1

The Pneumatic Airbag JackStudent: Michael Morel

Class: ET 493

Advisor: Dr. Rana Mitra

May 6, 2015

2

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.

3

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.

4

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

5

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

6

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 -

7

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

8

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.

9

Design

** Design shown with optional lift pad

10

- Current Base Plate Dimensions