Threaded & Locking Devices Flashcards
Other than safety shoes and glasses, what other types of personal protective equipment should be worn in a loud atmosphere with work being done overhead? List 3 examples.
Gloves
Earplugs
Hard hat
Where would you find the grade of a metric bolt and nut? What would you want to look for exactly?
Metric fasteners indicate property class with numbers. The higher the class number the higher the tensile strength.
What is a good reason to maintain good housekeeping in your work area? List 3 reasons.
Tripping hazards can be avoided if walkways are kept clear of boxes, parts, pallets and tools.
Oil spills should be cleaned up immediately to avoid slips or falls.
Access to electrical panels, fire extinguishers and exits must be kept clear of obstacles.
Good housekeeping creates a safe workplace and improves productivity.
What is the difference between a screw and a bolt?
A bolt is any fastener used with a nut and is tightened and released by applying torque to the matting nut. A screw is different from a bolt because it mates with an internal thread. The difference between screw and bolt is its application.
What is a plow bolt? Name one application
Plow bolts are designed to hold the plowshare to the moldboard. The head is countersunk with a square shoulder. It sits flush to allow dirt or gravel to pass easily. Plow bolts are used on many types of heavy construction equipment, such as snowplows, road graders, and scoop shovels.
What is the main advantage when selecting an elevator bolt for a specific application? Also state the possible application.
Elevator bots were originally designed for attaching elevator buckets to conveyer belts, elevator bolts are similar to carriage bolts, except the head is thin and flat. Elevator bolts have a square neck that resists turning when the nut is tightened or remover. The large head provides a greater bearing surface for soft materials. Elevator bolts are used in grain elevators and other conveyer systems.
What are the two systems, Metric and Imperial, ways to determine the strength of a hex head cap screw?
The markings found on bolt head indicate the fasteners grade or property class. Both grade and class refer to the tensile strength of the bolt. Imperial standard bolts are marked with lines to indicate grade or they may be blank. Metric fasteners indicate property class with numbers.
When measuring the length of a socket head cap screw vs a flat head cap screw, where would you properly measure the overall length?
Overall length of flat head cap screw is total length of the screw, top of the head to the end of the thread. Overall length of socket head cap screw does not include head length, measure from the bottom of the head to the end of the thread.
What style of nut is held in position with a cotter pin?
Castellated nut
Acorn nuts serve one main purpose, this is to _______________________.
Protect the thread or to protect nearby objects from contact with the thread.
Hex nuts can be found in different thicknesses. What is the purpose of the hex nut that is thin? Give an example of where you would find/use this style of nut.
Jam nuts are thinner than regular hex nuts and are paired with hex nuts to lock them in position. Jam nut is often used when a nut needs to be locked in place without clamping against another object. The jam nut essentially acts as the “other object” as the two nuts are tightened against each other. Jam nuts are also used as a locknut to prevent vibration from loosening a bolted joint. Used in steering locking tie rod end in place. Used in vibration bowl to prevent nuts from loosening.
Nylon lock nuts differ from a prevailing torque lock nut. What is this obvious difference?
All metal lock nuts are also called distorted thread nuts or crimp nuts because the locking action is created by crimping the nut to cause a distortion in the threads. The distorted thread creates a prevailing torque due to what is known as the interference thread fit. Meaning, the threads within the nut are designed to grab hold of a mating bolts threads when installed which creates the locking action.
Nylon insert lock nuts create their locking action from a nylon ring that is inserted into the top of the nut. When a nylon insert lock nut is mated with a receiving screw, the nylon will then compress around the threads, creating a secure lock between both the nut and screw.
How many times should you use these nuts from question 11? (Not found in your module)
Only use one time
How are machine screws determined?
Machine screws are smaller than machine bolts, usually less than ¼” in diameter and never larger than ¾”. Machine screw dimensions are given with two numbers separated by dash. The first number indicates the screw’s diameter the second indicates thread pitch.
List the three most commonly used drivers for the different machine screws.
Standard, keystone or slotted
Phillips cross slot
Robertson
Give three examples of where you would use a set screw and four different set screw point styles?
Uses:
Hub
Collar
Gear
Sleeve
Point styles: Knurled point Flat point Oval point Cone point
Which style of set screw would you want to use on a application that does not need a lot of “grip” and also does the lease amount of marring to the surface?
Oval point set screw
For ease of assembly/disassembly, what should you do to the shaft before screwing a setscrew onto it to hold it in position? What is another consideration when drilling and tapping your set screw hole into the hub?
For ease of assembly and disassembly, it is good practice to file a small flat under the point of the set screw. It is good practice to use two set screws set at 90° to each other. When considering drilling and tapping another hole for set screw, set it 90° from first hole.
What is a stud? Give a common application.
Studs are cylindrical shafts that are threaded on both ends. One end of the stud, called the metal end, is threaded into a workpiece. The other end, called the nut end, passes through a clearance hole in a mating part. A nut is then used to tighten the assembly together. Used on milling machine to clamp work piece to the table.
What is the difference between a thread forming screw and a thread cutting screw? Give three types of each.
Thread-forming screws are used to assemble sheet metal, plastics and soft metals, such as brass and aluminum. The screw forms a thread by displacing or rolling the material. No cutting occurs and the thread material adjacent to the screw pilot hole wraps around the threads. Types : A, AB, B and C
Thread-cutting screws cut a thread in the parent material, which can be aluminum, zinc, steel sheet, cast iron, brass or plastic. The thread form is very similar to a machine screw thread. Types: BG, BT, D and T
List three commonly used anchors used in industry and write a short explanation of how they work?
Lead screw anchors are resilient lead alloy anchors that conform to uneven surface to provide a gripping action. The flanges are set by placing a pipe over the bolt and into the hole. When you strike the pipe, the lead anchor spreads the flanges out to the hole wall where they grip.
Expansion shields for machine bolts and lag screws are designed to expand as the screw is screwed into the anchor, thus giving the holding power.
Toggle bolts are machine screws with spring-loaded, double-flanged anchors for securing in hollow walls. Toggle bolts require a relatively large hole to pass the anchor through.
A special bolt that has jack-bolt built into them for setting a preload is referred to as?
Multi-jackbolt tension bolts
What could be used to repair a stripped-out thread?
Threaded inserts are used to repair damaged internal threads.
Define the following terms:
Nominal size
The size used for identifying the thread
