This repair kit contains the seals, gaskets, and valve components needed to restore the function of the trailer control valve. It sits in the hydraulic system of the host tractor, managing the flow of fluid that operates the trailer's braking or tipping circuits. A leaking or sluggish valve causes delayed response or loss of trailer control. The kit's components match the original valve's internal geometry, so the cracking pressure and flow rates are maintained. On installation, clean the valve bore thoroughly and lubricate the new seals with hydraulic fluid before assembly.