Hydraulic jack

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Jack used for dissection
Jack used for dissection

Contents

Executive Summary

In order to learn more about the process of designing a part, group 10 took apart a Big Red car Jack. The device is designed to use hydraulic fluid and one-way valves to raise a ram rod so as to lift 4-ton vehicles in order for the user to be able to change tires. The jack is operated using a removable handle, which is pumped up and down, raising the jack, which in turn lifts the car.

After testing and dissection, we concluded that the jack was both easy to use and very compact. The jack did not take very long to achieve the desired result and required minimal energy to use. In order to get a better understanding of the jack we performed Failure Modes and Effects Analysis (FMEA), Design for Manufacture and Assembly (DFMA) and Design for Environment (DFE).

FMEA allowed the group to get a better understanding of the failure modes and the impact the failure modes had on the user. One possible failure mode is the jack could slip from under the car causing the elevated car to fall on the user.

DFMA gave us knowledge on the manufacturing and assembly. We concluded that the product and the manufacturing had been fairly optimized since the product does not have very many extraneous parts and the product is relatively cheap.

DFE showed the group the environmental impact of the jack. EIO-LCA (Economic Input Output-Life Cycle Analysis) was used to see the greenhouse gas emission over the lifetime of the product in the various sectors of the US economy. It was concluded that the production of the hydraulic fluid had the largest percentage of Carbon.

Stakeholder Needs

The main stakeholder for this product is the consumer. The consumer is the main person operating the device and is the one who will suffer the most if it fails. Cost, reliability and safety are a few of the needs the consumer has from the product. However, the consumer isn’t the only group that this product has an impact on. Retailers, manufacturers, and Shippers/transporters also have interactions with the product.

Consumers

  • Cheap
  • Reliable/Maintainable
  • Easy to use
  • Safe
  • Moveable between cars
  • Compact/Light

Retailers

  • Easily displayable
  • High Demand
  • Low to no maintenance required
  • Profitable

Manufactures

  • Made from common materials
  • Few parts
  • Easily assembled
  • Assembly can be automated to reduce cost
  • Replaceable parts
  • High demand

Shipping/Transport

  • High Demand
  • Easily shippable/Light weight
  • Durable

Product Functionality

Step-by-Step Instructions

Step 1.
Step 1.
Step 2.
Step 2.
Step 3.
Step 3.
Step 4.
Step 4.

To raise:

  1. Turn valve screw clockwise to tighten it and create a pressure seal
  2. Place jack under car and turn extender rod until it reaches the bottom of the car
  3. Insert handle into pump handle housing
  4. Raise and lower handle to pump up car

To lower:

  1. Turn valve screw clockwise
  2. Twist down extender rod
  3. Pull jack out from under car

Usability Study

How it's used

Hydraulic bottle jack lifting car
Hydraulic bottle jack lifting car

The Big Red Hydraulic Bottle Jack can be operated with everything in the packaging. It does not need any additional fluid, or an electrical source. The eight-pound jack can lift vehicles weighing up to 4 tons simply by moving a handle up and down. Once the vehicle is lifted the jack can maintain the car at the required height to change a tire. To compensate for different size cars, a worm screw is attached at the top tat can extend upwards to assist in the lifting of cars that are taller.

User Study

When the group tested the jack, without using the instruction, we found the jack very confusing. However, once we read the instructions and tried operating it, we discovered that the jack was in fact very easy to use. Although it was easy to use, there were some problems with the jack. It had trouble getting under smaller cars, which is understandable since it is designed for 4-ton cars. Also pumping the handle was challenging since the user had to kneel on the ground and lift the handle once it was lowered to pump it repeatedly. The release screw was also difficult to rotate by hand. However, with the handle bar inserted, the task became easier, but still challenging.

Unscrewing valve screw
Unscrewing valve screw


One of our group members gave the jack without instructions to another Carnegie Mellon student and had them jack up their car. Without help, the person also struggled initially using the jack, but ultimately decided that the jack was very compact and easy to use.


