Oil-filled pump station for wide-body dumper oil-gas spring

Abstract

The utility model provides an oil-filled pump station for an oil-gas spring of a wide-body dumper. The oil-filled pump station comprises a hydraulic oil tank, a gear pump, a high-pressure filter, a triple manual reversing valve and an oil return filter, an inlet of the gear pump is in circulation connection with oil in the hydraulic oil tank; an outlet of the gear pump is in circulation connection with a high-pressure filter; an outlet of the high-pressure filter is in circulation connection with a P port of a triple hand-operated direction valve; a port A of the triple manual reversing valve is connected with a liquid filling hose, the tail end of the liquid filling hose is connected with a liquid filling connector, and the liquid filling connector is connected to an oil-gas cylinder of the oil-gas suspension system in a circulating mode. A port T of the triple manual reversing valve is in circulation connection with an oil return filter which is arranged at the top of the hydraulic oil tank and is in circulation connection with the hydraulic oil tank. High-pressure hydraulic oil is output, the oil filling speed is increased, and the oil filling efficiency is improved; the manual reversing valve is easy and efficient to operate, safety is guaranteed, and meanwhile the workload is remarkably reduced; after oil filling is completed, hydraulic oil is prevented from flowing out, and the use performance of the hydro-pneumatic suspension system is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of mining vehicles for transporting ore and earth, and in particular to an oil filling pump station for an oil-gas spring of a wide-body dump truck. Background Art

[0002] With the development of society and production technology, construction machinery is increasingly used in production and industry. As an important transportation equipment in open-pit mining, wide-body dump trucks have the advantages of heavy load and high working efficiency.

[0003] As an important component of wide-body dump trucks, the suspension system is independent on the left and right sides. The suspension oil and gas cylinders of two or more axles on the same side are connected to the accumulator through a hose to carry the upper system such as the frame and cargo box. At the same time, during the operation of the vehicle, the vibration and impact of uneven roads on the vehicle can be absorbed by the internal oil pressure and air pressure balance, reducing the impact on the vehicle operation, thereby ensuring the smooth operation of the vehicle.

[0004] According to the total weight of the upper part of the equipment when it is unloaded and loaded, the nitrogen pre-charge pressure of the accumulator can be determined to ensure that the oil pressure and air pressure can reach a good balance. The oil-gas cylinder has a certain oil filling length under normal conditions, and the total stroke of the oil-gas cylinder can meet the stroke requirements of extension and retraction during use. When the oil-gas suspension system is in the unloaded state of the equipment, high-pressure hydraulic oil is injected into the oil-gas suspension system to achieve the extension of the oil-gas cylinder piston to the specified length.

[0005] However, the existing oil-gas suspension systems on the market have the following problems during debugging and use:

[0006] 1. The oil filling process requires the frame to be lifted by a jack or lifting equipment, which is cumbersome and very dangerous.

[0007] 2. When filling the oil, the hydraulic oil flows naturally into the suspension system, the filling speed is slow, and the filling efficiency is low;

[0008] 3. The air in the suspension system is not easy to be exhausted. When the hydraulic oil is mixed with air during use, it is easy to cause the hydraulic oil to oxidize and deteriorate, affecting the performance of the suspension system. Utility Model Content

[0009] In view of this, the purpose of the utility model is to design an oil filling pump station for the oil-gas spring of a wide-body dump truck, which uses an electric motor to drive a gear pump to rotate and output hydraulic oil with a certain pressure to provide oil filling for the oil-gas suspension system, speed up the oil filling speed, and improve the oil filling efficiency; the oil filling and exhaust of the oil-gas suspension system are realized through a manual reversing valve, and the operation is simple and efficient; there is no need to suspend the frame when the suspension system is filled with oil, which ensures safety and significantly reduces the workload; after the oil filling is completed, the filling hose can be disconnected to prevent the hydraulic oil from flowing out, thereby ensuring the performance of the oil-gas suspension system.

