Mechanical Engineering
ME 251 Project – Fall 2020 Page 1 of 10
ME251 Statics, Fall 2020 Design Project
As you progress through your engineering career, you will find that constructing engineering
samples, test fixtures, and prototype parts will become an integral part of your work assignments.
Showing physical parts to fellow engineers and managers will help you communicate your ideas
and help with the problem-solving process. You might need to provide samples to potential
clients to help your company win a new contract. As a start down your engineering path, you
have been provided a simple model to build which will act as a demonstration sample for your
project. You then need to determine specific engineering parameters for your vehicle and
specify several engineering components. You will need to answer several short essay questions.
Your project involves
1. Building your demonstration sample.
2. Determine the center of gravity of your vehicle.
3. Determine the reaction forces at EACH wheel.
4. Determine the bearing reaction forces and select an appropriate set of wheel bearings for
the application.
5. Determine the internal reactions at specific locations in the spindle.
6. Documenting your work in a final report
1. Building your demonstration sample.
Your project is based on the vehicle you were given at the beginning of the semester. The first
step of the project is to build your vehicle. Use the instructions that came with the vehicle to
assemble it. Take three pictures documenting the build process. The final picture is to include
you along with your finished vehicle. Communicating “lessons learned” to other engineers is a
vital part to improving future products and is used extensively in industry. As part of your final
report, include at least two lessons learned to communicate to the engineers who worked on the
original design/packaging of the small-scale vehicle. These may be related to build issues you
had and/or opportunities for changes to improve the product. Just like the real world, you must
justify your suggestions.
2. Determine the center of gravity of your vehicle
Using the following pages, look up the vehicle parameters that matches your vehicle in the
uploaded Project Data file (.pdf) in Canvas. Determine your vehicle’s center of gravity relative
to the coordinate system given. The following pages show general component locations relative
to the required coordinate system. The coordinate system origin is the centerline of the front
wheels with positive distances towards the rear of the vehicle. The major components are: (1)
Front Wheels, (2) Rear Wheels, (3) Frame, (4) Engine, (5) Cargo Weight, and (6) Ballast.
Location of the center of gravity is an important vehicle parameter. In your report discuss the
effect the location of the center of gravity might have on the operation of the vehicle. Give some
thought as to how these types of vehicles may operate and the conditions they might be exposed.
Studying your model may provide some insight to this question.
ME 251 Project – Fall 2020 Page 2 of 10
Figure 1: Heavy Duty Fork Truck
X
1 2
3
4
5
6
ME 251 Project – Fall 2020 Page 3 of 10
Figure 2: Underground Loader
X 1
2
3
4
5
6
ME 251 Project – Fall 2020 Page 4 of 10
Figure 3: Log Handler
X 1 2
3
4
5
6
ME 251 Project – Fall 2020 Page 5 of 10
Figure 4: Mobile Crane
X
1 2
3
4
5
6
ME 251 Project – Fall 2020 Page 6 of 10
Figure 5: Drilling Machine
X
1 2
3 4 5
6
ME 251 Project – Fall 2020 Page 7 of 10
Figure 6: Smooth Drum Soil Compactor. This vehicle only has one front “wheel” and the weight
given is for the complete roller “wheel”.
X
1 2
3
4
5 6
ME 251 Project – Fall 2020 Page 8 of 10
3. Determine the reaction forces at EACH wheel
Using the same weights and dimensions used in the center of gravity calculation, determine the
normal reaction force EACH wheel exerts on the ground. Assume the vehicle is symmetrical
with respect to the x-y plane.
4. Determine the bearing reaction forces and select a set of wheel bearings for the application
The uploaded Project Data file in Canvas also gives the
dimensions and weight you are to use for this part of
the project. DO NOT USE THE WHEEL WEIGHTS
OR REACTIONS CALCULATED IN THE CG
PORTION ABOVE FOR THE FOLLOWING
CALCULATIONS. This is being done to prevent
carry-thru mistakes in the calculations. The values to
use are specifically assigned to each student. The
drawing to the right is a wheel/hub/spindle assembly
typical of many automotive and industrial vehicles.
Load W acts at the tire contact patch (26 in. from
spindle centerline) which is in contact with the ground
and is assumed to act through the centerline of the
wheel. Wheel offset A is the distance from the wheel
centerline to where the wheel is bolted to the hub, i.e.
wheel mounting surface. For this drawing, the wheel is
shown with a positive offset which means the hub face
is outboard (i.e. in this drawing to the right of) the
wheel centerline. B is the distance from the hub face
to the centerline of the outer bearing F1. C is the
distance from the centerline of F1 to the centerline of
inner bearing F2. D is the wheel backspacing which is
the distance from the wheel bead to the wheel
mounting surface. E is the wheel width which is
measured from the inner wheel bead to outer wheel bead.
Assuming a factor of safety of 1.75 (i.e. multiply the given load W by 1.75), determine the
bearing reaction forces and select an appropriate set of tapered roller bearings from the table
below. Bearing F1 has an inner diameter of 1-3/4 in. while bearing F2 has an inner diameter of
2-1/4 in. Use the boxed Dynamic Load Rating column for your selection. Hints: Assume the
wheel/hub interface acts as a fixed joint, and the hub is adequately supported by the roller
bearings (i.e. no reaction moments are generated by the bearings).
ME 251 Project – Fall 2020 Page 9 of 10
5. Determine the internal reactions at specific locations in the spindle
Designing the spindle requires understanding of the
stresses at various portions along its length.
Understanding how to calculate the stresses will be
covered in ME353. However, the first step in
determining the stresses requires determining the
internal reactions at specific points, which you have
learned to do in ME251. Using the bearing reaction
forces calculated previously (not the rated values),
calculate the spindle reactions at the upright and the
internal reactions (N, V, M) just to the left of F2, just to the right of F2, just to the left of F1 and
just to the right of F1. Report your results in a table or shear and moment diagrams.
9350
2100
14800 3320
12900
2890
13500 3030
20100 4510
24100
5420
23400 5270
25100
5650
31700
7120
35100
7900
16200
3650
31900 7180
27900
6280
25100
5650
41700 9370
ME 251 Project – Fall 2020 Page 10 of 10
6. Final report
This is an individual project and each person is required to submit a report. The project grade
(150 pts) will be determined by the quality of the written report and the accuracy of the
calculations. Clarity of the text, drawings, calculations, and your ability to communicate the
engineering steps to solve the problem all constitute the quality of the report. It should be
professional, easy to understand, and include all requested information. The report text
(excluding calculations as noted below) is to be typed single-spaced 12 pt. font with a single
space between paragraphs (just like this project file).
In your report, include the three requested construction documentation pictures (remember to be
in the final one with your vehicle). The pictures should be approximately 3-in. high. Include in
the build section your lessons learned for the build phase.
In the section with the center of gravity calculation and wheel reaction calculations, include the
short essay answer on the importance of the center of gravity location.
The major part of the report is your engineering calculations. The report must include all FBDs
used in the calculations. At a minimum these are, FBD of the entire vehicle used to find the
center of gravity and wheel reactions, FBD of the hub/wheel assembly used to find the bearing
reactions, and a FBD of the spindle used to find the upright reactions and internal reactions. You
must show all calculations in a neat and orderly fashion. They can be handwritten but must be
organized and easy to read. If you realize your handwriting is hard to read, it is suggested you
type out equations using the equation tool in Microsoft Word. You may use a program such as
Microsoft Excel to perform your calculations BUT you MUST show and explain the setup of all
the calculations you used as if they were done by hand.
Finally, add a conclusion to your report which summarizes the key points. The report is due by
11:59 pm Friday December 11, 2020.