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Mechanical Work Session Exercises - Assignment | MECH 311, Assignments of Mechanical Engineering

Material Type: Assignment; Class: Introduction to Mechanical System Design; Subject: Mechanical Engineering; University: Kettering University; Term: Unknown 1989;

Typology: Assignments

Pre 2010

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MECH 311
MECHANICAL WORK SESSION EXERCISES
Objective: The following exercises will help you learn how to design and/or
analyze several common machine components. These devices are most
likely to be used in your designs. You will become familiar with mechanical
power, belt drives, gears, coil springs and DC-motors.
Exercise I: Power and Belt Drives
Consider the belt drive where shaft A is being driven by a motor at a
constant speed and a constant torque. It is observed that the 10-kg weight
is being lifted at a constant rate of 2 m/s. Also, it is known that the belt drive
is 95% efficient.
a) What is the power being delivered by the motor?
b) What is the torque being delivered by the motor?
c) What is the RPM of the motor?
A
B
10
kg
R=30 cm
R=20 cm
R=10 cm
pf3
pf4

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MECH 3 11

MECHANICAL WORK SESSION EXERCISES

Objective: The following exercises will help you learn how to design and/or analyze several common machine components. These devices are most likely to be used in your designs. You will become familiar with mechanical power, belt drives, gears, coil springs and DC-motors.

Exercise I: Power and Belt Drives Consider the belt drive where shaft A is being driven by a motor at a constant speed and a constant torque. It is observed that the 10-kg weight is being lifted at a constant rate of 2 m/s. Also, it is known that the belt drive is 95% efficient.

a) What is the power being delivered by the motor? b) What is the torque being delivered by the motor? c) What is the RPM of the motor?

A B

10 kg

R=30 cm

R=10 cm R=20 cm

Exercise II: Gears In Exercise I above, let’s replace pulleys A and B with two gears in such a way that the behavior of the 10-kg weight does not change. Both gears have a diametral pitch of 5 teeth/cm while the smaller gear has 20 teeth.

a) What is the number of teeth of the bigger gear? b) What is the pitch diameter of each gear? c) What is the center distance between gears?

Exercise IV: Linkage Design In the crank mechanism shown below, the crank is driven by a constant- velocity motor which imparts a torque, T. The piston is resisted by an extension coil spring of stiffness K. The spring is placed such that when θ=0, the spring is stretched δ units. Note that θ=0 is defined at the right- dead center position, where the piston is at its farthest location from the motor.

We would like to know the maximum torque that the motor must provide in order to turn the crank through a full cycle. To do this:

  1. Relate the torque, T, to the position of the crank, θ. Write a spreadsheet

program that plots T vs. θ. Provide the output of your spreadsheet.

  1. Compare your spreadsheet results with your Working Model simulation? For example, does your maximum torque match what the Working Model simulates? How about the average torque? Provide the output of the spreadsheet containing the data exported from the Working Model simulation.

Useful Knowledge:

  • Free Body Diagram
  • Equations of Equilibrium
  • Two-force member
  • Trigonometry

Thought Process Map:

θ

T K

Crank length = L (^) C Rod Length = LR

θ SpringDeformation SpringForce T