[0010] The utility model provides an oil filling pump station for an oil-gas spring of a wide-body dump truck, comprising:

[0011] Hydraulic oil tank, gear pump, high-pressure filter, triple manual reversing valve (oil charging control valve), return oil filter; the inlet of the gear pump is connected to the oil in the hydraulic oil tank; the outlet of the gear pump is connected to the high-pressure filter, and the outlet of the high-pressure filter is connected to the P port of the triple manual reversing valve; the high-pressure hydraulic oil output by the gear pump enters the oil-gas suspension system after passing through the high-pressure filter, ensuring the cleanliness of the oil entering the oil-gas suspension system and preventing impurities in the hydraulic oil tank from entering the oil-gas suspension system and affecting its operation.

[0012] The A port of the triple manual reversing valve is connected to a liquid filling hose, the end of the liquid filling hose away from the A port is connected to a liquid filling joint, and the liquid filling joint is fluidly connected to the oil and gas cylinder of the oil and gas suspension system;

[0013] The T port of the triple manual reversing valve is connected to the return oil filter, and the return oil filter is arranged on the top of the hydraulic oil tank and is connected to the hydraulic oil tank. The return oil filter removes pollutants and impurities in the return oil to improve the cleanliness of the oil entering the hydraulic oil tank.

[0014] Furthermore, the triple manual reversing valve has three working positions, namely, a middle position, an upper working position, and a lower working position; wherein, in the middle position, the P port and the T port of the triple manual reversing valve are connected, and the oil flows directly from the P port to the T port back to the hydraulic oil tank, and the suspension system is in a no-load state. At this time, the output power of the gear pump and the motor is very small, thus avoiding power waste and ensuring that the motor has good starting performance;

[0015] When in the upper working position, the P port of the triple manual reversing valve is connected to the A port, and the oil flows from the P port through the A port through the filling hose into the oil-gas suspension system to fill the oil-gas suspension system;

[0016] When in the lower working position, the A port of the triple manual reversing valve is connected to the T port, and the oil flows into the oil-gas suspension system through the filling hose to fill the oil, and the air in the oil-gas suspension system is discharged from the T port.

[0017] Furthermore, when the triple manual reversing valve is in the lower working position, when the oil filling amount of the oil-gas suspension system exceeds the set value, causing the oil-gas cylinder to extend too far, the excess hydraulic oil is discharged from the T port.

[0018] Furthermore, the manual reversing handle of the triple manual reversing valve is a self-locking handle, which can prevent personnel from operating it continuously during the oil filling process, thereby effectively reducing work intensity.

[0019] Furthermore, a matching filling valve is installed on the upper part of the oil and gas cylinder, and this position is conducive to exhausting the air in the oil and gas cylinder; the filling valve is a one-way valve type, and the filling valve is opened during oil filling to replenish the required hydraulic oil into the oil and gas cylinder and the suspension system, and at the same time exhaust the air in the system; when the oil filling is completed, the filling valve is closed to prevent the oil in the suspension system from flowing out.

[0020] Furthermore, the filling joint is connected to the filling valve via threads, and a threaded ejector pin is integrated on the filling joint, and the threaded ejector pin is used to push open a steel ball of a one-way valve to open the filling valve.

[0021] Furthermore, the liquid filling hose and the liquid filling connector are connected via threads.

[0022] Furthermore, a liquid level gauge is installed on the side wall of the hydraulic oil tank, and the liquid level gauge displays the change of the liquid level in a wide range, so that the operator can judge whether the tank needs to be added with hydraulic oil in time.

[0023] Furthermore, an air filter is installed on the top of the hydraulic oil tank, and the air filter achieves balance of internal and external air pressures of the hydraulic oil tank when filling with oil.

[0024] Preferably, the air filter can be used as a refueling port of the hydraulic oil tank to replenish the lack of hydraulic oil in the hydraulic oil tank.

[0025] Furthermore, the triple manual reversing valve is integrated with an inlet overflow valve, and a one-way check valve is integrated at the inlet of the triple manual reversing valve.

