Car jack

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=Executive Summary=
=Executive Summary=

Revision as of 21:43, 11 February 2007

Contents

Executive Summary

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

  1. User kneels down in next to car.
  2. Jack is placed flat under car.
  3. Crank arm end placed into eyelet or car.
  4. Crank arm held up in one hand and rotated clockwise with the other.
  5. 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.
  6. User continues to rotate crank arm as the jack lifts the car until the desired height is reached.
  7. 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 dissection page.

Cad Model and Simulation

Shown above is a model of the car jack being analyzed in this study. The major components have been labeled.

Design for manufacturing and assembly (DFMA)

DFA

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. The fasteners used to join the upper and lower arms as well as the upper and lower base serve multiple purposes, both hold the parts together as well as acting as pivots to allow motion of the device. 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.

DFM

This jack has been designed to minimize manufacturing costs. The parts have been designed to be symmetric thus minimizing the number of unique parts required. For example the left and right upper arms are the same exact part utilizing the same dies during production. The left and right pins only differ in that one has a thru-hole while the other is tapped. There seems to be only two gauges of sheet steel used in the construction of this jack. This minimizes the number of separate raw materials that would have to be purchased to construct the product. By minimizing the number of different raw materials required, larger amount of necessary material can be ordered resulting in savings from buying larger quantiles.

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)

In the process of conducting the failure mode effects analysis, we were able to see that most of the failure modes dealt more with the user, than the jack itself. Preliminary analysis of the jack showed that it could stand up to a significant amount of force before failure, much more than it would take under normal usage. Where safety concerns come into play come mostly from users not using the product as intended or using it incorrectly. The complete analysis can be viewed on the Car Jack Failure Mode Effects Analysis page.

Preliminary Analysis

To go with the analysis of the car jack from the design, usability, and manufacturing standpoints we have bgun conducting a preliminary analysis from a mechanical standpoint. This is discussed in further detail in the page Car Jack Preliminary Analysis

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