Five-Stage Mast Upright with Reverse Nested Rails
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Solution Overview
Problem
Existing five-stage lift truck upright designs, such as the 'six-pack' and 'quad-plus-one', suffer from increased weight, reduced load capacity, and limited maneuverability due to fore/aft stacking of mast sections, which affects battery life and requires wider aisle spaces, reducing storage efficiency.
Innovation Solution
A five-stage upright design with a unique rail configuration where the innermost three rails are staggered forward and the additional two rails are reverse nested, reducing the overall fore/aft dimension and load center, allowing for a smaller chassis and improved stability, and enabling the use of twin lift cylinders to enhance load handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If six separate mast sections are utilized to provide five stage lift, then the desired lift height is achieved, but the unnecessary weight reduces load capacity and adversely affects battery life
Solution Approach 1:
The patent applies nesting by placing one mast section inside another, where the second mast section is positioned inside the first mast section. This nested configuration allows five-stage lift capability while reducing the total number of separate mast sections from six to five, thereby eliminating unnecessary weight without compromising the achievable lift height.
2Length of stationary object
If mast sections are stacked in the fore/aft direction, then five stage lift is achieved, but the load center increases which further reduces lifting capacity
Solution Approach 1:
The patent transitions from fore/aft stacking to a lateral arrangement where mast sections are positioned side-by-side rather than end-to-end. This dimensional change in the configuration of mast sections reduces the load center dimension while maintaining the five-stage lift capability, as the mast sections are arranged to minimize the horizontal distance from the load to the truck's center of gravity.
3Length of stationary object
If fore/aft stacking of mast sections is used, then five stage lift is provided, but the overall length of the truck increases thereby increasing aisle space requirements
Solution Approach 1:
The patent uses nesting to place mast sections inside one another, which compactly arranges the five-stage lift mechanism within a smaller fore/aft envelope. This nested configuration significantly reduces the overall length of the truck compared to fore/aft stacking, thereby decreasing the aisle space required for effective operation while maintaining full five-stage lift capability.
4Length of stationary object
If quad-plus-one upright configuration is used, then five stage lift height is achieved, but the fore/aft stacking increases the load center thereby reducing lifting capacity
Solution Approach 1:
The patent changes the arrangement from fore/aft stacking (quad-plus-one configuration) to a lateral side-by-side arrangement of mast sections. This dimensional reconfiguration reduces the load center dimension while maintaining five-stage lift height, thereby preserving or enhancing lifting capacity by minimizing the moment arm that must be counterbalanced.
Data Source
AI summary
An upright for a lift truck includes a first group of mast sections in a first stagger arrangement where a first mast section of the first group of mast sections is fixed to the lift truck. The upright further includes a second group of mast sections in a second stagger arrangement that is reverse nested inside the first stagger arrangement. Further, the upright includes a drive system for telescopingly extending and retracting the second mast sections relative to the first mast section.