[0026] Preferably, the opening pressure of the inlet overflow valve is set according to the filling pressure requirement. When the pressure reaches the set value, the inlet overflow valve opens, and the high-pressure hydraulic oil overflows back to the hydraulic oil tank through the inlet valve to prevent the pressure from continuing to rise. The one-way check valve can prevent the reverse flow of high-pressure hydraulic oil in the oil-gas suspension system caused by shutdown or improper operation, thereby protecting the gear pump and motor.

[0027] The application operation process of the utility model mainly includes: before starting and operating the oil filling pump station, check whether the liquid level in the hydraulic oil tank meets the oil filling demand through the liquid level gauge. If not, the hydraulic oil needs to be supplemented through the air filter. Check that the return oil filter and high-pressure filter on the hydraulic oil tank can work normally, the motor start switch is in the off state, the manual reversing handle of the triple manual reversing valve is in the middle position, the oil filling pipe and the filling joint are connected correctly, and there is no oil leakage and pressure relief. The filling joint is first connected to the filling valve of the oil and gas cylinder through a thread. After the thread is tightened, tighten the threaded ejector pin so that the threaded ejector pin can open the one-way valve steel ball on the filling valve.

[0028] Start the motor (the low-pressure assembly and commissioning workshops are generally connected to the power supply, and it is convenient to get electricity). After the oil filling pump station runs smoothly, check whether the joints and pipes are not tightened. Move the handle of the triple manual reversing valve of the oil-gas cylinder of the oil-gas suspension system on one side of the vehicle to the oil filling position on one side and the exhaust position on the other side. While injecting hydraulic oil into the oil-gas suspension system, exhaust the air in the oil-gas suspension system. When the air is exhausted and the hydraulic oil flows out continuously, move the handles on both sides of the oil filling and exhaust to the non-middle working position on the other side, and start exhausting the oil filling side (because the oil port connecting the oil-gas cylinder and the accumulator is lower than the oil filling port, air will remain at this height difference position). After exhausting, continue to let the oil circulate in this working position for a period of time to discharge the hydraulic oil that may be mixed with air. At this point, the exhaust work of the oil-gas suspension system is completed. Move the exhaust side handle to the middle position. At this time, the hydraulic oil can only enter the oil-gas suspension system but cannot flow out. Under the action of hydraulic pressure, the piston of the accumulator moves, and the oil-gas cylinder extends. Measure the extended length and compare it with the required value. Fine-tune the operating handle of the triple manual reversing valve to fine-tune the extended length of the oil-gas cylinder to the specified value.

[0029] After the oil filling is completed, place the handle of the triple manual reversing valve in the middle position, turn off the motor switch, and after the motor stops completely, loosen the threaded ejector of the filling joint, disengage the one-way valve in the filling valve, and place the handle of the triple manual reversing valve in the exhaust position to unload the pressure in the oil filling pipeline. Then loosen the threads between the filling valve and the filling joint. The oil-gas suspension system on this side completes the initial oil filling and adjustment.

[0030] Follow the same steps and methods to fill and exhaust the oil and gas suspension system on the other side of the vehicle. After the vehicle is filled with oil, check whether the extension length of each oil and gas cylinder meets the requirements and make adjustments.

[0031] Compared with the prior art, the beneficial effects of the utility model are:

[0032] The utility model discloses an oil filling pump station for the oil and gas spring of a wide-body dump truck, which uses a motor-driven gear pump as a power source, outputs hydraulic oil with a certain pressure to fill the suspension system, accelerates the oil filling speed, and improves the oil filling efficiency; when the suspension system is filled with oil, there is no need to suspend the frame, and only the filling joint needs to be connected to the filling port of the oil filling pump station, which ensures the safety and significantly reduces the workload; the triple manual reversing valve is unloaded when in the neutral position, which ensures that there is no load or the load is very small when the motor is started, and the operation mode is manual reversing, and the corresponding handle is operated according to the filling needs, which is simple and efficient; a corresponding filling valve is installed on the oil and gas cylinder, and a matching filling joint is installed on the filling hose of the pump station, and after the oil filling is completed, the filling hose can be disconnected to prevent the hydraulic oil from flowing out, which effectively ensures the performance of the oil and gas suspension system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] By reading the detailed description of the preferred embodiment below, various other advantages and benefits will become clear to those skilled in the art. The accompanying drawings are only for the purpose of illustrating the preferred embodiment and are not to be considered as limiting the present invention.

