Fork Drive Slip Coupling Motor Overload Protection
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Solution Overview
Problem
Existing lifting devices, particularly forklift trucks, face challenges with the electrical drive systems for reach forks, including motor overload and inefficient space utilization, especially when using electric motors instead of hydraulic or pneumatic systems.
Innovation Solution
The integration of an electric motor within the fork's carrier part, coupled with a slip coupling and planetary reduction gear, allows for a compact and lightweight motor setup, preventing overload and enabling selective control, along with a screw spindle and nut mechanism for precise displacement, and a blocking mechanism to prevent undesired movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If an electric motor is integrated into the carrier part of the fork, then space utilization is optimized and the motor can be positioned away from the proximal side, but the motor may be subjected to overload conditions
Solution Approach 1:
A slip coupling is introduced as an intermediary component between the electric motor and the drive mechanism. This slip coupling acts as a mechanical fuse that allows relative movement between motor and load when overload occurs, preventing motor damage while maintaining the compact integrated design. The slip coupling accommodates the contradiction by providing overload protection without requiring additional space or compromising the integrated motor configuration.
2Reliability
If a heavy-duty motor is used to prevent overload, then reliability improves, but the motor size and weight increase
Solution Approach 1:
The slip coupling serves as a protective intermediary that enables the use of a lighter motor by mechanically limiting the transmission of overload forces. Instead of oversizing the motor to handle peak loads, the slip coupling allows the motor to be sized for normal operation while protecting it from damage during abnormal conditions, thus reducing motor weight and overall system mass.
3Length of stationary object
If the motor is positioned close to the sliding mechanism, then transmission distance is reduced, but the proximal side of the carrier part may be weakened
Solution Approach 1:
The electric motor is extracted from the proximal side region of the carrier part and positioned in an available space elsewhere in the structure. This extraction eliminates the conflict between motor placement and structural integrity at the proximal side, while the slip coupling enables the motor to be positioned at a distance without significantly increasing transmission complexity or length.
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 configuration enhances the reliability and safety of the fork's operation by preventing motor overload and optimizing space, allowing for efficient and controlled extension and retraction of the reach forks, while ensuring the motor's longevity and precise control.
Implementation Method 1
The drive preferably comprises a transmission, which can in particular be a planetary reduction gear
Implementation Method 2
the transmission comprises a slip coupling. This is particularly advantageous in the sense that it is hereby possible to prevent the electric motor burning out or being overloaded
Implementation Method 3
a combination of a screw spindle connecting to the electric motor and a nut engaging the screw spindle
Data Source
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AI summary
The invention relates to a fork (l) of a lifting device, such as a forklift truck. The fork comprises a carrier part (2) with a proximal side (4) where the carrier part is connected to the lifting device m the situation of use, and a distal side which is remote from the lifting device in the situation of use. The fork also comprises a sliding part (5) which is displaceable m a direction running between the proximal side and the distal side, and which sliding part is connected to the carrier part. The fork also comprises a drive (6, 7, 8) between the carrier part and the sliding part for selectively lengthening and/or shortening the fork, wherein the drive comprises an electric motor (8) and the transmission comprises a slip coupling (13).