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Design, Construction, and Evaluation of an Automotive Bridge Jack
By
Thomas Gomes Jr
BioResource and Agriculture Engineering
BioResource and Agriculture Engineering Department
California Polytechnic State University
San Luis Obispo
2011
ii
SIGNATURE PAGE TITLE : Design, Construction and Evaluation of an
Automotive Bridge Jack
AUTHOR : Thomas Gomes Jr
DATE SUBMITTED : June 9th, 2011
Mark A. Zohns Senior Project Advisor Signature Date Richard A. Caveletto Department Head Signature Date
iii
ACKNOWLEDGEMENTS
First, I would like to thank Cal Poly Transportation Services and their employees for sponsoring this project.
Second, I would like to thank Dr. Mark A Zohns who provided guidance through the challenging aspects of the project.
Third, I would like to thank Virgil Threlkel who was willing to entertain any question and train me on any equipment I was unfamiliar with.
Fourth, I would like to thank my parents and family for supporting me throughout my educational career.
iv
ABSTRACT
This Senior Project discusses the design, construction and evaluation of an automotive lift. This lift will be hydraulically powered with a 6000 lb lifting capacity. The lift constructed in this project will be installed within a current 4 post drive on vehicle lift and allows the user to lift one axle of a vehicle a few inches off the ramp of the drive on lift in order to remove the tires.
v
DISCLAIMER STATEMENT
The university makes it clear that the information forwarded herewith is a project resulting from a class assignment and has been graded and accepted only as a fulfillment of a course requirement. Acceptance by the university does not imply technical accuracy or reliability. Any use of the information in this report is made by the user(s) at his/her own risk, which may include catastrophic failure of the device or infringement of patent or copyright laws.
Therefore, the recipient and/or user of the information contained in this report agrees to indemnify, defend and save harmless the state, it officers, agents and employees from any and all claims and losses accruing or resulting to any person, firm, or corporation who may be injured or damaged as a result of the use of this report.
vi
TABLE OF CONTENTS
SIGNATURE PAGE .......................................................................................................................................... ii
ACKNOWLEDGEMENTS ................................................................................................................................ iii
ABSTRACT ..................................................................................................................................................... iv
DISCLAIMER STATEMENT .............................................................................................................................. v
LIST OF FIGURES .......................................................................................................................................... vii
LIST OF TABLES ........................................................................................................................................... viii
INTRODUCTION ............................................................................................................................................. 1
LITERATURE REVIEW ..................................................................................................................................... 2
PROCEDURES AND METHODS ....................................................................................................................... 4
Design Procedure ...................................................................................................................................... 4
Construction Procedure ............................................................................................................................ 8
Testing Procedure ................................................................................................................................... 10
RESULTS ...................................................................................................................................................... 12
DISCUSSION ................................................................................................................................................. 14
RECOMMENDATIONS ................................................................................................................................. 15
APPENDICES ................................................................................................................................................ 17
APPENDIX A: HOW PROJECT MEETS REQUIREMENT FOR THE BRAE MAJOR ......................................... 17
APPENDIX B: DESIGN CALCULATIONS ..................................................................................................... 20
APPENDIX C: DEFINITIONS ...................................................................................................................... 29
APPENDIX D: CONSTRUCTION DRAWINGS ............................................................................................. 30
vii
LIST OF FIGURES
Figure 1. Leading manufacturer’s Bridge jack (BendPac 2011) .................................................... 2 Figure 2: Bridge Jack Assembly Component Identification ........................................................... 4 Figure 3: Upper center support with enclosure for sleeve bearing ................................................. 5 Figure 4: Upper Sliders shown inserted into Upper Center Support .............................................. 5 Figure 5:Bridge Jack roller assembly set onto BendPak Lift ......................................................... 6 Figure 6: Adapter plate to be welded to end of the smaller tubing. ................................................ 6 Figure 8: Bearing Enclosure and lower pin support ....................................................................... 7 Figure 7: Adapter plates that bolt to the larger tubing sections ...................................................... 7 Figure 9: Tapping 5/16-18 threads into center frame section ......................................................... 8 Figure 10: Sleeve bearing enclosure and fixed pin sleeve tacked in place. .................................... 9 Figure 11: Welding sleeves to support the pin in bending and provide lateral stability ................. 9 Figure 121: Testing the bridge jack using the BRAE hydraulic Test Bench ................................ 10 Figure 13: Proof Load Test setup .................................................................................................. 10 Figure 14: Part drawing of 1 in pin ............................................................................................... 