Five Speed Transmission
Team: Ladd Lundquist, Nate Merrill, Alex Palmer, and Amy Stamps
Sponsor: Novak Conversions
Design Descripition
System Overview
The final design is a self-contained overdrive unit with gears on two parallel shafts. The unit is installed between the original transmission and the transfer case. The three main subsystems are the Gears, the Linkages, and the Case. The gear train generates a 25% overdrive. The linkages switch the system between direct drive and overdrive. The case contains the gears, shafts, and oil. Each subsystem is connected mechanically.
Gear Subsystem
Linkages Subsystem
Case Subsystem
Gear Subsystem
The gear subsystem has 4 helical gears; one on the input shaft, two on the cluster shaft, and one on the output. The two pinions both have a tooth count of 28 teeth, and both gears have a tooth count of 32 teeth. When shifting, the linkages move the sliders, which mesh with the blocker rings and change the gear’s speed.
Linkages Subsystem
The linkage subassembly is what allows the user to shift between overdrive and direct drive. The main components are two shift forks, two shift rails, a pivoting mechanism, detent system, and a cartridge to contain it all. The entire subassembly is self-contained and fully assembled before being installed into the case.
Case Subsystem
The case subsystem includes the front and back halves of the case, as well as the shafts, bearings, and retaining plates. The purpose of the case is to support the gears, contain the oil and to protect the gears and oil from dirt and grime. The bolt patterns are modular to allow for different transmissions.
Project Descripition
Off-road enthusiasts often require a strong transmission system capable of handling high torque loads while also providing efficient performance to reach trailheads quickly. The overdrive unit currently in production that can handle 600 ft-lbs. of torque only works for one transmission. We want to develop an overdrive adapter unit that can work for multiple different transmissions.
Requirements and Constraints
- 25% Overdrive Capabilities
- Compatible with T 18, T 19, T 98, SM465
- Handles 600 ft-lbs. of Torque
- Complies with AGMA 9 Standards
- All Parts Machined in House or OTS
- Width under 6 inches, Height under 14 inches
Final Design Exploded View
Performance Review
This design needs further analysis to meet all customer functional requirements. The requirements with numerical values are shown in the table below. The torque rating and gear ratio values were found using computational analysis. The lifetime is estimated based on existing gear and transmission designs. The overall size and weight of the overdrive is too large to bolt a transfer case to it at the proper angle to be installed in a vehicle. Scaling down the size of the unit will also reduce the dry weight.
| Torque Rating | Gear Ratio | Lifetime | Dry Weight | Width | In house | |
|---|---|---|---|---|---|---|
| Target | 600 ft lb. | 0.700 : 1 | 300k mi | 40 lb. | 4.0 in | 100% |
| Threshold | 450 ft lb. | 0.790 : 1 | 200k mi | 50 lb. | 5.5 in | 75% |
| Predicted | 500 ft lb. | 0.750 : 1 | 200k mi | 50 lb. | 5.1 in | 90% |
| Actual | 600 ft lb. | 0.765 : 1 | 200k mi | 70 lb. | 5.3 in | 95% |
Conclusions
How Well Design Meets Requirements
The design meets the majority of the requirements in the problem description. It generates a 25% overdrive and can be completely manufactured at Novak Conversions. Additional testing is still necessary to determine the strength and lifetime of the unit. The design exceeds the weight and size requirements.
Lessons Learned
This senior design project has taught our team valuable lessons about project planning, team collaboration, and design principles. When working on design projects it’s important to plan for unexpected things to happen and be willing to adapt to continuous change. We learned to design with manufacturing and assembly in mind while we collaborated with machinists.
Future Work
The next step in the design process is thorough testing of the prototype. Rapid design iteration and testing will reveal any flaws and lead to informed design decisions. We also recommend scaling down the size of the unit. The linkage subsystem is a new concept. Novak Conversions could spend more time researching automotive linkages to improve the effectiveness of the subsystem.