Crane Running Wheel Hub Connection Design
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Solution Overview
Problem
Existing running wheels for cranes experience high internal stresses due to thermal treatment processes and oversizes in press fits, leading to reduced load-bearing capacity and wear resistance.
Innovation Solution
The running wheel design incorporates a second form fit with a stop surface to prevent relative movement between the hub and shaft or wheel rim, reducing the oversize required for press fits and allowing the connection to primarily transmit torques, thereby minimizing sliding and internal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oversizes are provided in press fits to ensure secure connection, then connection reliability is improved, but internal stresses increase and load-bearing capacity decreases
Solution Approach 1:
The connection is segmented into two independent functions: the press fit transmits only torque (circumferential forces), while the second form fit with stop surface prevents lateral movement. This segmentation allows the press fit to use minimal oversize, reducing internal stresses while maintaining connection reliability through the combined action of both connection elements.
Solution Approach 2:
The invention adds a dimensional element by introducing a stop surface that acts in a different direction (lateral direction) than the press fit (axial direction). This dimensional addition allows the press fit to be minimized for torque transmission only, while the stop surface handles lateral stability, thereby reducing overall internal stresses.
2Reliability
If oversizes are provided in press fits to ensure secure connection, then connection reliability is improved, but wear resistance decreases
Solution Approach 1:
By segmenting the connection functions, the press fit is reduced to minimal oversize needed only for torque transmission. This reduction minimizes the contact pressure and frictional wear in the press fit interface, thereby improving wear resistance while maintaining connection reliability through the complementary second form fit.
3Strength
If thermal treatment processes are applied, then surface hardness is improved, but internal stresses increase
Solution Approach 1:
The segmentation of connection functions allows the press fit to use minimal oversize, which in turn minimizes the internal stresses generated during thermal treatment processes. The second form fit with stop surface provides the necessary lateral stability without requiring additional press fit oversize, thereby reducing the cumulative internal stresses from both press fit and thermal treatment.
Data Source
AI summary
A running wheel (1, 2) for a crane (16), in particular gantry crane, comprising a shaft (3), a wheel rim (4) and a hub (5) connecting the shaft (3) to the wheel rim (4) for rotation therewith, at least one connection between the hub (5) and the shaft (3) and/or between the hub (5) and the wheel rim (4) having a press fit (6) and a first form fit established by a first stop surface (8), the first form fit blocking a relative movement of the hub (5) in relation to the shaft (3) or the wheel rim (4) in a first direction (17) running parallel to an axis of rotation (7) of the running wheel (1, 2), wherein the connection additionally has at least one second form fit established by a second stop surface (9), wherein the second form fit blocks the relative movement of the hub (5) in relation to the shaft (3) or the wheel rim (4) in a second direction (18) opposed to the first direction (17).