I. Power System (Energy Source)

• Battery pack:
  • The mainstream ones are lead-acid batteries (low cost and simple maintenance) or lithium-ion batteries (high energy density, fast charging, long service life, commonly used in high-end models).
  • The capacity is usually measured in "ampere-hours (Ah)", which determines the endurance of the forklift. For example, a 48V/500Ah battery can support continuous operation for 4-8 hours (depending on the load and working conditions).
  • It is installed in the counterweight area or at the bottom of the forklift, serving both as a power supply and balancing the center of gravity of the vehicle body (to prevent rollover).
• Charger:
  • A device that uses an external power source to charge the battery. Lead-acid batteries need to be matched with a dedicated charger (constant voltage and constant current charging), and lithium battery chargers have intelligent protection functions (to prevent overcharging and overheating).
• Battery Management System (BMS):
  • It monitors the battery's voltage, current, temperature, and state of charge (SOC) in real-time to prevent overcharging, over-discharging, and short circuits, thereby extending the battery life. In case of abnormalities, it alarms through the controller or limits power output.

II. Drive System (Travel and Steering)

• Drive motor:
  • Most use DC permanent magnet motors or AC asynchronous motors (the latter has higher efficiency and requires less maintenance). Speed control is achieved by adjusting the motor speed through the controller.
  • It is installed near the drive wheel and drives the wheel to rotate directly or through a reducer.
• Transmission mechanism:
  • It includes a reducer (reduces motor speed and increases torque), a differential (ensures the speed difference between left and right wheels when turning), etc., to efficiently transmit power to the drive wheel.
• Steering system:
  • Mechanical steering: Commonly used in small forklifts, the steering wheel drives mechanical connecting rods or hydraulic booster cylinders to drive the steering wheel (mostly front-wheel steering).
  • Full hydraulic steering: Mainstream in medium and large forklifts. The steering wheel controls the steering hydraulic pump, and steering is realized by hydraulic oil pushing the steering cylinder, making operation more convenient.
  • Electric Power Steering (EPS): Equipped in high-end models. The controller adjusts the amount of power assistance according to the vehicle speed and steering angle, making steering light at low speeds and stable at high speeds.
• Brake system:
  • Service brake: It includes mechanical brake (brake pads rub against the brake wheel) and energy recovery brake (the motor switches to generator mode during deceleration to recover kinetic energy and recharge the battery).
  • Parking brake: A handbrake or foot-operated mechanical locking device that locks the drive wheel to prevent the vehicle from rolling.

III. Hydraulic System (Cargo Loading and Unloading)

• Hydraulic pump:
  • Driven by a hydraulic motor, it converts mechanical energy into hydraulic energy and transmits pressure through hydraulic oil.
  • The flow rate can be adjusted through the controller (for example, the operating handle controls the speed of the hydraulic pump) to control the action speed (such as slow lifting and fast lowering).
• Hydraulic cylinder:
  • Lifting cylinder: Vertically installed on the mast. When hydraulic oil is injected, it pushes the piston rod to extend, driving the fork to rise; otherwise, it descends.
  • Tilt cylinder: Connects the mast and the vehicle body, controlling the mast to tilt forward (unloading) or backward (preventing cargo from sliding off). The angle usually does not exceed 10°-15°.
  • Lateral shift cylinder (optional): Installed on the fork frame to realize left and right fine adjustment of the fork, facilitating precise alignment.
• Hydraulic valve group:
  • It includes a reversing valve (controls the direction of hydraulic oil, such as switching between lifting and lowering), a flow valve (adjusts the flow rate to control the action speed), and a pressure valve (limits the maximum pressure of the system to prevent overloading).
  • It is controlled by the controller or mechanical handle to realize precise switching of actions.
• Hydraulic oil tank and pipelines:
  • Stores hydraulic oil (anti-wear hydraulic oil), and the pipelines connect various components to ensure the circulation of hydraulic oil.

IV. Operation and Control System (Human-Computer Interaction and Logical Control)

• Controller (ECU/VCU):
  • The Electronic Control Unit (ECU) or Vehicle Control Unit (VCU) receives operation instructions (such as acceleration and lifting) and sensor signals (such as battery power and fork height), calculates, and outputs control signals to coordinate the work of the motor, hydraulic pump, brake, and other components.
• Operating devices:
  • Travel operation: Accelerator pedal (controls the speed of the drive motor), brake pedal, forward/backward reversing lever, steering wheel.
  • Loading and unloading operation: Lifting/lowering handle, forward/backward tilting handle (some with lateral shift handle), which converts operation instructions into electrical signals through displacement sensors and transmits them to the controller.
  • Auxiliary operation: Key switch (start/shutdown), emergency stop button (cuts off all power), horn, light control, etc.
• Instrument and display:
  • A liquid crystal display or pointer instrument displays information such as power, driving speed, fault codes, and fork height (in some models), facilitating the driver to monitor the status.

V. Body Structure (Frame and Bearing)

• Frame:
  • A steel structure frame that bears the weight of the entire vehicle and the cargo load, with high strength (needs to withstand the reaction force of the lifted cargo).
• Mast system:
  • Composed of an inner mast, an outer mast, and a fork frame. The lifting cylinder is installed on the inner mast, and the fork frame is driven to lift through a chain, which is the core structure for cargo lifting.
  • The mast height determines the maximum lifting height (such as 3 meters, 5 meters, 7 meters, and can reach more than 12 meters in special working conditions).
• Fork:
  • An L-shaped steel structure installed on the fork frame, directly bearing the cargo. It can be replaced with different lengths or types according to the cargo size (such as anti-skid forks and paper roll forks).
• Counterweight:
  • A cast iron or concrete block installed at the rear of the forklift, balancing the torque when the fork is loaded with heavy cargo and preventing the forklift from tipping forward (a core safety component).

VI. Safety Auxiliary System

• Limit protection:
  • The limit switch at the highest/lowest position of the fork automatically stops the action when reaching the limit position to prevent mechanical damage.
• Overload protection:
  • A weight sensor detects the cargo weight. When it exceeds the rated load, the controller cuts off the lifting power and alarms.
• Acoustic and optical warning:
  • Reverse radar/camera, turn signals, warning lights, and reverse buzzer prompt surrounding personnel to pay attention to safety.
• Protection devices:
  • Cab overhead guard (against falling objects), seat belt (mandatory to wear, and startup is restricted when not worn), anti-skid pedals, etc.

Summary