
Unit 60: 
Dynamics of Machines 


Unit code:

H/601/1411



QCF level:

4



Credit value:

15






• Aim
This unit
will deepen learners’ knowledge of the principles and techniques used in the
design of machine elements.
• Unit abstract
This unit will develop learners’ understanding of the parameters and
characteristics of mechanical systems. Learning outcome 1 is concerned with the
characteristics of a wider range of power transmission elements. Learning
outcome 2 will introduce learners to an indepth analysis of some common
mechanical systems using both analytical and graphical techniques. Learning
outcome 3 is concerned with mechanical vibrations and in particular the
transient and steadystate response of massspring systems to disturbing
forces.
• Learning outcomes
On successful completion of this unit a
learner will:
1
Be able to
determine the kinetic and dynamic parameters of power transmission system
elements
2 Be able to determine the kinetic and dynamic
parameters of mechanical systems
3
Be able to
determine the behavioural characteristics of translational and rotational
massspring systems.
Unit content
1
Be able
to determine the kinetic and dynamic parameters of mechanical power
transmission system elements
Gears: gear
geometry; velocity ratios of simple, compound and epicyclic gear trains; acceleration
of geared systems
Screw drives: motion on an inclined plane; efficiency of
squarethreaded lead screws and screw jacks
Flywheels: turning moment diagrams for reciprocating
engines and presses; determination of required flywheel moment of
inertia to satisfy specified operating conditions
Universal couplings: Hooke’s joint; constant velocity joint; conditions for
a constant velocity ratio
2 Be able to determine the kinetic and dynamic
parameters of mechanical systems
Cams:
radial plate and cylindrical cams; follower types; profiles to give uniform
velocity; uniform acceleration and retardation and simple harmonic
motion outputs; output characteristics of eccentric circular cams, circular arc
cams and cams with circular arc and tangent profiles with flatfaced and roller
followers
Plane mechanisms:
determination of instantaneous output velocity for the slidercrank mechanism,
the fourbar linkage and the slotted link and Whitworth quick return motions;
construction of velocity vector diagrams; use of instantaneous centre of
rotation
Resultant
acceleration: centripetal,
tangential, radial and Coriolis components of acceleration in plane
linkage mechanisms; resultant acceleration and inertia force; use of Klein’s
construction for the slider crank mechanism
Gyroscopic
motion: angular velocities of
rotation and precession; gyroscopic reaction torque; useful applications
eg gyrocompass and gyrostabilisers
3
Be able
to determine the behavioural characteristics of translational and rotational
massspring systems
Natural vibrations: massspring systems; transverse vibrations of beams and
cantilevers; torsional vibrations of single and tworotor systems;
determination of natural frequency of vibration; whirling of shafts
Damped
vibrations: representative
secondorder differential equation for massspring system with damping;
transient response of a massspring system to an impulsive disturbance; degrees
of damping; frequency of damped vibrations; logarithmic decrement of amplitude
Forced
vibrations: representative
secondorder differential equation for a damped massspring system subjected to
a sinusoidal input excitation; transient and steady state solutions; amplitude
and phase angle of the steady state output; effect of damping ratio; conditions
for resonance
Learning outcomes and assessment criteria

Learning outcomes

Assessment criteria for pass




On successful completion of

The learner can:




this unit a learner will:












LO1 Be able to determine the


1.1

analyse geared systems to determine
velocity ratio



kinetic
and dynamic



and required accelerating torque



parameters
of mechanical


1.2

determine the operating efficiency of screw
jacks



power
transmission system







and lead screws




elements














1.3

analyse turning moment diagrams for
reciprocating






engines and presses to determine the
required






flywheel parameters for specific operating
conditions





1.4

analyse the characteristics of Hooke’s
joints and






constant velocity joints and recognise the
conditions






for a constant velocity ratio









LO2 Be able to determine the


2.1

determine the output motion of radial plate
and



kinetic
and dynamic



cylindrical cams



parameters
of mechanical


2.2

determine the velocities and accelerations
of points



systems







within plane mechanisms and the associated
inertia













Forces





2.3

analyse systems in which gyroscopic motion
is






present to determine the magnitude and
effect of






gyroscopic reaction torque









LO3 Be able to determine the


3.1

determine the natural frequency of
vibration in



behavioural
characteristics of



translational and rotational massspring
systems



translational
and rotational


3.2

determine the critical whirling speed of
shafts



massspring
systems













3.3

determine the transient response of damped
mass






spring systems when subjected to a
disturbance





3.4

determine the steady state response of
damped






massspring systems when subjected to
sinusoidal






excitation.








Guidance
Links
This unit is
intended to provide progression from Unit 2: Engineering Science and Unit
4: Mechanical Principles.
Essential requirements
There are no essential requirements for this unit.
Employer engagement and vocational contexts
Delivery of this unit will benefit from
centres establishing strong links with employers willing to contribute to the
delivery of teaching, workbased placements and/or detailed case study
materials.
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