Interpretation ID: aiam3648
Oshkosh Trucks
2307 Oregon Street
Oshkosh
Wisconsin 54901;
Dear Mr. Dobbs: This responds to your recent telephone request asking whether Standar No. 121, *Air Brake Systems*, would prohibit the use of a hand control that would allow the vehicle operator to apply only the rear brakes if the driver so chooses. You question whether this can be proper in light of the requirement that vehicles be equipped with brakes that act on all wheels. Although the standard requires brakes acting on all wheels, nothing in the standard prohibits the type of hand control that you mention.; For years, tractor-trailer combinations have been equipped with brake acting on all wheels. Some of these combinations also have been equipped with hand controls that allow the operator to activate only the trailer brakes. It has been argued that in some instances this control can be used to produce beneficial results in combination vehicles. While we can see no beneficial results that could possibly be gained by the use of hand controls in trucks, such a control would not be prohibited by the standard. The standard simply requires a service brake system acting on all wheels. The trucks that you mentioned would still have this system, and therefore, would continue to comply with the standard.; You should note that the agency does not encourage the use of such han controls, particularly on trucks. This type of control provides an opportunity for vehicle operators to lessen the effectiveness of their braking systems. Should an operator use the hand control instead of the full service brakes in a stop and create an accident, there could be the potential for tort liability for both the operator that purchased vehicles with such systems and for the manufacturer who installed them knowing that they could lead to the easy misuse of the braking system. We suggest that you contact your attorneys for further guidance in this area.; Sincerely, Frank Berndt, Chief Counsel