(2) Coupling mechanism. The coupling mechanism (which is usually of the socket type) shall must be securely fastened to the drawbar in such a manner as to assure safe and effective transfer of the maximum loads, including dynamic loads, between the manufactured home structure and the hitch-assembly of the towing vehicle. The coupling shall must be equipped with a manually operated mechanism so adapted as to prevent disengagement of the unit while in operation. The coupling shall must be so designed that it can be disconnected regardless of the angle of the manufactured home to the towing vehicle. With the manufactured home parked on level ground, the center of the socket of the coupler shall not be less than 20 inches nor more than 26 inches from ground level.

(3) Chassis. The chassis, in conjunction with the manufactured home structure, shall must be designed and constructed to effectively sustain the designed loads consisting of the dead load plus a minimum of 3 pounds per square foot floor load, (example: free-standing range, refrigerator, and loose furniture) and the superimposed dynamic load resulting from highway movement but shall not be required to exceed twice the dead load. The integrated design shall be capable of insuring rigidity and structural design loads. The integrated structure must be capable of ensuring the integrity of the complete manufactured home structure and to insure ensuring against excessive deformation of structural or finish members during the intended life of the home.

(4) Running gear assembly. -

(i) Design criteria. The design load used to size running gear assembly, as part of the chassis, shall be designed to perform, as a balanced system, in order to effectively sustain the designed loads set forth in § 3280.904(b)(3) and to provide for durable dependable safe mobility of the manufactured home. It shall components must be the gross static dead weight minus the static tongue weight supported by the drawbar. Running gear must be designed to accept shock and vibration, both from the highway and the towing vehicle and effectively dampen these forces so as to protect the manufactured home structure from damage and fatigue. Its components shall must be designed to facilitate routine maintenance, inspection, and replacement.

(ii) Location. Location of the running gear assembly shall must be determined by documented engineering analysis, taking into account the gross weight (including all contents), total length of the manufactured home, the necessary coupling hitch weight, span distance, and turning radius. Weights shall be checked with the home in a level position ready for transport. The coupling weight shall must be not less than 12 percent nor more than 25 percent of the gross weight.

(5) Spring assemblies. Spring assemblies (springs, hangers, shackles, bushings, and mounting bolts) shall must be capable of withstanding all supporting the running gear design loads as outlined in § 3280.904(b)(3) , without exceeding maximum allowable stresses for design spring assembly life as recommended by the spring assembly manufacturer. The capacity of the spring system shall assure, must ensure that under maximum operating load conditions, sufficient clearance shall be is maintained between the tire and manufactured home's frame or structure to permit unimpeded wheel movement and for changing tires.

(6) Axles. Axles, and their connecting hardware, shall must be capable of withstanding all of the design loads outlined in § 3280.904(b)(3) supporting the static running gear design loads, without exceeding maximum allowable stresses for design axle life loads as recommended by the axle manufacturer. The number of axles required and load capacity necessary to provide a safe tow and good ride characteristics shall be determined and documented by engineering analysis. Those alternatives listed in § 3280.903(c) may be accepted in place of such an analysis.

(

must not be less than those required to support the design load.

(i) Recycled axles. Before reuse, all axles, including all component parts, must be reconditioned as required pursuant to a program accepted by a nationally recognized testing agency. The recycling program must be approved, and the axles must be labeled by a nationally recognized testing agency. Recycled axles and their components must utilize compatible components and be of the same size and rating as the original equipment.

(ii) [Reserved].

(7) Hubs and bearings. Hubs and bearings shall meet the requirements of § 3280.904(b)(3) and good engineering practice. Both of these components shall be accessible for inspection, routine maintenance and replacement of parts.

(8) Tires, wheels, and rims. Tires, wheels, and rims shall meet the requirements of § 3280.904(b)(3). Tires shall be selected for anticipated usage.

(9) Brake assemblies.

(i)

must be selected, sized, and fitted to axles so that static dead load supported by the running gear does not exceed the load capacity of the tires. Tires must not be loaded beyond the load rating marked on the sidewall of the tire or, in the absence of such a marking, the load rating specified in any of the publications of any of the organizations listed in Federal Motor Vehicle Safety Standard (FMVSS) No. 119 in 49 CFR 571.119, S5.1(b). Wheels and rims must be sized in accordance with the tire manufacturer's recommendations as suitable for use with the tires selected.

(i) Inflation pressure. The load and cold inflation pressure imposed on the rim or wheel must not exceed the rim and wheel manufacturer's instructions even if the tire has been approved for a higher load or inflation. Tire cold inflation pressure limitations and the inflation pressure measurement correction for heat must be as specified in 49 CFR 393.75(h).

(ii) Used tires. Whenever the tread depth is at least 1⁄16 inch as determined by a tread wear indicator, used tires are permitted to be sized in accordance with 49 CFR 571.119. The determination as to whether a used tire is acceptable must also include a visual inspection for thermal and structural defects (e.g., dry rotting, excessive tire sidewall splitting, etc.). Used tires with such structural defects must not be installed on manufactured homes.

(9) Brake assemblies -

(i) Braking axles. The number, type, size, and design of brake assemblies required to assist the towing vehicle in providing effective control and stopping of the manufactured home shall must be determined and documented by engineering analysis. Those alternatives listed in § 3280.903(c) may be accepted in place of such an analysis. Unless substantiated in the design to the satisfaction of the approval agency by either engineering analysis in accordance with § 3280.903(a)(1) or tests in accordance with paragraph (b)(9)(ii) of this section, there must be a minimum of two axles equipped with brake assemblies on each manufactured home transportable section.

(ii) Stopping distance. Brakes on the towing vehicle and the manufactured home shall (a drive-away/tow-away) must be capable of assuring ensuring that the maximum stopping distance from an initial velocity speed of 20 miles per hour does not exceed 40 feet (U.S. Department of Transportation Regulations).

(10) Lights and associated wiring. Highway safety electrical lights and associated wiring shall conform to applicable Federal requirements in terms of location and performance. The manufacturer shall have the option of meeting this requirement

35 feet in accordance with 49 CFR 393.52(d) for 2 or fewer vehicles in drive away or tow away operation.

(iii) Electrical brake wiring. Brake wiring must be provided for each brake. The brake wire must not be less than the value specified in the brake manufacturer's instructions. Aluminum wire, when used, must be provided with suitable termination that is protected against corrosion.

(10) Lamps and associated wiring. Stop lamps, turn signal/lamps, and associated wiring must meet the appropriate sections of FMVSS No. 108 in 49 CFR 571.108, which specify the performance and location of these lamps and their wiring. The manufacturer may meet these requirements by utilizing a temporary light/wiring harness, which has components that meet the FMVSS No. 108. The temporary harness is permitted to be provided by the manufactured home transportation carrier.

[40 FR 58752, Dec. 18, 1975, as amended at 86 FR 2524, Jan. 12, 2021]