§393.49
Single Valve To Operate All Brakes
Question 1: Does a combination of vehicles using a
surge brake to activate the towed vehicle's brakes comply with §393.49?
Guidance: No. The surge brake cannot keep the
trailer brakes in an applied position. Therefore, the brakes on the combination
of vehicles are not under the control of a single valve as required by §393.49 (see question
number 1 in §393.48)