After doing research and self evaluations on the jack, the group has concluded that the item is very compact and light for a jack. The group also concluded that its size makes it very easy to store in a car and the design makes the jack very easy to use. Since there aren’t very many exposed moving parts and there is not combustion, the jack is fairly safe. Its steel design also makes it very robust and hard to damage. Some of the corrections the group would make is possible widening the base to prevent tipping as well as improving the handle to prevent it from getting lost. Also allowing the jack to work for a larger variety of cars cold be another improvement.

Assembly

The following is an exploded view of the hydraulic jack. The parts each number corresponds to are listed below the picture and in the Bill of Materials section.

Hydraulic bottle jack assembly
Hydraulic bottle jack assembly

1. Inner Handle

2. Outer Handle

3. Alligator Clip

4. Pins

5. Pump Connector Rod

6. Link Connector Screw

7. Pump Handle Housing

8. Pump Rod

9. Pump O-Ring

10. Pump Plastic Ring

11. Pump Housing

12. Pump Housing Washer

13. Valve Screw

14. Valve Screw O-Ring

15. Valve Ball Bearing

16. Base

17. Plastic Bumper

18. Plastic Fluid Filter

19. Base Plastic Washer

20. Ramrod Rubber O-Ring

21. Ramrod Plastic O-Ring Retainer

22. Ramrod Base

23. Ramrod Shell

24. Extender Screw

25. Inner Chamber

26. Outer Cylinder

27. Rubber Plug

28. Large Plastic Cap Ring

29. Outer Cylinder Screw Cap

30. English Warnings

31. Alternate Language Warnings

Bill of Materials

The following is a list of the 31 parts that make up the hydraulic bottle jack. Most pieces are made of steel, that has been shopped in some way, usually on a mill or a lathe. The non steel parts are either rubber or plastic and are purchased or injection molded. The table can be sorted by Part Number, Quantity, Weight, Material, and Manufacturing Process.

Part Number Name Quantity Weight (g) Function Material Manufacturing Process Image
1 Inner Handle 1 78 Inner handle piece, used to pump fluid Painted steel Bent, Welded
2 Outer Handle 1 134 Outer handle piece, used to pump fluid Painted steel Bent, Welded
3 Alligator Clip 2 <1 Used to hold Pins (#4) in place Aluminum Purchased
4 Pin 2 7 Used to hold pump structure together Steel Purchased
5 Pump Connector Rod 2 25 Connects Pump Handle Housing (#6) to Base (#16) Painted steel Stamped
6 Link Connector Screw 1 5 Connects Pump Connector Rods (#5) to Pump Handle Housing (#7) Painted steel Riveting
7 Pump Handle Housing 1 98 Connects handle (#1&2) to Pump Rod (#8) Painted steel Stamped, Bent, Welded
8 Pump Rod 1 42 Moves up and down to pressurize the jack Painted steel Automated Lathe Process, Drilled
9 Pump O-RIng 1 <1 Creates a pressure seal for the pump Rubber Purchased
10 Pump Plastic Ring 1 <1 Holds the Pump O-RIng (#9) in place Plastic Purchased
11 Pump Housing 1 74 Limits the Pump Rod (#8) motion to 1D Painted steel Automated Lathe Process, Threaded
12 Pump Housing Washer 1 1 Provides separation between the base and the bottom of the Pump Housing (#11) Steel Purchased
13 Valve Screw 1 18 Allows for release of pressure in jack Painted steel Automated Lathe Process, Threaded, Stamped
14 Valve Screw O-RIng 1 <1 Creates pressure seal around the Valve Screw (#13) Rubber Purchased
15 Valve Ball Bearing 3 1 Creates or releases liquid seal allowing for flow between chambers Steel Purchased
16 Base 1 1049 Holds entire jack together, houses the various valves in the jack Painted steel Cast Steel, Automated Mill Process, Threaded
17 Plastic Bumper 1 <1 Holds Valve Ball Bearing (#15) in place Plastic Injection Molded
18 Plastic Fluid Filter 1 <1 Filters debris during liquid flow Plastic Injection Molded
19 Base Plastic Washer 1 <1 Seals base of Inner Chamber (#25) Plastic Purchased
20 Ramrod Rubber O-Ring 1 <1 Creates pressure seal around Ramrod Shell (#23) Rubber Purchased
21 Ramrod Plastic O-Ring Retainer 1 1 Holds Ramrod Rubber O-RIng (#20) in place Plastic Purchased
22 Ramrod Base 1 98 Keeps liquid out of Ramrod Shell (#23) and prevents sticking to Base (#16) Steel Automated Lathe Process
23 Ramrod Shell 1 310 Moves up and down lifting and lowering anything on the jack Steel Automated Lathe Process, Threaded
24 Extender Screw 1 176 Allows for extra heigh to be reached by the jack Steel Automated Lathe Process, Threaded, Riveted
25 Inner Chamber 1 314 Constrains Ramrod Shell (#23) to 1D motion Steel Automated Lathe Process, Threaded
26 Outer Cylinder 1 405 Houses liquid Painted steel Stamped, Bent, Welding
27 Rubber Plug 1 <1 Allows for initial filling of jack with hydraulic fluid Rubber Purchased
28 Large Plastic Cap Ring 1 <1 Prevents rubbing between Outer Cylinder Screw Cap (#29) and Outer Cylinder (#26) Plastic Purchased
29 Outer Cylinder Screw Cap 1 160 Caps jack and prevents pressure leak Painted steel Cast Steel, Automated Lathe Process, Drilled, Threaded
30 English Warnings 1 <1 Provides warnings in English Paper Printed
31 Alternate Language Warnings 1 <1 Provides warnings in Spanish and French Paper Printed

