Work Vehicle Joystick Interlock for Parking Brake Protection
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Solution Overview
Problem
Existing control systems in earth moving machines like track loaders risk damaging the parking brake or reducing its useful life due to improper activation when both joysticks are operated simultaneously, posing safety hazards.
Innovation Solution
A hydraulic control system that uses independent signals that can be actuated separately one with respect to the other acting on respective input means, comprising a first valve and a second valve, to inhibit the operation of the ground engaging means if both control signals are in an activation state, ensuring the brake is maintained in a fail-safe configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both joysticks are made operative for controlling vehicle motion and implement operation, then the vehicle control versatility is improved, but the parking brake reliability deteriorates due to risk of improper activation
Solution Approach 1:
The control system is segmented into independent control circuits: a first circuit for implement operation (second joystick) and a second circuit for vehicle motion (first joystick). The parking brake is exclusively integrated into the motion control circuit, creating functional separation that prevents improper activation while maintaining full control versatility.
Solution Approach 2:
The control system introduces an intermediary logic that monitors the state of both joysticks and prevents simultaneous activation of implement operation and vehicle motion. This intermediary control mechanism ensures that when the parking brake is engaged, the motion control joystick cannot activate the brake release, thereby protecting brake reliability while preserving operational versatility.
2Reliability
If the parking brake is mechanically locked during implement operation, then the brake safety is improved, but the brake durability deteriorates due to forced mechanical lock from motion joystick
Solution Approach 1:
The system replaces direct mechanical coupling between the motion joystick and brake release mechanism with an electro-hydraulic control system. The motion control joystick now controls hydraulic actuators rather than directly mechanically releasing the brake, eliminating the risk of forced mechanical lock that would reduce brake durability while maintaining safety through controlled hydraulic release.
Solution Approach 2:
The control system performs preliminary verification of brake state before allowing motion control activation. When the parking brake is detected as engaged, the system proactively prevents any command from the motion joystick that would force brake release, thereby protecting the brake mechanism from damaging mechanical stress and extending its service life.
3Ease of operation
If the motion control joystick can activate the parking brake release, then the operational convenience is improved, but the harmful factors increase due to potential brake damage
Solution Approach 1:
The control system incorporates feedback monitoring of the parking brake state and joystick positions. When the system detects that the parking brake is engaged, it provides feedback to the control logic to block any motion control commands that would attempt to release the brake, thereby eliminating the harmful effect of potential brake damage while preserving operational convenience through proper sequential control procedures.
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
Prevents improper activation of the motion system while the parking brake is engaged, protecting the brake from damage and ensuring safe operation by maintaining it in a fail-safe state, reducing oil consumption and overall energy costs.
Implementation Method 1
the brake is only released by fluid pressure
Data Source
AI summary
A work vehicle is provided with a body and ground engaging means configured to allow motion of the body on ground, and braking means for locking ground engaging means, and an operative element carried by said body and configured to execute a specific working operation. The work vehicle further includes a first and a second joystick configured to respectively control the operation of ground engaging means and operative element based on movement of joystick and first and second input means configured respectively to control the activation/deactivation of parking brake functionality of the work vehicle and the activation/deactivation of hydraulic systems of work vehicle. Furthermore, the work vehicle includes a control system configured to receive second and first control signals derived from first and second input means respectively and each configured to assume a respective activation value and a respective deactivation value and inhibit the operation of the joystick linked to the operation of ground engaging means if both control signals are in activation state.