Interpretation ID: 1984-4.13

TYPE: INTERPRETATION-NHTSA

DATE: 12/21/84

FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA

TO: Western Star Trucks Inc. -- Stan R. Gornick, MVSS Compliance Specialist

TITLE: FMVSS INTERPRETATION

ATTACHMT: 7/20/84 letter from Frank Berndt to Hino Motors (U.S.A.) Inc.

TEXT:

Stan R. Gornick, P. Eng. MVSS Compliance Specialist Western Star Trucks Inc. 2076 Enterprise Way Kelowna, British Columbia V1Y 6HB Canada

This is in reply to your letter of December 10, 1984, informing us of compliance difficulties with respect to braking systems on two concrete mixer trucks which "are scheduled to be shipped the last week of December." You have asked for an "exemption to the certification requirements of FMVSS 105 and FMVSS 121."

Although you have stated that the mixer is being installed elsewhere, your letter implies that Western Star will nevertheless be the certifier of the assembled vehicle and not must its initial stage manufacturer. That you are the certified as the assumption on which this letter is based. We have reviewed your letter and have determined that it is the air brake standard, No. 121, with which these vehicles must comply. I enclosed a copy of a recent interpretation covering air-over-hydraulic systems similar to yours which reiterate earlier interpretations. I would like to point out that there is no legal requirement in the United States that a manufacturer conduct the tests specified in the safety standards before he certifies compliance. Your certification may be based on a good faith conclusion that were the vehicles to be tested in the manner specified they would conform to the stopping distance requirement. This conclusion can be based, for example, on computer analyses (such as that provided you by Rockwell International with respect to requirements other than stopping distances), engineering studies or mathematical analyses.

We have no authority to provide exemptions within a time frame that is responsive to your problem. There are detailed requirements for petitions and the public must be offered an opportunity to comment on them. The entire process requires three to four months.

Having filed two inconsequentiality petitions in 1984, Western Star is familiar with that procedure, but the agency has no wish to encourage manufacture of nonconforming vehicles with the implied promise that such petitions would be granted. We therefore advise you to reconsider the compliance status of the two concrete mixers in light of our comment that certification need not be based upon actual vehicle testing, with the thought that you may conclude that the trucks can be certified as meeting Standard No. 121.

Sincerely,

Frank Berndt Chief Counsel

Enclosure (7/20/84 Letter from Frank Berndt to Hino Motors (U.S.A.) Inc. omitted here.)

December 10, 1984

Office of Chief Counsel, NHTSA

Dear Sir:

Western Star Trucks Inc. has been awarded the contract to manufacture two only concrete mixer trucks. These vehicles are 6X6's with LRockwell SSHD 44,000 lb. tandem rear axles arid Fabco SDA23 -23,000 lb. front axles. The load distribution is 21,780 lbs. on the front axles and 44,000 lbs. on the rear.

The problem I am facing is that the Fabco front driving axle cannot accomodate air chambers, therefore it is manufactured with hydraulic brakes.

Now I have a vehicle with air brakes on the rear wheels and hydraulic brakes on the front wheels with an air over hydraulic actuator.

FMVSS 121 and FMVSS 105 do not indicate how to deal with vehicles equipped with both air and hydraulic systems.

We have had Rockwell International do a computer analysis of our braking system and they agree with the sizes of brakes, linings, air chamber sizes, etc. and have issued a certificate stating "THE BRAKES APPROVED ARE CERTIFIED TO MEET APPLICABLE DYNAMETER REQUIREMENT OF FMVSS 121 PARAGRAPH 55.4 WHEN APPLIED WITHIN THE LIMITING CONDITIONS OF VEHICULAR BRAKE RECOMMENDATION APPROVAL NO. C-04817 - CERTIFICATION NOT APPLICABLE TO VEHICLE STOPPING REQUIREMENTS".

The test data we have on file does not cover this brake configuration, therefore, we would have to perform a complete set of brake test; to verify FMVSS compliance.

The problems I have with this are: 1) We are not installing the mixer on the vehicle. It is being installed elsewhere.

2) To do a proper brake test the vehicle should be equipped as it will be used in the field.

3) A mixer contains an unstable load as it will shift as the brakes are applied. Therefore, to conduct a test in the laden condition it should contain concrete so that the weight transfer effects will be taken into account.

As the truck manufacturer we cannot certify compliance to FMVSS 105 and 121 for the reasons stated above and the mixer installer will not have the facilities or experience to conduct the required tests.

From our experience with 6X4 mixer vehicles with air brakes on all wheels we are confident the vehicle will pass all required braking tests.

In view of the above circumstances we are applying for an exemption to the certification requirements of FMVSS 105 and FMVSS 121.

These vehicles are scheduled to be shipped the last week of December. If an answer to my request can be made prior to this date it would be greatly appreciated. I may be contacted via a collect call to 604-860-3319, ext. 526.

If you require any additional information please contact me by telephone as letters from the United States generally take two weeks to arrive here.

Sincerely,

WESTERN STAR TRUCKS INC.

PER:

Stan R. Gornick, P. Eng. MVSS Compliance Specialist

SRG/az

c.c. Glen Ashdown Bruce Mabbett