[0034] In the attached picture:

[0035] Figure 1 The utility model is a system architecture diagram of an oil filling pump station for an oil-gas spring of a wide-body dump truck.

[0036] The symbols in the accompanying drawings are:

[0037] 1—Hydraulic oil tank; 2—Liquid level gauge; 3—Air filter; 4—Gear pump; 5—High-pressure filter; 6—Triple manual reversing valve; 7—Filling hose; 8—Filling connector; 9—Return oil filter. DETAILED DESCRIPTION

[0038] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0039] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0040] It should be understood that although the terms first, second, and third may be used in the present disclosure to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0041] The utility model embodiment provides an oil filling pump station for a wide-body dump truck oil and gas spring, see Figure 1 As shown, it includes: a hydraulic oil tank 1, a gear pump 4, a high-pressure filter 5, a triple manual reversing valve 6, and an oil return filter 9; the inlet of the gear pump 4 is connected to the oil in the hydraulic oil tank 1; the outlet of the gear pump 4 is connected to the high-pressure filter 5, and the outlet of the high-pressure filter 5 is connected to the P port of the triple manual reversing valve 6; the high-pressure hydraulic oil output by the gear pump 4 enters the oil-gas suspension system after passing through the high-pressure filter 5, so as to ensure the cleanliness of the oil entering the oil-gas suspension system and prevent the impurities in the hydraulic oil tank 1 from entering the oil-gas suspension system and affecting the operation.

[0042] The A port of the triple manual reversing valve 6 is connected to a filling hose 7, and the end of the filling hose 7 away from the A port is connected to a filling joint 8. Preferably, the filling hose 7 and the filling joint 8 are connected by threads; the filling joint 8 is connected to the oil and gas cylinder of the oil and gas suspension system;

[0043] The T port of the triple manual reversing valve 6 is connected to the return oil filter 9, which is arranged on the top of the hydraulic oil tank 1 and is connected to the hydraulic oil tank 1. The return oil filter 9 filters out pollutants and impurities in the return oil to improve the cleanliness of the oil entering the hydraulic oil tank 1.

[0044] The triple manual reversing valve 6 has three working positions, namely, the middle position, the upper working position and the lower working position. When in the middle position, the P port and the T port of the triple manual reversing valve 6 are connected, and the oil flows directly from the P port to the T port back to the hydraulic oil tank 1, and the suspension system is in a no-load state. At this time, the output power of the gear pump 4 and the motor is very small, which avoids power waste and ensures that the motor has good starting performance.

[0045] When in the upper working position, the P port of the triple manual reversing valve 6 is connected to the A port, and the oil flows from the P port through the A port through the filling hose 7 into the oil-gas suspension system to fill the oil-gas suspension system;

[0046] When in the lower working position, the A port of the triple manual reversing valve 6 is connected to the T port, and the oil flows into the oil-gas suspension system through the filling hose 7 to fill the oil, and the air in the oil-gas suspension system is discharged from the T port. When the oil filling amount of the oil-gas suspension system exceeds the set value, causing the oil-gas cylinder to extend too far, the excess hydraulic oil is discharged from the T port.

[0047] The manual reversing handle of the triple manual reversing valve 6 is a self-locking handle, which can prevent personnel from operating it all the time during the oil filling process, effectively reducing the work intensity.

