12 1/4 X 5 12K HYD LH US FSA

Dexter Axle Trailer Brake Assembly; Dexter 12-1/4 Inch Diameter x 5 Inch Width; Uni-Servo FSA; Hydraulic Brake System; Drum Brake Type; 12000 Pound Axle; Left Side; With Brake 023-416-00/ Instruction Sheet 059-637-00; Boxed. Dexter offers several varieties of hydraulic trailer brakes. Your vehicle may be equipped with drum brakes or disc brakes. The hydraulic brakes on your trailer are much like those on your automobile or light truck. The hydraulic fluid from a master cylinder or actuation system is used to actuate the wheel cylinder which, in turn, applies force against the brake shoes and drum. The main difference between automotive hydraulic brakes and hydraulic trailer brakes is the trailers actuation system. These systems respond to the braking signal from the tow vehicle and supply the required brake fluid volume and pressure to the trailer brakes. Uni Servo type of hydraulic brake utilizes a single acting cylinder. Upon actuation, the primary shoe is pressed against the brake drum, which causes the shoe to move in the direction of rotation. This movement in turn actuates the secondary shoe through the adjuster assembly. Braking in reverse is significantly less effective than in the forward direction. Another variation is called a "free backing" brake which is commonly used on trailers with a surge hitch system. When backing with a surge brake hitch, normal brakes are applied through the surge mechanism and if there is more brake force on the trailer than the tow vehicle can override, no backing is possible. The free backing plate was developed to allow backing in this application. This brake has a primary shoe on pivot which allows normal application in the forward direction but allows the primary shoe to rotate away from the drum surface when backing. Features: Spider Assembly Is High Strength Ductile Iron With Integral Cast Hydraulic Cylinder. Designed For Long Life Under Heavy Duty Braking Conditions; Adjuster Spring Holds Heel Ends Of Brake Shoes Engaged With Adjuster Link; Anchor Post Of High Strength Steel To Accept High Torques Of Heavy Duty Brake Service; Retractor Spring Assures Uniform Return Of Both Brake Shoes Alter Stop; Positive Brake Shoe Hold-Down For Smooth Brake Shoe Movement; Limited 90 Day Warranty.