pit crew design review by dan chapman, tim wilson, and jon miller january 24, 2003
Post on 19-Dec-2015
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Piston (Bimba)
Specifications:2.5 in Bore2 in StrokeSingle acting with a spring
returnWill deliver a force of 440 lbf
at 90 psi; this produces a lug torque of 185 ft*lb
Cost:Piston with a pivot mount is $115.60
Weight:32 oz or 2 lbs
Three-Way, Two-Position Valve (McMaster-Carr)
Specifications:
Max operating pressure of 150 psi
Actuated by a lever
Dimensions (2.16” x 2.48” x 1.26”)
Cost:
$73.09
Weight:
Unknown (estimated .5 lbs)
Regulator(Valin)
Specifications:
3000psi max inlet and 400psi max outlet
Cost:
$190.00
Weight:
1.5 lbs (est.)
Modified Ratchet(Sears)
Specifications:
– Craftsman ½” ratchet driver Model #44809
Cost:
– $21.00
Weight:
– 1.44lbs (excludes adapter and socket)
Prototype Parts List and Cost SummaryCategory Description Price ea. Total
Piston Housing $90.00 1 $90.00
Pivot Attachment $25.60 1 $25.60
Clevis Bracket w/ Pin $19.80 1 $19.80
Rod Pivot $10.85 1 $10.85
Regulator 0-3000psi inlet, 0-400psi outlet $190.00 1 $190.00
High Pressure Fittings Street 90's $14.60 2 $29.20
Hex nipple $2.70 2 $5.40
Needle Valve $62.70 2 $125.40
Low Pressure Hose Nipple $4.52 4 $18.08
3-Way Valve $73.09 1 $73.09
Ratchet $21.00 1 $21.00
HousingMounting Plate (.5" Aluminum) (12x20) $79.20 1 $79.20Angle Iron Piston Mount (3x3x.5) (3" length) $5.19 1 $5.19Automatic Triggor Connection (.09" Aluminum) (2x12) $1.44 1 $1.44Aluminum Mount for Ratchet (3" square aluminum x 3" long) $16.73 1 $16.73
Bottle High Pressure Air Canister
$710.98
Prototype Weight Summary
Piston Cylinder and Mounts 2.46 lbsRegulator 1.5 lbs3-way valve (est.) .5 lbsRatchet 1.44 lbsBottle 2.08 lbsHousing plate and
other attachments (est.) 17.7 lbsHP & LP fittings (est.) .75 lbsTOTAL ~25 lbs
Prototype Testing
Goals:– Actual vs. theoretical performance
• Operating pressure
• Torque output
• Safety of system
• Identify which components are overly conservative
– Size and weight reduction– Worst case scenarios
Testing Outcomes
Optimization of components – Pre-set regulator– Minimize number of valves– Smallest possible canister – Determine ideal bottle pressure– Custom piston-cylinder– Minimum size of total package
(What we anticipate will happen)
Prototype Testing Metric
Prototype 1Volume of prototype ~1152 in 3̂Pressure of the canister 2000psi
Operating Pressure of piston 100psi
Estimated Cost $710.98Weight 25 lbs
Time to remove a lug nut at 100 ft-lb
Time to remove a lug nut at 150 ft-lb
Maximum breaking torqueHuman factors (user friendly, how obvious to use is this?)Number of lugs with 1 tank 6
to be determinedto be determined via user testingto be verified with testing
approximateapproximate (we will optimize this)
to be determined
to be determined
Comments:it would fit in a box this size
maximum pressure (we will optimize)theoretical value (we will optimize this)
Biggest Safety Concerns
• High pressure—what is the minimum operating pressure that will give the desired result?
• Hazards analysis—what pinch-points exist, how can they be removed through design?
• Canister safety—can the system be packaged so that it cannot be misused?
Schedule
Task Week# 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2DesigningMachine Parts for Lock-boxMachine Ratchet & Adapter AttachmentMachine HousingTestingTesting Analysis & Re-designAdditional MachiningRe-TestingDocumentation &Wrap-upDesign Expo
May
Sp
ring
Break
AprilJan Feb March
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