KR102092777B1 - Speed improvement system for hydraulic jib crane by using hydraulic relief and check valves - Google Patents

Abstract

The present invention is to provide a speed enhancing system of hydraulic jib crane using a hydraulic relief valve and a check valve. In addition to an internal relief valve in a main control valve, a poppet-typed external relief valve is additionally installed outside the main control valve. The speed enhancing system of the present invention indirectly controls the pressure of a hoisting line through which a fluid flows to a hoist motor. Therefore, sufficient flow rate and hydraulic pressure can be secured toward the hoist motor. Accordingly, even when overload is set to a rated load × 110% level, the hoisting speed can be easily implemented at the rated speed. In addition, it is possible to prevent flow loss from occurring in the main control valve.

Description

Speed improvement system for hydraulic jib crane by using hydraulic relief and check valves}

The present invention relates to a system for improving the speed of a hydraulic jib crane using a hydraulic relief valve and a check valve, and more specifically, as the internal relief valve in the main control valve is opened earlier than the set pressure, the flow rate does not sufficiently flow to the hoist motor, thereby lifting the crane. It relates to a system for improving the speed of a hydraulic jib crane using a hydraulic relief valve and a check valve to prevent the hoisting speed of the pipe from being lowered and to easily implement the hoisting speed at a rated speed.

In general, a ship jib crane is installed in the dock to lift and evacuate the ship to land in the event of a typhoon or tsunami, and a jib crane is installed in the dock of the shipyard to move various heavy objects, and also for large-scale work such as barges Jib cranes are installed directly on ships, and jib cranes are used in particular for marine cranes in offshore projects.

Existing shipowner's requirements for the jib crane are set to Safe Working Load (SWL) x 125% under overload (SWL) according to the relevant ship-class regulations, and under the rated load (SWL) conditions. It is delivered after verifying the rated speed (10M / MIN).

However, the current owner requirements for the jib crane are set to the overload (Overload) at a rated load (SWL) × 110% level, in consideration of the user's safety aspect, and the rated speed under the rated load (SWL) condition. 10M / MIN).

However, the hoisting speed satisfies the rated speed under the rated load condition after the overload is set to the rated load x 125%, but the hoisting speed is rated at the rated load condition after the overload is set to the rated load x 110%. There is a problem that is lowered to less.

That is, when the overload is set to the rated load (SWL) x 125% level, sufficient pressure / flow rate is secured toward the hoist motor, so that the speed drop of the rated load does not occur, but the overload is set to the rated load x 110% level. When set, there is a problem that the hoisting speed is lowered than the rated speed because sufficient pressure / flow rate is not secured toward the hoist motor.

As a result of analyzing the cause of this problem, when the overload is set to the rated load (SWL) × 110% level, the internal relief valve installed in the main control valve is opened at a pressure lower than the set pressure, resulting in a flow rate. It was analyzed that the hoisting speed fell below the rated speed because it did not flow sufficiently to the hoist motor.

For reference, the main control valve refers to a device that controls the flow direction to control each operation of the jib crane, and the internal relief valve mounted in the main control valve prevents the function and damage of the hydraulic circuit when a pressure runaway occurs. It refers to a kind of safety valve.

Publication Patent Publication No. 10-2012-0135904 (2012.12.17)

The present invention has been devised to solve the above-described conventional problems, and by installing a poppet type external relief valve on the outside of the main control valve in addition to the internal relief valve in the main control valve, the hoist flows through the hoist motor. By indirectly controlling the pressure of the sting line, sufficient flow rate and hydraulic pressure can be secured toward the hoist motor, and accordingly, the hoisting speed can be easily implemented at the rated speed even when the overload is set to the rated load × 110% level. The purpose of the present invention is to provide a system for improving the speed of a hydraulic jib crane using a hydraulic relief valve and a check valve.

In addition, the present invention is to increase the pressure load (flow through load) on the hoisting line facing the hoist motor, so as to solve the problem that a large amount of flow loss occurs in the main control valve, a check valve for bypass is additionally mounted on the hoisting line. By controlling the pressure load (flow through load) to be low, the purpose is to provide a system for improving the speed of a hydraulic jib crane using a hydraulic relief valve and a check valve to prevent flow loss from occurring in the main control valve. have.

