Inspeção de avarias da escavadora sem rotação

Avaria da escavadora sem rotação: Verificou-se que não havia movimento de rotação, enquanto os outros movimentos eram normais.

Quando o manípulo de operação é colocado na posição rotativa, o óleo de controlo atinge a válvula de controlo e empurra a haste da válvula rotativa para alimentar o óleo de alta pressão fornecido pela bomba de óleo de trabalho traseira para o motor rotativo; Ao mesmo tempo, o circuito de óleo que controla o retorno do óleo ao depósito é cortado, aumentando a pressão da válvula de libertação do travão, empurrando a haste da válvula para permitir a entrada de outro óleo de pressão auxiliar no pistão do travão, abrindo o dispositivo do travão de oscilação e fazendo com que o motor de oscilação actue; O motor rotativo produz potência através da pequena engrenagem da caixa de velocidades, que engrena com o anel da engrenagem rotativa para gerar um movimento rotativo.

Análise e inspeção das causas das avarias:

De acordo com o princípio de funcionamento do mecanismo rotativo, existem três razões para o mau funcionamento, nomeadamente o circuito principal de óleo de trabalho, a transmissão mecânica e o circuito de óleo de controlo.

(1) Inspeção do circuito principal de óleo de serviço

Se a pressão do circuito principal de óleo de oscilação for baixa, não será possível gerar uma ação de oscilação. Medir a pressão do sistema do circuito principal de óleo de trabalho. Existe um bujão de óleo hexagonal interno na saída de pressão da bomba de óleo de trabalho traseira. Retire-o e instale um manómetro. Acionar o manípulo rotativo para acelerar o motor diesel. A pressão medida atinge 23,5 MPa, que é a pressão normal de funcionamento do sistema. Isto indica que todos os componentes hidráulicos do circuito principal do óleo de trabalho estão normais.

(2) Inspeção da parte da transmissão mecânica

O motor rotativo produz energia através da pequena engrenagem da transmissão, que gira em torno do anel de engrenagem rotativo. Durante este processo de saída de potência, se as engrenagens que engrenam entre si estiverem encravadas, também não haverá ação de rotação.

Geralmente, um engate anormal da mudança pode provocar um ruído anormal. Atualmente, o condutor não ouviu qualquer som anormal durante o funcionamento, pelo que as falhas mecânicas da transmissão podem ser temporariamente excluídas.

(3) Inspeção do circuito do óleo de controlo

Uma vez que todas as outras acções da escavadora são normais, isso indica que a bomba de óleo auxiliar que fornece a pressão do óleo de controlo está a funcionar normalmente. Existem três circuitos de óleo de controlo para a ação rotativa, nomeadamente o circuito de óleo que controla a haste da válvula rotativa, a válvula de libertação do travão e o circuito de óleo que entra no pistão do travão de estacionamento. A análise específica é a seguinte.

Ao acionar o manípulo rotativo, há um forte fluxo de óleo ao tocar no tubo de óleo de pressão do motor rotativo, indicando que o óleo da pressão de trabalho principal chegou ao motor rotativo, a haste da válvula rotativa da válvula de controlo pode ser aberta normalmente e o circuito de óleo de controlo está a funcionar normalmente. Medir a pressão do óleo no pistão do travão de estacionamento. Abrir a junta do tubo do circuito de óleo para o motor rotativo, instalar a junta de três vias e o manómetro, e a pressão medida atinge 4MPa, indicando que a pressão do circuito de óleo é normal.

Medir a pressão do óleo na válvula de libertação do travão. Abrir a junta do tubo do circuito de óleo para o motor rotativo, instalar a junta de três vias e o manómetro, e a pressão medida é de 0,4-0,6MPa. Obviamente, esta pressão é demasiado baixa (a pressão de trabalho normal deve ser de 4MPa) para abrir a válvula de libertação do travão, e o óleo de controlo do outro circuito não pode fluir para o pistão do travão, muito menos abrir o dispositivo do travão rotativo. Por conseguinte, não há ação na rotação. Há duas razões para a baixa pressão neste circuito de óleo. Uma é que a válvula de controlo tem fugas, fazendo com que a pressão do óleo que entra na válvula de libertação do travão diminua. (Ligue o manómetro à junta do tubo de óleo de controlo da válvula de controlo à válvula de libertação do travão e a pressão do óleo medida é de apenas 0,4-0,6 MPa, o que indica que a avaliação da fuga da válvula de controlo está correcta); a segunda razão é que a válvula de libertação do travão tem fugas devido ao desgaste, o que aumenta a folga de ajuste (após a desmontagem e a inspeção, a haste da válvula e o orifício da válvula encaixam bem e não há qualquer fenómeno de encravamento).

