Analysis of the reasons for the sudden stop of electric forklift movement

The sudden stop of electric forklifts may be caused by various factors, including electrical systems, mechanical components, safety devices, and software control. The following are detailed reasons and specific manifestations:

1、 Electrical system malfunction

1. Battery issue

Battery aging or low battery level

Even if the instrument displays sufficient power, aging batteries may experience sudden power outages due to increased internal resistance resulting in insufficient actual output voltage. For example, in a certain case, the forklift frequently restarted after being fully charged due to the battery cell voltage being below 13V.

Connection failure

Oxidation, loosening, or disconnection of battery plugs may result in instantaneous power outages. In a certain fault case, the battery pack experienced abnormal voltage during charging due to CAN bus grounding interference, ultimately leading to communication failure and inability to drive.

2. Controller malfunction

Controller hardware damage or software error

Internal short circuit of the controller, current sensor failure (fault code CURRENT SHUNT FAULT) or hardware failure protection (HW FAILSAFE) triggering may cause power interruption.

In a certain case, the decoding chip of the controller was damaged due to CAN bus interference, causing the instrument to display "communication failure" and unable to drive.

wiring problem

Fuse blown, main control circuit broken or poor contact: For example, in a certain fault, the drive circuit is interrupted due to the adhesion of the main contactor (MAIN CONT WELLED), and the forklift suddenly stops.

Electromagnetic interference: For example, the CAN bus between the charger and the BMS control board generates spike voltage due to grounding interference, which damages the decoding chip.

2、 Motor and transmission system malfunction

1. Motor malfunction

Motor internal short circuit, winding open circuit, or carbon brush wear

A short circuit in the motor winding may cause overcurrent protection to activate, resulting in a sudden power outage. In a certain case, the motor experienced abnormal heating due to a short circuit in the commutator, ultimately resulting in the inability to start.

Carbon brush wear (length less than 1/3 of the original length) or poor contact may cause power interruption.

Motor overheat protection

Long term overload or poor heat dissipation triggers temperature protection (fault code THERMAL CUTBACK), cutting off power output.

2. Transmission system malfunction

Gear/chain breakage or jamming

In a certain case, the abnormal lifting of the fork was caused by the electromagnetic valve of the hydraulic system being stuck, resulting in the inability to transmit power to the driving wheels.

Damaged drive wheel bearings

Bearing wear or breakage may cause sudden jamming during driving.

3、 Safety device triggered

1. The emergency stop button has not been reset

The operator accidentally touched the emergency stop button and did not reset it in time, directly cutting off the control circuit.

2. Collision bar triggering

When a forklift collides with an obstacle, the internal circuit of the anti-collision strip is connected, triggering the controller to cut off power protection.

3. Seat sensor malfunction

The seat did not detect the driver correctly, and the safety system locked the driving function.

4、 Software and parameter abnormalities

1. Controller program error

In a certain case, a system software bug caused the dashboard to crash and unable to receive operational commands.

2. Parameter configuration error

Wrong accelerator type selection (fault code THOTTLE FAULTRA1) or improper mode switch setting (ANTI-TIEDOWN mode triggered), resulting in power interruption.

5、 Hydraulic system related malfunction

1. Hydraulic pump malfunction

Insufficient pressure in the hydraulic system may cause abnormal lifting and lowering of the forks, indirectly affecting driving stability. For example, in a certain case, the hydraulic pump was damaged, resulting in no response during lifting operations and the forklift being unable to move.

6、 Diagnostic and validation methods

1. Battery testing

Use a multimeter to measure the voltage of a battery cell (≥ 13V/cell after fully charged), and replace the battery if it falls below the threshold.

Check if the battery plug is oxidized or loose to ensure reliable connection.

2. Controller diagnosis

Confirm hardware damage through fault codes (such as LED code 1 corresponding to current sensor fault) and CAN bus waveform testing (such as peak voltage exceeding decoding chip withstand voltage).

Restart the controller or refresh the software program to eliminate software errors.

3. Motor inspection

Disassemble the motor and check the length of the carbon brush and the resistance value of the winding to confirm that there is no short circuit or open circuit.

Measure the temperature of the motor and eliminate the triggering of overheating protection.

4. Verification of safety devices

Manually reset the emergency stop button and check if the seat sensor circuit is conductive.

Test the anti-collision strip circuit to ensure no abnormal triggering.

5. Hydraulic system testing

Check the hydraulic oil level and oil quality, and replace the turbid or low level oil.

Test the working sound of the hydraulic pump and confirm that there is no jamming or damage.

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