This is a way of marking territory if they are rubbing the sides of their faces on the object. Cats have scent glands around their lips and on their chins. The facial pheromones that they mark with are signals of a happy or calm cat to other cats.
The part that simultaneously enables the axle to flex while transmitting the driving force is called a drive axle joint, and is also known as a constant velocity (or CV) joint. The CV Boot is a ribbed, rubber flexible boot that keeps water and dirt out of the joint and the special grease inside the joint.
What does Cv mean? Literally Cv means coefficient of velocity. Cv is generally used to compare flows of valves. The higher the Cv, the greater the flow. It is sometimes helpful to convert Cv into SCFM(Standard Cubic Feet per Minute) and conversely, SCFM into Cv. Although Cv represents flow capacity at all pressures, SCFM represents flow at a specific air pressure. Therefore, the following chart relates Cv to SCFM at a group of pressures. To obtain SCFM output at a particular pressure, divide the valve Cv by the appropriate factor shown below.