Mechanical Function

The jack is made up of a series of concentric cylinders each of which is pressurized and holds differing amounts of hydraulic fluid. When the handle is inserted into the pump mechanism and moved up and down, fluid is pumped from a reservoir in the outer cylinder into the space in the bottom of the inner chamber, pushing the ramrod shell upward. This fluid is kept inside the inner cylinder by a high-pressure valve located in the base of the jack, consisting of a check valve and a debris filter to keep unwanted solids from breaking the seal created by the ball bearing. The jack can be released by loosening the valve screw at the jack’s base, thus allowing the fluid to return to the outer cylinder until the valve screw is tightened again. This release of fluid will then lower the ramrod shell, lowering the car and allowing the jack to be removed. The ramrod also has a section that can be unscrewed, providing extra length to the mechanism.

Jack contains 3 concentric cylinders
Jack contains 3 concentric cylinders
Fluid can flow through holes located in base
Fluid can flow through holes located in base
Valve screw can be loosened to release fluid
Valve screw can be loosened to release fluid

Design for Manufacturing and Assembly (DFMA)

Chanshu Tongrun Auto, the company that manufactures this particular product, produced roughly 10 million car jacks in 2010 [1]. As a result, the jack is made with two primary design goals: sufficient strength to lift 4 tons of material off the ground and simple, easily mass-produced parts.

Manufacturing

Nearly all of the parts in the hydraulic bottle jack are either machined from steel stock or purchased from other suppliers, with the exception of the cast steel base and end cap. Most of the machined steel tubes appear to have been turned on a lathe in a job shop, but given Changshu Tongrun's incredibly high output, they were probably made in some sort of automated process.

