CN216382090U - Performance test platform of hydraulic oil cylinder - Google Patents
Performance test platform of hydraulic oil cylinder Download PDFInfo
- Publication number
- CN216382090U CN216382090U CN202122538238.8U CN202122538238U CN216382090U CN 216382090 U CN216382090 U CN 216382090U CN 202122538238 U CN202122538238 U CN 202122538238U CN 216382090 U CN216382090 U CN 216382090U
- Authority
- CN
- China
- Prior art keywords
- valve
- electromagnetic directional
- pump
- hydraulic
- oil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Fluid-Pressure Circuits (AREA)
Abstract
The utility model discloses a performance test platform of a hydraulic cylinder, which comprises an oil tank, three motor-pump sets, a control valve set, a tested hydraulic cylinder rack and a pressure sensor, wherein the three motor-pump sets are connected with the oil tank through a pipeline; the three motor-pump sets are respectively a squirrel-cage three-phase asynchronous motor one-control pump set, a variable frequency motor-main pump set and a squirrel-cage three-phase asynchronous motor two-high pressure pump set. The utility model reasonably uses different types of hydraulic pumps aiming at different test projects, and achieves the aims of optimizing the output power of the system and reducing the energy consumption of the test system. The utility model can accurately detect the minimum starting pressure of the hydraulic oil cylinder by selecting a proper pump and a proper control loop. The hydraulic control one-way valve is used for switching the hydraulic circuits, and is simple and reliable. The utility model is simple and convenient, can automatically complete detection through the controller, and is convenient to operate.
Description
Technical Field
The utility model belongs to the field of performance test of hydraulic cylinders, and particularly relates to a performance test platform of a hydraulic cylinder.
Background
With the continuous revolution and development of industrial technologies, the hydraulic transmission technology is widely applied in the industrial fields, such as hydraulic excavators, loaders and bulldozers in the field of engineering machinery; pump trucks, pile drivers, etc. in the field of construction machinery. The hydraulic transmission equipment mainly comprises a power element, a control element, an execution element, accessories and the like; the conventional hydraulic oil cylinder is an actuator capable of realizing linear reciprocating motion and is a widely used hydraulic actuating element in various hydraulic systems. Therefore, the quality and performance of the hydraulic rams are important factors in ensuring reliable operation of the hydraulic system.
The factory performance detection of the hydraulic oil cylinder mainly comprises stroke detection, minimum starting pressure detection, pressure resistance detection and buffer performance detection. The existing conventional factory performance test bed adopts an asynchronous motor and a single constant-pressure variable pump to detect the performances: the test bed motor using the test system is always in a high energy consumption working condition, and meanwhile, the high voltage and the low voltage are frequently switched, so that the test precision cannot be guaranteed.
SUMMERY OF THE UTILITY MODEL
Aiming at solving the defects of high energy consumption and low precision caused by adopting a single constant-pressure variable pump to carry out all tests in the traditional test technology, the utility model provides a hydraulic oil cylinder performance test platform adopting 3 hydraulic pumps of different types; the frequent switching of high pressure and low pressure is avoided, the output power of the system is optimized, and the energy consumption of the test system is reduced.
In order to achieve the technical purpose, the technical scheme of the utility model is as follows:
the utility model firstly provides a performance test platform of a hydraulic cylinder, which comprises an oil tank, three motor-pump sets, a control valve set, a tested hydraulic cylinder rack and a pressure sensor, wherein the three motor-pump sets are arranged on the oil tank;
the three motor-pump sets are respectively a squirrel-cage three-phase asynchronous motor one-control pump set, a variable frequency motor-main pump set and a squirrel-cage three-phase asynchronous motor two-high pressure pump set; wherein, the motor in each motor-pump group drives the corresponding pump to work;
the control valve group comprises a plurality of overflow valves, a proportional overflow valve, an electromagnetic directional valve and a hydraulic control one-way valve;
the control pump, the main pump and the high-pressure pump are respectively and independently connected with an oil suction port of the oil tank through an oil suction filter; the oil return port of each valve in the control valve group is connected with the oil return port of the oil tank;
an oil outlet of the control pump is respectively connected with an overflow valve, a proportional pressure reducing valve, an oil inlet of a first electromagnetic reversing valve and an oil inlet of a second electromagnetic reversing valve; an oil outlet of the main pump is respectively connected with oil inlets of the first proportional overflow valve and the third electromagnetic directional valve; an oil outlet of the high-pressure pump is respectively connected with oil inlets of a second proportional overflow valve and a fourth electromagnetic directional valve and an outlet of a one-way valve of an outlet of the proportional pressure reducing valve through an outlet one-way valve; the proportional pressure reducing valve is connected with an inlet of the proportional pressure reducing valve outlet one-way valve; the overflow valve, the first proportional overflow valve and the second proportional overflow valve are respectively connected with an oil return port of an oil tank;
two working oil ports of the electromagnetic directional valve III are respectively connected with the left side and the right side of the hydraulic oil cylinder to be tested through a hydraulic control one-way valve I and a hydraulic control one-way valve II; two working oil ports of the fourth electromagnetic directional valve are respectively connected with the left side and the right side of the hydraulic oil cylinder to be tested; the first electromagnetic directional valve is connected with a control oil way of the first hydraulic control one-way valve, and the second electromagnetic directional valve is connected with a control oil way of the second hydraulic control one-way valve;
pressure sensors are respectively arranged in the left and right side chambers of the hydraulic cylinder to be tested, and pressure sensors are arranged on oil ways connected with the left and right sides of the hydraulic cylinder to be tested.
