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MiniBaja2/Transmission Design Selection Login

Design Selection Overview1.Considerations2.Analysis3.Results4.Material Specifications

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Final Drive Report About SAE Mini Baja Customer Requirements Benchmarking/Research Brainstorming Glossary Refferences

OverviewThrough the benchmarking and brainstorming process many of the design questions were answered. The rough idea that had only provided us with the ability to assist the continuation of design for the remaining systems of the Mini Baja. The design that was chosen to be the most desirable, was the design which incorporates the use of a Reverse Gear, Limited Slip Differential, a Dog Gear , and Access Panel. We found this design to be most likely to provide us with the desired function and performance during the competition.

ConsiderationsThe prefered gear ratio that the Mini Baja team are designing for is a 10:1. With this ratio of input to output rotation we feel that a successful performance of the vehicle will result. Although because we as a team lack in time to dedicate to and experience with the design of a Mini Baja, we found it very adventageous to impliment Dr. Samuel Drakes Suggestion of incorporating a Access Panel which will assist in quick gear changes.

The second consideration was the use of a Detroit Gearless Locker. An understanding of how to design this component into the gear train and what size the output gear and shafts would be was very unclear. With the purchase of a housing assembly formally used in the Honda Rubicon/Rancher ATV in the front differential(See Figure 10 Below) these questions were answered. The assembly now allowed the locker to be encased within the assembly and the assembly bearings providing a mounting to the case. The output gear could now be mounted to the assembly and provide the final constraints for the gear and shaft sizes.

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Mini Baja 2Important Items Customer Requirements Functional Specifications Benchmarking Brainstorming Updates Project Organization 04 & 05 Car Pics Prototypes SolidWorks Files Budget to date Group Presentations and Reports Sponsors Portland OR info

Team Members

Lance Allen Adam Howe Matt Bennett Will Radford Josh Banks Jeremy Stout Dustin Wallis Daniel Schaugaard

Individual Reports

Frame Design, Will Radford Final Drive, Jeremy Stout Front Suspension, Adam Howe Torque Converter, Josh Banks Rear Suspension, Lance Allen

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Figure 10: Carrier Assembly for Detroit Gearless Locker

A third consideration is to ensure that the axle shaft splines mate with the splines of the locker. The current shafts that the Mini Baja Team has are 20 spline NTN with Shudderless Freering Tripod Joint (SFJ), this type of joint uses a plunge bearing housing, which provides limited horizontal motion. If the articulation of the Mini Baja is to great then this type of joint could not be used. A Constant Velocity Joint (CVJ) with a slip yoke would then be required to perform this motion.

The final consideration to be made in the design of the final drive is the mounting of the Driven unit of the (CVT). JoshuaBanks has devoted plenty of time in considering which shaft size should be used with the Driven and Drive units. The result is a 1 Shaft with a 1/4 keyway. This specification will provide the information needed to design an input shaft size.

AnalysisTo determine the specifics of the final drive components an extensive amount of analysis had to take place. Dr. Samuel Drake was very helpful in assisting the Mini Baja Teams with this analysis. Through his recommendations and design development a complete final drive design was built using Alfa One. With the use of Alfa One the correctness in the manufacturing of the components will be ensured.

A gear ratio of 9.5833333 for the forward gears and 11.68254 for the reverse gears was achieved. Which is approximately what was desired for the outcome, although no attempt has been made toward designing additional gear raios, that will take place during the spring semester, when a better understanding of what differing ratio will be needed. As was stated

Shock Absorbers, Matt Bennett Steering and Braking, Dustin Wallis Frame Manufacturing, Daniel Schaugaard

Project NotesFinal Drive Suspension Frame Steering

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previously the constraining size for the gears was the output gear. once this was determined a module of 2 was used to determine the remaining gear sizes.

Some more variables that define the gear make-up had to be defined before the design could be completed. A few of these variables are the pressure angle, tooth hieght which is made up of the addendum(a)(added on) and the dedendum(d)(subtracted from). Pressure angles can be designed for any degree, although there are three standard values 14.5deg, 20deg, and 25deg. The 14.5deg is now considered obsolete, and the 20deg being the most commonly used value. Therefor we chose to use this as our value. The addendum and dedendum are easily solved for since the module(m) is known.

m = d/N eqn(1)3 a = m eqn(2)\\3 b = m/1.25 eqn(3)\\3

Specification Fwd Chain (P)Fwd

Chain (G)

Fwd Output

(I)

Fwd Output

(G)

Rev Input (P)

Rev Input

(I)

Rev Output

(I)

Rev Output

(G)Module 2 2 2 2 2 2 2 2

Diametric Pitch 32 80 36 138 42 128 36 138

Number of Teeth 16 40 18 69 21 64 18 69

Gear Ratio 9.5833333 11.68254Velocity Ratio 0.821429 2.39583

Table 1: Deteremination of gear size

ResultsDr. Samuel Drake was very helpful in assisting the MiniBaja1 & MiniBaja2 Teams with the design and material specifications for the final drive. Figures 11 thru 14 are the Alfa One drawings that were developed by Dr. Drake.



Figure 11: Input Shaft With Dog Gear & Shifting Mechanism(Drawing Courtesy of Dr. Samuel Drake)

Figure 12: Input Shaft & Counter Shaft (Drawing Courtesy of Dr. Samuel Drake)



Figure 13: Input Shaft, Counter Shaft & Output Shaft(Drawing Courtesy of Dr. Samuel Drake)

Figure 14: Input shaft and countershaft with Shifting Mechanism(Drawing Courtesy of Dr. Samuel Drake)

Material SpecificationsThrough cordination with Dr. Samuel Drake Kurt Williams of the Mini Baja 1 team generated and ordered the following list of materials for the final

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drive. The materials have arrived, with the manufacturing of the compenents scheduled to begin soon.

Input Reverse Sprocket Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City, Utah. Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Input Pinion Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City, Utah. Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Idler Reverse Sprocket Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City, Utah. Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Idler Input Gear Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City, Utah. Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Idler Output Gear Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City, Utah. Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Output Gear Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City, Utah. Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Input Shaft Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City Utah. Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Idler Shaft Material Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City Utah. Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Dog Clutch Material Material Specifications: 4140HT material with a rockwell hardness (2832) Source: Specialty Steel, Salt Lake City Utah.



Machine Work: Advanced Manufacturing Laboratory, Dr. Samuel Drake, Salt Lake City, Utah.

Axles Seals (2) Material Specifications: Source: National Seal Company, Chicago Rawhide

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