In order to achieve the above object, the present invention provides an oil tank in which hydraulic oil is stored, a hydraulic pump for pumping hydraulic oil in the oil tank, and a direction of hydraulic flow rate supplied from the hydraulic pump to control each operation of the jib crane. The main control valve to be controlled, the discharge side of the main control valve and a hoist motor connected by a hoisting line, and a counter balance mounted on the hoisting line to control the pressure of the flow rate from the main control valve to the hoist motor to a predetermined level Includes a valve,

In addition to the internal relief valve installed in the main control valve so as to indirectly control the pressure of the hoisting line through which the flow rate flows to the hoist motor, an external relief valve is installed outside the main control valve, and the counter balance valve is embedded. Provided is a hydraulic relief valve and a check valve for improving the speed of a hydraulic jib crane using a check valve, characterized in that a bypass valve connected to a counter balance valve is installed outside the hoist block.

In particular, an external relief valve block connected to an internal relief valve is installed outside the main control valve, and an external relief valve is installed on the external relief valve block.

Preferably, the external relief valve is characterized in that it is adopted as a relief valve of a poppet type (Poppet Type) superior to the dynamic characteristics compared to the internal relief valve of the pivot type.

More preferably, the external relief valve functions to compensate for the pressure lost in the internal relief valve adopted as a pivot type, so that the overload (in consideration of the safety aspect of the user as the current owner requirement for the jib crane) Overload) is set to the rated load (SWL) × 110% level, and it is adopted to meet the requirements for rated speed (10M / MIN) under the rated load (SWL) condition.

On the other hand, the check valve for the bypass is characterized in that it is adopted to reduce the occurrence of differential pressure ΔP that increases the pressure of the main control valve while reducing the flow through load of the counter balance valve.

The present invention through the above-described problem solving means provides the following effects.

First, a poppet type external relief valve is additionally installed on the outside of the main control valve to indirectly control the pressure of the hoisting line through which the flow flows to the hoist motor, thereby ensuring sufficient flow and hydraulic pressure toward the hoist motor. Accordingly, the hoisting speed can be easily implemented at the rated speed even when the overload is set to the rated load × 110% level.

Second, as the current owner requirements for jib cranes, the overload is set to the rated load (SWL) × 110% level in consideration of the user's safety side, and the rated speed under the rated load (SWL) condition. 10M / MIN).

Third, a check valve for bypass is additionally mounted on the hoisting line so that the pressure load (flow-through load) is adjusted to be low, thereby preventing flow loss from occurring in the main control valve, and accordingly existing hoist motor The high pressure load (flow through load) on the hoisting line facing to solves the problem of large flow loss in the main control valve.

1 is a schematic diagram for a speed improving system of a hydraulic jib crane according to the present invention,
2 is a detailed hydraulic circuit diagram for a speed improving system of a hydraulic jib crane according to the present invention,
Figure 3 is a hydraulic circuit diagram showing an enlarged portion "X" of Figure 2 to explain the flow of hydraulic oil,
Figure 4 is a schematic diagram showing the structure of the internal relief valve of the pivot type,
Figure 5 is an actual photo showing an example of installing a relief valve block having an external relief valve on the outside of the main control valve for the speed improving system of the hydraulic jib crane according to the present invention,
Figure 6 is a schematic diagram showing a poppet type of external relief valve structure,
Figure 7 is a real photo showing an example of the installation of the check valve for the bypass hoisting line for the system for improving the speed of the hydraulic jib crane according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram for a speed improving system of a hydraulic jib crane according to the present invention, and FIG. 2 is a detailed hydraulic circuit diagram for a speed improving system of a hydraulic jib crane according to the present invention.

1 and 2, the hydraulic system of the jib crane controls each operation of the oil tank 10 in which hydraulic oil is stored, the hydraulic pump 20 for pumping hydraulic oil in the oil tank, and the jib crane. In order to do so, the main control valve 30 which controls the direction of the hydraulic flow rate supplied from the hydraulic pump 20 and the hoist motor 60 connected by the discharge side of the main control valve 30 and the hoisting line 40 It is configured to include.

In addition, the hoisting line 40 is equipped with a counter balance valve 50 for controlling the pressure of the flow rate from the main control valve 30 to the hoist motor 60 to a predetermined level.

In particular, the main control valve 30 is composed of a type of flow control block in which a plurality of valves are combined therein to serve to distribute hydraulic oil in three movements (floating, rotating, jib raising) lines of a jib crane. Inside, the hoisting control valve spool (31, HOISTING CONTROL VALVE SPOOL), the compensator valve (32, COMPENSATOR VALVE), the internal relief valve (33, INTERNAL RELIEF VALVE), and the main compensator valve (34, MAIN COMPENSATOR VALVE) etc. are combined in a predetermined arrangement.

