8,500lb Disc Brake Actuator - Tie Down Engineering ModelThe Model 850E works by the "surge" or "push" of the trailer toward the tow vehicle. This automatically synchronizes the trailer brakes with the tow vehicle axle brakes. When the trailer pushes against the tow vehicle, the actuator telescopes together and applies the force to the master cylinder, supplying hydraulic pressure to the brakes. The built-in dampening shock absorber retards the telescoping shock against the hitch ball. Be sure to comply with the regulations for brakes in your state. Brake laws are sometimes minimum standards, and users may wish to add additional brakes to a trailer.Read the tow vehicle owner&&';;s manual on towing capacity and other towing recommendations before installing brakes or this actuator. The Model 850E Actuator is completely assembled and ready to bolt into place if not all ready-installed. Manufactured for tongue sizes: 3"x 3", 3"x 4" & 3"x 5".Features: 8,500 lbs. capacity Fits 2" in. hitch ball For use with disc brakes Maximum Actuator Capacity: Gross Load: 8,500 lbs. Maximum Tongue Load: 850 lbs. The actual in-service rating is limited to that of the ball and hitch or the least-rated component on the tow vehicle or trailer being used, or the trailer manufacturer&&';;s G.V.W.R. shown on the certification label, whichever is lower (note: G.V.W.R. is the Gross Vehicle Weight Rating, which includes the trailer and the load weight as a total gross weight). Quick Guide (pdf)Owner&';s Manual (pdf)