Interpretation ID: nht73-6.3

DATE: 11/14/73

FROM: AUTHOR UNAVAILABLE; Lawrence R. Schneider; NHTSA

TO: Rolls-Royce Motors Limited

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of October 16, 1973, requesting a clarification of S7.2 of Federal Motor Vehicle Safety Standard No. 301 (9-1-75) (Docket No. 70-20; Notice 2).

As you are aware, a proposed amendment to Federal Motor Vehicle Safety Standard No. 301 (9-1-75) was published on August 20, 1973 with an anticipated September 1975 effective date (Docket No. 73-20; Notice 1). In the event that the proposed amendment of loading conditions is adopted, the present passenger car requirement, that the vehicle be at its GVWR during testing, will be superseded by the requirement that the passenger car be loaded "to its unloaded vehicle weight plus its rated cargo and luggage capacity weight, secured in the luggage area, plus the weight of the necessary dummies." Under these specifications, rear seat occupant weight will not be a factor of the test load condition unless a specific test requirement calls for dummies to be placed in designated rear seating positions. The proposed amendment would also make it unnecessary to firmly fix the dummies to the vehicle as is presently the case under S7.2.

We have also noted your views on luggage capacity weight and are placing your letter in Docket No. 73-20 as a comment to be considered.

If you require any further clarification, please do not hesitate to let us know.

OCTOBER 16, 1973

The Administrator National Highway Traffic Safety Administration,

Dear Sir,

49 CFR, PART 571 Docket No. 70-20; Notice 2 Standard No. 301 - Fuel System Integrity

Rolls-Royce Motors Limited seeks clarification on the meaning of S 7.2 as published in the Federal Register 38 FR 22397, dated August 20, 1973.

S 7.1 requires the vehicle under test to be loaded to its GVWR and S 7.2 requires weight in excess of the unloaded vehicle weight to be firmly fixed to the vehicle so that it absorbs no significant portion of the vehicle's Kinetic energy.

It seems to us that the only way in which the added weight can absorb the vehicle's Kinetic energy is by actual deformation of the weight itself. Thus, it would be unacceptable to apply added weight which would reinforce the front structure of the vehicle. This would be entirely logical with a front engined vehicle, but would pose serious problems with a rear engined vehicle in which the luggage compartment was at the front of the vehicle. Would there not be practical difficulties in achieving the correct weight distribution, and is it not reasonable for the designer to intend the luggage in these circumstances to absorb some of the vehicle's Kinetic energy, particularly that due to its share of the total mass, when the vehicle is loaded to its GVWR?

2

Rolls-Royce Motors Limited does not make vehicles with luggage stowage capacity at the front, so that particular problem is of no immediate concern to us at this moment. We would, however, be very concerned if the conditions of S 7.2 were to be applied to any future rear barrier crash test, and hence our interest in seeking clarification. Our own suggestion would be to omit the luggage weight from the vehicle test weight, while a specification is drawn up for inexpensive test pieces representing more closely the density and crush characteristics of real life passenger luggage. Such test pieces would be stowed in the luggage compartment but not secured to the vehicle structure, again representing more closely real life conditions.

Docket No. 73-20, Notice 1. proposes an amendment to Standard No. 301, effective September 1975, which would permit the installation of dummies in the front outboard seating positions. It is not clear to us how the weight of the rear seat occupants is to be provided when ballasting the vehicle up to its GVWR. We sincerely hope that S 7.2 of Docket No. 70-20, Notice 2, will not be interpreted to mean that the added weight due to rear seat passengers must be rigidly attached to the vehicle. For obvious economic reasons, which are of vital importance to the low volume manufacturer, we would want to combine testing against Standard No. 301 with testing against other Standards, such as No. 208, and S 5.1 of Standard No. 208 requires anthropomorphic test devices to be installed at each designated seating position. The restraint systems used for these dummies to demonstrate compliance with Standard No. 208 could not be described as rigid.

We should, therefore, be most grateful if you could clarify the requirements of S 7.2 of Standard No. 301 regarding the means to be used for installing additional weight to bring the test vehicle up to its GVWR.

Yours faithfully,

J. B. H. Knight Chief Development and Car Safety Engineer

Copies to: Trevor Williams Rolls-Royce Motors Inc. New Jersey.

K. B. Barnes The Society of Motor Manufacturers & Traders Ltd. London.