At this time, when the overload is set to the rated load (SWL) × 125% level as described above, a sufficient pressure / flow rate is secured toward the hoist motor 60 along the hoisting line 40, thereby reducing the speed of the rated load. On the other hand, when the overload is set to the rated load (SWL) × 110% level, the internal relief valve 33 mounted in the main control valve 30 is opened at a pressure lower than the set pressure, so that the flow rate is hoisted. There is a problem in that the hoisting speed of the hoist motor 60 is lowered than the rated speed because it does not sufficiently flow to the motor 60.

Attached Figure 3 is a hydraulic circuit diagram showing an enlarged portion "X" of Figure 2 to explain the flow of hydraulic oil, the red line in red indicates the pump supply line through which hydraulic oil from the hydraulic pump 20 flows, yellow The yellow line of indicates the operating lines of the compensator valves 32 and 34 and the internal relief valve 33, and the blue line of blue indicates the tank return line for the return of hydraulic oil.

When the oil pumped from the hydraulic pump 20 through the portion indicated by "P" in the pump supply line is supplied to the main control valve 30, the main control valve 30 is operated by three jib cranes (floating, It rotates and rotates the jib) to distribute hydraulic oil.

For example, when the oil supplied to the main control valve 30 passes through the compensator valve 32, when the control valve lever (not shown) is operated in the hoisting direction, the hoisting is performed. When the control valve spool 31 forms a flow path and hydraulic pressure is supplied to the hoist motor 60, the hoist motor 60 is driven and the hoisting winch connected to the hoist motor 60 rotates to operate. The hoisting operation for supporting the jib crane is performed.

At this time, when the flow rate toward the internal relief valve 33 in the main control valve 30 exceeds the set pressure (eg, 150 BAR), the valve is opened, and hydraulic oil is drained into the tank return line indicated by the blue line.

However, while the overload is set at the rated load (SWL) x 110% level, the rated speed of 10 m / s must be satisfied, but the internal relief valve 33 mounted in the main control valve 30 is lower than the set pressure. In the early opening, pressure loss occurs, so that the flow rate does not sufficiently flow to the hoist motor 60, and the hoisting speed of the hoist motor 60 decreases below the rated speed.

For example, if the set pressure of the internal relief valve 33 is 160 bar, it has a pivot type valve structure (refer to FIG. 4) with poor dynamic characteristics, and thus an early opening phenomenon occurs at a pressure of 140 bar, resulting in a hoist. When the sting output decreases, and the overload is set to the rated load (SWL) x 110% level, there is a problem in that the hoisting speed of the hoist motor 60 is lowered than the rated speed.

In addition, due to the above problems, it affects the compensator valves 32 and 34, which is accompanied by a problem of lowering the flow compensation function of the compensator valves 32 and 34.

In order to solve this conventional problem, the present invention additionally installs a poppet type external relief valve 100 outside the main control valve 30 in addition to the internal relief valve 33 installed in the main control valve 30. Therefore, the main point is to indirectly control the pressure of the hoisting line through which the flow rate flows to the hoist motor.

2 and 5, an external relief valve block (110, EXTERNAL RELIEF VALVE BLOCK) connected to an internal relief valve (33) is installed outside the main control valve (30). The external relief valve 100 is installed on the relief valve block 110.

At this time, the external relief valve 100 is adopted as a relief valve of a poppet type (Poppet Type) superior in dynamic characteristics compared to the pivot-type relief valve as shown in FIG.

Therefore, the external relief valve 100 functions to compensate for the pressure lost in the internal relief valve 33 adopted as a pivot type, so that the overload is set to the rated load (SWL) × 110% level. And can satisfy the rated speed of 10m / s.

In more detail, the external relief valve 100 functions to compensate for the pressure lost in the internal relief valve 33 adopted as a pivot type, thereby safeguarding the user's safety as a current owner requirement for jib cranes. Considering the side, it is possible to satisfy the requirement of rated speed (10M / MIN) under rated load (SWL) conditions while setting the overload to the level of rated load (SWL) × 110%.

For example, the set pressure of the external relief valve 100 is set to 160 bar, which is the rated load (SWL) × 110% level, and the set pressure of the internal relief valve 33 is rated load (SWL) × 125% level By setting the phosphorus to 200 bar, the external relief valve compensates for the occurrence of flow and pressure loss inside the main control valve 30.