Resolução de problemas: Um Guia Detalhado para o Diagnóstico e Resolução de Avarias de Válvulas de Controlo em Escavadoras

Excavators are complex pieces of machinery that rely heavily on their hydraulic systems to perform a variety of tasks, from digging and lifting to rotating and moving. One of the critical components in this hydraulic system is the control valve. The control valve regulates the flow and direction of hydraulic fluid, enabling precise control over the excavator’s movements. However, when a malfunction occurs, it can severely impact the performance and efficiency of the machine. This detailed guide delves into the process of troubleshooting a control valve malfunction, including the steps taken to diagnose the issue, the repair process, and the measures to prevent future problems.

Compreender o papel das válvulas de controlo nas escavadoras

Control valves are essential for directing hydraulic fluid to different parts of the excavator. They are responsible for controlling the flow rate and pressure of the hydraulic fluid, which in turn controls the speed and force of the machine’s movements. The primary functions of control valves in an excavator include:

• Regulating Fluid Flow: Control valves manage the flow of hydraulic fluid to various actuators, such as cylinders and motors, which drive the excavator’s movements.
• Controlling Direction: By adjusting the direction of fluid flow, control valves determine the direction in which the machine’s components move.
• Maintaining Pressure: Control valves help maintain the necessary pressure levels within the hydraulic system to ensure efficient operation.

Given their critical role, any malfunction in the control valve can lead to significant operational issues, such as erratic movements, reduced power, and complete failure of specific functions.

Sintomas de avarias nas válvulas de controlo

Before diving into the troubleshooting process, it’s essential to recognize the common symptoms of control valve malfunctions. These symptoms can help in early detection and prompt action to prevent further damage to the excavator. Common signs of control valve issues include:

• Erratic Movements: Inconsistent or jerky movements of the excavator’s arm, bucket, or tracks.
• Loss of Power: Reduced force or speed in hydraulic functions, indicating a possible issue with fluid flow or pressure.
• Hydraulic Fluid Leaks: Visible leaks around the control valve area, suggesting seal or component failure.
• Unusual Noises: Hissing, whining, or knocking sounds from the hydraulic system, which could indicate fluid flow disruptions or air ingress.
• Sobreaquecimento: Excessive heat in the hydraulic system, often caused by restricted fluid flow or pressure imbalances.

Diagnóstico da avaria da válvula de controlo

The first step in troubleshooting a control valve malfunction is a thorough diagnosis. This involves a systematic approach to identify the root cause of the problem. Here’s a detailed breakdown of the diagnostic process:

1. Inspeção visual

Begin with a visual inspection of the control valve and the surrounding hydraulic components. Look for signs of wear, damage, or leaks. Pay close attention to the following:

• Seals and Gaskets: Check for any visible cracks, tears, or deterioration in seals and gaskets that might cause fluid leaks.
• Connections and Hoses: Inspect the hydraulic hoses and connections for signs of wear, damage, or loose fittings.
• Valve Body: Examine the control valve body for any signs of physical damage, such as cracks or corrosion.

2. Análise de fluidos hidráulicos

The condition of the hydraulic fluid can provide valuable insights into the health of the control valve and the entire hydraulic system. Perform the following checks:

• Nível de fluido: Ensure that the hydraulic fluid level is within the recommended range. Low fluid levels can cause air to enter the system, leading to erratic movements and reduced performance.
• Qualidade do fluido: Check the color, viscosity, and presence of contaminants in the hydraulic fluid. Dark, cloudy, or contaminated fluid indicates the need for a fluid change and potential issues with the control valve.

3. Ensaio de pressão

Pressure testing the hydraulic system can help identify issues related to fluid flow and pressure regulation. Use a hydraulic pressure gauge to perform the following tests:

• System Pressure: Measure the overall system pressure to ensure it is within the manufacturer’s specifications. Deviations from the recommended pressure levels can indicate valve malfunctions.
• Pressure Drops: Check for any significant pressure drops across the control valve, which can suggest internal leaks or blockages.

4. Ensaios funcionais

Conduct functional tests to observe the performance of the control valve under different operating conditions. These tests can help pinpoint specific issues:

• Actuator Response: Operate the excavator’s functions, such as lifting the arm, rotating the body, or moving the tracks, and observe the response. Slow, weak, or inconsistent movements can indicate control valve problems.
• Directional Control: Test the directional control by moving the actuators in various directions. Difficulty in changing direction or delayed responses can be signs of valve issues.