As a preferable scheme of the utility model, the first electromagnetic directional valve and the second electromagnetic directional valve are two-position four-way electromagnetic directional valves, the first electromagnetic directional valve is used for controlling the first hydraulic control one-way valve, and the second electromagnetic directional valve is used for controlling the second hydraulic control one-way valve.
As a preferable scheme of the utility model, the third electromagnetic directional valve and the fourth electromagnetic directional valve are three-position four-way electromagnetic directional valves.
As a preferred scheme of the utility model, the extension end of the hydraulic cylinder to be detected is provided with a pull rope type displacement sensor.
In a preferred embodiment of the present invention, the control pump and the main pump are gear pumps, and the high-pressure pump is a plunger pump. The maximum output pressure of the plunger pump is 40 Mpa.
As a preferred scheme of the utility model, the test platform further comprises a controller, the controller is connected with the pressure sensor and the displacement sensor to acquire sensor signals, the controller is connected with the motor-pump, and the controller is respectively connected with the first electromagnetic directional valve, the second electromagnetic directional valve, the third electromagnetic directional valve and the fourth electromagnetic directional valve.
Compared with the prior art, the utility model can achieve the aims of optimizing the output power of the system and reducing the energy consumption of the test system by reasonably using different types of hydraulic pumps aiming at different test projects: when the stroke detection and the buffer performance detection are carried out, the variable frequency motor and the gear pump set are used, so that the output flow can be quickly and flexibly adjusted; when the minimum starting pressure detection is carried out, the squirrel-cage three-phase asynchronous motor and the gear pump set are used, the output pressure is controlled through the pressure reducing valve, and the minimum starting pressure of the hydraulic oil cylinder is accurately tested; when the pressure resistance test is carried out, the variable frequency motor and the quantitative gear pump set are firstly used for enabling the hydraulic oil cylinder to move in place, and then the variable frequency motor and the quantitative gear pump set are switched into the high-pressure pump for carrying out the pressure resistance test on the hydraulic oil cylinder, so that the effects of rapidness and energy conservation are achieved.
According to the utility model, through switching of the output pumps, the test can be completed quickly, and the energy consumption of the test can be reduced; the minimum starting pressure of the hydraulic oil cylinder can be accurately detected by selecting a proper pump and a proper control loop. The hydraulic control one-way valve is used for switching the hydraulic circuits, and is simple and reliable. The utility model is simple and convenient, can automatically complete detection through the controller, and is convenient to operate.
Drawings
FIG. 1 is a hydraulic schematic of the test platform of the present invention;
fig. 2 is a schematic diagram of three motor-pump sets of the hydraulic system of the present invention.
Detailed Description
The utility model will be further illustrated and described with reference to specific embodiments. The technical features of the embodiments of the present invention can be combined correspondingly without mutual conflict.
As shown in fig. 1 and 2, the performance testing platform of the hydraulic cylinder comprises an oil tank, three motor-pump sets, a control valve set, a tested hydraulic cylinder rack and a pressure sensor; a temperature sensor 2 and a level gauge 4 are provided on the tank for monitoring the temperature and the level, respectively.
The three motor-pump sets are respectively a squirrel-cage three-phase asynchronous motor I8-control pump 11 set, a variable frequency motor 9-main pump 12 set and a squirrel-cage three-phase asynchronous motor II 10-high pressure pump 13 set; wherein, the motor in each motor-pump group drives the corresponding pump to work; the control pump 11 and the main pump 12 are gear pumps, and the high-pressure pump 13 is a plunger pump.