Here, the flow and pressure loss compensation process of the external relief valve 100 will be described in more detail as follows.

First, when the hydraulic pump 20 sucks hydraulic oil inside the oil tank and discharges hydraulic oil to each line to generate hydraulic power, the main control valve 30 receives the hydraulic oil from the hydraulic pump 20 and receives the jib. The hydraulic oil is distributed to the hydraulic lines for the 3 operations of the crane (floating, rotating, jib raising).

For example, hydraulic oil is supplied to the hoist motor 60 through the main control valve 30 through the counter balance valve 50 which is a drop prevention valve, so that the floating operation of the jib crane can be performed.

At this time, the internal relief valve 33 is set at a rated load (SWL) × 125% level (for example, 200 bar), so that it is opened early at a pressure lower than the set pressure, so that a small amount of hydraulic oil leaks out. Cause losses.

Even if such a flow rate and pressure loss occur, the set pressure of the external relief valve 100 connected to the internal relief valve 33 is set to a rated load (SWL) × 110% level (eg, 160 bar). By controlling a small amount of hydraulic oil leaking from the internal relief valve 33 from the external relief valve 100 to compensate for the rated output, the safety of the user as a current owner requirement for the jib crane Considering the side, it is possible to satisfy the requirement of rated speed (10M / MIN) under rated load (SWL) conditions while setting the overload to the level of rated load (SWL) × 110%.

As described above, by installing the poppet type external relief valve 100 on the outside of the main control valve 30, indirectly controlling the pressure of the hoisting line through which the flow rate flows to the hoist motor, is sufficient for the hoist motor. The flow rate and hydraulic pressure can be secured, and accordingly, the hoisting speed can be easily implemented at the rated speed even when the overload is set at the rated load × 110% level.

On the other hand, the present invention is a high pressure load (flow through load) to the hoisting line facing the hoist motor to solve the problem that the flow rate loss is largely generated in the main control valve, the check valve for bypass to the hoisting line 40 ( There is another point in one point to prevent the flow rate loss from occurring in the main control valve 30 by additionally mounting 200 to control the pressure load (flow through load) to be low.

1 and 2, the hoisting line 40 is connected between the discharge side of the main control valve 30 and the hoist motor 60, and the main control valve 30 is connected to the hoisting line 40. ) Is equipped with a counter balance valve 50 that controls the pressure of the flow rate from the hoist motor 60 to a predetermined level, and as shown in FIGS. 2 and 7, the counter balance valve 50 has a hoist block 210 ).

At this time, when the flow rate from the main control valve 30 to the hoist motor 60 through the counter balance valve 50 of the hoist line 40, the flow rate passing through the counter balance valve 50 is free flow ( By flowing in the Free Flow) direction, a differential pressure ΔP is generated inside the counter balance valve 50 to increase the pressure of the main control valve 30, and thereby the main control against the flow rate supplied from the hydraulic pump 20 The pressure rise of the rear end of the valve is caused and affects the operation of the internal relief valve.

To solve this conventional problem, a check valve 200 for bypass connected to the counter balance valve 50 is additionally installed outside the hoist block 210 in which the counter balance valve 50 is embedded.

The bypass check valve 200 serves to reduce the flow-through load of the counter balance valve 50 while reducing the differential pressure ΔP, and furthermore, the check valve for bypass in the counter balance valve 50 ( By passing the flow rate to 200), it serves to supplement the insufficient flow rate generated by the differential pressure ΔP.

As described above, the pressure load (flow-through load) is high in the hoisting line that transfers the flow rate to the hoist motor 60 via the counter balance valve 50, so that the flow rate loss in the main control valve is largely eliminated. , By installing the check valve 200 for the bypass as described above, so that the pressure load (flow through load) is adjusted to be low, it is possible to prevent the flow rate loss from the main control valve 30, thereby Accordingly, it is possible to solve the problem that the flow rate loss in the main control valve is large due to the high pressure load (flow through load) in the hoisting line facing the hoist motor.

Meanwhile, an anti-corrosion coating layer may be applied to the external relief valve 100, the external relief valve block 110, and the bypass check valve 200 to prevent corrosion of the metal surface. The coating material of this anti-corrosion coating layer is benzimidazole 20% by weight, propylene glycol methyl ether 30% by weight, hafnium 15% by weight, molybdenum emulsion (MoS2) 10% by weight, aluminum oxide 15% by weight, bisphenol F type diglycol Dill ether is composed of 10% by weight, the coating thickness can be formed to 8㎛.