31 Figure 15: Part drawing of tubing flange ...................................................................................... 32 Figure 16: Part drawing of Top Slider .......................................................................................... 33 Figure 17: Part drawing of Roller Assembly ................................................................................ 34 Figure 18: Part drawing of cylinder Sleeve 1 ............................................................................... 35 Figure 19: Part drawing of Cylinder Sleeve 2 .............................................................................. 36 Figure 20: Part drawing of Bottom Frame Extension ................................................................... 37 Figure 21: Part drawing of Adapter Plate Upper .......................................................................... 38 Figure 22: Part drawing of Adapter .............................................................................................. 39 Figure 23: Part drawing of 8 in pin ............................................................................................... 40 Figure 24: Part Drawing of Scissor Lift Arm ............................................................................... 41 Figure 25: Part drawing of Upper Center Section ........................................................................ 42 Figure 26: Part Drawing of Center Frame Section ....................................................................... 43
viii
LIST OF TABLES
Table 1. Design parameters of automotive lift components (Automotive Lift Institute 2006) ...... 3 Table 2: Baldwin Test Results when nearly collapsed ................................................................. 13 Table 3: Baldwin Test results when in middle of travel ............................................................... 13 Table 4: Baldwin Test results when fully raised ........................................................................... 13
1
INTRODUCTION
Many tools in the automotive industry are designed to help technicians access difficult to reach places and improve ergonomic comfort. When a technician is working on a vehicle at floor level they must lean over the vehicle, kneel next to the vehicle or lie under the vehicle to complete the job. These positions can be awkward and strain the technician’s muscles or joints. A solution to this problem is lifting the vehicle to a comfortable working height allowing the technician to work in the fully upright position. There are two styles of lifts that can accomplish this; the first style lifts the vehicle by the frame allowing the suspension to fully droop and the tires to be removed. The second style is a drive on lift where the vehicles weight is supported by its tires while the vehicle is on the lift. Removing the tires on this second style of lift requires the addition of a bridge jack that spans the area between the lifting ramps. Cal Poly Transportation Services uses a drive-on lift that works well for routine services and inspections that do not require removal of the tires. Currently to remove the tires while the vehicle is on this lift the technician must insert a steel plate and use a bottle jack to lift the vehicle up to a height where a jack-stand can be placed underneath. Commercially available bridge jacks are too wide for the narrow wheelbase electric vehicles on campus meaning the technician would have to remove the bridge jack to drive the electric vehicle onto the lift. The objective of this project was the design and construction of a custom bridge jack for Cal Poly Transportation Services that accommodates vehicles ranging from narrow wheelbase Electric Vehicles to 1 ton pickups.
Current L
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3
Industry Standards on Design Parameters
The Automotive Lift Institute along with American National Standards Institute recommends the following design parameters when designing or selecting components for automotive lifts. These design parameters provide guidelines on how much component design strength must exceed the strength required for that component when the jack is at maximum capacity. For example when selecting flexible hose for the hydraulic system you would select a flexible hose with a working pressure rating four times the pressure required to raise the maximum weight the jack is rated for.
Table 1. Design parameters of automotive lift components (Automotive Lift Institute 2006)
Component Design Parameters Pumps 150% working pressure rating Rigid Piping 300% working pressure rating Hydraulic Hose 400% working pressure rating Valves and Fittings 300% working pressure rating Cylinders 300% working pressure rating Bearings Strength factor* of 3 Fasteners Strength factor* of 4 Ductile Metal Strength factor* ≥ 3 Non-ductile Metal Strength factor* ≥ 5 *See Appendix D for definitions
4
PROCEDURES AND METHODS
Design Procedure Design constraints placed on this project came about from discussions with the project sponsor and project supervisor. Standards set by the American National Standard for Automotive lifts concerning strength factors were adhered to when designing for the rated load capacity.
The bridge jack shown in figure 2 operates as a scissor lift with the hydraulic cylinder located horizontally between the lower pins. The adjustable frame and upper sliders accommodate different wheelbase vehicles ranging from electric vehicles to full size pickups. The roller assembly on the end of the frame extensions shown allows the technician to move the bridge jack to lift either the front or the rear axle of the vehicle.
1. Upper Center Support 4. Frame Extensions 2. Upper Sliders 5. Scissor Lift Arms
3. Center Frame Section 6. Roller Assembly Due to the geometry of the scissor lift the hydraulic cylinder must exert the most force to counteract the vehicle weight when the bridge jack is in its lowest position. When fully collapsed the hydraulic cylinder must exert a theoretical force of 8700 lbs to raise a 6000 load. As the scissor lift arms extend the hydraulic cylinder has greater leverage against the vertical force applied by the vehicle being lifted. To lift the same 6000 lb load when the jack is fully extended requires a theoretical force of 3500 lbs (see Appendix B for further information).
Design began by working with a SolidWorks model to pinpoint weak spots in the design. Components of the bridge jack requiring special attention were the top sliders and the pins the hydraulic cylinder acts on. Design methodology of the main components of the bridge jack is explained below.
Upper Center Support. The Upper Center Support section was decided upon based on the need to have other tubes inserted into the Upper Center Support. This tubing size was driven through selection of the upper slider dimensions.