The control valve group comprises a plurality of overflow valves, a proportional overflow valve, an electromagnetic directional valve and a hydraulic control one-way valve;
the control pump, the main pump and the high-pressure pump are respectively and independently connected with an oil suction port of the oil tank through an oil suction filter; the oil return port of each valve in the control valve group is connected with the oil return port of the oil tank; an oil outlet of the control pump 11 is respectively connected with an overflow valve 14, a proportional pressure reducing valve 15, an oil inlet of a first electromagnetic directional valve 19 and an oil inlet of a second electromagnetic directional valve 20; an oil outlet of the main pump 12 is respectively connected with oil inlets of a first proportional overflow valve 16 and a third electromagnetic directional valve 21; an oil outlet of the high-pressure pump 13 is respectively connected with oil inlets of a second proportional overflow valve 18 and a fourth electromagnetic directional valve 22 and an outlet of a one-way valve 17 of an outlet of the proportional pressure reducing valve through an outlet one-way valve; wherein, the proportional pressure reducing valve 15 is connected with the inlet of the proportional pressure reducing valve outlet one-way valve 17; the overflow valve 14, the first proportional overflow valve 16 and the second proportional overflow valve 18 are respectively connected with an oil tank oil return port;
two working oil ports of the third electromagnetic directional valve 21 are respectively connected with the left side and the right side of the hydraulic oil cylinder to be tested through a first hydraulic control one-way valve 24 and a second hydraulic control one-way valve 23; two working oil ports of the fourth electromagnetic directional valve 22 are respectively connected with the left side and the right side of the hydraulic oil cylinder to be tested; the first electromagnetic directional valve 19 is connected with a control oil path of the first hydraulic control one-way valve 24, and the second electromagnetic directional valve 20 is connected with a control oil path of the second hydraulic control one-way valve 23; pressure sensors are respectively arranged in the left and right side chambers of the hydraulic cylinder to be tested, and pressure sensors are arranged on oil ways connected with the left and right sides of the hydraulic cylinder to be tested.
In an embodiment of the present invention, the first electromagnetic directional valve 19 and the second electromagnetic directional valve 20 are two-position four-way electromagnetic directional valves, the first electromagnetic directional valve 19 is used for controlling the first pilot-controlled check valve 24, and the second electromagnetic directional valve 20 is used for controlling the second pilot-controlled check valve 23. As a preferable scheme of the present invention, the third electromagnetic directional valve 21 and the fourth electromagnetic directional valve 22 are three-position four-way electromagnetic directional valves.
The extension end of the hydraulic oil cylinder to be measured is provided with a pull rope type displacement sensor. The maximum output pressure of the plunger pump is 40 Mpa.
As a preferable scheme of the utility model, the test platform further comprises a controller, the controller is connected with the pressure sensor and the displacement sensor to acquire sensor signals, the controller is connected with the motor-pump, and the controller is respectively connected with the first electromagnetic directional valve 19, the second electromagnetic directional valve 20, the third electromagnetic directional valve 21 and the fourth electromagnetic directional valve 22.
The concrete test steps for testing the hydraulic oil cylinder by using the performance test platform are described in detail below, and the test mainly comprises stroke detection, minimum starting pressure detection, pressure resistance detection and buffer performance detection.
1) When the stroke is detected, a first squirrel-cage three-phase asynchronous motor 8 for controlling the gear pump 11, a second squirrel-cage three-phase asynchronous motor 10 for closing the plunger pump, the rotating speed of the variable frequency motor 9, the pressure of the overflow valve 14, the pressure of the first proportional overflow valve 16, the pressure of the second proportional overflow valve 18, the first electromagnetic directional valve 19, the first hydraulic one-way valve 24, the second electromagnetic directional valve 20, the second hydraulic one-way valve 23, the first pressure sensor 25, the second pressure sensor 26 and the displacement sensor are arranged in the controller, the measured physical quantity is converted into an electric signal and transmitted to the controller, the fourth electromagnetic directional valve 22 is controlled to be in the middle position, the third electromagnetic directional valve 21 is controlled to enable the hydraulic oil cylinder to reciprocate, and the stroke of the hydraulic oil cylinder is recorded;
