Jiaozuo brake

Consisting of an air source and control components. The air source includes air compressor, pressure regulating device, double needle Barometer, front and rear axle air reservoirs, low air pressure alarm device, oil and water drain valve, air intake valve, safety valve and other components, and the control device includes brake pedal, pull rod, parallel dual chamber brake valve, cam opening brake, etc.

The air compressor first inputs compressed air into the wet air storage cylinder through a one-way valve, separates oil and water, and then enters the front and rear chambers of the air storage cylinder through the one-way valve. Then, the brake valve controls the inflation of air into the brake chamber to achieve braking.

Figure 7-1 Dual circuit pneumatic brake transmission device for Dongfeng EQ1092 car

Divided into two circuits (as shown in Figure 7-1): one circuit is connected to the front brake chamber through the air reservoir, the rear chamber of the dual chamber brake valve, and the other circuit is connected to the rear brake chamber through the air reservoir, the front chamber of the dual chamber brake valve, and the quick release valve. When one circuit fails, the other circuit can still operate to maintain a certain braking capacity of the car, thereby improving the safety of driving.

1. Air compressor

The function of an air compressor is to generate compressed air, which is the power source for the entire pneumatic braking system.

It is fixed on the bracket on one side of the engine and driven by the crankshaft pulley through a V-belt connection.

Common air cooled reciprocating plug gas compressors (as shown in Figure 7-2) can be divided into two types based on the number of cylinders: air-cooled single cylinder and air-cooled double cylinder.

The air compressor has a crank connecting rod mechanism similar to the engine. The lower end of the cylinder body made of cast iron is connected to the crankcase with bolts. The outer part of the cylinder body is cast with heat dissipation fins. The aluminum cylinder head is fastened to the upper end face of the cylinder body with bolts, and a sealing cylinder gasket is installed between them. There are inlet and exhaust chambers on the cylinder head, each with a plate shaped valve in opposite directions inside, which is pressed onto the valve seat with a spring. The exhaust valve is connected to the air storage cylinder through the exhaust pipe, and the intake valve is connected to the small air filter through the intake duct. A unloading device (unloading chamber or unloading valve) is installed above the intake valve.

2. Pressure regulator

(1) The function of the Pressure regulator: the Pressure regulator is to control the air pressure in the air reservoir within the specified range, and enable the air compressor to unload and idle when the air pressure exceeds the specified range, so as to reduce the power loss of the engine.

The connection mode of Pressure regulator usually includes parallel connection and series connection.

Figure 7-2 Schematic diagram of piston gas compressor

(2) The structure of the Pressure regulator is shown in Figure 7-3. Two pipes with filter elements are installed on the Pressure regulator housing, and the joints are respectively connected with the unloading chamber and the air reservoir. A diaphragm phase pressure regulating spring is installed between the shell and the cover, and the hollow tube is fixedly connected with threads in the diaphragm. The hollow tube can slide in the central hole of the shell, with a sealing ring between them, and the upper side has a radial hole connected to the axial hole. The lower part of the Pressure regulator is equipped with an exhaust valve which is connected with the atmosphere.

Figure 7-3 Diaphragm Pressure regulator

3. Dual pipeline parallel dual chamber diaphragm brake control valve

(1) The function of the brake control valve: The brake control valve controls the compressed air entering the brake chamber and trailer brake valve from the air reservoir, that is, controls the working air pressure of the brake chamber. At the same time, it has a progressive follow-up effect during the braking process. Thus, there is a certain proportional relationship between the working air pressure of the brake chamber and the stroke of the brake pedal, ensuring stable, reliable, and safe braking.

(2) The composition of the brake control valve is shown in Figure 7-4: mainly composed of upper casing, lower casing, balance arm, diaphragm, valve and other components.

Figure 7-4 Structural schematic diagram of parallel dual gun brake control valve

B exhaust port; E exhaust valve port; V balance chamber.

4. Brake chamber

(1) Function of the brake chamber: convert the input air pressure into the mechanical force of the brake cam, so that the wheel brake produces Friction torque.

There are two types of brake chambers: diaphragm type and piston type.

(2) The structure of the brake chamber: The diaphragm type brake chamber used in the Jiefang CA1092 car (as shown in Figure 7-5). It mainly consists of components such as a cover, diaphragm, shell, and return spring.

Figure 7-5 Schematic diagram of diaphragm brake chamber

5. Cam opening wheel brake

The structure of the cam opening type wheel brake (as shown in Figure 7-6) is similar to that of the hydraulic cylinder brake, except that the brake cam is used as the opening device. The front and rear brake shoes are made of malleable cast iron, and both are matched with the eccentric journal clearance of the lower end support hole and support pin, and are axially limited by a baffle and locking pin. When not braking, the return spring pulls the upper support surface of the brake shoe against the cam of the brake camshaft. The cam is integrated with the shaft, mostly made of medium carbon steel, and its surface is high-frequency quenched to improve its wear resistance. The brake camshaft is fixed on the brake base plate through a support, and its tail spline shaft is inserted into the spline hole of the brake adjustment arm. In order to reduce friction between the camshaft and the support, bronze bushings are installed at both ends of the support, and lubrication nipples are available for regular lubrication. Install a sealing washer at the outer end of the bushing, and limit and adjust the axial displacement of the camshaft with a thrust washer and adjusting washer.