Car jack
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Contents |
About
This is the project Wiki for Team 8 in 24-441 Engineering Design Course. The product we have chosen to analyze is a car jack.
Group Members
- Matt Wasserman
- Alberto Guzman
Product Study
Function
- Typically used to lift up the corner of a car, normally for changing a tire.
Input
- Crank, which rotates threaded rod
Output
- Vertical motion up or down that locks in place
- As a result of the design and upward motion imparts a force.
Normal Use
- User kneels down in next to car.
- Jack is placed flat under car.
- Crank arm end placed into eyelet or car.
- Crank arm held up in one hand and rotated clockwise with the other.
- When upward motion of jack gets close to car frame, user aligns jack as necessary make sure it is securely aligned with the pinch weld on the car's frame.
- User continues to rotate crank arm as the jack lifts the car until the desired height is reached.
- After the user is done changing the tire the crank arm is rotated counter-clockwise until the jack is completely closed
Special Considerations
- Might be difficult for some users to kneel down next to car and reach under for correct placement.
- Depending on lighting, can be difficult to ensure proper alignment.
- When rotating crank arm it is easy to bash knuckles into the ground
- Must be careful (cannot rotate to fast, must be in right position) when rotating or else the entire jack, not just the threaded rod, rotates. The jack must then be repositioned. This is the case when the jack has not yet secured itself between the car and the ground.
Other Uses
- Separating two objects
- Bending Pipe
- Lift heavy objects
- Push heavy objects.
Stakeholders
- Car driver/passenger (user)
- They must use the actual product
- Car Manufacturer
- They must contract to another company or design and manufacture a jack to go with each automobile
- Jack manufacturer, if not part of car company
- They must design and build the jack for the car company or as an after-market replacement
- Employees of car or jack manufacturer
- They play a role in the design or manufacture of the jack and are paid for that role
- Business and employees that sell after-market jacks
- They sell and make a profit off of the after-market jacks
- Suppliers and distributors of after-market jacks
- Supply and distribute after-market jacks to companies to sell
Product Dissection
From the dissection of our study car jack were were able to learn a considerable bit about the components, materials, design and manufacture of the device. Generally, the jack was designed to be manufactured quickly and easily with a few components. Also it was made such that it could not be taken apart by the user. Most of the compoinets are stamped and bend sheet steel, for quick and easy manufacture. A few components, like the arms, which have the same weights, are stamped using the same die, and just bent differently, again to simplify the manufacturing process. Using the top and bottom pins like rivets prevents the user from disassemblying the jack, for reasons of ensuring safe use of the device and ensuring stability. Complete documentation of the dissection can be found on the Car jack product dissectionpage.
Design for manufacturing and assembly (DFMA)
During the dissection of the car jack it became quickly apparent that this product was not intended to be disassembled. All of the fasteners has been mechanical fixed using either a rivet or other forums of plastic deformation of steel to secure it to the complete assembly. Dissecting the jack required destroying these connection. This method of assembly reduces the possibility of a user disassembling the product and reassembling it in an incorrect and unsafe way. It is critical that these fasteners be secure as a failure of any component of this product could result in serious injury or death of the user.
This jack has been designed to minimize construction costs. The system has designed to be symmetric thus minimizing the number of unique parts. For example the left and right upper arms are the same exact part requiring the same dies to be made. The left and right pins only differ in that one has a thru-hole while the other is tapped. In other parts such as the collar the use of a separate fastener has been avoided by simply crushing the collar into to the thread. This securely fixes the two parts together without the need of an additional part.
Design For Environment (DFE)
This style of car jack (manual screw jack) will require no renewable energy input during its construction. Energy will be needed to produce the steel used by all of the parts. Energy will also be used to run the machines that do the stamping/forming/assembly of the parts. Unlike hydraulic jacks which may require oil during there usage cycle this jack has been lubricated at the factory for the life of the product. The only input of energy needed during usage is work from the user.
This jack is made entirely out of steel. Parts have been coated with either a powder coat or some form of electro plating to protect them from the elements. Since all parts of this product are the same material recycling it would not require manual disassembly. The entire product could be shredded and sold as scrap steel to be recycled.
Failure Mode Effects Analysis (FMEA)
Item & Function | Failure Mode | Effects of Failure | S | Causes of Failure | O | Design Controls | D | RPN | Recmd Actions | Responsibility & Deadline | Actions Taken | S | O | D | RPN |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Car Jack, used to lift corner of a car | Structural Failure | Car drops, can injure user, damage car | 9 | To much downward force, component failure | 5 | Ensure that the jack can be produced consistently with a high factor of safety | 5 | 225 | - | - | Preliminary FEA of jack showed approx 22,000 lb could be placed on jack before failure | 3 | 2 | 5 | 42 |
Rusting of jack over time | Failure of jack | 9 | Steel the material of the jack, can rust over time making it brittle | 5 | Make sure that coating is well applied | 5 | 225 | - | - | Steel coated to protect from elements, also placement during storage keep it protected from elements | 3 | 3 | 5 | 45 | |
Car falls off of jack | Car drops, can injure user and damage car | 9 |
| 7 | Detection not possible from a pre-release standpoint | 1 | 63 | Study base more indepth to see how well it adapts for uneven ground, and study connection point with car frame |
| Include more written and pictographic documentation with and printed on jack saying to use on level ground | 7 | 6 | 1 | 42 | |
User getting under car | User injury | 9 | Small workspace easy to be injured, car falling off of jack | 4 | Detection not possible from a pre-release standpoint | 1 | 36 | Study base more indepth to see how well it adapts for uneven ground, and study connection point with car frame |
| Include more written and pictographic documentation with, and printed on jack, saying to use on level ground, not to get under jack, and to keep hands away from pinch points | 7 | 4 | 1 | 28
| |
User gets fingers/hand caught in pinch point | User injury | 9 | Careless or uninformed user | 5 | Detection not possible from a pre-release standpoint | 1 | 36 | Study pinch points |
| Include more written and pictographic documentation with, and printed on jack, cautioning about the pinch points | 7 | 4 | 1 | 28
| |
User not using device as intended | User injury, damage to other items | 9 | Any number of reasons including jack slipping or applying too much force | 2 | Detection not possible from a pre-release standpoint | 1 | 18 | Think about how often this happens, general user stupidity |
| Include more written and pictographic documentation with and printed on jack saying to use on the device as intended | 7 | 2 | 1 | 14 | |
User scraping knuckles on ground | User injury | 8 | Position of jack and design of rod for turning | 8 | Detection not possible from a pre-release standpoint | 1 | 64 | Study deisgn and look at ways to improve this problem |
| - | - | - | - | -
| |
User having difficulty aligning with frame | Car can fall off of jack resulting in user injury | 8 | Location of frame makes it difficult to spot where the jack needs to go in daylight as well as at night | 7 | Detection not possible from a pre-release standpoint | 1 | 56 | Study deisgn and look at ways to improve this problem |
| - | - | - | - | - |