The braking device of the forklift includes two modes: hand brake and foot brake. Hand brakes are divided into disc type, drum type and belt type, and most of their transmission parts are mechanical. There are hydraulic type and pneumatic type of foot brake, and the hydraulic type is divided into general hydraulic type and vacuum supercharged hydraulic type.
Although there are many forms of foot brakes, the fault phenomena are basically the same. Here we focus on analyzing and judging the common faults of the hydraulic brake system. The forklift hydraulic braking system is mainly composed of brake pedal, brake master cylinder, brake cylinder, wheel brake and oil pipe.
During the operation of the counterbalance forklift truck, the speed of acceleration and braking of the forklift is one of the important factors reflected in the performance of the forklift, and it also depends on the two accessories of the forklift braking system. The brake pump in the forklift braking system can be mainly divided into brake cylinder, brake master cylinder, brake booster pump and so on. Next, Linktour will introduce to you the working principle of the forklift brake pump.
1. Forklift brake master cylinder, also known as "brake master cylinder" and "brake master cylinder", is the main matching part of the vehicle braking system. The brake master cylinder of forklift is mostly hydraulic brake type. The brake master cylinder using hydraulic brake has a tank pool for storing brake oil on the top, and the piston and oil inlet and outlet ports are located in the cylinder below.
The working principle of the forklift brake master cylinder is: when the brake pedal is stepped on, the master cylinder piston moves to the right, the spring is compressed, the leather cup closes the oil return hole, and the liquid in the cylinder generates pressure to push the oil outlet valve through the oil pipe. into each wheel cylinder. At this time, the wheel cylinder piston expands outward, pushing the brake shoe to contact the brake drum to produce a braking effect. When the brake pedal is released, the piston of the brake master cylinder of the forklift will go back by the thrust of the return spring. At this time, the oil pressure in the brake system will decrease, so the brake shoe will return to the initial position, forcing the brake fluid in the wheel cylinder to flow Back to master cylinder. At this time, the oil outlet valve of the brake master cylinder of the forklift is closed, and the brake fluid pushes open the oil return valve and flows back into the master cylinder through the oil return valve to release the brake.
When the brake pedal is stepped on continuously, that is, when the brake pedal is stepped on and released rapidly, the piston of the master cylinder will return quickly. Due to the resistance of the oil pipe and the oil valve of the master cylinder to the brake fluid, the brake fluid cannot move with the piston. At the same time, it returns to the master cylinder, and at this time, a partial vacuum is generated at the inner end of the cup of the master pump, and the brake fluid stored in the annular space of the piston passes through the six small holes in the piston head and replenishes to the inside of the cup through the edge of the cup. end. If you step on the brake pedal again, you will get greater braking efficiency due to the increase in oil volume. When the brake fluid flows into the right cavity of the piston through the six small holes on the head of the forklift piston and the edge of the cup, the brake fluid in the oil storage chamber also flows into the left cavity of the piston and the annular space through the oil inlet hole to prepare for continuous braking. Use it when braking. When the brake pedal is fully released, the brake fluid flowing back from the wheel cylinder to the master cylinder will exceed the capacity of the master cylinder, so the excess brake fluid will flow back to the oil storage chamber through the oil return hole.
2. The brake cylinder of the forklift is hydraulic brake type, which is one of the indispensable forklift accessories of the forklift braking system. The main function is to push the brake pads, and the brake pads rub against the brake drum to reduce the speed of the vehicle and stop it.
The working principle of the forklift brake cylinder is: after stepping on the brake pedal, the push rod pushes the brake master cylinder to generate thrust, pressurize the brake oil and push it to the brake cylinder, and the piston inside the cylinder begins to move left and right under pressure to push the brake pads. The oil brake master cylinder is composed of the brake master cylinder and the brake fluid storage tank. They are connected to the brake pedal at one end and the brake hose at the other end. Brake fluid is stored in the brake master cylinder, and has an oil outlet and an oil inlet. When stepping on the brake, the oil outlet is opened and the oil inlet is closed. Under the pressure of the piston of the pump body, the brake oil pipe is squeezed out of the oil pipe to flow to each brake cylinder for braking function. when the brake pedal is released. The oil outlet in the brake master cylinder will be closed, and the oil inlet will be opened, so that the brake oil will flow back from each brake sub-cylinder into the brake master cylinder and return to the original state.
3. Forklift brake booster pump. The forklift brake booster pump is a vacuum chamber with a large diameter. There is a diaphragm (or piston) with a push rod in the middle inside, which divides the chamber into two parts. The atmosphere communicates, and the other part is connected with the engine intake pipe through a pipeline. It uses the principle of inhaling air when the engine is working to cause a vacuum on one side of the booster pump, and a pressure difference relative to the normal air pressure on the other side, using this pressure difference to enhance the braking thrust. It should be noted that forklift brake booster pumps are generally suitable for forklifts of three tons or more, and ordinary small-tonnage forklifts may not have forklift brake booster pumps.
The electric forklift travel braking system is composed of vacuum pump, vacuum tank, vacuum booster, brake master cylinder, brake cylinder, wheel brake and brake pedal, etc. The brake type is vacuum booster, hydraulic drive, internal expansion Front wheel brakes.
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