2.
3. 6.
5.
4.
Figure 2: Bridge Jack Assembly Component Identification
1.
The sleevcenter sudesignedsupport t
Upper Slmoment upper slidselecting
Roller Aautomotijack can the rear o
Figure 4:int
ve bearing thupport from td to be a posithe box when
Figure
liders. Thesewhen they aders fully ex
g a load capa
ssembly. Thve lift the brroll forward
of the vehicl
: Upper Slidto Upper Ce
hat slides ontipping in theitive stop whn the sleeve
e 3: Upper c
e sections of are fully extextended showcity.
he roller asseridge jack re
d and back we.
ders shown ienter Suppor
n the upper cee case uneve
hen the lift rebearing reac
center suppo
f tubing wereended. A simwed this port
CthTle
FsTww
Sthacthre
embly was deests in (Figur
within the lift
inserted rt
enter supporen loading. Teaches max lches the end
ort with enc
e sized basedmple bendingtion of the d
Center Framehe same mat
This allowedength of rect
Frame Extename rectang
These extenswidths basedworking on.
Scissor Lift Ahe minimumchieve. The he ratios requequirements
esigned to sere 4). By inct. This allow
rt is fully encThe box encllifting heighof travel.
closure for s
d on the maxg stress calcudesign to be t
e Section. Thterial used fo
d the materiatangular tub
nsions. The frgular tubing sions allow td on the vehi
Arms. The lim overall wid
length of eauired betwee.
et into a sectcorporating r
ws the technic
closed to prelosing the sl
ht. The box i
sleeve bearin
x stress due tulation compthe limiting
he center fraor the upper
al to be cut fring.
frame extensused for the
the operator icle wheelba
ift arm lengtdth we were ach section wen pins to m
tion of the Brollers into thcian to lift ei
event the uppeeve bearings gusseted to
ng
to the bendinpleted with thfactor when
ame section center supp
rom the sam
ions are the upper sliderto select 4 fr
ase they are
th was limitetrying to
was based upmeet lift trave
Bendpak he design theither the fron
5
per g is o
ng he
is ort.
me
rs. frame
ed by
pon el
e nt or
Adapter plateock dimensiodapter plates e for the wel
plates were and an outsidens were weldeel extension
ment of the slplates.
Fig
Figure
es. The tubinons. Adapterfit snugly in
ld seam in th
also cut withe dimension ded to this adns not only aleeve bearing
gure 5:Bridg
e 6: Adapter
ng inserted inr plates werento the cornehe larger tubi
h an inside dthat fit the o
dapter allowallow the bridg when nece
ge Jack rolle
r plate to be
nto the centee designed thers of the larging.
dimension slioutside of th
wing them to dge jack to b
essary but als
Bridge
er assembly
welded to e
er frame secthat weld to thger tubing an
ightly largerhe larger tubi
be bolted tobe disassembso decrease t
Bend
e Jack
set onto Be
end of the sm
tion will havthe end of thand have a ga
r than that ofing (see figuo the larger obled for inspthe bearing
dPak Lift
endPak Lift
maller tubin
ve a sloppy fe sliding tubap to provide
f the smallerure 6). Steel outside tubinpection and stress on the
ng.
6
fit if bing. e
r
ng.
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Bearing Esupports jack disaplate the load. Lower Pifor disasswelded to
Figurbo
Enclosure. Tit from movssembly. Thbearing ride
in Support. Tsembly but fo the center
re 7: Adaptelt to the larg
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The lower beving in the vehe bearing enes on is weld
The lower fixfully supportframe sectio
Figure 8: B
er plates thager tubing ns
Lift Cyselecterequireextensithe Briwas selexert oB).
Pin Sizupper pdetermisupportshear ston werepins webendingwas fourequire
earing enclosertical directnclosure asseded fully acro
xed pin in thts the pin in on.
Bearing Enc
at
ylinder Seleed based on ements. A 1ion while thidge jack to lected based
on the pins t
zing. Static apins and worine the maxiting the uppetress of 3.8 Ke found to here also analg from the found that the d sleeves to
sure allows ttion. The topembly is weloss the botto
he scissor lifthe horizont
closure and
ction. The lthe minimu
10 in Travelhe jack is co
reach full hd on the amo lift the 60
analysis was rking througimum shear er center supKSI. The pin
have a shear slyzed for maforce appliedpins the hydsupport the
the bearing tp section is blded to the com to keep th
ft arms has atal direction.
lower pin s
lift cylinderum lifting hel cylinder reollapsed andheight. The
mount of forc000 lb load (
completed sgh a free bod
on each pinpport have a ns the hydraustress of 14.
