Runner Hub Lifting for In-Place Stub Shaft Bearing Replacement
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Solution Overview
Problem
The complexity and size of hydroelectric units make it difficult to access and replace components like the stub shaft bearing without disassembling the entire runner and stub shaft assembly, leading to extended downtime due to limited space and the need for component removal.
Innovation Solution
A runner hub lifting device is used to lift the runner hub, allowing the stub shaft bearing to be removed and replaced without disassembling the stub shaft, using hydraulic rams and hub supports to transfer the load and facilitate the installation of a new bearing while the stub shaft remains installed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the stub shaft bearing is replaced by removing the stub shaft from its operational location, then the bearing can be accessed and replaced, but the hydroelectric unit experiences extended downtime
Solution Approach 1:
A lifting device is introduced as an intermediary tool to support the runner hub, enabling the bearing to be replaced without removing the stub shaft. The lifting device acts as a mediator that temporarily bears the load, allowing access to the bearing while maintaining the stub shaft in its operational location.
Solution Approach 2:
The lifting device is installed and the runner hub is lifted to the second position before the bearing removal process begins. This preliminary action of lifting and supporting the runner hub enables subsequent bearing replacement to proceed without requiring stub shaft removal.
2Loss of time
If the runner hub is lifted to access the stub shaft bearing, then the bearing can be replaced without removing the stub shaft, but additional lifting equipment is required
Solution Approach 1:
The lifting device is divided into multiple components including base supports, a ram base plate, hydraulic rams, and a hub support plate. These segmented components can be individually installed and assembled within the confined space of the discharge ring, making the complex lifting device manageable and installable without requiring complete disassembly of the hydroelectric unit.
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
This method significantly reduces the time required for stub shaft bearing replacement, from typically 12 weeks to less than six weeks, by enabling in-place maintenance without the need for full disassembly and reassembly of the runner and stub shaft assembly.
Implementation Method 1
at least one hydraulic ram mounted on the ram base plate
Implementation Method 2
The hydraulic rams lift the runner hub to the second position
Data Source
AI summary
The stub shaft bearing for a stub shaft can be replaced while the stub shaft remains installed in a hydroelectric unit. A runner hub lifting device may be positioned within a discharge ring surrounding a runner hub. The runner hub lifting device may lift the runner hub, and a stub shaft bearing may be removed from a stub shaft. The stub shaft bearing may be disassembled into bearing sections while located in a chamber in the hydroelectric unit. The bearing sections may be removed from the chamber through a service hatch in the chamber. A replacement stub shaft bearing may be moved into the chamber and installed on the stub shaft. The runner hub lifting device may lower the runner hub.