Captive Pin Drawbar Retention for Trailer Hitch Alignment
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Solution Overview
Problem
Existing trailer hitch systems require users to reach under the bumper and maneuver a pin to align with a drawbar, which can be awkward, especially when using accessories like bike carriers that interfere with the pin insertion process.
Innovation Solution
A captive pin mechanism attached to a pin arm on the drawbar, which extends forward and aligns with the receiver tube's pin hole, sliding into place under spring force, allowing for easy alignment and retention without manual manipulation during drawbar insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual pin insertion method is used, then the user can control the pin placement, but the operation becomes awkward and difficult when accessories are present
Solution Approach 1:
The pin arm is pre-positioned on the drawbar at a location that ensures the captive pin will automatically align with the receiver tube hole when the drawbar is inserted to the correct depth. This preliminary positioning eliminates the need for manual alignment during operation.
Solution Approach 2:
The captive pin mechanism is designed to automatically align and insert itself into the receiver tube hole without requiring manual manipulation. The spring force drives the pin into the hole, and the pin arm's geometry ensures proper alignment, making the system self-servicing.
2Adaptability or versatility
If accessories like bike carriers are attached to the drawbar, then the drawbar functionality is enhanced, but the pin insertion process becomes more difficult
Solution Approach 1:
The pin arm is positioned on the drawbar at a location that ensures the captive pin will automatically align with the receiver tube hole when the drawbar is inserted to the correct depth. This preliminary positioning eliminates the need for manual alignment during operation.
Solution Approach 2:
The captive pin mechanism is designed to automatically align and insert itself into the receiver tube hole without requiring manual manipulation. The spring force drives the pin into the hole, and the pin arm's geometry ensures proper alignment, making the system self-servicing.
3Length of moving object
If the pin needs to clear the receiver tube and reinforcing ring during insertion, then the pin range of motion must be sufficient, but the mechanism becomes more complex
Solution Approach 1:
The pin arm combines multiple functions into a single component: it positions the captive pin, provides the range of motion needed to clear the receiver tube and reinforcing ring, and guides the pin into the hole. The spring provides both the driving force and the retention mechanism.
Solution Approach 2:
The pin arm serves multiple purposes: it acts as a mounting structure for the captive pin, provides the necessary travel distance for the pin to clear obstacles, guides alignment with the receiver tube hole, and works with the spring to provide both insertion force and retention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates easy and convenient coupling of the drawbar to the trailer hitch receiver, ensuring the pin automatically falls into place, eliminating the need for manual alignment and reducing the awkwardness of inserting accessories.
Implementation Method 1
The captive pin slides into the pin receiving hole under force of a spring
Data Source
AI summary
At a given insertion depth (D) of a drawbar (22, 60) in a trailer hitch receiver tube (24, 68), a pin arm (26, 56, 74) attached to the drawbar extends forward beside the receiver tube and holds a captive pin (21, 51, 76) beside a pin receiving hole (30, 71) in the receiver tube. A spring (36) urges the captive pin into the pin receiving hole to retain the drawbar in the receiver tube. The pin arm may be attached to the drawbar via a crossbar (40, 70, 73). Receiver tubes of different sizes (24, 68) may be accommodated by a drawbar size adapter (62) that slips over the drawbar, enlarging it, and by a vertical adjustment mechanism (83) for the pin arm (74) that aligns the pin with the pin receiving hole in either a smaller (24) receiver tube or a larger (68) receiver tube.