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Detailed Description
Title
Design of SAE Baja Portal Gearboxes with an Integrated AWD System
Department(s)
Mechanical Engineering
Creator(s)
Advisor(s)
Date of Original
6/11/2023
Description
A set of portal gearboxes were designed for the Society of Automotive Engineers (S.A.E.)
Baja challenge, an international collegiate competition where students design, build and compete
in a series of off-road racing challenges. The introduction of the new mandatory four-wheel drive
rule has prompted an influx of research and development into different four-wheel-drive designs.
Portal gearboxes were designed to serve as the main final drive reduction for the 2022-2023 car.
A portal gearbox is a gear set located within the profile of each wheel that increases the height of
the driveshaft input location. This portal gearbox design increases the effective ground clearance
by 3.2 in, improves steering geometry, and houses a set of sprag clutch bearings. Sprag clutch
bearings allow for free rotation in one direction and can transmit torque in the other. The sprag
bearings were utilized in the design to create a mechanically biased all-wheel-drive (AWD)
system. They also greatly decrease the rolling resistance of the drivetrain system when coasting.
The portal gearboxes feature a 3:1 reduction to supply a peak torque of 433 ft-lbs to the wheel.
The gearboxes were designed to fit within a standard 10 in x 5 in aluminum wheel, allowing for
no compromise in tire selection or off-road performance. The main challenges of the design were
the rigorous loadings seen at the wheel, the slim profile required, the manufacturability, and the
integration with multiple other components like braking and suspension. The portal gearboxes
were implemented on the 2022-2023 Union College Baja car and competed in SAE Oshkosh Baja
event in Wisconsin on May 4th
-7
th
Baja challenge, an international collegiate competition where students design, build and compete
in a series of off-road racing challenges. The introduction of the new mandatory four-wheel drive
rule has prompted an influx of research and development into different four-wheel-drive designs.
Portal gearboxes were designed to serve as the main final drive reduction for the 2022-2023 car.
A portal gearbox is a gear set located within the profile of each wheel that increases the height of
the driveshaft input location. This portal gearbox design increases the effective ground clearance
by 3.2 in, improves steering geometry, and houses a set of sprag clutch bearings. Sprag clutch
bearings allow for free rotation in one direction and can transmit torque in the other. The sprag
bearings were utilized in the design to create a mechanically biased all-wheel-drive (AWD)
system. They also greatly decrease the rolling resistance of the drivetrain system when coasting.
The portal gearboxes feature a 3:1 reduction to supply a peak torque of 433 ft-lbs to the wheel.
The gearboxes were designed to fit within a standard 10 in x 5 in aluminum wheel, allowing for
no compromise in tire selection or off-road performance. The main challenges of the design were
the rigorous loadings seen at the wheel, the slim profile required, the manufacturability, and the
integration with multiple other components like braking and suspension. The portal gearboxes
were implemented on the 2022-2023 Union College Baja car and competed in SAE Oshkosh Baja
event in Wisconsin on May 4th
-7
th
Genre
thesis
Publisher of Digital Record
Union College Schaffer Library Digital Projects
Source
Union College Schaffer Library Special Collections
Contact Information
Union College Schaffer Library Special Collections, 807 Union St., Schenectady, NY 12308; 518-388-6620; https://www.union.edu/schaffer-library
Harmful Language Statement
Language
English