This project plans to alleviate the cumbersome and stressful situation of changing a tire. Current designs for car jacks are clumsy, slow, or too bulky to be portable to fit within an average car. Thus enters the Portable Car Jack with its easy-to-use, time-efficient, and safe design. The design requirements include minimal user input and the ability to lift and hold the weight of a car safely while staying compact and portable. Although the design is tailored towards average car drivers, it can see major use in roadside assistance services.
Proof of Concept
The assembly utilizes both spring energy and pneumatics to lift a prescribed weight. Four of these subassemblies will be assembled in series to lift the weight. The gear teeth will help move the assembly upwards by use of a gear shaft that will be cranked by the user. This action will compress the spring. The piston serves two purposes. The first purpose is to provide additional work via C02 canisters if the user is unable to fully crank the gears, or if the gear mechanism were to fail. Secondly, the piston is used as a damper to help control the descent of the weight. The current locking mechanism, pin supports, prevent unwanted vertical motion.
A single cartridge of CO2 powers the prototype. The cartridge feeds into an air-fill valve, also known as a Schrader valve, which sends the CO2 through a backflow prevention valve, helping to keep the pressure in the main reservoir. The reservoir has a needle valve, used for controlled descent of the car, and a pressure-set safety valve. The safety valve will open if the pressure in the reservoir exceeds a preset value. Once the CO2 is threaded in the Schrader valve the pressure difference will drive the piston upwards, and thus lift the car. Keeping the pressure difference between the two faces of the piston is an O-ring, which will side on the face of the reservoir with the help of MDS (molly) grease. To account for variable car ride height, the differential plate can be twisted to reach that height. The plate uses a fast-precision ACME thread to allow for fast and easy adjustment to ride height. This differential plate connects to the piston by a hydraulic tube, which has two weld-on sleeves that will fasten both the pressure vessel piston and the differential plate. A linear bearing is included on the reservoir cap to guide the motion of the tube. To keep an airtight seal, x-rings are included on the cap of the reservoir. The cap includes a wire snap ring groove which also helps in retaining the pressure.
This portable car jack design will be more user friendly and efficient than conventional car jacks in the market today. It’s quick setup time and even faster lift time will ease the stress and pressure that comes with roadside emergencies such as changing a tire or any other situation requiring a portion of a vehicle to be lifted. The use of a small, lightweight CO2 cartridge as the input delivers all the strength and benefits of a floor jack with the portability of a scissor jack, while requiring significantly less effort by the user.
The fabrication was done both in the UNR machine shop and that of the sponsor. The use of manual lathe operations allowed for quick fabrication times. The advantages of using manual equipment rather than CNC is the quick troubleshooting issues and quicker turn-around time for single components. With 6061-T6 aluminum and 1018 steel making the bulk of the material, machining left a clean finish for each part. Aluminum made up the main reservoir and piston shaft in order to keep the product lightweight.
Once done with machining, welding was the next portion of the assembly process. The differential plate was welded to the threaded adjuster screw and the two threaded sleeves were welded to the hydraulic tube making a double-threaded shaft for simple assembly of the jack
The valving was secured to the main reservoir via threading and the use of thread sealant tape to ensure proper sealing. Before putting everything together the reservoir inner walls were lined with grease for easier motion of the piston shaft and to preserve the o-ring. Finally, the reservoir cap was fitted with a bearing to allow for linear motion of the piston. A groove was machined for another o-ring in the main reservoir and a lip was included in the bearing carrier to properly seat a snap ring. The snap ring will fit in a groove in the main reservoir that will essentially lock everything in place.
