8 CHAPTER ONE to make alignment. Insert a new cotter pin through the nut and hole, then tap the head lightly to seat it. Bend one arm over the flat on the nut and the other against the top of the stud or bolt (Figure 13). Cut the arms to a suitable length to prevent them from snagging on clothing or skin. When the cotter pin is bent and its arms cut to length, it should be tight. If it can be wiggled, it is improperly installed. Do not reuse cotter pins, as their ends may break and al- low the cotter pin to fall out and the fastener to loosen. @ Full support '..,iot-?--:-~~..,....4~ areas Circlips Circlips can be internal or external design.
They are used to retain items on shafts (external type) or within tubes (internal type). In some applications, circlips of varying thickness are used to control the end play of parts assemblies. These are often called selective circlips. Re- place circlips during installation, as removal weakens and deforms them. Two basic styles of circlips are available: machined and stamped circlips. Machined circlips (Figure 14) can be in- stalled in either direction (shaft or housing) because both faces are machined, thus creating two sharp edges. Stamped circlips (Figure 15) are manufactured with one sharp edge and one rounded edge.
When installing stamped circlips in a thrust situation, the sharp edge must face away from the part producing the thrust. When in- stalling circlips, observe the following: a. Remove and install circlips with circlip pliers. See Circlip Pliers in this chapter. b. Compress or expand circlips only enough to install them. c. After the circlip is installed, make sure it is com- pletely seated in its groove. Engine Oil Oil for marine and automotive four-stroke engines is classified by the American Petroleum Institute (API) and the Society of Automotive Engineers (SAE) in several categories. Oil containers display these classifications on the top or label.
API oil classification is indicated by let- ters; oils for gasoline engines are identified by an "S" and oils for diesel engines are identified by a "C". LUBRICANTS Periodic lubrication ensures long life for any type of equipment. The type of lubricant used is as important as the lubrication service itself, although in an emergency the wrong type of lubricant is better than none at all. The following paragraphs describe the types of lubricants most often required. Be sure to follow the manufacturer's recommendations for lubricant types. Generally, all liquid lubricants are called oil.
They may be mineral-based (including petroleum bases), natu- ral-based (vegetable and animal bases), synthetic-based or emulsions (mixtures). Grease is an oil to which a thick- ening base has been added so that the- end product is semi-solid. Grease is often classified by the type of thick- ener added; lithium soap is commonly used. Viscosity is an indication of the oil's thickness. The SAE uses numbers to indicate viscosity; thin oils have low numbers while thick oils have high numbers. A "W" after the number indicates that the viscosity testing was done at low temperature to simulate cold-weather operation. En- gine oils fall into the 5W-30 and 20W-50 range.
Multi-grade oils (for example lOW-40) are less viscous (thinner) at low temperatures and more viscous (thicker) at high temperatures. This allows the oil to perform effi- ciently across a wide range of engine operating condi-