Lift Arm Stop With Automatic Stowing Mechanism
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Solution Overview
Problem
Existing lift arm assemblies in compact construction vehicles lack an efficient mechanism to lock the lift arm in a raised position without mechanical failure or unnecessary complexity, particularly in all-wheel steer utility vehicles.
Innovation Solution
A hydraulic lift arm assembly with a movable lift arm stop that can be automatically detached and reattached to resist retraction of the lift cylinder rod, allowing the lift arm to be securely locked in a raised position and easily lowered, featuring a stowing mechanism for clearance and structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical locking mechanism is added to hold the lift arm in a raised position, then the reliability of the lifted position is improved, but the device complexity increases
Solution Approach 1:
The stop assembly automatically engages with the cylinder body when the lift arm is in the raised position, and automatically disengages when the lift arm is lowered. The spring mechanism automatically returns the stop to its initial position after engagement. This self-servicing mechanism eliminates the need for manual operation or complex control systems while maintaining reliable locking.
Solution Approach 2:
The stop assembly is integrated into the existing lift arm structure, combining the locking function with the existing hydraulic cylinder and lift arm components. The stop assembly merges the stopping function, spring mechanism, and engagement features into a single integrated unit that works with the existing system without requiring separate complex locking mechanisms.
2Reliability
If a stop assembly is added to resist cylinder rod retraction, then the lift arm locking capability is improved, but the ease of operation deteriorates
Solution Approach 1:
The stop assembly automatically engages and disengages based on the lift arm position. When the lift arm is raised, the stop automatically moves into engagement with the cylinder body to lock the position. When the lift arm is lowered, the stop automatically disengages without requiring manual intervention. This maintains ease of operation while providing reliable locking.
Solution Approach 2:
The stop assembly is designed to be movable rather than fixed, allowing it to dynamically adjust its position and engagement state based on the lift arm's movement. The spring mechanism enables the stop to move freely during operation and automatically engage only when needed, maintaining operational simplicity while providing locking capability.
3Adaptability or versatility
If the stop is made detachable for stowing, then the adaptability of the system is improved, but the reliability of the locking function deteriorates
Solution Approach 1:
The stop assembly transitions from a fixed state during operation to a detachable stowed state when not in use. The spring mechanism maintains the stop in its operational position during lifting operations, ensuring reliable locking. When the lift arm is lowered and the stop is no longer needed, it can be detached and stowed, providing adaptability without compromising locking reliability during active use.
Solution Approach 2:
The stop assembly is pre-positioned and pre-loaded with the spring mechanism before operation begins. This preliminary positioning ensures that the stop is ready to engage immediately when the lift arm is raised, maintaining reliable locking from the start of operation. The pre-loaded spring ensures consistent engagement force throughout the operating cycle.
Data Source
AI summary
A hydraulic lift arm assembly includes a lift arm, a lift cylinder raising and lowering the lift arm, a lift arm stop, and a stowing mechanism. The stowing mechanism automatically retains the lift arm stop in a stowed position in response to the lift arm stop moving into the stowed position. The lift arm stop is movable into a locked position in which the stop resists substantial actuation of the lift cylinder from an extended condition, and thereby resists substantial lowering of the lift arm from a raised position. The lift arm stop may include a slot and pin arrangement to permit linear and pivotal movement of the stop with respect to the lift arm. The linear movement may provide clearance for a tongue on the stop to pivot past a portion of the lift cylinder as the stop is moved into the locked position.