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The Pneumatic Airbag JackStudent: Michael Morel
Class: ET 493
Advisor: Dr. Rana Mitra
May 6, 2015
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AbstractFor decades, do-it-your-selfers have been working on their cars at home. For performing
maintenance under the car, they have relied on the basic hydraulic floor jack to lift the vehicle.
Up until recently, this has been the only type of floor jack. The floor jack that uses an airbag,
hence, the name airbag jack, has come into the market recently. This new design of a floor jack
uses an airbag and compressed air to lift the vehicle. Using compressed air is a completely new
delivery method. Automotive shops, dealers, and most home mechanics have an air compressor
to inflate tires, power pneumatic tools, and clean shop areas. Therefore, this product appeals to
many. However, the airbags used are not regular bags. They are automotive and industrial grade
bags used for air suspensions in cars, trucks, and tractor trailers. These heavy duty bags are
meant to handle and sustain the weight required. The purpose of this project is to improve on
existing products in terms of design and build a more efficient product overall.
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Project
My project will be the study, analysis, and further development of the airbag jack. The
current airbag jack being offered today has several design flaws including both safety and
functionality. I will apply different areas of engineering in my study, development, and redesign
of the jack. Examples include mechanical design, strength of materials, and statics. Mechanical
design will apply to the project as a whole. We are taught in this class the many things that
should be taken into consideration when designing any type of mechanical product. Strength of
materials will apply to the material I will use in my safety catch system, the base plate, and also
the airbag. The methods of Statics will be used in the actual loading and unloading of the safety
catch system that will be designed. I will also take into consideration a possible dynamic load
that can occur.
Problem
The previous design is not a stable, or easily maneuverable tool. The previous design also
has a major safety flaw. It does not include a safety catch in case the bag fails while
under load. This is a serious safety issue and could result in major injuries.
Solution
My new design will have everything mounted on one stable base plate. It will also
incorporate caster wheels for easy mobility. My new design will also incorporate two
safety mechanisms that would catch the load in case of bag failure. The safety
mechanisms would be set according the height of bag inflation. Also, this new design will
eliminate the need for two separate tools while lifting a vehicle (floorjack and jackstands)
by having them incorporated into one design. This increases overall efficiency of the job.
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Material Selection
When approaching my project, I needed to be careful as to what materials I would use.
My main concern was choosing materials that could handle my intended load(s). I also took into
consideration the safety factor and that not all users use products to recommended specifications.
Because of this, I designed my product to handle a load greater than what would be advertised.
My advertised, or recommended, weight load would be not to exceed 2 tons. I used this
number in comparison to other standard jack stands being offered on the market. In my
calculations, I used forty five hundred pounds as my load to ensure my materials selected can
handle the weight with no problem.
Product Material Breakdown
Air Bag: The air bag consists of carefully designed rubber / fabric bellows which contain a
column of compressed air. The bag construction is as follows: an inner liner of calendered
rubber, one ply of fabric reinforced rubber, a second ply of fabric reinforced rubber (with the
cords at a specific bias angle to the first ply), and an outer cover of calendered rubber. The upper
and lower bead plates are crimped to the rubber bellows to form an airtight seal. The plates are
then zinc/chromate plated for rust protection. The bag I chose to use is an Airlift Loadlifter 5000.
It has a 5000 pound rating. It’s deflated to inflated range is 2.8 – 12.5 inches. After measuring
several different car heights, I found that the inflated height of this bag will work.
Safety Locking Pin: The locking pins were one of the main products that needed to be carefully
looked at. Since these pins would bear most of the load in a double shearing force, I chose to use
T304 stainless steel round bar. The diameter of the pin would be .75 inches. I chose this stainless
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steel because it is ideal for applications where greater strength and superior corrosion resistance
is required. The yield strength of 304 is 35,000 PSI. With the diameter of the pin taken into
consideration, this accounts to an ultimate yield strength of 15,400 pounds roughly. The ultimate
shear stress was calculated to be 22,400 pounds. With these weight capabilities, this material was
more than suitable to do the job.
