Dock Leveler Lip Extension Mechanism Gravity Lock

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Solution Overview

Problem

Conventional dock levelers face challenges in extending and holding their lips due to loss of effective power at the start of extension, failure to fully extend due to wear and environmental factors, complexity leading to high maintenance costs, and temperature-sensitive hydraulic dampers that affect lip retraction speed.

Innovation Solution

A dock leveler with a geometrically arranged lip extension mechanism that uses gravity to engage and disengage, transitioning into a locking mechanism to hold the lip fully extended, eliminating the need for springs, mechanical latches, and hydraulic dampers, and reducing the number of components for simplified operation and maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a loaded spring is used to assist in extending the lip, then the lip can be extended, but the available force is contained when the lip is in its pendant position and does not start to work until the dock leveler is raised

Engineering Contradiction:

Improveassist spring forceVSAvoiddelay in spring activation

Core Design Contradiction:

PowerVSLoss of time

Solution Approach 1:

The spring is pre-loaded and positioned to immediately engage with the lip mechanism when the dock leveler begins to lower, eliminating the delay in force application. The spring's initial tension is configured so that it starts assisting lip extension from the very beginning of the lowering motion, rather than waiting for a specific position to be reached.

Inventive Principle:

Principle #10Preliminary action

2Power

If the tension or force of the assist springs is increased, then the lip extension is improved, but it becomes harder to walk the unit down

Engineering Contradiction:

Improvespring forceVSAvoiddifficulty to walk down

Core Design Contradiction:

PowerVSEase of operation

Solution Approach 1:

The spring force is made variable through a progressive engagement mechanism. As the dock leveler lowers and the lip extends, the spring's effective leverage and engagement point change dynamically, providing high initial force when needed for extension, then gradually reducing the force to facilitate easy walking down. The mechanism transitions from a high-force extension phase to a low-force retraction phase.

Inventive Principle:

Principle #15Dynamics

3Reliability

If conventional mechanical latch mechanisms are used to hold the lip extended, then the lip can be held in position, but the mechanism becomes complex with many components that increase manufacturing and maintenance costs

Engineering Contradiction:

Improvelip holding capabilityVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The spring-assisted extension mechanism is merged with the holding mechanism into a single integrated system. The same spring that provides extension force also maintains the lip in the extended position through continuous gentle pressure, eliminating the need for separate mechanical latches, locks, or holding devices. This unified approach reduces component count while maintaining reliability.

Inventive Principle:

Principle #5Merging (Combining)

4Speed

If hydraulic dampers are used to restrict lip retraction, then the lip can be controlled during retraction, but the viscosity of the hydraulic fluid is sensitive to changes in temperature affecting retraction speed

Engineering Contradiction:

Improvelip retraction speedVSAvoidtemperature sensitivity

Core Design Contradiction:

SpeedVSTemperature

Solution Approach 1:

The hydraulic damper system is replaced with a purely mechanical friction-based retraction control mechanism. This could include friction pads, drag links, or friction-based joints that provide consistent resistance to lip retraction regardless of temperature. The mechanical friction mechanism does not rely on fluid viscosity, eliminating the temperature sensitivity problem inherent in hydraulic systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution provides consistent power for extending and holding heavier lips, reduces maintenance needs, and allows for a wider range of motion with lower manufacturing and maintenance costs, while ensuring the lip returns to its pendant position under its own weight, addressing issues of wear and temperature sensitivity.

Implementation Method 1

A dock leveler with a geometrically arranged lip extension mechanism that uses gravity to engage and disengage

Methodology Applied

Scientific EffectGravity: Gravitation

Implementation Method 2

ensuring the lip returns to its pendant position under its own weight

Methodology Applied

Scientific EffectWeight: Gravitation

Data Source

PatentUS8132280B2Loading dock leveler with lip extension mechanism

Publication Date: 2012.03.13 NORDOCK

AI summary

A dock leveler with a deck and an extendable lip that hangs pendant when the deck is in a stored position. A lip extension mechanism engages when the deck is raised to a raised or cocked position. As the deck is lowered to an intermediate transition position, the extension mechanism extends the lip to a fully extended position. At the transition position, the lip extension mechanism automatically disengages and a lip locking mechanism automatically and simultaneously locks and holds the lip in its fully extended position. When the deck is further lowered so that the lip comes to rest on a truck trailer, the locking mechanism automatically released or unlocked. The lip returns to its pendant position when the deck is raised from the truck bed. After the truck pulls away from the dock, the deck is lowered to its stored position.