Hydraulic Transmission Control for Turtle-Rabbit Braking Switch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Agricultural and earth-moving machinery face challenges in precision operations due to the limited control over hydraulic motor displacement, leading to difficulties in switching between low-speed 'Turtle' and high-speed 'Rabbit' modes, resulting in inadequate braking capabilities and prolonged processing times.
Innovation Solution
An automatic switching method between Turtle and Rabbit modes is implemented, triggered by specific conditions such as accelerator pedal release and vehicle speed thresholds, allowing for impulsive activation of Turtle mode for short intervals to facilitate controlled deceleration and prevent hydraulic motor damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the hydraulic motor is forced to maximum displacement to perform low-speed operations, then the vehicle can move very slowly with high torque (Turtle mode), but the processing time becomes excessively long
Solution Approach 1:
The patent implements dynamic switching between two operating modes (Turtle and Rabbit) based on real-time operational needs. The control unit automatically selects Turtle mode for precision operations requiring very low speed and Rabbit mode for faster travel, optimizing both speed and time efficiency without manual intervention.
Solution Approach 2:
The system periodically switches between Turtle and Rabbit modes based on detected operational conditions. The control unit monitors speed and accelerator position continuously, activating Turtle mode only when precision operations are detected and switching back to Rabbit mode when they are completed, creating a rhythmic pattern of speed adjustment that balances precision and efficiency.
2Speed
If the transmission operates in Rabbit mode, then the vehicle can move at higher speed, but the braking ability becomes insufficient when the accelerator is fully released
Solution Approach 1:
The control unit continuously monitors vehicle speed and accelerator position to detect when precision operations are in progress. This feedback mechanism triggers automatic switching to Turtle mode, which provides enhanced braking capability through maximum hydraulic motor displacement, ensuring the vehicle can reliably stop when needed during precision tasks.
3Ease of operation
If manual switching between Turtle and Rabbit modes is implemented, then the operator can control the operating mode, but the ease of operation is reduced due to the need for manual intervention
Solution Approach 1:
The control unit automatically detects when precision operations are in progress by monitoring speed and accelerator position, and autonomously switches between Turtle and Rabbit modes without operator intervention. This self-service approach simplifies operation while the control unit manages the complexity of mode switching based on detected operational conditions.
Data Source
Figure 1
Figure 2
AI summary
Method of controlling a hydraulic transmission of an agricultural vehicle or earth-moving machine, in which the hydraulic transmission is of the series type, in which a vehicle wheel (W) is connected to a hydraulic motor (H) in which a hydraulic pump (P) is arranged to power said hydraulic motor, the hydraulic motor (H) being variable displacement in which the displacement is variable and a function of a load applied to the wheel defining a first operating mode or fixed at a predetermined displacement value due to activation of a command signal (TURTLE/RUBBIT SWITCH), defining a second operating mode, the method comprising a first step (Step 1) of automatically activating said command signal for a predetermined time interval (T) when a accelerator is lower than a predetermined threshold (AC_TH1) and the vehicle speed is lower than a first speed threshold (VS1).