ax normal strd by the hydrdraulic cylindpin in bendi
to move horibolted on to center frame he plate from
a removable . This Pin su
support
r travel was eight ests at full d retracts 8 icylinder bo
ce we neede(see Append
starting withdy diagram to. The pins
a theoretical mulic cylinder1 KSI. Thesress due to raulic cylindder acts on ing.
izontally butallow for brisection. The
m bending u
cover that alupport will b
7
in for ore ed to dix
h the o
max r act se
der. It
t idge e ¼”
under
llows be
8
Figure 9: Tapping 5/16-18 threads into center frame section
Construction Procedure
Rectangular Tubing. All rectangular tubing used in the construction of the bridge jack was cut with the Marvel 8 band saw in shop 6. After cutting the tubing sections to final dimensions holes were located and center drilled using one of the knee and column mills located in shop 7. Due to the large pin diameter these holes were finished using the large drill press in shop 7.
The 5/16” holes that allow the adapter plates to be bolted on were drilled using one of the smaller drill presses in shop 7.
Scissor Lift Arms. The scissor lift arms were burned out on the CNC plasma and de-burred after cutting. The plates were welded together before drilling to ensure all holes are in the same location. Initial holes were cut out on the plasma and then drilled to 1” hole diameter using the large drill press located in shop 7. After drilling the pins were a tight fit in the holes and required reinstallation in the drill press in order to bore out the holes using a 1” reamer.
Roller Assembly. Material for the roller assembly was cut using the Marvel 8 bandsaw. The material was then de-burred and welded using the Airco MIG welder in shop 7.
Adapter Plates Welded to Smaller Tubing. These plates were drafted in AutoCad and burned out using the CNC plasma located in shop 6. After being cut out on the plasma theses plates were sanded to a smooth finish and welded to the ends of the upper sliders and frame extensions.
Adapter Plates Bolted to Larger Tubing. These plates were also cut on the CNC Plasma. The steel extensions that the bolts thread into were cut out on the Marvel 8 Band saw, de-burred and welded to the sections that were cut out on the plasma. These plates were inserted into the ends of the larger tubing sections and clamped in place to transfer punch the bolt holes from tubing to the steel extensions on the adapter plate. After drilling the holes to the correct size the holes were tapped to allow the 5/16 button head allen bolts to thread into them. Enclosures on Upper Center Support. The material for the sleeve bearing enclosure was cut using the band saw and welded using a MIG welder. After tacking the sleeve bearing enclosure on the Upper Center Support gussets were fabricated from ¼” plate and welded in place for support in the horizontal direction.
The fixedtacking thfrom ¼”
Bearing Etogether completein shop 7
d sleeve washe sleeve onplate and we
Figure 10:
Enclosure. Mas a subasse
ed it was tack7.
Welding sleing and prov
s cut from 1.n the Upper Celded in plac
: Sleeve bea
Material for tembly beforeked onto the
eeves to supvide lateral
5” stock andCenter Suppce for horizo
aring enclos
the bearing ee welding to e lower frame
pport the pinstability
d bored out tort and chec
ontal support
sure and fixe
enclosure wathe center fre sections an
Welding parts beinshort welcontinuin
Installatiomovemenlift arms ttwisting oin the lathdimensiofrom the using the the scissolocated in
n
to 1” using thcking alignmt.
ed pin sleev
as cut using rame sectionnd welded u
Procedure. Tng welded told sections anng with the w
on of sleevesnt. Sleeves wto prevent thon the pins. The and drillen. After drilsleeve stock band saw. T
or lift arms un shop 6.
he lathes in ment gussets
ve tacked in
the band sawns. After the sing the Airc
To minimizeogether partsnd allowed t
welding proc
s to prevent were installehe scissor lifThe sleeve s
ed to the desilling the sleek to the desirThese sleeveusing one of
shop 7. Aftewere fabrica
place.
w and put assembly wco MIG wel
e warping ofs were weldeto cool beforcess.
lateral ed on the scift arms from stock was plaired inside
eves were cured final lenges were weldthe MIG we
9
er ated
was der
f the ed in re
ssor
aced
ut gth ded to elders
Testing P
No Loadcorrect oand allow
The follo
Proof Lomaximumdeformat
Procedure
Testing. Thperation of t
wed the oper
Figure 121
owing test pr
oad Test. Opem rated load tion of any li
he lift was cythe Bridge jarator to check
1: Testing th
rocedures are
erate the lift capacity. Fo
ift structural
F
ycled from coack. No loadk for stabilit
he bridge jac
e outlined by
through its or a successfl elements ca
igure 13: Pr
ollapsed to fd cycling testty at differen
ck using the
y the Autom
full cycle twful test to takan occur.
roof Load T
full extensioted the bridgnt lift heights
e BRAE hyd
motive Lift In
wo times whike place no v
Test setup
on with no loge jack for ins during ope
draulic Test
nstitute (200
ile loading tovisually app
oad to ensurenternal bindieration.
t Bench
6).
o 150% of tharent
10
e ing
he
11
To mimic lifting the chassis of a vehicle the jack applied the vertical force developed through the upper slider extensions as shown in figure 13. During the proof load test no visual deformation of any components occurred when 8550 lbs (142% of capacity) of vertical force was applied.
