Instalation and Removing Of Fasteners Flashcards
What does ductility mean?
Ductility is the measure of how much a material can be deformed or drawn before it breaks
What is tension (tensile stress)?
Tension is the force that is applied to an object to stretch it lengthwise.
What is compression (compressive stress)?
Compression is the force acting on all materials between the bolt head and nut.
What is torque?
Torque is the turning force set by a wrench on the fastener.
What is elasticity?
The materials ability to be stretched without deformation.
What is elastic limit?
The maximum tension that an object can sustain and still return to its original shape.
What is proof load?
Proof load of a fastener is the highest recommended tensile load for that fastener.
Slightly lower then the yield point.
What is yield point?
Yield point is the point at which the fastener suffers permanent deformation when a tensile load is applied.
What is tensile strength?
Tensile strength is the maximum tensile load a fastener can support before it fractures.
What is shear strength?
Shear stress is measure at right angles to the axis of the bolt.
What causes thread shear in nuts?
Nut may not be thick enough
Nut or bolt may lack the plasticity necessary to deform under tension and distribute the load over more threads.
If the bolt is elongated the full tensile load falls on the first couple threads.
Thread flank area is to small
Not using washers on soft surfaces will result in?
Crushing
Failure on a fine thread is more common then failure on a course thread because why?
- on a 1/2” diameter nut 231% of the average stress on all threads is concentrated on the first fine thread compared with 179% of the course first thread.
- nuts dilate under load, shifting stress toward the weaker tips. The fine thread has less thread flank contact area.
What are the 4 styles of torque wrenches?
Click
Dial
Beam
Electronic
What is the efficiency loss on a 4:1 torque multiplier?
10%
4:1 refers to what in a torque multiplier?
Mechanical advantage.
400/3.6=111.1 ft lb torque required
This is the formula to figure out what to set your torque wrench to.
What is the formula to figure out adjusted torque setting for the use of adaptors?
Torque setting = lb x T/E = adjusted torque setting.
T = length of torque wrench
E = length of extension + length of torque wrench
What are some general rules when using lock wires?
Lock wire must:
be tight
Not be overstressed
Tension must tighten the item it is installed
Ends must be bent out of the way
Must not cross or obstruct a flow passage
What are the different methods for removing nuts?
Penetrating oil
Nut splitter
Hacksaw
Chisel
Heat
What are the tools to repair damaged external threads?
Thread chasing die nuts
Thread files
Hand thread repair tool-shafting
Spark plug hole repair tool
