Steering Head Dual-Row Bearing Preload for Torque Consistency
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Solution Overview
Problem
Industrial truck steering systems with electric steering face issues due to fluctuating steering torque caused by component tolerances and wear, affecting driver sensitivity and control precision.
Innovation Solution
A steering head with a dual-row bearing unit, featuring a steering shaft and an output shaft connected via internal and external threads, allowing for adjustable preload and constant steering torque, independent of component tolerances and wear, ensuring consistent resistance to rotational movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-row ball bearing with shaft seal is used, then the structure is simple, but the steering torque fluctuates due to component tolerances and wear
Solution Approach 1:
The bearing unit is divided into two separate bearing rows: a first bearing row supporting the steering shaft and a second bearing row supporting the output shaft. This segmentation allows independent preload application to each row, eliminating the torque fluctuations caused by a single bearing's tolerances and wear.
Solution Approach 2:
A preload force is applied in advance to the bearing rows through the threaded connection between steering shaft and output shaft. This preliminary action compensates for component tolerances and prevents wear-induced torque variations, ensuring consistent steering torque throughout the component's life.
2Reliability
If threaded connection is used to brace shafts, then steering torque becomes constant and adjustable, but the device complexity increases
Solution Approach 1:
The threaded connection between steering shaft and output shaft serves multiple functions: it braces the two shafts against each other, applies preload to both bearing rows, and enables adjustable steering torque. This multi-functionality justifies the added complexity by eliminating the need for separate adjustment mechanisms.
Solution Approach 2:
The steering torque can be adjusted by changing the preload force through the threaded connection. This parameter change capability allows optimization of steering characteristics and compensation for wear, providing consistent performance throughout the component's operational life.
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 a predefined and consistent steering torque, enhancing driver sensitivity and control precision by maintaining a defined torque level, regardless of wear or tolerance changes, thus improving the overall steering experience and reliability.
Implementation Method 1
The bearing unit has two bearing rows, one of which interacts with the steering shaft and one with the output shaft, each bearing row having rolling elements
Implementation Method 2
The steering shaft and the output shaft are provided with means to brace them against each other with a predefined force against the rows of bearings; the means on the steering and output shaft are an internal and an external thread
Implementation Method 3
The steering torque that occurs here is very low and is mainly applied by the shaft seal on the ball bearing
Data Source
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AI summary
Steering head (18) for a rotatable steering angle encoder on a forklift truck with - a steering shaft (28) which is provided for connection with the steering angle encoder, - an output shaft (30) which is provided for connection with a sensor system (52) which detects a rotary movement, and - a bearing unit (22, 24, 26) which has two rows of bearings arranged in an O-shape to each other, one of which interacts with the steering shaft (28) and one with the output shaft (30), - wherein means are provided on the steering and output shafts (30) to clamp the steering and output shafts (28, 30) against each other with a predefined force against the bearing unit.