What is the structure and working principle of grader?

The motor grader is mainly composed of engine, transmission system, traveling system, steering system, braking system, working device, hydraulic control system, electrical equipment and cab, as shown in Figure 2-27.

Figure 2-27 Basic composition of grader

(1) engine

Generally, air-cooled or water-cooled multi-cylinder diesel engines are used. Most diesel engines use exhaust gas turbocharging technology.

(2) Transmission system

The transmission system is generally composed of a main clutch, a hydraulic torque converter, a gearbox, a rear axle gearbox and a balance box in series, as shown in Figure 2-28. There are two configurations of transmission in transmission system, one is manual transmission and the other is power shift transmission.

Figure 2-28 Composition of Hydromechanical Transmission System

(3) Drive system

The drive system includes a frame and wheels. The frame is a box-shaped integral structure and an arc-shaped welded structure. The bow-shaped longitudinal beam at the front end is a single truss beam with box section, and the working device and its operating mechanism are suspended or installed on this beam. The rear of the frame consists of two longitudinal beams and 1 rear beam. The engine, transmission mechanism and cab are installed on the frame. The rear part of the frame is hinged with the rear axle housing through a guide plate and a bracket, and the front nose is supported on the front axle by a steel seat.

(4) Steering system

The steering system includes front wheel steering system and rear axle steering hydraulic system.

The steering system of grader adopts hydraulic steering system, which is mainly composed of steering transmission mechanism, steering hydraulic cylinder, steering control valve and steering hydraulic oil pump.

In addition to the front wheel deflection steering system, other steering systems are provided to expand the working range, reduce the turning radius and reduce the lateral force. If the rear four wheels are deflected, the front wheels are inclined.

The front frame deflection system can reduce the turning radius of the grader. Especially suitable for places where diagonal operation is needed.

(5) Brake system

The braking system includes foot braking device and hand braking device.

The brake of the foot brake device adopts the shoe brake which is hydraulically opened and automatically boosted. The brake transmission mechanism adopts double pipeline gas-liquid type (from the brake master cylinder to the middle and rear wheels respectively). The brake of the hand brake device is a shoe brake with cam opening and automatic force increasing, and the brake transmission mechanism is mechanical.

The pneumatic-hydraulic integrated service braking system consists of a pneumatic-hydraulic driving mechanism and four wheel brakes, and the wheel brakes are symmetrical self-energizing. The compressed air output by the air compressor enters the gas storage tank after passing through the oil-water separator and the air pressure controller (the control system pressure is 0.5MPa). When the grader brakes, the compressed air pushes the piston in the booster through the control of the brake pedal and the brake valve, and the brake fluid of the master cylinder is pressed into the brake cylinders of the four wheel brakes respectively, so as to push the brake shoes to produce braking effect.

(6) Working device

The working devices of grader include scraper, scarifier and bulldozer, among which scarifier and bulldozer belong to auxiliary working devices.

(1) scraper. The scraper is mainly composed of scraper, traction frame and rotating ring, as shown in Figure 2-29. The scraper consists of a cutter body and a blade. The front end of the traction frame is a ball hinge, which is hinged with the front end of the frame, so the traction frame can rotate and swing in any direction around the ball hinge. The rotating ring is supported on the traction frame and can rotate around the traction frame under the drive of the rotating drive device, thus driving the scraper to rotate at will within the range of 360 degrees. There are two sliding rails on the back of the scraper, which are supported on the sliding grooves of the angle locators on both sides respectively, and can slide horizontally under the push of the scraper side-moving oil cylinder. The angle locator is hin with that lower end of the lug plate of the rotate ring, and the upper end is fixed with a nut; When loosening the nut, the shovel angle can be adjusted.

Figure 2-29 Scraper

② scarifier. The scarifier is mainly used to loosen hard soil, remove roots and stones from the soil, and repair gravel and gravel roads. The scarifier is installed at the rear of the scraper, and is mainly composed of rake teeth, shaft and safety spring, as shown in Figure 2-30.

Figure 2-30 scarifier

There are 6 rake teeth, which are installed on the shaft. When it is not working, the rake tooth tip faces upwards and is positioned by the safety spring. When the scarifier needs to work, remove the safety spring, and after the handle is pulled out of the lever shaft, the rake teeth can be placed in the working position. After the rake teeth are put down, push the lever shaft back. If it is necessary to reduce the number of rake teeth, a gasket should be placed in the middle. When loosening the soil, use a scraper to lift the oil cylinder, so that the scarifier can get a suitable depth of penetration.

③ Bulldozer shovel. Bulldozer is an auxiliary device of grader, as shown in Figure 2-3 1. It is mainly used for auxiliary bulldozing of large graders.

Figure 2-3 1 bulldozer

(7) Hydraulic operating system

The hydraulic system is mainly composed of oil tank, hydraulic pump, multi-way valve, hydraulic cylinder and scraper rotary hydraulic motor.

The hydraulic control system of the grader drives the hydraulic device of the whole vehicle, including the lifting of the scraper, the left and right inclination of the scraper, the left and right rotation of the scraper, the lifting of the scarifier, the deflection of the steering wheel and the braking of the brake. It usually consists of multiple oil circuits.

(8) Electrical equipment

Electrical equipment consists of storage battery, generator and regulator, starter, instrument and lighting device. The circuit adopts single-wire system, the negative electrode is grounded, and the rated voltage is 24V.