Mr. Dietmar K. Haenchen
Manager, Vehicle Regulations
Volkswagen of America, Inc.
3800 Hamlin Road
Auburn Hills, MI 48326

Dear Mr. Haenchen:

This responds to your request for an interpretation of Standard No. 118, Power-operated window, partition, and roof panel systems. You asked whether the "squeezing force limitation" of S5 applies only to the first attempt to close a power operated window, partition, or roof panel system (power-operated system) and not to immediately following attempts to close. You explained that an operator may initiate more than one closing attempt in order to assure the closing of the power operated system under adverse conditions such as low temperature or the presence of ice in the power operated system's track. As discussed below, the S5 squeezing force limitation applies to each closing attempt.

By way of background information, Standard No. 118 requires that a power operated system, while closing, must comply with one of two alternative provisions. The first, S4, generally specifies requirements for situations where a person is expected to be in the immediate vicinity of the vehicle to supervise the closing. The second, S5, covers "unsupervised" closings, i.e., automatic closings or closings where the person initiating the closing is further away from the vehicle.

In the rulemaking establishing S5, NHTSA recognized that unsupervised closings increase the risk that persons, especially children, could be caught between a closing system and the frame. Therefore, to the extent that a power operated system permits unsupervised closings, the agency decided to require an automatic reversal mechanism that reverses the window direction upon its meeting an obstruction. More specifically, if an obstruction is between 4 and 200 mm from any part of the vehicle structure with which the closing system mates, S5 requires window reversal before a force of 100 Newtons is encountered.

S5 does not specify different squeezing force limitation requirements for different closing attempts. Therefore, a

power operated system must meet the same requirements for each closing attempt. We note that since the requirements of S5 address unsupervised closings, the same safety concerns about children being caught between a closing system and frame would be relevant to each closing attempt.

I note that NHTSA decided not to apply the S5 squeezing force limitation requirement to unsupervised closings within the area between 4 mm and any part of the vehicle structure with which the closing system mates. The agency recognized that injury from system closure is not possible in this area, and that unnecessary automatic reversal could result from the system's misalignment or obstruction from ice. Thus, during unsupervised closing, if the system encounters an obstruction less than 4 mm from any part of the vehicle structure with which the closing system mates, the power operated system need not reverse.

I hope that this information is helpful. If you have any further questions, please contact Dorothy Nakama of my staff at (202) 366-2992.


John Womack Acting Chief Counsel

ref:118 d:5/17/95