When is non-positive sealing preferred? Explain it.

Classification of hydraulic seals 1. Hydraulic seals can be classified according to the method of sealing as a. Positive Sealing b. Non-positive sealing 2. Hydraulic seals can be classified according to the relative motion exist between the seals and other pars as a. Static seal b. Dynamic seal 3. Hydraulic seals may be classified according to geometrical cross section as a. O-Ring seal b. V-Ring & U-ring seal c. T-ring seal d. Piston cup packings e.Piston rings f.Wiper rings A positive seal prevents even a minute amount of oil from getting past. Positive seals do not allow any leakage whatsoever (external or internal). A non-positive seal allows a small amount of internal leakage, such as the clearance of the piston to provide a lubrication film. hope you find it helpful zero