Service Main Piston Bushing Dual Spring Ramps

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing brake control valves for railway vehicles, such as the ABDX-type, lack a mechanism to consistently retain the service slide valve in its service position, leading to potential premature movement to either the boost or jump position due to variations in pressure differential and friction, which can result in system failures, especially when excessive lubricant is used.

Innovation Solution

Incorporating a second spring ramp in the main piston bushing to provide a secondary delay mechanism that engages the wing spring of the main piston assembly, ensuring the service slide valve remains in the service position by requiring an increased pressure differential to move beyond this position, thus preventing premature transitions to the boost or jump positions and enhancing friction to maintain stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single spring ramp is used in the main piston bushing, then the preliminary quick service function is achieved, but the service slide valve cannot be consistently retained in the service position

Engineering Contradiction:

Improveconsistency of service slide valve positioningVSAvoidnumber of spring ramps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The single spring ramp is segmented into two distinct spring ramps (first and second spring ramps) positioned at different locations on the main piston bushing. The first spring ramp provides the preliminary delay for quick service, while the second spring ramp provides an additional delay to retain the service slide valve in the service position, thereby resolving the inconsistency in valve positioning without excessive complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second spring ramp is positioned to engage the wing spring before the service slide valve can prematurely move to the boost or jump position. This preliminary engagement creates a mechanical barrier that prevents unwanted valve movement, ensuring consistent retention in the service position during normal brake operations

Inventive Principle:

Principle #10Preliminary action

2Reliability

If friction and pressure differential are the only mechanisms to stop the service slide valve, then the system remains simple, but the valve position becomes inconsistent

Engineering Contradiction:

Improveservice slide valve position consistencyVSAvoidstopping mechanism force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The second spring ramp acts as an intermediary mechanical element between the wing spring and the service slide valve. Instead of relying solely on friction and pressure differential forces, the spring ramp provides a physical barrier that mediates the stopping action, ensuring consistent valve position by preventing premature movement to boost or jump positions

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If excessive lubricant is used, then the sliding friction decreases, but the service slide valve may prematurely move to boost or jump position

Engineering Contradiction:

Improvesliding frictionVSAvoidservice slide valve position stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The second spring ramp provides a preliminary mechanical constraint that counteracts the effect of reduced friction from excessive lubricant. By engaging the wing spring before the service slide valve can move prematurely, the spring ramp creates a counter-balancing force that prevents unwanted valve movement even when lubricant reduces the normal frictional stopping mechanism

Inventive Principle:

Principle #9Preliminary anti-action

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

The additional spring ramp effectively retains the service slide valve in its service position during initial brake applications, reducing the risk of system failures by requiring additional force to move beyond the service position, even under conditions of low sliding friction, and making the design more robust to variations in lubricant application.

Implementation Method 1

The first spring ramp being provided to act as a delay by engaging the wing spring of a main piston assembly

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The second spring ramp being provided to act as a secondary delay by engaging the wing spring of the main piston assembly to retain the service slide valve in the service position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

the only mechanism that stops the service slide valve in this position is a combination of the friction between the service slide valve face and its seat

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS9555790B2Service main piston bushing containing two spring ramps

Publication Date: 2017.01.31 WABTEC HLDG CORP

AI summary

A main piston bushing for a service valve portion of a brake control valve includes a cylindrical sidewall defining a central passageway extending longitudinally through the main piston bushing, the central passageway being surrounded by an internal surface of the cylindrical sidewall. The central passageway is configured to receive the main piston assembly of the service valve portion. The internal surface of the cylindrical sidewall includes a first ramp and a second ramp defined therein, the first ramp and the second ramp being configured to engage a portion of the main piston assembly of the service valve portion to restrain movement of the main piston assembly.