Benzimidazole, propylene glycol methyl ether, and bisphenol F-type diglycidyl ether play a role of preventing corrosion and discoloration.

Hafnium is a transition metal element with corrosion resistance, and serves to have excellent water resistance and corrosion resistance.

Molybdenum emulsifier plays a role in imparting slidability and lubricity to the surface of the coating.

Aluminum oxide is added for the purpose of fire resistance and chemical stability.

The reason for the numerical limitation of the ratio of the constituent components and the coating thickness as described above, as a result of analyzing the results through the test results while the inventor repeatedly failed several times, exhibited the optimum corrosion protection effect at the ratio.

In addition, the hoist motor 60 may be coated with an anti-fouling coating layer made of an anti-pollution coating composition to effectively achieve prevention and removal of contaminants.

The anti-fouling coating composition contains cocamidopropylbetaine and ampho glycinate in a molar ratio of 1: 0.01 to 1: 2, and the total content of cocamidopropyl betaine and ampho glycinate is 1 to 10% by weight.

The cocamidopropyl betaine and ampho glycinate are preferably 1: 0.01 to 1: 2 as the molar ratio, and when the molar ratio is outside the above range, the applicability of the hoist motor 60 is lowered or moisture absorption on the surface after application There is a problem that the coating film is removed by increasing.

The cocamidopropyl betaine and ampho glycinate are preferably 1 to 10% by weight in the total composition aqueous solution, and if it is less than 1% by weight, there is a problem that the applicability of the hoist motor 60 decreases, and exceeds 10% by weight If it is, it is easy to cause crystal precipitation due to an increase in the thickness of the coating film.

On the other hand, as a method of applying the composition for preventing contamination to the hoist motor 60, it is preferable to apply it by a spray method. In addition, the final coating film thickness of the hoist motor 60 is preferably 550 ~ 2000Å, more preferably 1100 ~ 1900Å. If the thickness of the coating film is less than 550 이, there is a problem that deterioration occurs in the case of high temperature heat treatment, and if it exceeds 2000 Å, there is a disadvantage that crystal precipitation on the coated surface is likely to occur.

In addition, the present composition for preventing contamination can be prepared by adding 0.1 mol of cocamidopropyl betaine and 0.05 mol of ampho glycinate to 1000 ml of distilled water, followed by stirring.

In addition, a metal mesh foam is attached to the outer surface of the hydraulic pump 20. The metal mesh foam is a metal mesh form having pores.

The temperature discoloration layer is applied to the surface of the metal mesh foam and is configured to penetrate the surface of the metal mesh foam.

The temperature discoloration layer may be applied to two or more temperature discoloration materials that change color when the temperature reaches a predetermined temperature or more, and is separated into two or more sections according to the temperature change to determine a stepwise temperature change. A protective film layer for preventing the temperature change layer from being damaged may be applied on the temperature change layer.

Here, the temperature discoloration layer may be formed by applying a temperature discoloration material having a discoloration temperature of 40 ° C or higher and 60 ° C or higher, respectively. The temperature discoloration layer is for detecting a temperature change of the hydraulic pump 20 by changing the color according to the temperature of the hydraulic pump 20 that is indirectly heated as the internal temperature rises by the heater unit. The temperature of the hydraulic pump 20 is transferred to the metal mesh foam, and the temperature discoloration layer reacts according to the temperature change of the metal mesh foam, and as a result, the temperature change of the hydraulic pump 20 can be sensed.

The temperature discoloration layer may be formed by applying a temperature discoloration material that changes color when it reaches a predetermined temperature or more to the surface of the metal mesh foam. In addition, the temperature discoloration layer is generally composed of a microcapsule structure of 1 to 10㎛, and can exhibit colored and transparent colors due to the binding and separation phenomenon depending on the temperature of the electron donor and the electron acceptor in the microcapsule.

In addition, the temperature discoloration layer has a fast color change, and may have various discoloration temperatures such as 40 ° C, 60 ° C, 70 ° C, 80 ° C, and the like, and the color change temperature can be easily adjusted in various ways. The temperature discoloration layer may be used for various kinds of temperature discoloration materials based on the principle of molecular rearrangement of organic compounds and spatial rearrangement of atomic groups.

