Search Interpretations


Adam Schumann, Engineer

Thoroughbred Motorsports

P. O. Box 369

22661 FM15

Troup, TX 75789

Dear Mr. Schumann:

This responds to your request for an interpretation of Federal Motor Vehicle Safety Standard (FMVSS) No. 122, Motorcycle Brake Systems. You wish to know whether a prototype brake system design for a three-wheeled motorcycle would meet FMVSS No. 122. Based on the information you provided to the agency and the analysis below, Ive concluded that because the product would not meet the requirement at S5.1.2.1 that each reservoir filler opening have its own cover, seal, and cover retention device, it would fail to meet FMVSS No. 122.

The National Highway Traffic Safety Administration (NHTSA) is authorized to issue FMVSSs that set performance requirements for new motor vehicles and new items of motor vehicle equipment (See 49 U.S.C. Chapter 301). NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Instead, manufacturers are required to self-certify that their vehicles and equipment conform to all applicable safety standards that are in effect on the date of manufacture. FMVSS No. 122 specifies performance requirements for motorcycle brake systems.

In your letter you describe your product as a three-wheeled motorcycle with approximately 143 horsepower. Unlike many motorcycles, your product will have a steering wheel instead of handle bars, a foot throttle operated by the drivers right foot, and a brake pedal operated by the drivers left foot. You state that the brake system will use a standard Ford Ranger dual master cylinder with a split reservoir with a single cap. The brake system and the brake foot pedal will actuate both front and rear systems simultaneously. You note that FMVSS No. 122 states at S5.1.2.1:

S5.1.2.1 Each master cylinder will have a separate reservoir for each brake circuit, with each reservoir filler opening having its own cover, seal, and cover retention device.

You asked whether NHTSA will accept the use of this standard passenger vehicle master cylinder on the motorcycle if it does not have two individual caps for each of the reservoirs.

Since your product would be classified as a motorcycle, it must meet the FMVSSs that apply to motorcycles, including FMVSS No. 122. As you are aware, although it would have a master cylinder with split reservoirs, front/rear, your design would have only one filler cover and seal. Each reservoir filler opening would not have its own cover, seal and cover retention device, as specified in S5.1.2.1. Your motorcycle would therefore not meet S5.1.2.1 of FMVSS No. 122.

You also seek confirmation that your product need not meet FMVSS No.123, Motorcycle controls and displays. The application section (S3.) of FMVSS No. 123 states: This standard applies to motorcycles equipped with handlebars As indicated above, you state in your letter that your motorcycle will incorporate a steering wheel instead of handle bars. Therefore, FMVSS No. 123 would not apply to your motorcycle.

* * *

With respect to FMVSS No. 122 above, our research on this issue revealed that the requirement for a separate reservoir for each brake circuit, with each reservoir filler opening having its own cover, seal and cover retention device, was proposed in a notice of proposed rulemaking (NPRM) of March 24, 1971 (57 FR 5516), to establish the safety standard on motorcycle brake systems. The NPRM did not discuss the reason for the requirement that each reservoir filler opening have its own cover, seal and cover retention device. The proposed language was made final (see 47 FR 5033, March 9, 1972), took effect on September 1, 1973, and has not been changed since.

In light of the design of your product, and history of the relevant rule, I would like to indicate in closing that this agency provides a procedure through which parties may petition to change regulations where safe and functional alternatives to existing rules are identified and can be demonstrated. In the event you believe your design can be supported in this way, please consider the procedure that is explained at NHTSAs regulation at 49 CFR Part 552, Petitions for rulemaking, defect, and noncompliance orders.

I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.


Anthony M. Cooke

Chief Counsel



Final 1/18/07; Dot rewrote per TC 2/2/07


cc:NCC-112, subj/chron, Docket Std. 122, DN, NVS-100, NVS-200