Operation Test. Operate the lift through its full cycle 5 times while loaded to the maximum rated load capacity. During this test the function of the load holding devices and the operating control system should be observed. During one of the tests the operator should release the control mechanism when the lift is nearly collapsed to see make sure the load does not free fall. On hydraulically operated lifts the oil level should be checked while the lift is fully extended and pressure gauges should be placed in line to record operating pressures.
Lowering Speed Test. The lowering speed should be recorded from full extension to the nearly collapsed dimension. A successful test is determined by the ability to maintain the lowering speed below 20 ft/min
Load Holding Device Test. While the lift is loaded at 150% of rated capacity the load shall be supported by the load holding device in the position that induces the most stress on the load holding device. During the test the load holding device should experience no visual deformation and exhibit no impaired function after the test.
The operation test and lowering speed test are not applicable to the scope of this senior project and will be performed when the permanent hydraulic system is installed. The load holding device test was not performed since the jack has no load holding device in current form meaning technicians will use this bridge jack as a lifting apparatus only and provide mechanical support for the vehicle while servicing using jack stands to support the weight of the vehicle.
General Oand traveused on tportions
Lateral Mthan desibegin swprevent tfound du
Lift Opertechniciaframe as Proof LoHydraulihydraulicmaximumvertical fcollapsed
Observationeled from cothe upper sliof the frame
Movement ofired. This lat
waying and tihem from pi
uring initial t
Figure 13
ration. The an must treatmechanical
oad Test Resuic Test Benchc power suppm cylinder foforce developd, and 10” ab
s. Under no llapsed to fuders and low
e with a smo
f the lift. Duteral movemp the bridgeivoting on thtesting.
: Side view
lift does nott this bridge jsupports on
ults. During h with a hydply is capablorce of 10,50ped at three bove fully co
R
load conditiully extendedwer frame exoth sliding a
uring initial tment may resu
jack over. She pins. Thes
w of lift with
t incorporatejack as a lift
nce the vehic
the proof lodraulic powele of produci00 lbs (see Alifting heigh
ollapsed. Re
RESULTS
ions the bridd with no intxtensions proaction when
esting the brult in seriousSleeves werese sleeves cu
h arrows sho
e a mechanicting device acle is at the d
oad test the Ber supply pluing a maxim
Appendix B)hts 1” above sulting verti
dge jack cyclterference isovide a snugadjusting th
ridge jack has operator ine welded to tured the later
owing direct
cal stop at thiand put jack desired heigh
Bridge Jack wumbed to themum pressure). The jack wfully collap
ical forces ar
Lateral M
led with no issues. The adg fit for the ahe frame wid
ad more latenjury if the vthe scissor liral movemen
tion of mov
is time. Duristands unde
ht.
was placed ie hydraulic ce of 2000 ps
was tested fopsed, 6.5” abre listed in th
Movement
internal binddapter platesdjustable
dth.
ral movemevehicle were ift arms that nt problem
ement
ing use the er the vehicle
in the Baldwcylinder. Thii resulting in
or maximum ove fully he tables bel
12
ding s
nt to
e
win is n a
low.
13
Table 2: Baldwin Test Results when nearly collapsed
1” into travel Fluid Pressure in Cylinder (PSI) Resulting Vertical Force (LBS)
600 975 1000 1890 1400 2780 2000 4100
Table 3: Baldwin Test results when in middle of travel
6.5” into travel Fluid Pressure in Cylinder (PSI) Resulting Vertical Force(LBS)
600 1734 1000 3000 1500 4800 2000 6600
Table 4: Baldwin Test results when fully raised
10” into travel Fluid Pressure in Cylinder (PSI) Resulting Vertical Force (LBS)
600 2600 1000 4100 1500 6350 2000 8550
14
DISCUSSION
Construction phase took longer than anticipated. This was due in part to incorrectly estimating required shop time and to changes made to the design during the construction phase. Examples are the need for brackets between the center frame sections that keep the two pieces locked in position relative to each other and boxing in the ends of the upper sliders to support the section when vertical loads are applied.
The original design called for strips of steel to be inserted into the outer frame tubing. These strips of steel would reduce the inside dimension of the outer tubing to provide a snug fit for the smaller tubing that slides in and out of the center frame section. Through further observation of current lifting devices the new design of welding an adapter plate to the end of the sliding tubing and have a removable adapter that bolts to the larger fixed portion of the tubing was implemented. This design allows full disassembly of the bridge jack for inspection and replacement of wear items.
