Automobile Transmission Intermediate Shaft Strength
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Solution Overview
Problem
The Ford AOD, AODE, and 4R70W transmissions face durability issues due to the small outer diameter of the intermediate shaft, leading to stress concentrations and torque limitations, which restrict their use in high-demand applications like racing or engines with higher torque and horsepower outputs.
Innovation Solution
The method involves replacing the intermediate shaft and direct clutch cylinder with a modified direct clutch cylinder that includes an outer drum fixed to an extended shaft, eliminating the splined connection and allowing for a larger diameter shaft, thereby increasing the transmission's strength without altering the existing space constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the intermediate shaft outer diameter is increased to reduce stress concentrations and improve strength, then the transmission durability and torque capacity improve, but the space envelope defined by the forward sun gear and other radially outward components is exceeded
Solution Approach 1:
The patent resolves the space constraint by changing the dimensional approach - instead of increasing the intermediate shaft diameter radially (which would exceed the space envelope), the shaft is extended axially (in another dimension) to transmit torque directly to the clutch drum, bypassing the need for a larger diameter while maintaining strength and durability in high-demand applications
2Reliability
If the intermediate shaft outer diameter is increased to improve fatigue strength, then the transmission can handle higher torque and horsepower, but the transmission component layout and space constraints prevent such increase
Solution Approach 1:
The patent merges the intermediate shaft function with the clutch drum connection by extending the shaft to directly engage the clutch drum, eliminating the need for separate splined connections and components. This integration improves reliability for high-torque applications while maintaining the existing transmission component layout without adding complexity
3Force
If replacement intermediate shafts with higher strength materials are used, then the torque capacity improves, but the small diameter and stress concentrations at the spline connection remain limiting factors
Solution Approach 1:
The patent extracts the problematic splined connection between the intermediate shaft and clutch drum, replacing it with a direct shaft extension that engages the clutch drum. This eliminates the stress concentration at the spline connection while maintaining improved torque capacity through the extended shaft design
Data Source
AI summary
Methods of modifying a OE prior art transmission, including Ford's AOD, AODE and 4R70W transmissions, to strengthen the transmission by replacing components known to fail. In one example, the intermediate shaft and direct clutch cylinder of an OE transmission are replaced to eliminate the splined connection joining the two components, to simultaneously eliminate the weak splined connection while also making space within the transmission available for an increased diameter shaft. Aspects of the present disclosure also include kits for increasing the strength of a transmission and methods of assembling a transmission.