Understand the structure and working principle of forklifts, and analyze and compare the advantages and disadvantages of power forklifts and internal combustion forklifts.

I. Overall Structure of Forklifts

There are various types of forklifts, but regardless of the type, they are basically composed of the following four major parts:

(1) Power section. It provides power for forklifts and is usually installed at the rear of the forklift, and can also be used as a counterweight.

(2) Chassis. Accept the power from the power unit to make the forklift move and ensure its normal operation.

(3) Work section. It is used for forking and lifting goods.

(4) Electrical equipment.

Due to the differences in structure and installation position among the above four major components that make up forklifts, various types of forklifts have been formed. Balanced forklifts are a common type of forklift. Now let's take this type of forklift as an example to introduce the composition of each part of the forklift.

1. Power supply section

The power part of internal combustion forklifts mostly adopts reciprocating piston internal combustion engines as the power source. It has gasoline engines, diesel engines and liquefied petroleum gas engines. The power unit of an electric forklift consists of a battery and a DC series-excited motor. In recent years, new types of forklifts have been constantly emerging, and their power sources are either dual-fuel or dual-power.

A powertrain is a device that accepts power and transmits it to the transmission system. It generally has two types: mechanical transmission systems and hydraulic mechanical transmission systems. The former consists of a friction clutch, gear transmission, universal joint transmission device, the main transmission device installed on the drive axle and a differential. The latter uses a hydraulic torque converter instead of a friction clutch, with the rest of the components being the same as the former. In recent years, new types of forklifts have been introduced, featuring a fully hydraulic transmission system. The reduction of transmission components ensures reliability.

2. Chassis section

The traveling mechanism is a device that ensures the rolling operation of the forklift and supports the entire forklift. It is composed of a bracket, axles, wheels and suspension devices, etc. The front axle of a forklift is a drive axle. This is to increase the axle load of the front axle during heavy-load handling, improve the adhesion mass on the drive wheels, enhance the adhesion to the ground, and ensure that the driving force of the engine can be fully exerted. Its rear axle is a steering shaft. The steering mechanism is located in front of the driver, and the gearshift lever and other control levers are on the right side of the driver's seat.

The steering system is a system used to make the forklift move in the direction determined by the driver's will. According to the different energy required for steering, forklift steering systems can be divided into mechanical steering systems and power steering systems. The former uses the driver's physical strength as the power source for steering and is composed of three parts: the steering gear, the steering transmission mechanism and the control mechanism. The latter is a steering device that uses the driver's physical strength and engine power as steering energy. Under normal circumstances, only a small portion of the energy required for a forklift to turn is provided by the driver, while the majority is provided by the engine. It is provided by the rear-steering power unit. However, when the power steering device malfunctions, the driver should generally still be able to independently undertake the task of steering the vehicle. When forklifts are in operation, their steering and movement are highly variable. To reduce the operational burden on drivers, most internal combustion forklifts adopt power steering devices. The commonly used power steering devices include three types: integral power steering devices, semi-integral power steering devices and power boosters.

The braking system is the system that slows down or stops a forklift. It consists of a brake and a braking transmission mechanism. Braking systems can be classified into three types based on their sources of braking energy: manual braking systems, dynamic braking systems, and servo braking systems. The former uses the driver's physical strength as the braking energy source; The middle one relies entirely on the potential energy in the form of air pressure or hydraulic pressure converted from the power of the engine as the braking energy source. The latter is a combination of the former and the latter.

On counterbalanced forklifts, counterweights are installed at the rear of the forklift to balance the mass of the goods at the front of the forklift. The power unit (internal combustion engine) or battery of a forklift is generally installed at the rear of the forklift to achieve local balance.

3. Work section

The working part is the direct working mechanism of the forklift for loading and unloading operations. It consists of the following five parts:

(1) Tools for taking objects. It is a variety of working accessories represented by forks, used for forking, picking and shoveling goods.

(2) Hoisting the shelves. It is used to install forks or other working accessories and drag the goods up and down together.

(3) Mast. It is the frame of the working device, and most of the components of the working device are installed on the frame. Two-section door frames include an outer door frame and an inner door frame that can be raised and lowered along the outer door frame. The three-section gantry is composed of three gantries: the inner one, the middle one and the outer one.

(4) Gantry tilting mechanism. The forward and backward tilting of the mast is mainly achieved through the tilting cylinder.

(5) Upgrade the institution. The power unit and traction device for pulling goods up and down. It is mainly composed of sprockets, chains and lifting cylinders that drive the shelves up and down.

(6) Hydraulic control system. It is a comprehensive control device that can complete actions such as lifting goods and tilting masts in a timely manner through a hydraulic system. It is composed of hydraulic components, pipelines and control mechanisms, etc.

4. Electrical equipment

Electrical equipment mainly consists of batteries, forklift lighting, various warning and alarm signal devices, as well as other electrical components and circuits. The electric forklift is equipped with a series DC motor. Internal combustion engine forklifts are equipped with electric starters. In addition, gasoline engine forklifts are also equipped with high-voltage electric spark ignition devices.