Fmea

Alternative Fuel Group

Steering Decision Presentation
By: Dan Groll Alt. Fuel Group Suspension/Braking Sub-Group

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Alternative Fuel Group

Overview
• Decision • Functional Design • FMEA • Calculations • Manufacture
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Alternative Fuel Group Pitman Arm Vs Rack and Pinion Steering System
Pitman Arm •Higher turning ratio Rack and Pinion •Requires 3-4 complete revolutions from lock to lock •Possible Slippage •System of Gears

•Less Sensitive to Errors in assembly •Less complex parts

•Ease of machining

•Need to be ordered or specially designed

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Alternative Fuel Group

Pittman Arm Steering System

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Alternative Fuel Group

FMEA
Failure Modes
RPN= (SEV)*(OCC)*(DET) Mounting Issues 24 = (3) * (4) * (2)

Weld Fracture Removal of lubricant Loose Fittings Peg Failure

160 6 30 30

= (8) * (2) * (10) = (3) * (2) * (1) = (3) * (5) * (2) = (3) * (2) * (5)

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Alternative Fuel Group

FMEA
Weld Fracture (RPN=160)
RPN= (SEV)*(OCC)*(DET) SEV = 8 Significant danger depending on circumstances May work but almost useless

OCC= 2

Very small chance of occurrence Forces in steering system are not very significant

DET=10

No chance to detect and avoid

One possible solution is to add set screws

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Alternative Fuel Group

Approximating the Steering Column Length
The Steering column length should be approximately 31 inches long

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Alternative Fuel Group

Calculating Wheel Angle θ The minimum requirement for turning radius is 10 ft
Turning Radius, r

90o-θ
Wheel base

In order to prevent under steer this will be used for the maximum turning radius

θ

To calculate the corresponding wheel angle:
Law of Sines

r Wheelbase = sin(90) sin(θ )

θ req = sin −1 ⎜

⎛ 4.625 ft ⎞ ⎛ Wheelbase ⎞ ⎟ = 27 o = sin −1 ⎜ ⎟