To this end, the temperature discoloration layer is preferably formed to be separated into two or more sections according to temperature changes by applying two or more temperature discoloration materials having different discoloration temperatures. The temperature discoloration layer is preferably a temperature discoloration material having a discoloration temperature of relatively low temperature and a temperature discoloration material having a discoloration temperature of relatively high temperature, and more preferably has a discoloration temperature of 40 ° C or higher and 60 ° C or higher. A temperature discoloration layer may be formed using a temperature discoloration material.

Through this, it is possible to check the temperature change of the hydraulic pump 20 so that the temperature change of the hydraulic pump 20 can be detected, and accordingly, it is visually checked whether the current hydraulic pump 20 is in a normal driving state or an overheated state. There is an advantage that can be easily confirmed.

In addition, the protective film layer is applied on the temperature discoloration layer to prevent the temperature discoloration layer from being damaged due to external impact, and it is easy to check whether the temperature discoloration layer is discolored, and at the same time, consider that the temperature discoloration material is weak to heat, and to improve the insulation It is preferable to use a branched transparent coating material.

10: Oil tank
20: hydraulic pump
30: main control valve
40: hoisting line
50: counter balance valve
60: hoist motor
31: Hoisting control valve spool
32: Compensator valve
33: internal relief valve
34: main compensator valve
100: external relief valve
110: external relief valve block
200: bypass check valve
210: hoist block

Claims (5)

To control the direction of the hydraulic flow rate that is supplied from the hydraulic pump 20 to control each operation of the jib crane, and the oil tank 10 in which the hydraulic oil is stored, the hydraulic pump 20 for pumping hydraulic oil in the oil tank, The main control valve 30 and the hoist motor 60 connected by the discharge side of the main control valve 30 and the hoisting line 40 and the main control valve 30 mounted on the hoisting line 40 It includes a counter balance valve 50 for controlling the pressure of the flow rate from the hoist motor 60 to a predetermined level,
In addition to the internal relief valve 33 installed in the main control valve 30 to indirectly control the pressure of the hoisting line 40 through which the flow rate flows to the hoist motor 60, the outside of the main control valve 30 A separate external relief valve 100 is installed in the
A bypass check valve 200 connected to the counter balance valve 50 is installed outside the hoist block 210 in which the counter balance valve 50 is embedded;
The external relief valve block 110 connected to the internal relief valve 33 is installed outside the main control valve 30, and the external relief valve 100 is installed in the external relief valve block 110;
The external relief valve 100 is adopted as a poppet type relief valve having better dynamic characteristics than the pivot type internal relief valve 33;
The external relief valve 100, the external relief valve block 110, and the bypass check valve 200 are coated with an anti-corrosion coating layer, the coating material of the anti-corrosion coating layer is benzimidazole 20% by weight, propylene glycol methyl It is composed of 30% by weight of ether, 15% by weight of hafnium, 10% by weight of molybdenum emulsion (MoS2), 15% by weight of aluminum oxide, and 10% by weight of bisphenol F-type diglycidyl ether, and the coating thickness of the anti-corrosion coating layer is 8 Is formed in micrometers;
The hoist motor 60 is coated with an anti-contamination coating layer made of a composition for anti-contamination coating, wherein the composition for anti-contamination coating includes molar ratio of cocamidopropyl betaine and ampho glycinate in a ratio of 1: 0.01 to 1: 2. There is;
A metal mesh foam is attached to the outer surface of the hydraulic pump 20, and a temperature discoloration layer is applied to the metal mesh foam, and the temperature discoloration layer includes two or more temperature discoloration materials that change color when the temperature is higher than a predetermined temperature. It can be applied to the surface of the metal mesh foam and separated into two or more sections according to the temperature change to determine the stepwise temperature change, and a protective film layer is applied on the temperature change layer to prevent the temperature change layer from being damaged. A speed improving system of a hydraulic jib crane using a hydraulic relief valve and a check valve.
delete delete The method according to claim 1,
The external relief valve 100 functions to compensate for the pressure lost in the internal relief valve 33 adopted as a pivot type, and is an overload in consideration of the safety aspect of the user as the current owner requirement for the jib crane. Hydraulic relief valve, which is adopted to meet the requirement of rated speed (10M / MIN) under rated load (SWL) conditions, with (Overload) set to rated load (SWL) × 110% level, and A system for improving the speed of a hydraulic jib crane using a check valve.
The method according to claim 1,
The bypass check valve 200 is a hydraulic pressure, characterized in that it is adopted to reduce the flow through load of the counter balance valve 50 and at the same time reduce the differential pressure ΔP that increases the pressure of the main control valve 30 Speed-up system for hydraulic jib crane using relief valve and check valve.

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