Design for Manufacturing Features and Improvements
Design Objective Strengths Areas of Improvement
Minimize Part Count
  • Cast steel base contains most of the complex pump apparatus
  • No extraneous or decorative parts
  • Change the pump joints to be riveted instead of pinned
  • Use a single pump lever handle
Standardize Components
  • Bearings, connector pins, O-rings and washers appear to all be purchased in bulk, and can probably all be used for the different jacks that Chanshu Tongrun produces
  • Ensure most parts are made of similar diameter pipe to the same parts used in other size jacks, to make part purchasing easier
Commonize Product Line
  • Many of the parts are machined from tube stock, which could either be easily made by a skilled machinist or fabricated en masse in an automated process
  • Base and screw cap are both made of cast steel
  • None
Standardize Design Features
  • Pump connector rods are identical pieces of stamped steel
  • None
Keep Designs Simple
  • Most parts are machined using very simple processes
  • Most parts demonstrate axial symmetry
  • None
Multifunctional Parts
  • Pump handle also doubles as a crank handle to help open the release valve
  • Extender screw allows the jack to work on many vehicles
  • Include a part that can extend the surface area of the base, providing for a sturdier jack
Ease of fabrication
  • Most parts are either purchased or machined from simple tube stock
  • Use softer, easier-to-machine metals like aluminum for parts that aren't under lots of pressure
Avoid Tight Tolerances
  • Fittings are sealed with washers and O-rings, making tight seals without needing perfectly machined steel
  • Pump is held with loose pin joints, and pump levers fit loosely
  • None
Minimize Secondary & Finishing Operations
  • Entire assembly appears to be assembled, then spray-painted
  • Cast steel parts are not finished at all, they still are very "bumpy"
  • Instructions are printed on a label, not painted on
  • None

Assembly

To simplify assembly, nearly all of the parts are designed to screw into one another, eschewing complex fasteners or joints. The only major exception is the pump assembly, which experiences the greatest range of motion and is therefore held together with simple pin joints. In addition, almost the entire pump apparatus is contained within the cast steel base, making assembly significantly easier at the cost of making the part more difficult to manufacture.

Design for Assembly Features and Improvements
Design Objective Strengths Areas of Improvement
Use Sub-assemblies
  • The ramrod appears to have been assembled separately
  • The pump apparatus could be redesigned so that it could be made as a separate sub-assembly
Mistake-Proofing
  • Inner chamber can be assembled in either direction - it has no "up" side
  • None
Minimize Fasteners
  • Most pieces screw into each other, with the exception of a few very simple pin joints
  • None
Minimize Handling
  • None - Unfortunately, most of the jack appears to need to be assembled by hand
  • None
Minimize Assembly Direction
  • The entire jack is built off of the cast steel base
  • Only other operation is filling the jack once it's assembled
  • Place filling valve on the top of the jack, so it can be filled while upright
Provide Unobstructed Access
  • If assembled in the correct order, every part is easily accessed
  • Filling is made much easier by including a hole in the side of the reservoir, which is then plugged
  • None
Maximize Assembly Compliance
  • Many parts are machined out of steel tube stock or stamped out of steel, allowing for sharp edges
  • Cast steel base has rounded edges and a rough surface
  • None

Failure Modes and Effects Analysis (FMEA)

After considering all of our system components, we identified eight major areas where our product could fail. Most of the major areas are made up of external components of the product, parts which the user interacts with while he/she operates the system: the handle assembly, the pump structure, the base, the extended screw, the alligator clips, and the valve screw. Unless the product is dissected, the remaining areas cannot easily be reached.

Even though the probability of failure of the internal components is low, their severity and detection of failure are very high. If these parts needed to be replaced it would be extremely difficult for the user to take the system apart. We recommend a design that makes these parts more accessible. That way elements such as the hydraulic liquid and parts can be changed when needed. This will allow the user to maintain the jack which will guarantee safety and durability.

The external components failure depends on their design and on the user. The probability of the components failing ranges from moderate to high. If these parts fail, the system will not work properly and the user will potentially be placed in serious danger. In order to prevent such failures, we recommend redesign, testing, and new material designation for parts.

  • FMEA Ratings are based on tables 14.12 ("Rating for Severity Failure"), 14.13 ("Rating for Occurrence of Failure"), & 14.14 ("Rating for Detection of Failure") from the textbook "Engineer Design" by Dieter, G. and L. Schmidt.


