Dual Offset Orbital Caster Mounting Assembly
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Solution Overview
Problem
Caster designs, particularly single and twin wheel casters, face issues with easy direction change due to uneven wheel contact and misalignment, leading to increased rolling resistance and 'lock-up' when casters are misaligned with the direction of thrust, causing difficulty in starting movement and precision placement.
Innovation Solution
A dual pivot caster assembly with a laterally offset mounting system that allows the caster wheel to pivot and orbitally revolve, enabling alignment with the direction of thrust applied to the object, comprising a transfer plate with cylindrical openings and bearing assemblies supporting a mounting post and a clevis-like bracket for the wheel axle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single wheel caster uses a clevis bracket with head angle and rake offset, then the caster can pivot about a vertical axis and rotate the wheel about a horizontal axis, but the wheel cannot turn easily about the pivot axis due to uneven contact area requiring differing linear velocities, causing sliding and dragging (scrubbing)
Solution Approach 1:
The invention divides the wheel assembly into two separate wheels instead of one wheel, allowing each wheel to rotate independently about the horizontal axis. This segmentation enables different portions of the contact area to have different linear velocities without causing scrubbing, as each wheel can rotate at its own rate.
Solution Approach 2:
The invention adds an additional degree of freedom by allowing the wheel assembly to pivot about both a vertical axis and a horizontal axis simultaneously. The clevis bracket is configured with specific head angles and rake offsets that enable this dual-axis movement, transforming the motion from constrained single-axis pivoting to multi-dimensional movement.
2Object-generated harmful factors
If a narrower wheel is used to minimize scrubbing, then rolling resistance is reduced, but greater pressure (force per unit area) is applied to the floor surface
Solution Approach 1:
By dividing the load-bearing function across two wheels instead of one, the invention effectively doubles the contact area with the floor surface. This segmentation of the support function allows each individual wheel to be narrower without increasing pressure, while the combined contact area of both wheels distributes the load.
3Ease of operation
If twin wheels are attached to opposite ends of the axle with the pivot shaft between them, then the ability to turn about the vertical pivot axis is enhanced, but the wheels and axle ends are vulnerable to impact and collision damage
Solution Approach 1:
The invention inverts the traditional twin-wheel configuration by positioning the pivot shaft at one end of the axle rather than between the wheels. This reversal protects the wheel ends and axle from direct impact exposure, as the pivot shaft now serves as the forward-most component in the direction of motion.
4Volume of moving object
If the axle does not extend through the wheel in twin wheel design, then space is saved, but the loading of the wheel on the axle is not symmetric and the bearing surfaces are narrow
Solution Approach 1:
The invention employs a dynamic bearing arrangement where the wheel is free to rotate about the horizontal axis while the axle remains fixed in position. This dynamic configuration allows the wheel to maintain contact with the axle through rotational movement, providing sufficient bearing surface area without requiring the axle to extend through the wheel, thus optimizing space utilization.
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 dual pivot system eliminates 'lock-up' by allowing the caster wheel to easily align with the thrust direction, reducing frictional resistance and facilitating smooth movement in any direction, enhancing maneuverability and reducing wear on the wheel.
Implementation Method 1
reducing frictional resistance
Data Source
AI summary
A caster assembly has a dual pivot assembly in the caster mounting that is laterally offset, whereby the caster wheels may not only pivot about a wheel pivot axis that extends through the plane of the caster wheel, but also revolve orbitally about a mounting pivot axis that is laterally offset from and parallel to the wheel axis. A transfer plate supports a pair of bearing assemblies, one of them securing a mounting post secured to the bottom of an object. The other bearing assembly supports a cylindrical head post that extends to a clevis-like bracket that supports a caster wheel.