Drawbar Hammer Strap Trigger Mechanism for PTO Clearance
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Solution Overview
Problem
Existing drawbar hammer straps often extend too high, risking contact with power-take-off (PTO) equipment and fail to securely lock and prevent rotation of the drawbar pin, leading to excessive wear.
Innovation Solution
A drawbar hammer strap assembly featuring a cross pin mount with a trigger mechanism that pivots to lock the drawbar pin in place, preventing rotation and allowing for low-profile operation with PTO clearance, utilizing a wire form latch and lever arm to engage the implement tongue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hammer strap is extended higher to accommodate the drawbar pin and trigger mechanism, then the pin can be securely locked and rotation prevented, but the strap may contact the PTO when operating over uneven terrain
Solution Approach 1:
The trigger mechanism is positioned laterally offset from the vertical centerline of the hammer strap, allowing the pin locking function to be achieved without increasing the vertical height of the strap assembly. This lateral dimensionality change enables the latch to engage the pin from the side rather than requiring vertical extension.
Solution Approach 2:
The trigger and latch mechanism are integrated within the existing hammer strap structure, with the trigger pivotally coupled to the strap and the latch member nested within the strap body. This nesting allows the locking mechanism to be contained within the compact strap footprint without adding external height that would reduce PTO clearance.
2Device complexity
If a simple pin without locking mechanism is used, then the device complexity is reduced, but the pin cannot remain securely fixed and experiences excessive wear due to rotation and movement
Solution Approach 1:
The trigger mechanism is designed to be actuated by the implement tongue itself during the coupling process. As the tongue is positioned and engaged, it automatically triggers the latch to release or secure the pin without requiring separate manual operation. This self-service approach adds reliability without proportionally increasing complexity.
Solution Approach 2:
The locking function is extracted as a separate trigger mechanism that can be independently actuated, rather than integrating the locking features directly into the pin itself. This separation allows the pin to remain relatively simple while the trigger provides the secure fixation through a dedicated latching system.
3Ease of operation
If the operator must manually secure the pin without a trigger mechanism, then the device complexity is minimized, but the operator must leave their seat to properly secure and verify the pin position
Solution Approach 1:
The implement tongue serves a dual function: it both positions the implement for coupling and acts as the actuator for the trigger mechanism. When the tongue is inserted and engaged, it automatically triggers the latch to secure the pin, eliminating the need for separate manual intervention and allowing the operator to remain seated.
Solution Approach 2:
The coupling action and the pin securing action are merged into a single operational sequence. The same motion that positions the implement tongue also actuates the trigger mechanism, combining two functions (implement positioning and pin locking) into one coordinated movement that improves ease of operation.
Data Source
AI summary
A vehicle drawbar hammer strap assembly may be coupled to an implement tongue with a drawbar pin. A cross pin with a lever arm is operable to releasably hold the drawbar pin. A trigger is engagable with the tongue and the cross pin, and is pivotal from a latched position wherein it engages the cross pin and holds the cross pin in its locked position to an unlatched position wherein it is spaced apart from the cross pin. The tongue engages the trigger and pivot the trigger in an over-center manner from its latched to its unlatched position. The trigger includes a latch member attached to a wire form part which is pivotally coupled to the hammer strap. The latch member is engagable with the lever arm and with an end of the tongue.