[0048] A matching filling valve is installed on the upper part of the oil and gas cylinder, and this position is conducive to exhausting the air in the oil and gas cylinder; the filling valve is a one-way valve type. When filling with oil, the filling valve opens to add the required hydraulic oil to the oil and gas cylinder and the suspension system, and at the same time exhausts the air in the system; when filling with oil is completed, the filling valve closes to prevent the oil in the suspension system from flowing out.

[0049] The filling joint 8 is connected to the filling valve through threads. A threaded ejector pin is integrated on the filling joint 8. The threaded ejector pin is used to push open the one-way valve steel ball to open the filling valve.

[0050] A liquid level gauge 2 is installed on the side wall of the hydraulic oil tank 1. The liquid level gauge 2 displays the change of the liquid level in a wide range so that the operator can judge whether the tank needs to be filled with hydraulic oil in time.

[0051] An air filter 3 is installed on the top of the hydraulic oil tank 1, and the air filter 3 realizes the balance of the internal and external air pressure of the hydraulic oil tank 1 when filling the oil. The air filter 3 can also be used as a refueling port of the hydraulic oil tank 1 to replenish the hydraulic oil missing in the hydraulic oil tank 1.

[0052] The triple manual reversing valve 6 is integrated with an inlet overflow valve, and a one-way check valve is integrated at the inlet of the triple manual reversing valve 6. The opening pressure of the inlet overflow valve is set according to the filling pressure requirement. When the pressure reaches the set value, the inlet overflow valve opens, and the high-pressure hydraulic oil overflows back to the hydraulic oil tank 1 through the inlet valve to prevent the pressure from continuing to rise. The one-way check valve can prevent the reverse flow of high-pressure hydraulic oil in the oil-gas suspension system caused by shutdown or improper operation, and plays a role in protecting the gear pump 4 and the motor.

[0053] The operation process of this embodiment in practical application is as follows:

[0054] Before starting and operating the oil filling pump station, check whether the liquid level in the hydraulic oil tank 1 meets the oil filling demand through the liquid level gauge 2. If not, the hydraulic oil needs to be supplemented through the air filter 3. Check that the return oil filter 9 and the high-pressure filter 5 on the hydraulic oil tank 1 can work normally, the motor start switch is in the off state, the manual reversing handle of the triple manual reversing valve 6 is in the middle position, the oil filling pipe 7 and the filling joint 8 are connected correctly, and there is no oil leakage or pressure relief. The filling joint 8 is first connected to the filling valve of the oil and gas cylinder through a thread. After the thread is tightened, tighten the threaded ejector pin so that the threaded ejector pin can open the one-way valve steel ball on the filling valve.

[0055] Start the motor, and after the oil filling pump station runs smoothly, check whether the joints and pipes are loose. Move the handle of the triple manual reversing valve 6 of the oil-gas cylinder of the oil-gas suspension system on one side of the vehicle to the oil filling position on one side and to the exhaust position on the other side. While injecting hydraulic oil into the oil-gas suspension system, exhaust the air in the oil-gas suspension system. When the air is exhausted and the hydraulic oil flows out continuously, move the handles on both sides of the oil filling and exhaust to the non-middle working position on the other side, and start exhausting the oil filling side (because the oil port where the oil-gas cylinder is connected to the accumulator is lower than the oil filling port, air will remain at this height difference position). After exhausting, continue to let the oil circulate in this working position for a while to exhaust the hydraulic oil that may be mixed with air. At this point, the exhaust work of the oil-gas suspension system is completed. Move the exhaust side handle to the middle position. At this time, the hydraulic oil can only enter the oil-gas suspension system but cannot flow out. Under the action of hydraulic pressure, the piston of the accumulator moves, and the oil-gas cylinder extends. Measure the extended length and compare it with the required value. Fine-tune the operating handle of the triple manual reversing valve 6 to fine-tune the extended length of the oil-gas cylinder to the specified value.