Disassembly of the bridge jack is simple, fast and requires only two hand tools. One 3/16 allen wrench and a sturdy pair of external snap ring pliers can take the bridge jack from fully assembled to individual components in about 15 minutes.
15
RECOMMENDATIONS
There is potential for roller bearing and sleeve damage if the jack is operated while against the positive stops. The roller bearings are rated at 2970 lbs max radial load each the hydraulic cylinder can apply up to 10,600 lbs of force, much greater than the dynamic load capacity of the roller bearings.
Incorporating a mechanical stop would be beneficial to the customer and would eliminate the requirement to use jack stands after lifting the vehicle. In the case of having a mechanical stop the technician could apply the stop and lower the bridge jack until the positive stop is fully supporting the load relieving pressure on the hydraulic system. A positive stop could be in the form of a steel block placed against one end of the hydraulic cylinder or through the use a locking pin that would lock the scissor lift arms in position.
16
REFERENCES
Automotive Lift institute. 2006. Safety Requirements for Construction, Testing and Validation. Automotive Lift Institute, Inc. Cortlan, NY. Bendpac RJ-9 Rolling Bridge Jack Specifications. Available at: http://www.bendpak.com/car-lifts/4-post-bridge-jacks/RJ-9.aspx. Accessed March 10th 2011. Budynas R.G. and Nisbett K.J. 2011. Mechanical Engineering Design. McGraw-Hill Companies Inc. New York, NY CLRBJ8 Rolling Bridge Jack Product Overview. Available at
http://www.completehydraulic.com/lifts-bridge-jacks-clrbj8.html Accessed 1st March 2011.
Eaton Corporation. 2008. Industrial Hydraulics Manual. Eaton Fluid Power Training Maumee,OH Gold, J.E., Fulmer, S., Tak, S., Yuan, L. Ergonomic hazards in automotive service technicians. Department of public health, Temple University, Philadelphia, PA. J Cullins, Personal Communication, 7th March 2011
17
APPENDICES
APPENDIX A: HOW PROJECT MEETS REQUIREMENT FOR THE BRAE MAJOR
18
How Project Meets Requirements for the BRAE Major Major Design Experience - The project must incorporate a major design experience. Design is the process of devising a system, component, or process to meet specific needs. The design process typically includes the following fundamental elements. Explain how this project will address these issues. (Insert N/A for any item not applicable to this project.) Establishment of objectives and criteria
To meet the lift requirements of the transportation shop. Please see “parameters and constraints” section below for specific objectives and criteria for the project.
Synthesis and analysis
The project will require structural analysis of the steel frame and scissor lift components.
Construction, testing and evaluation
The bridge jack will be designed, constructed, tested, modified (if needed) and evaluated.
Incorporation of applicable engineering standards
This project will utilize AISC standards and ISO standards for hydraulic circuits.
Capstone Design Experience - The engineering design project must be based on the knowledge and skills acquired in earlier coursework (Major, Support and/or GE courses). Incorporates knowledge/skills from earlier coursework
129 Lab Skills/Safety, BRAE 152 3D solids modeling, 421/422 Equipment Engineering, Engineering Statics, BRAE 234 Intro to Mechanical Systems in Ag, Strengths of Materials, Technical Writing
Design Parameters and Constraints - The project should address a significant number of the categories of constraints listed below. (Insert N/A for any area not applicable to this project.) Physical
The bridge jack will be designed to have a minimum width of 42 inches and a max width of 61 inches. Fully collapsed the desired height is 11 in
Economic
The bridge jack will save labor time for shop customers.
Health and Safety
Warning: This is a lifting device should never be used as a load holding device during vehicle service. Placement of jack stands under
19
the vehicle or other means of mechanical support is necessary. Aesthetic
The finished bridge jack will display the max lifting capacity of the system.
Versatility
The bridge jack will be adjustable from the max desired width to the minimum desired width in 6 in increments.
