Abstract: One pair of emergency drag brake units are at each end of a vehicle. Each unit comprises a leg member with a serrate-toothed, ground-engageable foot telescopically movable in a support member carried by the frame. An elastic member is shown in one embodiment urging the leg downwardly to maintain pressure on the ground. Hydraulic jacks move the feet to braking positions engaging the ground while the axes of the leg members at each end of the vehicle are inclined toward the other end of the vehicle at an acute angle of 15.degree. or more relative to the vertical, thereby automatically enabling the so-inclined legs at the trailing end of a skidding vehicle to exert a greater frictional drag than the oppositely inclined legs at the leading end regardless of the vehicle's forwardly or rearwardly skidding orientation, and stopping it in a straight line. In one embodiment, the jacks swing the support members about pivots.