Design

Preliminary Steering Architecture 

Left: Steering architecture top-down view; right: side-vide of steering architecture past the fire wall. 

Connection Points

From the upright to the steering arm, there will be bolted connections to attach the two together rigidly. The tie rods will have rod-ends (spherical bearings) or clevises as the connection point depending on what is needed, same with the center link. The centrelink will be connected to the rack using either a rod end (and bolted) or using a set screw and jam nuts. Past the firewall, there will be a female spline rod to connect with the male spline end of the rack. Connected to the female spline will be a rod, connected to a u-joint (to allow for tilt adjustability of the steering wheel) along with a tilting mechanism similar to the one shown below. Lastly, there will be a male spline connecting steering wheel to the u-joint with a telescoping mechanism (will probably require a female spline with a slide fit and pins for adjustability). The column will be held up using a mounting jig with a collar and L bar with a shear pin (to allow for collapse). 

Components Past the Firewall 

The components past the firewall mainly consist of a steering column, shear pin and steering wheel, however, additional features will be constrained by interiors. 

Interiors requests: 

• telescoping (+/- 3 inches) 
• tilting (+/- 15 degrees) 

These functional requirements drove most of the design of steering past the firewall, the addition of a tilting mechanism (with u-joint), shear pins and an extra shaft was added. 

Fixture

For the steering shaft, a two-piece collar should be used to hold together the majority of the shafts due to their superior holding power to set screws (distributed forces vs point forces). As well, the shaft material will not affect the holding power of collars whereas set screws should be harder than the shaft material so when it is properly tightened, the set screw should actually indent the shaft (Source).

Tilt Mechanism

The tilt mechanism is made up of two plates to guide the movement of the steering column through the use of a bolt and threads through the middle portion. Tightening or loosening the handle/bolt will allow the angle to be adjusted. 

U-Joint

• The U-joint connects the lower steering column to the upper steering column. It is a part of the upper steering column assembly.
• The part can be found here.
• To mate this to the proper point of the master geometry, the feature Move/Copy was used in SolidWorks.
  • This was necessary as the U-joint CAD was supplied from the McMaster-Carr website as one part instead of as an assembly. Using this tool allows the part to rotate its individual components about a point.

Notes from end of August 2019

Current CAD Assem (August 27, 2019)

Component Materials

• Steering columns will have to use splined stock to maintain rotation between the wheel and all components when the steering column collapses (and to connect to u-joint). 
• All shafts below the rack will have to be threaded to connect to components since they need to be threaded, the shafts should be made of steel. 
• All other components in the system can be made from aluminum. 
• Probably going with the nylon shear pins we had on MSXII, unless better alternatives can be found

Plan Going Forward 

DRI Document Fall 2019