@ LittleInch Yes, this is a picture taken from agricultural trailer. I have seen this system in all agricultural trailers. I was just wondering whether it was for braking system or suspension! I am still confused why agricultural trailers do not have suspension system!!
LittleInch is correct, it is the mechanism to move the brake shoe's to the "on" position when activated by the hydraulic cylinder and of again when the cylinder is deactivated. Simple but effective for an agricultural trailer and not all that different from what you would find on heavy motor vehicles. For your interest it is not "connected" to the wheel / axle - but will be suspended from the axle and supported by the backing plate forming part of the brake system.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
Ag equipment does not use suspensions because it would cause more problems than it would help. Trailers would be more likely to tip over on a slope, and ride height changes with load. Tractors are basically equipment foundations with wheels. Plow depth could not be controlled if there is a suspension. Suspensions add cost and complexity, and provide no value at low speeds.
