The African National Congress is starting its “dispute resolution process” in a bid to address the a.
The grease that we buy at automotive supplies shops consists of three distinct parts: an ordinary lubricating oil called the base oil; an additive package ; and a thickener .
Greases provide a lubricating film on the surfaces of rolling elements and raceways and between ball and socket in a ball-joint.
The lubricant is a thin film of the base oil which is released as the fibrous network within the grease is ruptured under shear. The shearing takes place only in the portion of the grease which is in intimate contact with moving surfaces.
The rest of the grease remains intact and functions as a sealant and a reservoir from where base oil is gradually released towards the region of rupture.
The action can be compared to millions of microscopic sponges, each one gradually releasing oil into the work zone.
The greater the amount of shear stress the grease experiences (likened to squeezing the sponge), the faster it releases its hold on the base oil.
The "bleeding rate" of the grease has to be just right.
The stiffness of a grease is an important consideration when selecting the right grease for a particular application.
The National Lubricating Grease Institute has devised a standardised procedure to rate any grease on a 9 point stiffness scale, ranging from grade 000 to grade 6.
For general use on a car, the best all-round choice is a grade 2 lithium-based grease with molybdenum disulphide included in the additive package.
There are two points that the home mechanic should watch out for when it comes to greasing: do not overfill wheel bearings when repacking them with fresh grease; never mix different greases. It's best to standardise one grease for all grease points on your car and to do the greasing yourself.
There is one further grease that should be mentioned, namely rubber grease. Ordinary mineral oil-based grease should never be allowed to come into contact with rubber seals in hydraulic brake and clutch components. When assembling such components, use either silicone grease or vegetable oil-based rubber grease (often coloured red).