Safety Columns: The safety columns are the supports through which the locking pins slide
through. I chose to use A513 carbon steel for these. It will be in a square tube form with a .25
inch wall. Carbon steel is an alloy consisting of iron and carbon. It is the most common form of
steel because of its price value. Its higher carbon content means higher strength. It has yield
strength of 72,000 PSI. While two of these will be working in the design to bear the load, they
should handle the intended load with ease.
Base Plate: The base will have the air bag and safety columns mounted to it. For this, I chose to
use an ASTM A527/A653 galvanized steel sheet. The dimensions will be 24 inches long by 14
inches wide with a .25 inch thickness. Galvanized steel is simply hot rolled steel to which a zinc
coating has been applied for protection against corrosion. This is also a low carbon steel.
Price List
1. Air Lift Loadlifter 5000 Air Bag..……………………………………………...$85.59
2. A513 Steel Safety Columns (2”x2”x .25” 1’ tube)…………………………….$14.42
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3. T304 Stainless Steel Round Bar (1’ x .75”)…………………………………….$9.00
4. ASTM A527/A653 Galvanized Sheet (2’ x 2’ x .25”)…………………………$51.40
5. Brass Air Pressure Valve (Inlet/Outlet/Relief)……………………………..…...$13.98
6. Grey Rubber Caster Wheels (80 pound capacity)…………………...………2 x $4.47
7. Handle (Hot Rolled Plain Steel 3’ x .35”)…………….…………………………$9.97
8. Air Line Tubing (.25”)…………………………………………………………...$0.00
9. Brass Air Line Inlet/Outlet Fittings (.25”)………………....Male: $1.99..Female $2.19
10. Miscellaneous…………………………………………………………………….TBD
11. Machining / Labor……………………………………………………………......TBD
Total Material Cost: $197.48
** As of right now, the only machining / labor that will be needed is in the making of the
stainless steel pin, and welding the columns to the base plate. The rest of the assembly will be
completed by myself. With the design subject to change, the required machining / labor may
change as well.
Deliverables (Spring 2015)
Design a working safety catch system -
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Select the proper materials to be used in new design -
Perform necessary calculations to ensure the material selected is
suitable for the application -
- Apply: Mechanical Design, Strength of Materials, Statics
Create full graphic in Solidworks -
Build a specific material list (including costs) -
Over the course of the semester, I was able to complete all the tasks I assigned to myself.
However, there were a couple obstacles I had to work through. One obstacle was using
Solidworks. Since I was taught AutoCad in IT111, I was never exposed to Solidworks. I have
come to realize that this is a useful, yet complicated software. After a few hours of watching
tutorials and reading how-to’s, I was able to complete a graphic design that encompassed the
basic features of my design. The other obstacle I was running into was material selection. At
first, I was so overwhelmed with all of the possible materials I could choose. What I needed to
do was look at the value of the different steels and what strength properties they offered for the
price. From there I was able to select sufficient materials to be used in the assembly.
Timeline
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2/12-3/26: Establish an advisor, project, and prepare proposal report and presentation -
3/27-4/10: Further design catch system, become more familiar with Solidworks software -
4/10-4/24: Research and select possible materials to be used in different parts of the design -
4/24-5/8: Perform calculations to ensure materials will be suitable to handle possible loads and/or impacts -
5/8-TBD: Build a specific material list (including costs), continue Solidworks design -
*Timeline subject to changeI was able to complete all the tasks I assigned to myself before the final presentations.
My approach from here is to analyze the details in my design and make sure everything will
work and fit properly. From there I can begin purchasing and ordering everything to begin
assembly. I plan to do that at the end of summer, going into the fall semester. The only issue I
see in assembly is just finding a machine shop to machine my safety pins, and to also find a
welder to weld my safety columns to the base plate. Over the summer, I will look into these
issues to hopefully resolve both. The other small issue I see now is just funding the project. My
plan for this is to hopefully work extra hours at my current job to help fund the project. I am very
excited to assemble a final product. I really want to see my design become a reality.
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Design
** Design shown with optional lift pad
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- Current Base Plate Dimensions