20
APPENDIX B: DESIGN CALCULATIONS
21
Allowable stress as defined by the Automotive Lift Institute
1018 CD Steel: Sut/3= 63.8 KSI/3= 21.3 KSI
Welded Seam Tubing (A36 Mild Steel): Sut/3= 58 KSI/3= 19.3 KSI
Free body diagram of Scissor Lift Arm while jack is collapsed
3000 Lbs
Y=3160lbs
X=Fcyl=8300 lbs
Fcyl=8300 lbs
22
Free body diagram of Scissor Lift Arm while jack is extended
Y=3437 lbs
X= Fcyl=3220 lbs
F cyl= 3220 lbs
3000 Lbs
23
Required Cylinder Force to Counteract the vehicle weight
Vehicle Force(VF) [lbs] X Distance [in] Y Distance [in] Cylinder Force [lbs]
3000 10.6 9.9 3215.4
3000 10.70 9.7 3301.7
3000 10.81 9.6 3391.0
3000 10.91 9.4 3483.4
3000 11.01 9.2 3579.2
3000 11.12 9.1 3678.4
3000 11.22 8.9 3781.3
3000 11.32 8.7 3888.2
3000 11.42 8.6 3999.1
3000 11.53 8.4 4114.3
3000 11.63 8.2 4234.2
3000 11.73 8.1 4359.0
3000 11.84 7.9 4489.0
3000 11.94 7.7 4624.5
3000 12.04 7.6 4766.0
3000 12.15 7.4 4913.7
3000 12.25 7.3 5068.1
3000 12.35 7.1 5229.8
3000 12.45 6.9 5399.1
3000 12.56 6.8 5576.8
3000 12.66 6.6 5763.3
3000 12.76 6.4 5959.4
3000 12.87 6.3 6165.8
3000 12.97 6.1 6383.4
3000 13.07 5.9 6613.2
3000 13.17 5.8 6854.5
3000 13.28 5.6 7111.6
3000 13.38 5.4 7382.7
3000 13.48 5.3 7670.8
3000 13.58 5.1 7977.5
3000 13.65 4.9 8288.3
24
Bending stress on upper sliders
3000 ∗ 9.5 = 28500 in-lbs
1
1.48
∗
.19.3 KSI
3000 lbs3000 lbs
9.5 in
25
Bending Stress on Bearing Support
Assuming 5” of material is supporting in bending the theoretical stresses are as follows:
1500 ∗ .5 = 750 in-lbs
.125
125 . 25
12.00651
∗.
.14.4 KSI
1500 lbs
26
Roller Assembly
`
1500 ∗ 1.35 = 2025 in-lbs
.7083
.0840 via AutoCAD section drawing
∗.
.17.1 KSI
1500 lbs
1.35 in
Top View showing
cross‐section used
in calculations
Side View
Centroid location of material
resisting bending
27
Force on the Pins(lbs) Diameter (in) Shear stress Safety Factor shear
3000 0.5 15287 1.39
3000 0.625 9783 2.18
3000 0.75 6794 3.14
3000 0.875 4992 4.27
3000 1 3822 5.57
3000 1.125 3020 7.05
3000 1.25 2446 8.71
Max Pressure(PSI) Cylinder Bore(in) rod diameter Rod Area (sq in) Usable Area of piston (sq in) developed Force (lbs)
2000 1.5 1 0.785 0.98125 1963
2000 2 1.25 1.2265625 1.9134375 3827
2000 2.5 1.5 1.76625 3.14 6280
2000 3 1.5 1.76625 5.29875 10598
2000 3.5 1.75 2.4040625 7.2121875 14424
2000 4 2 3.14 9.42 18840
Max Cylinder Force [lbs] Moment [in‐lbs] C[in] I [in^4] Bending Stress [PSI] shear on pin Shear Stress [PSI]) safety factor bending
10597.5 10597.5 0.75 0.519178906 15309.0 6000.0 3397.0 1.39134
Force on pivoting pin
allowable bending stress=Sut/3=21.3 KSI
allowable shear stress=Sut/3=21.3 KSI
force (lbs) Pin Diameter (in) Area (sq in) Shear stress (PSI) Safety Factor
6700 1 0.785 8535 2.5
6700 1.25 1.2265625 5462 4.0
6700 1.5 1.76625 3793 5.7
6700 1.5 1.76625 3793 5.7
6700 1.75 2.4040625 2787 7.8
6700 2 3.14 2134 10.1
Force(lbs) M (in‐Lbs) C(in) I (in^4) Bending Stress(lbs/sq in) Safety Factor
3000 27000 1 1.6823 16050 1.3271
Bending Moment on Lower frame Extensions
Force (lbs) m(in‐lbs) C(in) I(in^4) Bending Stress(lbs/Sq in) Safety Factor
1500 15000 2 5.3073 5653 3.77
Force (lbs) Moment(in‐lbs) c(in) I (in^4) Bending Stress(lbs/sq in) Safety Factor
1500 750 0.125 0.013020833 7200 2.96
Bending Moment on Roller Assembly
Force (lbs) Moment (in‐lbs) C(in) I(in^4) Bending Stress(lbs/sq in) Safety Factor
3000 4500 0.125 0.100585938 5592 3.81
1018 Sut=63.8 KSI
Bending Moment With Sleeves and Bracing Installed
Bending Moment in Upper Sliders
Bending moment on ball bearing support
Allowable Bending Stress=Sut/3=21.3 KSI
