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By Eric chen | 28 June 2022 | 0 Comments

Genie-Boom Lift-S125-Electrical/Mechanical System-LSB4EO alarm cannot extend the last arm pole when

1. Case developer

Case developer: Yuan Jiajian
Business store: Guangzhou Maintenance Group
Case fixed manuscript time: 2022-2-16

2. Vehicle information registration

1. Manufacturer: Genie
2. Model: boom lift
3. Model: S125
4. Working time: 4553
5. Failure code: None
6. Fault system: Electrical/Mechanical System
7. Failure phenomenon: The device reported to the LSB4EO when the delay was extended to the last arm, and could not extend it.

3. fault phenomenon confirmation

The equipment has no alarm, and all other actions are normal. Only when the telescopic arm stretches to 100 feet, the alarm LSB4EO cannot be extended.

4. analysis of the cause

First analyze the alarm principle of LSB4EO: LSB4EO extends 100 feet to extend close to the limit switch. When the arms are extended, the limit switch is triggered and closed when it extends to 100 feet. If this switch is not closed, but the system detects the next limit switch LSB2RS (101 -foot extension of the security switch) has been triggered, then the LSB4EO error will be reported.

According to the fault phenomenon and drawing analysis, the judgment of the fault point is mainly the following points:
1. [Fault point 1]: LSB4EO limit switch failure
2. [Failure point 2]: LSB4EO limit switch line failure
3. [Fault point 3]: Mechanical failure (limit trigger board, armband deformation, etc.)


5. Check and repair steps

1. [LSB4EO]: Disassembling and decomposing limit switch inspections, normal breaks, triggering sensitivity. The switch is not damaged, the wiring is stable, and there is no rust, aging, and oxidation. Eliminate the limit switch failure.
2. [LSB4EO line failure]: When the arm pole is not extended, turn on the key switch and emergency stop switch, measure the limit switch No. 4 pin, 12V voltage, no voltage of No. 3 pin, normal. Note: LSB4EO's No. 3 and 4 pins are regularly opened. Only when the arm pole extends to 100 feet, the 3 and 4 pin will be closed.
When the arm rod extends, when the arm rod extends to 100 feet, the equipment reports the alarm. Measure the interruption and resistance between the 28th needle of the J2 plug of this wire (C76PBE) to the J2 plug of TCON, which is normal.

The picture is the needle wiring of the LSB4EO wiring diagram and the J2 plug of TCON.

[Mechanical failure]: According to the test results above, the LSB4EO cannot be triggered when the arm rod extends to 100 feet when the arms are extended to 100 feet.
Check the appearance of the arm rod, no impact deformation, etc., no coatings, debris, etc. Check the trigger board of the limit switch, everything is normal, no damage, deformation, no coating debris, etc.

In this step, it is still impossible to judge the cause and location of the fault. At this time, a long wire beam was connected to the No. 3 pin of LSB4EO, and the other end was empty. At this time, the arm rod raised up and began to extend, extended to 100 feet when the device failed to retract the arm rod to let it not call the alarm, and then connect the other end of the thread that just connected to the 3rd pin. Continue to do an extension, the arm pole can continue to extend without alarm. As a result, the cause of the fault is that when the device extends to 100 feet, the limit switch is not triggered. However, the reason for not triging is still not determined.

At this time, you want to observe the situation of the limited switch and the limit switch bracket of the thread of the armband to 100 feet. Considering that the arms are raised and the extension moves, it is not easy to observe and is not safe.

According to the drawings, the limit switch of each angle is short/disconnected, so that the device is above 65 ° by default. At this time, when the armband extension is extended, when the extension is extended to 100 feet, it is found that the positioning of the abrasion resistance block position of the limit switch bracket will be pushed in the root welding position of the root rod, so that the bracket will bounce, which makes the limit switch cannot be triggered. Essence Check the abrasive resistance block and find that the wear resistance block is relatively new. Contact the business stores for repairing equipment to communicate the previous maintenance situation. The business store informed them that they had replaced the abrasive resistance, and the equipment was sent to the equipment without a test machine.

Check the comparison of wear -resistant blocks and find that the shorter wear resistance block on the right. The position of the bolt hole is not symmetrical. If it is backpedal, the position of the wear resistance will be too backwards, resulting in the roots of the top of the third arm rod. The welding site ultimately causes the limit switch to not be triggered correctly.

Handling results: Adjust the position of the wear -resistant block. After the correct installation, the test machine is normal and the fault is eliminated.



6. Summary of experience and refinement

1. [Maintenance reminder]: During the maintenance equipment process, when disassembling and replacement of parts, be sure to be optimistic about how the original old parts are installed, it is best to make a mark or the like to ensure that the components are installed correctly.
This failure is still relatively simple, and artificial faults are generally difficult to check and deal with, because it does not speak logic and makes sense! Especially in the aspects of electrical and hydraulic, faults will cause great trouble for subsequent maintenance personnel.

2. [Experience Summary]:

Skills harvest: The alarm logic and working principles of the length of the arm pole and the limit switch of the arm rod.
Maintenance skills: When dealing with the faults of others' maintenance, we must communicate with the personnel who were previously repaired to understand the ideas and processing process of their inspection.

PS: In the later period, a fault that is exactly the same as this failure phenomenon is also processed, but the reason for the failure is that the steel wire rope is not adjusted properly. As a result, when the third arm is extended to 100 feet, the arm pole is more positioned than normal. Eventually, the welding of the root of the arm rod was pushed on the wear -resistant block of the limited switch bracket, and the entire bracket bounced upwards, causing the limit switch to not be triggered correctly. In the end, LSB4EO called the alarm when extending to 100 feet.

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