Bottom Steering Rack Component Decision Matrix

Owner	@Gerard Cardenas
Status	In Progress
Contributors	@Philip Bortolotti @Cesar Hernandez
Approved
Due date	Jun 2, 2024
Decision	We will use a coupler for the pinion input, two 5/8” OD intermediate and output hollow steel shafts, and steel 5/8-36 X 5/8 smooth bore u joints. The sequence of the assembly is as follows: Steering rack → 5/8”-36 spline coupler → 5/8” OD shaft → set screwed into the spline side of a 5/8”-36 spline u joint → smooth bore side welded onto 5/8” OD intermediate shaft → intermediate shaft welded onto smooth bore side of second 5/8” u joint → spline side of u joint set screwed onto steering wheel input shaft
On this page	1 Problem statement 2 Research insights 3 Solution hypothesis 4 Design options 5 Follow up 6 Source files

Problem statement

There are many options for components linking the steering wheel to the rack. This decision matrix is to decide the best option for each component.

Output Shaft to Coupler		Option 1	Option 2	Option 3

Output Shaft to Coupler	Option 1	Option 2	Option 3
Overview	Use a 5/8” OD shaft with a through hole to fix inside of splined coupler with bolt	Use a 5/8” OD steel shaft, insert shaft into coupler, and weld side of shaft onto edge of the coupler	Use a greater diameter steel shaft and weld edge of the shaft to the edge of the coupler
Screenshot
Link
Benefits and risks	Relatively easy to manufacture - no need for welding No need for a special shaft (splined shaft or DD shaft) Constraining with a bolt going through a through hole can deform the shaft (might have to use steel)	A stronger alternative to using a bolt to constrain shaft Need to use steel to weld onto the coupler Coupler steel grade not specified, may be risky to weld	Opens up the opportunity to use a u joint that has a shaft diameter other than 5/8” Coupler steel grade not specified, may be risky to weld
Criteria
Criteria

U-joint		Option 1	Option 2	Option 3

U-joint	Option 1	Option 2	Option 3
Overview	Smooth Bore	Spline	DD Shaft
Screenshot
Link
Benefits and risks	Can accommodate regular smooth pipes - no need for special shaft (spline shaft or D shaft) Only way to constrain the shaft is to weld the shaft onto the u joint - shaft needs to be same material as the u joint	No need to drill extra holes May be difficult to find a spline shaft (at least in the desired size) Shaft cannot be hollow - adds weight	No need to drill extra holes May be difficult to find a double d shaft (at least in the desired size) Shaft cannot be hollow - adds weight
Criteria
Criteria

Decision	Status	Next steps

Decision	Status	Next steps
	decided / in review / other

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