Abstract: A sway stabilization system to inhibit an undesirable sideways sway between a towed vehicle (15) and a lead vehicle (14) comprises a brake assembly (17) having towed vehicle parts and lead vehicle parts operatively connected together in parallel with the draw bar and hitch assembly (16). The towed vehicle parts include a sway transmission member (21) secured to a draw bar (18). The lead vehicle parts include a braking surface carrier member (22), which engages with the draw bar (18), for pivoting movement with the sway transmission member (21) about the axis of the hitch pin, the braking surface carrier member (22) being subject to braking action by clutch plates (33, 34) in response to undesirable sway being detected by a coupling sensor (36).