Identificar a causa principal: Fuga na válvula de controlo

In this case study, the primary symptom observed was erratic rotational movements of the excavator. Upon conducting the above diagnostic steps, it was determined that the main cause of the malfunction was leakage in the control valve. Here’s a detailed analysis of the findings:

1. Inspeção visual

During the visual inspection, hydraulic fluid leaks were detected around the control valve area. The seals and gaskets appeared worn and deteriorated, indicating a potential source of the leakage.

2. Análise de fluidos hidráulicos

The hydraulic fluid analysis revealed contamination with particles and moisture, which can accelerate wear and damage to the control valve components. The fluid’s color and viscosity suggested that it had not been changed according to the recommended maintenance schedule.

3. Ensaio de pressão

Pressure testing indicated significant pressure drops across the control valve, confirming internal leaks. The system pressure was also lower than the manufacturer’s specifications, further supporting the diagnosis of valve leakage.

4. Ensaios funcionais

Functional testing showed inconsistent and weak rotational movements, which aligned with the symptoms of control valve leakage. The directional control was also affected, with delays and difficulties in changing directions.

Reparação da válvula de controlo

Given the complexity and critical role of the control valve, repairing it requires careful attention and expertise. Here’s a step-by-step guide to the repair process:

1. Remoção da válvula de controlo

To access and repair the control valve, it is necessary to remove it from the excavator. This involves the following steps:

• Desligar as linhas hidráulicas: Carefully disconnect the hydraulic lines connected to the control valve, ensuring to cap them to prevent fluid spillage and contamination.
• Desligar as ligações eléctricas: If the control valve has any electrical connections, disconnect them to facilitate removal.
• Removing Mounting Bolts: Remove the bolts or screws securing the control valve to the hydraulic system or frame.

2. Desmontagem da válvula de controlo

Once the control valve is removed, disassemble it to inspect and replace the damaged components. This involves:

• Opening the Valve Housing: Carefully open the control valve housing, taking note of the arrangement and orientation of internal components.
• Inspecting Internal Components: Examine the internal components, such as seals, gaskets, and valve spools, for signs of wear, damage, or contamination.
• Cleaning and Replacing Parts: Clean all components thoroughly and replace any worn or damaged parts with new ones. Ensure that the replacement parts meet the manufacturer’s specifications.

3. Remontagem da válvula de controlo

After replacing the damaged components, reassemble the control valve with careful attention to detail:

• Reinstalling Internal Components: Reinstall the internal components in the correct order and orientation, ensuring proper alignment and fit.
• Sealing the Valve Housing: Securely close the valve housing, ensuring that all seals and gaskets are correctly positioned to prevent future leaks.

4. Reinstalação da válvula de controlo

With the control valve repaired and reassembled, reinstall it into the excavator:

• Mounting the Valve: Secure the control valve to the hydraulic system or frame using the mounting bolts or screws.
• Reconnecting Hydraulic Lines: Reconnect the hydraulic lines, ensuring that they are securely fastened and free from leaks.
• Reconnecting Electrical Connections: If applicable, reconnect any electrical connections.

5. Testar a válvula de controlo reparada

After reinstalling the control valve, perform comprehensive tests to ensure that the repair was successful:

• Ensaio de pressão: Conduct pressure tests to verify that the hydraulic system pressure is within the manufacturer’s specifications and that there are no significant pressure drops across the control valve.
• Testes funcionais: Operate the excavator’s functions to ensure smooth and consistent movements. Check for any signs of leaks or abnormalities.

Prevenir futuras avarias nas válvulas de controlo

To prevent future control valve malfunctions and ensure the longevity of the excavator’s hydraulic system, implement the following maintenance practices:

1. Verificações e mudanças regulares de fluidos

Regularly check the hydraulic fluid level and quality, and change it according to the manufacturer’s recommendations. Using clean, high-quality hydraulic fluid helps prevent contamination and reduces wear on the control valve components.

2. Inspeção de rotina e substituição de vedantes e juntas

Inspect seals and gaskets regularly for signs of wear and deterioration. Replace them as needed to prevent leaks and maintain optimal pressure within the hydraulic system.

3. Programa de manutenção regular

Implement a regular maintenance schedule that includes checking the condition of the control valve, hydraulic lines, and other components. Timely maintenance helps identify and address potential issues before they lead to significant malfunctions.

4. Formação de operadores

Ensure that operators are trained in the correct use and maintenance of the excavator’s hydraulic system. Proper operation and handling can reduce the risk of damage and prolong the lifespan of the control valve and other components.

5. Utilizar peças genuínas

Always use genuine parts and components that meet the manufacturer’s specifications when repairing or replacing parts of the hydraulic system. This ensures compatibility and reliability, reducing the risk of future malfunctions.