Machine Design Review: Springs and Flywheels

A set of 50 review flashcards covering mechanical engineering board exam questions on springs and flywheels.

What is a heavy rotating body which serves as a reservoir for absorbing and redistributing kinetic energy?

Flywheel

Which of the following is not a use of a spring: absorbing energy, measuring weight, source of energy in clocks, or measuring the thickness?

Measuring the thickness

What is the ratio of the mean diameter of the coil to the coil diameter called?

Spring index

What is the overall length of a spring called when it is compressed until all adjacent coils touch?

Solid length

What is the length of a coil spring under no load called?

Free length

In general, steel springs are made of relatively high carbon steel containing what percentage of carbon?

More that $0.5\%$

When heat treated wire is coiled cold, at what temperature should it be heated to relieve bending stresses after cooling?

$$500\text{ F}$$

What low cost spring material is suitable where service is not severe and dimensional precision is not needed?

Hard drawn wire spring

Which spring material is hard drawn with an $80\%$ reduction and made of high-grade steel?

Music wire

Which spring wire has good quality for impact loads at moderately high temperature?

Chromium-silicon

What type of spring has a helical coil wrapped into a circle forming an annular ring?

Garter spring

What type of spring consists of a thin flat strip wound up on itself as a plane spiral, usually anchored at the inside?

Motor spring

What type of spring is made in the form of a dished washer?

Belleville spring

In a laminated spring, why are the strips provided in different lengths?

Economy

What is an elastic stored energy machine element that will recover its basic form when released?

Spring

When a spring is made of ductile material, what is the curvature factor?

Unity

What is the solid length plus the clearance plus the maximum deflection of a spring called?

Free length

The majority of coil springs are made of coil tempered carbon steel wire containing what percentage of carbon?

$$0.60\text{ to }0.70\%$$

Experimental results indicate that the actual frequency of the spring is what percentage range?

$$10\text{ to }15\%$$

According to W. M. Griffith, the critical frequency of the springs should be held at least how many times the frequency of application of a periodic load?

$$20$$

What is the actual number of coils in a spring with squared and ground ends?

$$N + 2$$

What is the solid length of a spring with squared ends?

$$(n + 3)d$$

What is the free length of a spring with ground ends?

$$np$$

What is the shortest length for a spring during normal operation?

Operating length

What is the relationship between the force exerted by a spring and its deflection called?

Spring rate

What is the ratio of the mean diameter of the spring to the wire diameter called?

Spring index

What term refers to the axial distance from a point on one coil to the corresponding point on the next adjacent coil?

Pitch

What range should the spring index be for general industrial uses?

$$8\text{ to }10$$

What is the spring index of a valve and clutch?

$$5$$

What term refers to the space between adjacent coils when the spring is compressed to its operating length?

Coil clearance

The most practical spring designs produce a pitch angle that is less than what angle?

$$12^\circ$$

By what means do engine valves get shut?

Valve spring

Which steel material is used for leaf and coil springs?

AISI 4063

What is the circumference of a coil spring times the effective number of coils called?

Active length

What factor of safety is suggested for springs subjected to light service?

$$1.5$$

What spring refers to a flat or curved member made of thin superimposed plates and forming a cantilever or beam of uniform strength?

Laminated spring

What is the purpose of cross wire grooves?

Absorb shocks because of road unevenness

Which property of a parallel connection of springs is always constant according to the test key?

Thermal conductivity

From where is the speedometer drive generally taken?

Front wheel

What device is used for smoothing out the power impulse from an engine?

Flywheel

Between what ranges does typical flywheel hub length fall?

$$1.25D\text{ to }2.4D$$

What is the recommended coefficient of fluctuation of flywheels for punching, shearing, and pressing machines?

$$0.05\text{ to }0.10$$

What component is attached to the rear end of the crankshaft?

Flywheel

What is another name for a flywheel?

Balance wheel

What kind of energy is stored in flywheels?

Kinetic energy

What are the primary functions of a flywheel?

To keep the speed fluctuation within the desired limits, to limit the momentary rise or fall in speed during sudden change of load, and to keep the angular or retardation within prescribed limits as compared with a perfectly uniform angular speed (All of the above)

In many flywheel designs, about what percentage of the weight is concentrated in the hub and arms?

$$30\%$$

What large rotary machine part functions to store energy and produce uniform angular velocity of the shaft in a reciprocating engine?

Flywheel

What massive wheel assists by its inertia in securing uniform motion of machinery by resisting sudden changes of speed?

Flywheel

According to the test key, what is a function of a flywheel in engine stroke operation?

Complete the unuseful stroke