PIT Crew Design Review By Dan Chapman, Tim Wilson, and Jon Miller January 24, 2003
Initial Concepts
Design Selection
Prototype * *
Exploded view
Piston Cylinder Modified Ratchet 3-Way Valve Regulator Air Canister Limit Switch Bracing Attachment
Piston (Bimba) Specifications: 2.5 in Bore 2 in Stroke Single acting with a spring return Will 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 $ 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: $ 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 Summary
Prototype Weight Summary Piston Cylinder and Mounts2.46 lbs Regulator1.5 lbs 3-way valve (est.).5 lbs Ratchet 1.44 lbs Bottle2.08 lbs Housing plate and other attachments (est.) 17.7 lbs HP & LP fittings (est.).75 lbs TOTAL ~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
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
Concept of Final Product Addition of a safety trigger Ergonomical layout Optimized components