Alb. Mod. Shafting, fits, accessories Flashcards
____ are timing devices
Keys
____ should fail before anything destroys the gear train, hub or shaft.
Keys
A key should fit tightly into a keyway and keyseat otherwise:
it rocks back and forth under load and damages the shaft and hub
With a Pratt and Whitney key, how much of the key sits in the keyseat of the shft?
2/3
What do the rounded ends help with on a Pratt and Whitney key?
Helps with aligning the hub and key
What would the width of a 1014 woodruff key be?
5/16”
10 x 1/32
What would the diameter of a 1014 woodruff key be?
1-3/4”
14 x 1/8
A tapered gib head key should have a taper of:
1/8” over 12”
when driving in a tapered gib head key, what should remain for extraction purposes?
a gap
much like keys, _____ are external grooves and lands that manufacturers machine on a shaft to match with internal grooves and lands in a gear, collar, sleeve, or coupling
splines
a spline allows for:
High torque transfer
parts on a spline may be: (2)
- press fit
- free to move
splines may have a helical curvature. What 3 functions do they serve when they do? (3)
- act as drivers for the component they mesh with
- allow a helical gear to slip into mesh without gear clash
- counteracts axial or end thrust
Pillow block bearings sometimes have eccentric locking collars for locating a fixed bearing on a shaft. What direction would you turn the collar to lock it in place?
In the direction the shaft is going to be turning.
a quick detachable bushing (QD) is a common tapered bushing, recognizable by:
an axial split through the barrel and flange
A split taper bushing is similar to the QD bushing, however, it has an axial split through the barrel and is:
internally and externally keyed
This type of taper bushing has set screws and a series of threaded and non threaded holes that need to be paired and lined up:
taper lock bushing
when tightening a taper lock bushing, the threads on the holes you use will be on the ____ side
sprocket/outer side
locking devices are frictional shaft-hub locking devices that use a ________ to locate and lock hubs and gears onto a shaft.
double tapered thrust ring
You should not use a locking device for ______ applications.
cast iron hub applications
Note: this is due to the amount of press fit applied to the gear or hub
You use this on installation assemblies for positive bearing location. The internal tab locates the washer in the keyseat of the shaft or tapered sleeve and one of the external tabs is bent over to lock the nut in position.
Tapered sleeves
What are the 5 locking/positioning devices? (5)
- Set screws
- Tab washers
- Shear pins
- tapered dowel pins
- Retainer rings
Set screws are also known as:
Grub screws
_____ is used with tapered sleeves, where positive location is important.
Tab washer
____ are used to connect gears or other parts to a shaft, and designed to disconnect the machine drive in an overload position.
Shear Pins
Used when you require extremely precise location or when you frequently assemble or disassemble parts:
Tapered dowel pin
Tapered dowel pins are identified by: (2)
- Overall length
- Diameter at large end
Note: these pins have a 1/4” taper per foot
Retainer rings are also known as:
Snap rings
This provides a removable shoulder to locate, retain or lock components on shafts, bores, or inside housings:
Retainer rings/snap rings
These retainer rings do not require a special recess. The inclined prongs bend to position and lock the ring in place:
Self locking ring
these retainer rings are available in both left and right hand winds. Slotted rings can be internal or external.
spiral wound rings
The two main stresses that a shaft needs to stand up to are: (2)
- Bending stress
- Torsional stress
Bending stress is a force applied by the weight of the shaft itself and the load perpendicular to the shafts axis. To keep them to a minimum:
keep loads close to bearings
The most common shape for shafting is a round cross section. Other cross sections are: (3)
- Square
- Hex
- Hollow
The purpose of line shafting is to:
supply power to or time a number of drives on a single shaft
The recommended max distance between bearings on a standard line shaft is:
8 feet
on a line shaft, gears, pulleys and sprockets should be as close to the _____ as possible
bearings
a line shaft has fixed and floating bearings to accomodate:
expansion
the fixed bearing on a line shaft should always be:
close to the main drive sprocket, pulley or gear
You should use _______ bearings on horizontal line shafts
pillow block
In regards to steel alloys, aluminum:
controls grain size and case hardens
In regards to steel alloys, carbon:
Principal hardening element.
Hardness increases with more carbon content, but looses ductility and weldability
In regards to steel alloys, chromium improves steels hardenability, abrasion resistance and wear resistance, but is also added for:
High temp applications
In regards to steel alloys, copper:
improves resistance to corrosion.
Note: when added in small amounts (under 1%) the copper does not significantly affect mechanical properties of steel
Lead does not alloy with steel. It remains in its elemental state when added, but it’s added to:
improve machinability
The difference between the limit of sizes is the
tolerance
____ expresses the range of permissible tightness or looseness between mating parts
fit
The letters “L” and “T” stand for how many 10, 000 of an inch ____ or ____ the fit is.
Loose or Tight
Note: A clearance fit would be designated with an “L” and an interference fit would be designated with a “T”
Clearance fit indicates that the shaft is always smaller than the bore size, or that the outside diameter of the bearing is always smaller than the:
housing bore
What does AISI stand for?
American Iron and Steel Institute
What does SAE stand for?
Society of Automotive Engineers
What does ASTM stand for?
American Society for Testing and Materials