Testing and Results
|Quantitative Objective||Engineering Specifications||Test Results|
|Time of Use||Within 5 minutes||PASS||<30 seconds|
|Ease of Assembly||Assembled within 3 or less steps||PASS||1. Twist Top Cap
2. Thread Cartridge
3. Press down on inlet valve
|Lifting Capabilities||Lift 1500 lbs||FAIL||1200 lb MAX|
|Space Encompassed||Must fit within 8 ft2 of floor space||PASS||0.78 ft2|
|Weight of Unit||Unit weighs within 50 lbs||PASS||Weighed in at 50 lb|
|Height Lifted||Jack will lift car at least 4 inches||FAIL||Lifted Car 3 inches|
We tested our product under three categories: strength, longevity, and live tests. The strength test added weight in increments until failure. The longevity test set weight on the product for 3 hours until the test was complete. The live test consisted of using the product in a live situation on an actual vehicle.
Testing for strength gave us a threshold for a max weight that the jack could lift. At 1200 lbs., the 200-psi safety valve activated, allowing for pressure to bleed out slowly. Although this counted as a fail for our original design objective of lifting 1500 lbs., the jack held steady for both continuous weight increase and max weight hold up to 1200 lbs. This led to testing for time limitations on the jack, which was done by lifting and holding 800 lbs. for 3 hours. During this step, the jack held steady with no bleeding occurring, which we concluded was enough to prove the jack’s stability and reliability over time.
From the live test, we saw that it did what it was designed to do, which was lift a vehicle in a timely manner. The average lift time for the jack, including threading of the CO2 cartridge, was approximately 25 seconds. There was a failure, however, regarding the stroke length of the piston in the jack. The piston was not able to travel far enough to lift the vehicle due to the vehicle suspension. The solution would be to increase the inner travel length of the piston by a minimum of 1.5 inches so that it would have enough length to lift the tire to the desired height.
The product solves the problem of car jacks lifting vehicles too slowly. This product decreases time spent lifting the vehicle and increases its simplicity by only involving 3 steps to lift the vehicle. During innovation day, the product received great attention and was highly admired by the general public.
Meet the Team
I was born in Las Vegas, Nevada, where I graduated from Silverado High School in 2012. I am the Battalion Commander of the UNR Army ROTC program and the highest ranking cadet in the state of Nevada. Upon graduation with my Bachelors of Science in Mechanical Engineering I will commission into the United States Army as an active duty officer.
I have a current GPA of 3.7, have been named in the College of Engineering’s Dean’s List six semesters out of my four years attending UNR, and have attended the Engineering Spring Celebration for Academic Excellence twice. I grew up in Las Vegas, Nevada and moved to Reno to study at UNR. Once I graduate I intend to apply for an engineering position with Boeing and gain experience working in aircraft manufacturing.
I was born in Reno, Nevada and raised between Reno and Billings, Montana. I attended Earl Wooster High School and graduated in the spring of 2012. Currently, I am working towards a Bachelor’s of Science in Mechanical Engineering. I am also an active member in the university community, being a former member of the men’s lacrosse team, and a member of Sigma Tau Gamma fraternity, as well as Tau Beta Pi engineering honor society. After graduation, I plan to either enroll in a master’s program, or become an active member in Engineers Without Borders.
I have obtained a 3.9 GPA in my academic career and plan to graduate summa cum laude. I am a member of Tau Beta Pi engineering honors society and have been frequently placed on the Dean’s list. I am originally from Dayton, Nevada and have lived in Nevada my entire life. I graduated from Dayton High School in 2012 and also graduated from Western Nevada College in 2014 with my Associates of Science Degree. Once I graduate I plan to find employment outside of Nevada, preferably in the west coast, as a controls engineer.
My hometown is Silver Springs, Nevada and I graduated from Silver Stage High School in 2012. After graduating with a Bachelor’s of Science in Mechanical Engineering, I plan on commissioning into the Air Force as an officer.
Sponsor: TKO Motorsports – Funded the project from Proof of Concept to Prototype construction
UNR Machine Shop: Tony Berendson – Assistance in construction/machining of prototype parts
Mentor: Matteo Aurelli – Advice and feedback regarding feasibility of design and improvements