[0056] After the oil filling is completed, place the handle of the triple manual reversing valve 6 in the middle position, turn off the motor switch, and after the motor stops completely, loosen the threaded ejector of the filling joint 8, disengage the one-way valve in the filling valve, and place the handle of the triple manual reversing valve 6 in the exhaust position to unload the pressure in the oil filling pipeline. Then loosen the thread between the filling valve and the filling joint 8. The oil-gas suspension system on this side completes the initial oil filling and adjustment.

[0057] Follow the same steps and methods to fill and exhaust the oil and gas suspension system on the other side of the vehicle. After the vehicle is filled with oil, check whether the extension length of each oil and gas cylinder meets the requirements and make adjustments.

[0058] So far, the technical solution of the utility model has been described in conjunction with the preferred embodiments shown in the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the utility model is obviously not limited to these specific embodiments. Without departing from the principle of the utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the utility model.

[0059] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. For those skilled in the art, the utility model may have various modifications and changes. Any modification, replacement, and improvement made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. An oil filling pump station for a wide-body dump truck oil and gas spring, characterized in that: include: Hydraulic oil tank, gear pump, high-pressure filter, triple manual reversing valve, return oil filter; the inlet of the gear pump is connected to the oil in the hydraulic oil tank; the outlet of the gear pump is connected to the high-pressure filter, and the outlet of the high-pressure filter is connected to the P port of the triple manual reversing valve; The A port of the triple manual reversing valve is connected to a liquid filling hose, the end of the liquid filling hose away from the A port is connected to a liquid filling joint, and the liquid filling joint is fluidly connected to the oil and gas cylinder of the oil and gas suspension system; The T-port of the triple manual reversing valve is fluidly connected to the return oil filter, and the return oil filter is arranged on the top of the hydraulic oil tank and fluidly connected to the hydraulic oil tank.

2. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 1 is characterized in that: The triple manual reversing valve has three working positions: middle position, upper working position and lower working position; when in the middle position, the P port and the T port of the triple manual reversing valve are connected, the oil flows directly from the P port to the T port back to the hydraulic oil tank, and the suspension system is in a no-load state; When in the upper working position, the P port of the triple manual reversing valve is connected to the A port, and the oil flows from the P port through the A port through the filling hose into the oil-gas suspension system; When in the lower working position, the A port of the triple manual reversing valve is connected to the T port, and the oil flows into the oil-gas suspension system through the filling hose to fill the oil, and the air in the oil-gas suspension system is discharged from the T port.

3. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 2 is characterized in that: When the triple manual reversing valve is in the lower working position, when the oil filling amount of the oil-gas suspension system exceeds the set value, causing the oil-gas cylinder to extend too far, the excess hydraulic oil is discharged from the T port.

4. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 1, characterized in that: The manual reversing handle of the triple manual reversing valve is a self-locking handle.

5. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 1, characterized in that: A matching filling valve is installed on the upper part of the oil and gas cylinder. The filling valve is a one-way valve type. When filling with oil, the filling valve is opened to add the required hydraulic oil to the oil and gas cylinder and the suspension system, and at the same time discharge the air in the system; when filling with oil is completed, the filling valve is closed to prevent the oil in the suspension system from flowing out.

6. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 5, characterized in that: The filling joint is connected to the filling valve via threads, and a threaded ejector pin is integrated on the filling joint. The threaded ejector pin is used to push open the one-way valve steel ball to open the filling valve.

7. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 1, characterized in that: The liquid filling hose is connected to the liquid filling connector via threads.

8. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 1, characterized in that: A liquid level gauge is installed on the side wall of the hydraulic oil tank, and the liquid level gauge displays the change of liquid level height within a wide range.

9. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 1, characterized in that: An air filter is installed on the top of the hydraulic oil tank, and the air filter achieves the balance of the internal and external air pressures of the hydraulic oil tank when filling the oil.

10. The oil filling pump station for the oil and gas spring of a wide-body dump truck according to claim 1, characterized in that: The triple manual reversing valve is integrated with an inlet overflow valve, and a one-way check valve is integrated at the inlet of the triple manual reversing valve.

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