Shafts And Attachments Flashcards
The term “FIT” can be defined as what?
The range of permissible tightness or looseness between two mating parts.
What are Kennedy Keys?
A pair of tapered keys installed 90 degrees apart from eachother on a shaft.
What is the standard taper for a key in inches?
- 1/96”
- Sometimes expressed as 1/8” in 12”
With a hollow shaft, a 25% reduction in weight reduces strength by how much?
6.25%
A key is a timing device that is designed to be what on a shaft?
The weakest part of a machine.
What is a Class 1 fit for a key on a shaft?
- A clearance fit, where there is a relatively free fit for the key to slide in the key seat.
What is a Class 2 fit for keys on a shaft?
Class 2 is a relatively tight fit, with a possible slight interference with the key seat.
What is a Class 3 fit for a key on a shaft?
Class 3 is a interference fit for permanent assemblies.
Most couplers are positively located on a rotating shaft by means of what?
Keys
Tolerence is defined as what?
The total permissble variation a given piece can be both over and undersized.
Which is more common, straight keys or taper keys?
Straight
What type of key is this?
What is the round part designed for?
- Woodruff Key
- The circular shape permits the key to allgin itself to suit either a parallel or a tapered shaft. The design minimizes any tendency of the key to tip when load is applied.
What is the taper ratio for a metric taper key?
1/100
Are set screws required with taper keys?
No
What is the carbon content of steel AISI 4340?
- 0.40%
What is a Dutchman?
A spacer for between a key and Drift Key when removing the key.
The Coefficient of Linear Expansion for Steel is what?
0.0000063” per inch per degree of F
Is Bar Stock made to oversized tolerence?
No
C type hubs have how many bosses?
Two Bosses
What is a Saddle Key?
An emergency key.
Lead improves what in steel?
Machinability
Is Key Stock made to an oversized tolerence?
Yes
Ferrous metal keys are made from what?
Cold worked steel.
Rectangular Key is also refered to as what?
Flat Key
What key should you not use with Cast Iron?
Taper Key. The Cast Iron could crack due to pressure.
A key identified as 1212 is what?
- Half-moonshape with a diameter of 1.5”
- Related to Woodruff Keys
What is the maximum allowance for fitted keys in unidirectional, low torque applications?
0.002” on the sides and 0.005” on the top.
What is the rule of thumb for sizing the width of a key for a given shaft?
- 1/4” per inch of shaft diameter.
What is a Gib-headed Key?
A rectangular key with an enlarged head on one end to facilitate quick extraction for frequent removal.
Which Key is secured with screws in the key?
Fixed Feather Keys
True or False: All shafting is usually manufactured in standard dimensions.
True
What is a Pratt-Whitney Key
A rounded end, drop in key.
When relative motion in the axial direction is required what key is best?
Feather Key
What are Keys typically made of?
Steel AISI 1020 in cold drawn condition
What are Offset Keys?
Keys with steps in them. They facilitate quick removal.
Name two types of Boxed Keys.
- Pratt and Whitney Key
- Buried Key
What are the two types of Feather Keys?
Fixed and Sliding
What is so special about Feather Keys?
They permit end movment for two parts either in operation or during assembly.
How are Woodruff Keys sized?
They are given in standardized sizes designated by a code.
The last two digits give the Nominal diameter in eighths of an inch.
The first digit(s) before the last two give the Width of the key in thirty-secondths of an inch.
Can you make Woodruff Keys from round stock?
Yes, in emergencies.
What is a Boxed Keyseat?
- A channel cut into the shaft for a Key to sit in.
- Not to be mixed up with an Open Keyseat which are cut at the end of a shaft.
Describe a Sled-Runner Keyseat.
Describe a Profile Keyseat.
Do Woodruff Keyseats need setscrews?
No, the the shape of the channel will hold the key in place.
What do you use to cut Keyseats in an attachment?
Milling Machines or manually: Broach and Arbor press
What insures positive contact between Keys and shafts?
Set Screws
What are Fox Wedges?
Wedges which are used to remove Gib-headed Keys.
Answer
D)
Answer
C)