FMEA - Hydraulic Bottle Jack
Item & Function Failure Mode Effects of Failure S Causes of Failure O Current Controls D RPN Recommended Action
BaseTips OverCar falls causing injury to the user and/or damage to the vehicle.10The jack is not properly placed under vehicle. The user does not place car supports after lifting. An uneven surface does not provide stability.4Position jack under a flat surface of the car, place supports, don't work on uneven ground.9360Change the shape of the base, more surface area. Make a multifunctional package to use as support for base.
Valve ScrewRemoved, LeaksLoss of hydraulic fluid. Balls bearings can fall out of place.9User unscrews the valve all the way out.6The manual instructs user on how to close and open valve.5270Place a stopper in the inside to prevent user from turning the valve further once opened.
Alligator ClipsSlip out/DeformPins fall out of place, pump structure no longer works.8Overload and misuse3Make sure to use pumping system appropriately. Do not overload pump connector rods.10240Use a different way to connect pins. Change the pins to a screw-nut system and eliminate this part.
Extender ScrewPlaced on an uneven surfaceCar may slip and screw bend8Jack is not properly placed under vehicle.4Position screw surface area under a flat area of the vehicle.8224The shape of the contact area could be altered.
BendsCan no longer use the jack, component must be replaced.8Overload2Limit weight on screw9144Make component a replaceable part.
Gets JammedHeight cannot be adjusted.8Wear/Corrosion4Lubricate when needed396Provide lubrication oil with product.
Handle AssemblyInner and/or outer handle bends.Cannot properly pump the car jack.7Misuse or damage by customer.4Do not overload the material. Store it in a safe place8224Design a rigid handle with a high Young's Modulus to resist deformation.
The inner and outer handles separate.Pumping the car jack becomes difficult and can lead to injury.3The user pulls while pumping which causes separation.7While pumping make sure the outer handle does not slip out of place.5105Design a handle assembly that locks the inner and outer handle.
O-ringsWear leads to breakageLoss of hydraulic liquid10Wear2If the jack has not been used for a while or has been used for years, test that it works before lifting a vehicle.10200Change system so it's easier for the customer to notice and maintain.
Plastic BumperGets out of positionOne of the ball bearings will fall out of place.10Wear or lack of lubrication, can cause plastic part to break and pop out of place.2The hydraulic liquid is a multifunctional component that provides lubrication.10200Allow the user to add liquid to the system if liquid lost.
Pump Housing & Pump Connector RodsWhile pumping/setting up the mechanism the user's finger(s) get stuck in between.Immediate injury.6Improper use of handle. The user leaves finger(s) at the pin connection while pumping.5The user should keep hands at a safe distance.6180Place a rubber stopper between the pump housing and the connector rods to prevent injury.
One of the components bends.Cannot properly pump the car jack.7Misuse or damage by customer.3Limit the force applied to these components.8168Use a rigid material to resist deformation. As a customer prevent damage by using the product appropriately.

Design for Environment (DFE)

This section discusses the major sources of greenhouse gas (GHG) emissions associated with this product, shown in detail in the table below. The largest source of GHG emissions from this product is the use of hydraulic fluid in the jack. This fluid is a petroleum product and is therefore made up of a large percentage of carbon. If congress were to pass a tax on CO2 emissions, the cost of the hydraulic fluid would be likely to increase, therefore increasing the initial cost and cost to maintain the jack. Cost of manufacturing the jack itself would also increase, but not so significantly as that of the fluid. That being said, overall the cost of both the jack and an initial fill of fluid is unlikely to increase by more than a dollar, so it wouldn't have a major impact on the sales of the jack. It is important to note that there are also GHG emissions associated with disposing of the jack. Because the fuel is petroleum based, it will release CO and CO2 into the environment as it decomposes. Recycling the jack would be a better option because you could safely dispose of the fuel and reuse the steel. Additionally, GHG emissions from the hydraulic fluid could be cut down by using a more environmentally friendly fluid such as a vegetable oil based product[3] or by choosing a fluid that does not need to be replaced so often.