Allowable Bending Stress=Sut/3=21.3 KSI
Allowable Bending Stress=Sut/3=21.3 KSI
Allowable Bending Stress=Sut/3=21.3 KSI
Force on upper pins
6000 lbs total
2 pins‐5 in long
Max cylinder force developed
1018 ultimate Strength=63.8 KSI
allowable normal stress=Sut/3=21.3 KSI
allowable shear stress=.4Sy=21.3 KSI
28
Cylin
der Fo
rce [lb
s]Moment [in
‐lbs]
C[in
]I [in
^4]Bending Stre
ss [PSI]
shear o
n pin
Shear Stre
ss [PSI])
safety facto
r bending
safety facto
r shear
3215.43215.4
0.50.0490625
32768.14096.0
5217.80.98877
8.16
3301.73301.7
0.50.0490625
33647.94206.0
5357.90.96291
7.95
3391.03391.0
0.50.0490625
34558.04319.8
5502.90.93755
7.74
3483.43483.4
0.50.0490625
35500.14437.5
5652.90.91267
7.54
3579.23579.2
0.50.0490625
36475.94559.5
5808.30.88826
7.33
3678.43678.4
0.50.0490625
37487.24685.9
5969.30.86429
7.14
3781.33781.3
0.50.0490625
38536.04817.0
6136.30.84077
6.94
3888.23888.2
0.50.0490625
39624.54953.1
6309.60.81768
6.75
3999.13999.1
0.50.0490625
40754.85094.4
6489.60.79500
6.56
4114.34114.3
0.50.0490625
41929.55241.2
6676.70.77272
6.38
4234.24234.2
0.50.0490625
43151.35393.9
6871.20.75085
6.20
4359.04359.0
0.50.0490625
44423.05552.9
7073.70.72935
6.02
4489.04489.0
0.50.0490625
45747.85718.5
7284.70.70823
5.85
4624.54624.5
0.50.0490625
47129.05891.1
7504.60.68747
5.68
4766.04766.0
0.50.0490625
48570.36071.3
7734.10.66707
5.51
4913.74913.7
0.50.0490625
50075.86259.5
7973.90.64702
5.34
5068.15068.1
0.50.0490625
51649.86456.2
8224.50.62730
5.18
5229.85229.8
0.50.0490625
53297.16662.1
8486.80.60791
5.02
5399.15399.1
0.50.0490625
55023.06877.9
8761.60.58884
4.86
5576.85576.8
0.50.0490625
56833.27104.2
9049.90.57009
4.71
5763.35763.3
0.50.0490625
58734.07341.8
9352.60.55164
4.55
5959.45959.4
0.50.0490625
60732.57591.6
9670.80.53349
4.41
6165.86165.8
0.50.0490625
62836.37854.5
10005.80.51563
4.26
6383.46383.4
0.50.0490625
65054.18131.8
10358.90.49805
4.11
6613.26613.2
0.50.0490625
67395.28424.4
10731.70.48075
3.97
6854.56854.5
0.50.0490625
69854.48731.8
11123.30.46382
3.83
7111.67111.6
0.50.0490625
72475.09059.4
11540.60.44705
3.69
7382.77382.7
0.50.0490625
75237.89404.7
11980.50.43063
3.56
7670.87670.8
0.50.0490625
78173.59771.7
12448.00.41446
3.42
7977.57977.5
0.50.0490625
81299.110162.4
12945.70.39853
3.29
8288.38288.3
0.50.0490625
84466.310558.3
13450.10.38358
3.17
Stress o
n pins to
hydrau
lic cylinder
1018 Sut=63.8 K
SI
allowable bending stre
ss=Sut/3=21.3 K
SI
allowable sh
ear stre
ss=Sut/3=21.3 K
SI
29
APPENDIX C: DEFINITIONS
Strength Factor: is defined as the ratio of the ultimate strength of the material to the design stress at rated load capacity (ALI 2006)
Ductile Metal: describes metal capable of sustaining not less than 5% elongation before fracture (ALI 2006)
Non-Ductile Metal: Describes metal not capable of sustaining 5% elongation before fracture (ALI 2006)
30
APPENDIX D: CONSTRUCTION DRAWINGS
Figure 14: Pa
rt drawing oof 1 in pin
31
Figur
re 15: Part d
drawing of ttubing flangge
32
Figu
ure 16: Part
t drawing off Top Sliderr
33
Figure 17: Part dra
awing of Rooller Assemmbly
34
Figure
18: Part dra
awing of cyllinder Sleevve 1
35
Figure
19: Part dra
awing of Cyylinder Sleevve 2
36
Figure 20:
Part drawin
ng of Bottomm Frame Exxtension
37
Figure 2
1: Part draw
wing of Adaapter Plate UUpper
38
Fig
gure 22: Par
rt drawing oof Adapter
39
Fi
gure 23: Pa
rt drawing oof 8 in pin
40
Figure 24: Part Dr
awing of Sccissor Lift AArm
41
Figure 25
5: Part draw
wing of Uppeer Center Seection
42
Figure 266: Part Draw
wing of Centter Frame Section
43
