Interpretation ID: 1982-1.32

TYPE: INTERPRETATION-NHTSA

DATE: 03/26/82

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Nissan Motor Co., Ltd. -- Shizuo Suzuki, Engineering Office of North America

TITLE: FMVSS INTERPRETATION

TEXT:

Nissan Motor Co., Ltd. Engineering Office of North America Suite 707 1919 Pennsylvania Avenue, N.W. P.O. Box 57105 Washington, D.C. 20037

This responds to your letter asking whether your new wiping system design meets the frequency requirements of Safety Standard No. 104. Windshield Wiping and Washing Systems.

By way of background information, I would point out that the agency does not give advance approvals of vehicles or equipment. The National Traffic and Motor Vehicle Safety Act places the responsibility on the manufacturer to determine whether its vehicles or equipment comply with applicable requirements. A manufacturer then certifies that its vehicles or equipment comply with all applicable standards. The following interpretation only represents the agency's opinion based on the information provided in your letter.

The system described in your letter operates on two settings. One of the settings provides continuous operation at a speed of about 75 cycles per minute. The wipers operate at the same speed for the second setting, but there is intermittence between each cycle. Because of the intermittence, the wipers operate only about 45 cycles per minute. As explained below, it is our opinion that such a system meets the frequency requirements of Standard No. 104.

Section S4.1.1 reads as follows:

S4.1.1 Frequency.

S4.1.1.1 Each windshield wiping system shall have at least two frequencies or speeds.

S4.1.1.2 One frequency or speed shall be at least 45 cycles per minute regardless of engine load and engine speed.

S4.1.1.3 Regardless of engine speed and engine load, the highest and one lower frequency or speed shall differ by at least 15 cycles per minute. Such lower frequency or speed shall be at least 20 cycles per minute regardless of engine speed and engine load.

S9.1.1.4 Compliance with subparagraphs S4.1.1.2 and S4.1.1.3 may be demonstrated by testing under the conditions specified in sections 4.1.1 and 4.1.2 of SAE Recommended Practice J903a, May 1966.

The primary issue for this interpretation is whether the system meets the requirement in section S4.1.1.1 for "at least two frequencies or speeds." This issue arises because the wipers operate at the same speed for the two settings, using intermittence to achieve a different number of cycles per minute. It is our opinion that the system does meet this requirement, since the language of the standard speaks of frequencies or speeds. While the speed may be the same for the two settings, the frequencies are different.

The system satisfies the requirements in sections S4.1.1.2 and S4.1.1.3 that one cycle or speed be at least 45 cycles per minute, that the highest and lowest frequency or speed differ by at least 15 cycles per minute, and that the lower cycle be at least 20 cycles per minute (assuming that the requirements are met regardless of engine load and engine speed).

While your wiping system design appears to meet the frequency requirements of Standard No. 104, we do have a possible concern about its safety. On its lower setting, between the periods of intermittence, the speed of the wiper blades would still be at a rate of about 75 cycles per minute. It is possible that operation at such a fast speed might cause chattering of the wipers when used during light precipitation. If that happened, drivers might be less likely to use their wipers during light precipitation. We suggest that you consider that possibility before going forward with your design.

Sincerely,

Frank Berndt Chief Counsel

October 19, 1981 Ref: 81-106-S

Mr. Raymond A. Peck, Jr., Administrator National Highway Traffic Safety Administration Room 5220 400 Seventh Street, S.W. Washington, D.C. 20590

Dear Mr. Peck:

We, Nissan Motor Company, Ltd., would like to take this time to ask you for your interpretation concerning the wiping frequency requirements of S.4.1.1. of FMSS 104.

Our questions can be found on the attached page.

Your interpretations will be appreciated very much.

Very truly yours,

NISSAN MOTOR COMPANY, LTD.

Shizuo Suzuki Washington Representative Safety

SS:rk

Attachment

cc: Mr. C. H. Raehn Head, Lighting & Visibility Group

QUESTION CONCERNING WIPING SPEED FOR MVSS 104

Please let us know if the following new wiping system meets the wiping frequency requirements of S.4.1.1. of MVSS 104.

New System

The wiping speed (or time) for a cycle (T) is all the same between low speed and high speed cycles.

*Insert figure here

Ordinary System

The wiping speed (or time) for a cycle is different from each other

*Insert figure here