Tractor Trailer Steering Cylinder Asymmetry

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Solution Overview

Problem

Existing tractor-trailer steering systems face challenges with unequal hydraulic cylinder travel, leading to 'sponginess' and increased hydraulic pressure, which affects steering performance and pavement damage, especially with larger loads.

Innovation Solution

A steering system with identical travel distance on each hydraulic cylinder, achieved through a configuration where sender and receiver cylinders are oriented oppositely and connected via equalizer arms, ensuring consistent piston travel and positive pressure at all times, reducing transverse or vertical loads on the cylinders.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard hydraulic steering systems are used with larger trailers, then steering capability is provided, but unequal cylinder travel causes system sponginess and increased hydraulic pressure

Engineering Contradiction:

Improvesteering consistencyVSAvoidsteering smoothness

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies asymmetry by configuring the second sender cylinder at a 180-degree angle relative to the first sender cylinder, and similarly positioning the receiver cylinders. This asymmetric arrangement ensures that both cylinders on each side travel equal distances during steering operations, eliminating the unequal travel that causes sponginess while maintaining reliable steering capability for larger trailers

Inventive Principle:

Principle #4Asymmetry

2Quantity of substance

If larger trailers are designed to carry bigger loads, then cargo capacity increases, but steering-related forces increase causing pavement damage

Engineering Contradiction:

Improvecargo capacityVSAvoidpavement damage

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of increased steering forces into a benefit by using the equalizer arm mechanism to distribute these forces evenly across both sender and receiver cylinders. This equalization reduces the peak forces transmitted to the pavement, allowing larger cargo capacity while minimizing pavement damage through balanced force distribution

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of operation

If hydraulic steering systems are used, then steering capability is provided, but transverse and vertical loads on cylinders reduce precision and increase wear

Engineering Contradiction:

Improvesteering capabilityVSAvoidcylinder alignment

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent introduces equalizer arms as intermediary components between the sender and receiver cylinders. These equalizer arms act as mediators that absorb and equalize the transverse and vertical loads, preventing these forces from directly affecting cylinder alignment and precision. The intermediaries allow hydraulic steering capability while protecting the cylinders from damaging lateral and vertical forces

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7686320B1Steering system for a tractor and trailer

Publication Date: 2010.03.30 ROBB TECH

AI summary

A steering system for a tractor and trailer includes first and second sender cylinders which are turned 180° with respect to each other, and first and second receiver cylinders which are turned 180° with respect to each other. First and second front link members connect the first and second sender cylinders to a front equalizer arm, and first and second rear link members connect the first and second receiver cylinders to a rear equalizer arm. The pistons of the cylinders travel in straight paths experiencing no side loads, and each piston travels the same distance as the tractor turns with respect to the trailer.