Explain the Principle of Working of Shock Transmission Unit?

The STU consists of a machined cylinder with a transmission rod that is connected at one end to the structure and at the other end to the piston of the cylinder. Inside the cylinder a specially formulated Silicone compound is filled in an unpressurized condition instead of normally used hydraulic oil. The compound doesn't adjust quickly to accommodate the movement and therefore locks up under the action of a sudden load. Under slow acting thermal, creep or shrinkage movements, the liquefied compound gradually migrates from one side of piston to the other and allowing the piston and cylinder to expand or contract with the structure.