Milestone 11: Clutch Box Build

Previous Drivetrain Analysis

The clutch serves as an isolation and critical torque transfer component of any drivetrain assembly. Specifically for the Wildcat Pulling Team, the mechanical clutch enables controlled engagement between the engine and downstream components. Without a clutch, torque spikes during engine start would impose significant shock loads on gears and shafts, increasing the likelihood of premature wear or catastrophic failure of driveline components.

For the 2024 and 2025 drivetrains on the Wildcat 3124 and Wildcat 3525, a mechanical clutch from Quarter Master was chosen. The 2024 drivetrain utilized a three-disc clutch. This configuration provided high torque capacity and minimal slip during operation. However, a trade-off was that the configuration of three clutch plates resulted in increased mass and higher disengagement force requirements. This negatively impacted operator ergonomics and drivetrain efficiency. In 2025, the Wildcat Pulling Team addressed these issues by acquiring a two-disc clutch from the same manufacturer. This decision reduced the mass of the system while still maintaining sufficient torque capacity for the 2025 competition. Reducing the clutch plates also significantly reduced the disengagement force, as noted by operators of both tractors.

Figure 1: Isometric view of the clutch box, looking at the face that bolts onto the right-angle gearbox

Figure 2: Isometric view of the clutch box, showcasing the location of the bearing press-fit into the housing.

2026 Drivetrain Proposal

Due to the success of the two-disk clutch, Wildcat Powertrain Solutions has elected to propose the same clutch to the Wildcat Pulling Team for the drivetrain of the Wildcat 3526. This phase of the project focused on purchasing the components needed for the clutch subsystem, along with the design and fabrication of the housing for the clutch. In accordance with the ASABE International Quarter Scale Tractor Student Design Competition, all clutch assemblies must be enclosed in a protective housing of either 1/8-inch mild steel or 1/4-inch aluminum. Consistent with the previous design, the clutch housing was manufactured from 1/4-inch and 1/2-inch aluminum plate to reduce weight when compared to 1/8-inch mild steel (Figure 1). As seen in Figure 2, the 1/2-inch face plate has a bored hole to press fit a roller bearing that provides radial support for the clutch shaft, ensuring smooth rotation under loads. Additionally, the housing incorporates removable 1/4-inch side plates for quick inspections, servicing, or replacement of clutch components and the hydraulic throwout bearing.

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