1. Air Compressor. The air compressor directly provides the air needed for braking and generates the required air pressure. It is the power supply device in the braking system. The air compressor consists of a crank-connecting rod mechanism, cylinder block, compression spring, intake valve, and exhaust valve. When the engine is running, the air compressor rotates, driving the piston downwards. Outside air enters the cylinder through the air filter and intake valve. When the piston moves upwards, the air in the cylinder is compressed, the pressure increases, overcoming the spring preload of the exhaust valve and causing it to open, allowing compressed air to enter the wet air receiver.
The pressure regulating valve consists of an inlet, an outlet, an inlet valve, an outlet valve, a compression spring, and a diaphragm. When the air pressure in the air reservoir rises to 0.78-0.81 MPa, the air pressure below the diaphragm is sufficient to overcome the spring preload, pushing the diaphragm downwards. This closes the inlet valve and opens the outlet valve, allowing compressed air from the air reservoir to enter the unloading chamber of the compressor. This causes the unloading diaphragm 4 and the unloading rod to move downwards, opening the inlet valve and allowing both cylinders to breathe.
2. Multi-circuit pressure safety valve. In a multi-circuit braking system, compressed air from the air compressor can be supplied to the air reservoirs of each circuit via the multi-circuit pressure safety valve. If one circuit fails and leaks, the pressure safety valve ensures that the remaining intact circuits continue to be supplied with air. The dual-circuit protection valve has one inlet, two outlets, two piston valves, and a compression spring. Normally, the piston valves, under the action of the compression spring, close the two outlets. When compressed air enters the inlet through the pressure regulating valve, it flows into the two air chambers through the two side passages. When the pressure in each air chamber exceeds 0.52 MPa, the force in both chambers exceeds the spring preload, pushing the two piston valves away from the valve seats on the outlet connectors. The compressed air then enters the two circuit air reservoirs through the two outlets.
If one circuit suddenly fails and leaks air during normal inflation, i.e., the pressure at one outlet is very low, and the air compressor stops supplying air, the pressure in the protection valve's chamber will also rise until the piston valve of the undamaged circuit reopens for re-inflation. However, the inflation pressure will be lower, only reaching 0.5-0.55 MPa, because if it exceeds this value, the piston valve on the other side will also open to release air.
3. Brake Valve. The brake valve is the main control device in the loader's service braking system. The brake valve mainly consists of an upper chamber piston, a lower chamber piston, a push rod, a roller, a balance spring, a return spring (for both chambers), an upper chamber valve, a lower chamber valve, an air inlet, an air outlet, an exhaust port, and a vent.
When the driver depresses the foot pedal, the pull rod pulls down one end of the pull arm, compressing the balance spring and causing the balance arm to move downwards. This first closes the exhaust valve and opens the intake valve. Compressed air from the air reservoir then enters the brake chamber through the intake valve, pushing the diaphragm and causing the brake cam to rotate, thus braking the wheels.
4. Manual Brake Valve. The manual brake valve controls the loader's parking brake and second brake (emergency brake). Because there is no requirement for progressive control of the parking brake, the manual brake valve is simply an air switch.
The manual brake valve consists of an operating handle, a compression spring, a valve, a core tube spring, an air inlet, an air outlet, and an exhaust port. The air inlet connects to the parking air reservoir, and the outlet connects to the relay valve. When the parking brake handle is in the parking position, the core tube is pressed against the control cam under the action of the spring. At this time, the intake valve is closed and the exhaust valve is open. The outlet is open to the atmosphere through the core tube and the exhaust port. At the same time, the energy storage spring brake chamber in the energy storage spring chamber is also open to the atmosphere through the relay valve. At this time, the loader is in the parking brake state. To resolve the parking brake, the control handle needs to be operated to close the exhaust valve and open the intake valve. The air pressure output from outlet B is used as a control signal input to the relay valve, which then opens a shortcut for charging air directly from the parking air reservoir into the energy storage spring chamber. When the air pressure reaches a level exceeding the spring pressure, the chamber push rod returns to its original position, thus resolving the parking brake.
5. Relay valve and quick-release valve. The air reservoir and brake chamber are generally only connected by a pipeline through the brake valve. Thus, charging the brake chamber from the air reservoir and venting compressed air to the atmosphere both require a return flow to the brake valve. When the air reservoir, brake chamber, and brake valve are far apart, this roundabout inflation and deflation will result in an excessively long lag time for braking and resolving the brakes, which is not conducive to the timely braking of the loader.
