Lead Screw Mechanism Manual Release for Vehicle Ramps
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Solution Overview
Problem
Existing vehicle access ramps with lead screw mechanisms require manual operation to be time-consuming and physically demanding, especially in the event of power failure, due to the need for a separate ratchet tool and incorrect operation of the drive train, which complicates manual extension and retraction of the ramp.
Innovation Solution
A mechanism that allows manual operation by disconnecting the platform from the lead screw, enabling the platform to be moved in or out by hand without rotating the lead screw, using a Bowden-type cable connected control handle to release the lock, reducing the force required and eliminating the need for separate tools, allowing quicker operation without bending at a low level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate ratchet tool is used to manually rotate the lead screw, then the ramp can be manually operated in the event of power failure, but the operation becomes time-consuming and physically difficult requiring the operator to bend or kneel down
Solution Approach 1:
The invention extracts the lead screw from the housing and provides it as a separate manual operating element. The lead screw is removably mounted in the housing, allowing it to be pulled out and used as a hand-crank handle. This extraction transforms the hidden drive mechanism into an accessible manual operating tool that the operator can grip and rotate without bending or kneeling, directly resolving the ease of operation problem while maintaining manual operation capability.
Solution Approach 2:
The lead screw serves as an intermediary element between the powered drive system and manual operation. When power is available, it functions as part of the motor-driven mechanism. When power fails, it is extracted and used as a manual crank handle, mediating between the operator's hand movements and the ramp's linear motion requirement. This dual role resolves the contradiction by providing both automated and manual operation modes through the same component.
2Reliability
If the ratchet tool is stored separately on the vehicle, then the ramp can be manually operated, but the operator may not know where it is stored or it may have become lost
Solution Approach 1:
The invention merges the manual operating tool (lead screw) with the ramp mechanism itself. Instead of being a separate stored tool like a ratchet, the lead screw is an integral part of the ramp assembly that is always in place and visible. The merging eliminates the need for separate tool storage and location memory, as the operating element is permanently associated with the ramp structure yet remains accessible for manual operation.
Solution Approach 2:
The lead screw serves multiple functions: it is part of the powered drive train during normal operation, serves as the manual operating crank when power fails, and acts as a structural component of the ramp mechanism. This multi-functionality eliminates the need for dedicated manual operation tools, resolving the contradiction by making the operating element universally integrated into the system.
3Ease of operation
If the operator applies turning force at the opposite end of the mechanism to rotate the lead screw, then the lead screw can be manually rotated, but force must be applied against the motor and drive mechanism which is not designed for it
Solution Approach 1:
The invention segments the lead screw operation from the powered drive train components. By making the lead screw removably mounted, it can be separated from the motor and gear mechanism. During manual operation, only the lead screw is rotated, not the entire drive train including the motor. This segmentation protects the motor and gears from manual operating forces while still enabling manual ramp operation, resolving the contradiction between ease of operation and drive train durability.
Solution Approach 2:
The lead screw is extracted from the powered mechanism and used as a standalone manual crank. This extraction removes the lead screw from the protected drive train components (motor, gears, bearings), allowing manual rotation without subjecting those components to forces they were not designed to withstand. The extraction resolves the contradiction by isolating the manual operation forces to only the lead screw itself.
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 easier and faster manual operation of the vehicle access ramp by reducing the physical effort needed, eliminating the need for separate tools, and allowing the ramp to be operated without rotating the lead screw, thus improving usability and efficiency in power failure scenarios.
Implementation Method 1
using a Bowden-type cable connected control handle to release the lock
Implementation Method 2
Lead screw mechanisms are used to translate rotary motion into linear motion
Implementation Method 3
a ratchet mechanism comprising a ratchet wheel and a ratchet plate
Data Source
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AI summary
The invention provides a lead screw mechanism 160, for example for a vehicle access ramp. The mechanism comprises a support frame 110, a lead screw 150 and an internally-threaded mounting 160. The lead screw 150 has an external thread and is rotatably mounted to the support frame 110. The mounting 160 is mounted on the lead screw such that, when the lead screw rotates, the mounting travels along the lead screw. The mounting comprises a housing 161, an internally-threaded insert 170 rotatably mounted in the housing and engaging with the lead screw, and a lock 164. The lock 164 has a locked position in which the insert 170 is rotatably fixed relative to the housing 161 and a released position in which the insert 170 is able to rotate in the housing 161. The invention provides a mechanism to manually release or disconnect the mounting from the lead screw, which provides a manual means of operation of the vehicle access ramp in the event of a power failure. With the lock 164 in the released position, the insert is free to rotate relative to the housing, so the platform 130 can be moved in or out by hand, moving the housing along the axial direction of the lead screw 150 while the insert rotates around the lead screw thread relative to the housing.