Movable External Access Step for Railway Bogie Clearance
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Solution Overview
Problem
Passenger cars with side doors located above bogies face challenges in accommodating external steps due to space conflicts, resulting in pivotable steps that fail to meet ergonomic and comfort standards, especially when platforms are low.
Innovation Solution
A passenger car design featuring a movable external access step that can be extended transversely, allowing independent definition of depth and height, and an actuator for automatic adjustment based on platform height, ensuring comfortable access and compliance with standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pivotable step is used to accommodate external access at a side doorway located above a bogie, then the step can be positioned to avoid interference with the bogie, but the depth of the step is limited and cannot meet ergonomic standards
Solution Approach 1:
The patent transforms the static pivotable step into a movable extendable step that can change its position dynamically. The step is equipped with a movement mechanism that allows it to extend in the longitudinal direction when needed, enabling it to achieve both adequate depth for ergonomic comfort and sufficient retraction distance to avoid bogie interference. This dynamic capability resolves the contradiction between step depth and bogie clearance.
Solution Approach 2:
The patent introduces movement in the longitudinal dimension to solve the space conflict. Instead of only pivoting in the transverse plane, the step can now extend and retract in the longitudinal direction, creating an additional degree of freedom. This dimensional change allows the step to achieve greater depth when retracted while maintaining adequate clearance from the bogie during operation.
2Ease of operation
If the external access step is made deeper to meet ergonomic standards, then passenger comfort is improved, but interference with the bogie increases when the car is in motion
Solution Approach 1:
The step is designed with dynamic movement capability, allowing it to extend to a deeper position during boarding operations to provide ergonomic comfort, and retract to a shorter position during car motion to prevent interference with the bogie. The movement mechanism enables the step to adapt its dimensions based on the operational state, resolving the contradiction between comfort and interference prevention.
Solution Approach 2:
The step can be extended in advance during the boarding process to provide adequate depth for passenger comfort, and then retracted before the car begins to move. This preliminary action sequence allows the system to optimize for comfort during static operations and for safety during dynamic operations without compromise.
3Length of stationary object
If the external access step is positioned closer to the platform to reduce height, then the step meets ergonomic standards, but the available space for the step is reduced due to the low platform height
Solution Approach 1:
The step utilizes dynamic extension in the longitudinal direction to compensate for limited vertical space. By extending forward when needed, the step creates additional horizontal space to achieve the required depth and height proportions for ergonomic compliance, even when the platform is at a low height. The movement mechanism allows the step to optimize its dimensions within the constrained space.
Solution Approach 2:
The patent resolves the space constraint by utilizing the longitudinal dimension for extension rather than being limited only by the vertical height available from the low platform. This dimensional approach allows the step to achieve adequate ergonomic dimensions by extending in the longitudinal direction, effectively compensating for the limited vertical space available.
Data Source
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AI summary
A passenger car (10) for railway transportation comprises a car body (12) supported on at least one bogie (14). The car body has at least one side doorway (34) for boarding and alighting from a vestibule (36), which is located at least partially above the bogie (14) and an external access step (62) movable in a transverse direction of the passenger car (100) between a retracted position and at least one protruding position. In the retracted position, the external access step (62) is located below the vestibule (36). The bogie (14) comprises a front set and a rear set of wheels (46), a front set and a rear set of left and right bearings (48), located between the left and right wheels (46) of the front and rear sets of left and right wheels, respectively. The doorway (34) is located between a front vertical transverse plane (400) containing a revolution axis (300) of the front set of left and right wheels (46) and a rear vertical transverse plane (400) containing a rear revolution axis (300) of the rear set of left and right wheels (46).