Another area where GHG emissions can be reduced is in the manufacturing of the jack. Already many parts of the jack are manufactured by processes with relatively low energy intensity. Most notable are the parts made by stamping and bending sheet metal, which are processes requiring relatively low energy input. The manufacturing of many other parts of the jack, such as its inner cylinders, seem to have been produced by an automated lathe machine. These processes can be designed to reduce energy usage by minimizing machinery necessary for their production.

DFE - Hydraulic Bottle Jack
Production Use End of Life
Pump ManufacturingHydraulic FluidLandfillSteel Recycling
Hydraulic Jack
Hydraulic Jack
[9]
Hydraulic Fluid
Hydraulic Fluid
[5]
Landfill
Landfill
[10]
Steel Recycling
Steel Recycling
[11]
Sector#33221B: Handtool Manufacturing#324199: All Other Petroleum and Coal Products ManufacturingN/A#331110: Iron and Steel Mills
Total mtCO2e/$1Million6482160 3360
Unit1 Hydraulic Jack1 Bottle of 32oz AW-32 Hydraulic Oil [4] 7 lbs of Steel
Units Per Lifetime115 1
Cost per Unit$15$5 $1.26
Lifetime Cost$15$75 $1.26
Implied mtCO2e0.00970.160.0120.0042
Cost with CO2 Tax of $30/mt$0.29$4.86$0.35$0.13
Assumptions *30 year lifetime *Jack is frequently used and maintained *Replaced oil every 2 years [4] *Oil costs $5 for 32oz [5]*Oil is petroleum based and therefore 85% carbon [6] *all of the carbon ends up as CO2*assumed it costs $360/ton of recycled steel [7]

Notes on this table:

  • The landfill CO2 is unlikely to be taxed, but are included here simply for reference.
  • These results are approximate, as each sector represents a range of products far beyond what's involved in a car jack.
  • If hydraulic fluid is changed every two years as recommended, then it is clearly the biggest source of CO2 emissions. However, if users rarely or never replace it, then CO2 emissions from the fluid will be on about the same scale as those from the other sources.

Team Member Roles

Melanie Jasper: Design for Environment (DFE) Lead

Derek Lessard: Design for Manufacturing and Assembly (DFMA) Lead

Daniel Mark: Bill of Materials and Mechanical Functions Lead

Gloriana Redondo: Failure Modes and Effects Analysis (FMEA) Lead

Daniel Tabrizi: Executive Summary, User Study, and Stakeholder Needs Lead

References

[1] Sales Volumn. http://www.tongrunjacks.com/static.php?id=5

[2] Dieter; Schmidt. Engineering Design, Fifth Edition. New York: McGraw-Hill, 2013

[3] http://en.wikipedia.org/wiki/Hydraulic_fluid

[4] http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=529258

[5] http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_x_7060033-P_x_x?cm_mmc=ACQ-_-Google-_-GPLA-_-7060033&ci_src=17588969&ci_sku=7060033&ci_gpa=pla&ci_kw=&gclid=CNS0j4imq7wCFcY7OgodmSwA2g#fragment-1

[6] http://en.wikipedia.org/wiki/Petroleum#Composition

[7] http://www.steelonthenet.com/commodity-prices.htmlhttp://www.steelonthenet.com/commodity-prices.html

[8]Carnegie Mellon University Green Design Institute. (2008) Economic Input-Output Life Cycle Assessment (EIO-LCA), US 1997 Industry Benchmark model [Internet], Available from:<http://www.eiolca.net> Accessed 3 February, 2014.

[9]http://www.amazon.com/Torin-T90403-Hydraulic-Bottle-Jack/dp/B000CO9YPG/ref=sr_1_1?ie=UTF8&qid=1391401771&sr=8-1&keywords=hydraulic+jack

[10]http://afexsystems.com/industries/landfill/

[11]http://thinkoutsidethebin.com/2011/04/30/anything-made-with-steel-can-be-easily-recycled/

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