ADVANTAGES OF MECHANICAL LEATHER PACKINGS

Mechanical leather packings, because of the very nature of the material from which they are produced, have advantages not possessed by other packings. The hide from which leather for mechanical leather packings is made is a natural product. Its individual fibers, each consisting of a bundle of fibrils, are interwoven in a non-directional pattern that is unmatched by any other material. Leather is pliable, tough and highly resistant to abrasion and wear.

 

a. Have Low Coefficient of Friction

Because of an extremely low coefficient of friction, little heat is generated when leather packings are used. This results in high efficiency and a long life. The fibrous structure of the leather surface carries a film of the actuating medium which in most cases functions as a lubricant and still further reduces the coefficient of friction.

Leather packings operate smoothly and do not cause chattering at low pressures and slow speeds. Because of their low coefficient of friction, they have a very low static seizure and do not require a relatively high pressure to start motion.

b. Do Not Readily Cold Flow

Leather packings, properly supported, because of the inherent natural strength of the leather from which they are made, will withstand the highest pressures to which any packing may be subjected with a minimum of cold flow or extrusion.

c.  Low in First Cost

Leather packings, due to their long life and the relative simplicity of die and tooling requirements, are comparatively low in cost.

d. Suitable for Wide Range of Pressures

Leather packings are called upon and are obtain­able to operate against pressures ranging from a few ounces up to many thousands of pounds per square inch. In general, the type of leather packing used with high pressure requirements should be one rec­ommended by the packing manufacturer as it may involve the application of special leathers and im­pregnancs.

e. Will Not Score or Abrade

Leather packings are non-abrasive and non-corrosive and actually tend to polish the metal surfaces which they contact. Most other packing materials operating under the same conditions have a tendency to score the metal or abrade the packing.

f. Adaptable to Different Types of Service

Leather packings are impregnated with suitable materials to make them adaptable to a wide range of operating conditions.

g. Great Stability

Since leather packings will not deteriorate due to either oxidation or sunlight, they can be kept in stock without loss of their desirable and essential qualities.

h. Not Affected by Sub-Zero Temperatures

Leather is unaffected by sub-zero temperatures and packings molded from it, when properly impregnated will remain operable under those conditions.

Pressures Encountered

Mechanical leather packings are called upon to operate against pressures ranging from a very few ounces up to many thousand pounds per square inch.

Under the category of mechanical leather packings are found delicate regulator diaphragms and some leather cup applications in which the actuating pres­sure is measured in ounces. At the other end of the range are heavy hydraulic applications involving pressures as high as 50,000 to 60,000 psi (pounds per square inch). Leather packings on special applications have been used at pressures as high as 140,000 psi.

Temperature Ranges

Leather is unaffected by sub-zero temperatures and packings made from it can therefore be used at these temperatures without cracking, breaking, or shattering. Almost all leather packings can be used at temperatures ranging from minus 30° F. to plus 150" F. Special packings are available for temperatures ranging from minus 70° F. to 210°F.