Design and Modification of Hydraulic System
Alpha Ind. Tech.
Design and Modification of Hydraulic System
1. The Needed Working Condition of Radio Remote Control System
To make underground LHD more efficient in satisfying operation under different working condition, In general, there are two operation modes of manual control and remote control, and manual control priority, both can be easily switched and interlocked.
To meet clients’ requirements, we generally do modification on existing underground LHD, that is, making proper modification of hydraulic circuit without affecting the original operation. To keep the original manual operation, the changes to the original hydraulic circuit shall be minimized.
The LHD refitted is the ALHD-2 Diesel Underground LHD of our company, mainly used in underground mine to shovel and transport the loose material after blasting. It is especially suitable for the working conditions with bad working conditions, narrow working places, low and muddy working faces. The design scheme is that there are both manual mode and remote control mode, manual mode for safe area, and using remote control mode when entering dangerous operation surface. To complete the entire cycle of shovel loading operation, pull out the dangerous working surface, then change to manual control, complete unloading by operator.
As a result, the entire remote control involves the work of hydraulic systems (including lifting and tipping), steering hydraulic system, brake hydraulic system, throttle hydraulic system and variable speed oil supply hydraulic system. Installing remote control solenoid valve on the basis of the original manual hydraulic circuit and make the remote control system modular. According to the actual needs of users to do, but also easy to install, reduce the changes of the original hydraulic system , in order to achieve the desired design results.
2. Remote Control Reconstruction of Braking Hydraulic System
The braking system of ALHD-2 Diesel LHD adopts full hydraulic double pipe braking system, and is equipped with multi disc wet brake and the America NO - SPIN anti-skid differential. The stopping brake acts on the front axle and the braking mode is spring brake and hydraulic release, which is safe and reliable when operating in bad environment, high water cut and muddy roadway. In order to maintain the system pressure reserve and ensure that the vehicle can be separated from the work site when the engine fails, three accumulators are set up, the pressure is maintained by the unloading valve, and the setting pressure range is 13 - 15MPa.
The system features: hydraulic brake, spring release. When brake needed while driving, depress the foot brake valve pedal, and then the pressure oil output by the foot brake valve is transmitted to the wet brake so as to realize the work brake. The output oil pressure is proportional to the stroke of the pedal valve.
The common design scheme of hydraulic remote control system is that an electrically controlled hydraulic circuit is connected in parallel on the basis of the original manual hydraulic circuit, so then manual control and remote control can be operated separately. Considering that this scheme requires the addition of a hydraulic system on the main control circuit, so the cost is high, and the complexity of the hydraulic system is increased, also the body is small, space for installation is limited. A remote control solenoid valve is connected in parallel with the braking system, oil supply just by one accumulator and a shuttle valve is arranged at the front and rear brake oil circuits. Remote control and manual control, independent operation, mutual non-interference. The front and back axles are the oil supply brake. Because of the braking in only one gear, the braking force changes little, so the proportional valve is not needed. Just using the common electromagnetic valve to realize the on-off of the oil circuit.
When operating, remote control solenoid valve is energized, B - T interlinked, the oil does not pass through the solenoid valve. In manual operation mode, the on and off of brake circuit is by stepping on the brake pedal. In remote control mode, the pedal valve is disconnected and the manual control does not work, when braking, the remote control electromagnetic valve is power-off, At this time, P - B interlinked, hydraulic oil gets into the front and rear bridge through the shuttle valve to achieve braking. The remote control module that reformed is shown in picture. The stopping brake is no longer equipped with a remote control electromagnetic valve, and the original electromagnetic valve is reformed to realize the function of remote control.
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