Shaft Terminology KC4 Flashcards
Why are shafts used?
They are used for the following reasons:
1) support
2) transmitting power
3) transporting a load
Why is case or surface hardening important for shafts?
It is used to help the shaft withstand the wear of the bushing riding directly on it.
Name a couple of methods of securing components such as gears and bearings to rotary shafts.
1) Linear shafts
2) Rotary shafts
3) Posts
4) Rods
What controls shaft rigidity? The material, geometry, or both? Why?
Rigidity cannot be controlled by material decisions, but only by geometric decisions. Deflection is not affected by strength but rather by stiffness as represented by the modulus of elasticity.
When starting a shaft design, what material selection is appropriate for the first iteration? Why?
It is good to start with an inexpensive, low or medium carbon steel for the first time through the design calculations. This allows for future modifications for whether we need to design for strength or deflection considerations.
When are shafts typically surface hardened? Why?
They are really only surface hardened if they serve as the actual journal or a bearing surface.
How many bearding should be typically used?
Two
How many bearings should be positioned to best support the load-carrying components?
It is best to support load-carrying components between bearings, rather than cantilevered outboard of bearings.
In what situations might components need to be mounted “outboard?” Regarding shaft length, what should you do in these situations?
Pulleys and sprockets often need to be mounted outboard for ease of installation of the belt or chain. The length of the cantilever should be kept short to minimize deflection.
What are best practices regarding shaft length?
Shafts should be kept short to minimize deflection and bending moments. However, some axial space between components is desirable to allow for lubrication flow and to provide access space for disassembly of components with a puller.
How are components located and held in place on a shaft?
The primary means of location is to position them against the shoulder of the shaft. Other methods include: retaining rings in grooves, sleeves between components, clamp-on collars, and press fits.
Why is the largest diameter of the shaft typically in the center?
For ease of assembly and disassembly and to allow components to be slid on from the ends.
Sometimes a shoulder is needed on both sides of a component. How might this be accomplished?
One of the shoulders must be created by such a means as a retaining ring or by a sleeve between two components.
