chapter 3
fasteners, sealants, and gaskets
name maximo punoo
date _____________ period 5
instructor olson
after studying this chapter, you will be able to:
- identify fasteners used on small gas engines and implements.
- remove and install various fasteners correctly.
- repair or produce internal and external threads.
- properly select and install fasteners.
- remove, select, and install gaskets correctly.
instructions: after studying chapter 3 of the text, complete the following questions and problems.
1. list at least four of the various conditions to which fasteners are exposed during service.
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2. a thread is a(n) _____ _____ that circles around a shaft, or in a hole.
2. ______
3. flat head screws or bolts must have their heads set into a(n) _____ hole so they will be flush with the surface.
3. ______
4. the most common angle for the heads of flat head screws is ______.

Question

Accepted Answer

### Question 1:
# Brief Explanations:
Fasteners in service (like in small gas engines) face conditions. Common ones: vibration (causes loosening), temperature changes (thermal expansion/contraction), corrosion (from moisture/chemicals), and mechanical stress (load/pressure). These affect fastener integrity.
# Answer:
Four conditions: Vibration, Temperature changes, Corrosion, Mechanical stress (or alternatives like moisture, chemical exposure, wear, impact).

### Question 2:
# Brief Explanations:
A thread is a helical ridge (or "inclined plane" - but more precisely, a helical structure) that circles a shaft or hole. The term for a thread's form is a "helical ridge" (or "screw thread" as a helical structure). So the blank is "helical ridge" (or "inclined plane" conceptually, but standard term is helical ridge/thread).
# Answer:
helical ridge (or "screw thread" - common answer: "helical ridge" or "inclined plane" but more accurate is "helical ridge")

### Question 3:
# Brief Explanations:
Flat - head screws need their heads flush, so they go into a "countersunk" hole. A countersunk hole is tapered to let the flat head sit flush with the surface.
# Answer:
countersunk

### Question 4:
# Brief Explanations:
Flat - head screws typically have a 82 - degree or 60 - degree angle? Wait, the most common angle for flat - head screw heads (wood screws, etc.) is 82 degrees (metric or some standards) or 60 degrees? Wait, actually, for flat - head screws (countersunk), the common angle is 82 degrees (in some systems) or 60 degrees (machine screws). But the standard answer for many technical contexts (like small gas engines/mechanics) is 82 degrees? Wait, no, correction: The most common angle for the heads of flat - head screws (countersunk) is 82 degrees (metric) or 60 degrees (imperial)? Wait, actually, the typical angle for flat - head screws (especially wood screws) is 82 degrees, but in some mechanical contexts, 60 degrees. But the standard answer here (likely) is 82 degrees? Wait, no, let's recall: The countersunk angle (angle of the flat - head) is commonly 82 degrees (for metric) or 60 degrees (for UNC/UNF). But in small engine mechanics, the common angle for flat - head screws is 82 degrees? Wait, maybe I'm overcomplicating. The standard answer for this type of question (textbook on small engines) is 82 degrees? Wait, no, actually, the most common angle for flat - head screw heads is 82 degrees (the angle between the two conical surfaces of the countersunk head). So the answer is 82° (or 60°? Wait, no, let's check: Flat - head screws (countersunk) have a cone - shaped head. The angle of the cone (the included angle) is typically 82 degrees (for metric) or 60 degrees (for imperial). But in many technical textbooks, especially for small engines, the answer is 82 degrees. Wait, but maybe the textbook here uses 82 degrees. Alternatively, 60 degrees? Wait, no, let's think again. The correct answer for the most common angle of flat - head screw heads is 82 degrees (the countersink angle). So the answer is 82 degrees (or 82°).
# Answer:
82° (or 82 degrees)

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