thereby tightening the cable 302 against the fixed point 308 since the inner wall 250 is affixed to the brake pedal arm 420 of the towed vehicle the towed vehicle 39 s brakes are applied in the preferred embodiment the cable 302 is a coated flexible cable known to the trade referring to fig2 and 4 the air cylinder 110 is mounted to the brake pedal arm 420 of the towed vehicle using the mounting plate 260 and mounting bolts 230 and mounting nuts 225 as input air is applied to the air input port 200 the cable 302 is tightened against the mounting point 308 the inner wall 250 is secured to brake pedal arm 420 as air is applied to the air cylinder 110 the outer wall 210 is extended away from the firewall 309 thereby applying the towed vehicle 39 s brakes as indicated in fig4 a in operation positive air pressure and flow is provided from a towing vehicle brake system to inlet line 100 air pressure in proportion to brake pressure in the towing vehicle is provided to cylinder 110 to apply the brakes in the towed vehicle in proportion to the braking in said towing vehicle air flow and pressure from line 100 also flows to the valve 104 the air valve 104 is a solenoid operated valve spring biased to normally closed as shown in fig1 in the preferred embodiment of the present invention a signal from vacuum switch 125 can call for pressure to be supplied when the vacuum in brake booster 107 of the towed vehicle gets low when air pressure from the towed vehicle passes through valve 104 it is supplied to venturi 102 and the positive flow of air through the venturi 102 creates a vacuum.