2) when the minimum starting pressure is detected, opening a squirrel-cage three-phase asynchronous motor I8 of a control gear pump 11, closing a squirrel-cage three-phase asynchronous motor II 10 of a plunger pump, setting the rotating speed of a variable frequency motor 9 to be 0, setting the pressure of an overflow valve 14, setting the pressure of a proportional overflow valve I16, setting the pressure of a proportional overflow valve II 18, controlling a first electromagnetic directional valve 19 to close a first pilot-operated check valve 24, controlling a second electromagnetic directional valve 20 to close a second pilot-operated check valve 23, controlling a third electromagnetic directional valve 21 to be in a middle position, setting a proportional pressure reducing valve 15 to be the minimum setting pressure, and controlling a fourth electromagnetic directional valve 22 to be in a right position in a controller; the first pressure sensor 25 converts the measured physical quantity into an electric signal and transmits the electric signal to the controller, meanwhile, the setting of the proportional pressure reducing valve 15 is increased through the controller, the pressure of the proportional pressure reducing valve is set to be a set pressure change speed, until the hydraulic oil cylinder can normally move, and the electric signal of the first pressure sensor 25 is recorded;
3) when pressure resistance detection is carried out, a first squirrel-cage three-phase asynchronous motor 8 for controlling the gear pump 11, a second squirrel-cage three-phase asynchronous motor 10 for closing the plunger pump, the rotating speed of the variable frequency motor 9, the pressure of the overflow valve 14, the pressure of the first proportional overflow valve 16, the pressure of the second proportional overflow valve 18, the first electromagnetic directional valve 19, the first pilot-operated check valve 24, the second electromagnetic directional valve 20, the second pilot-operated check valve 23, the pressure sensors, the pressure sensor 25, the second pressure sensor 26 and the displacement sensor are arranged in the controller, measured physical quantities are converted into electric signals and transmitted to the controller, and the fourth electromagnetic directional valve 22 is controlled to be in a middle position; controlling a third electromagnetic directional valve 21 to extend or retract the hydraulic oil cylinder to the right position, controlling a first electromagnetic directional valve 19 to close a first hydraulic control one-way valve 24, controlling a second electromagnetic directional valve 20 to close a second hydraulic control one-way valve 23, controlling a third electromagnetic directional valve 21 to enable the third electromagnetic directional valve to be in a middle position, opening a second squirrel-cage three-phase asynchronous motor 10, setting the pressure of a first proportional overflow valve 16, and controlling a fourth electromagnetic directional valve 22 to enable a plunger pump 13 to be connected with a pressure-resistant cavity of the hydraulic oil cylinder; setting pressure resistant time through a controller, and checking the pressure resistant condition of the hydraulic oil cylinder;
4) when the buffer performance is detected, a controller is opened to control a squirrel-cage three-phase asynchronous motor I8 of a gear pump 11, a squirrel-cage three-phase asynchronous motor II 10 of a plunger pump, the rotating speed of a variable frequency motor 9 is set according to the buffer speed, the pressure of an overflow valve 14 is set, the pressure of a proportional overflow valve I16 is set, the pressure of a proportional overflow valve II 18 is set, a first electromagnetic directional valve 19 is controlled to open a first pilot-operated check valve 24, a second electromagnetic directional valve 20 is controlled to open a second pilot-operated check valve 24, a first pressure sensor 25, a second pressure sensor 26, a third pressure sensor 27, a fourth pressure sensor 28 and a displacement sensor convert the measured physical quantity into an electric signal and transmit the electric signal to the controller, the fourth electromagnetic directional valve 22 is controlled to be in the middle position, the third electromagnetic directional valve 23 is controlled to extend or retract a hydraulic oil cylinder, the values of the pressure sensor and the displacement sensor are recorded, the time of entering a buffer zone is judged according to the value of the pressure sensor, and calculating the buffer length and the buffer effect of the hydraulic oil cylinder according to the data.
The utility model reasonably uses different types of hydraulic pumps aiming at different test items, and achieves the aims of optimizing the output power of the system and reducing the energy consumption of the test system: when the stroke detection and the buffer performance detection are carried out, the variable frequency motor and the gear pump set are used, so that the output flow can be quickly and flexibly adjusted; when the minimum starting pressure detection is carried out, the squirrel-cage three-phase asynchronous motor I + gear pump set is used, the output pressure is controlled through a pressure reducing valve, and the minimum starting pressure of the hydraulic oil cylinder is accurately tested; when the pressure resistance test is carried out, the variable frequency motor and the gear pump set are firstly used for enabling the hydraulic oil cylinder to move in place, and then the variable frequency motor and the gear pump set are switched into the high-pressure plunger pump for carrying out the pressure resistance test on the hydraulic oil cylinder, so that the effects of rapidness and energy conservation are achieved.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (7)
1. A performance test platform of a hydraulic cylinder is characterized by comprising an oil tank, three motor-pump sets, a control valve group, a tested hydraulic cylinder rack and a pressure sensor;
the three motor-pump sets are respectively a squirrel-cage three-phase asynchronous motor one-control pump set, a variable frequency motor-main pump set and a squirrel-cage three-phase asynchronous motor two-high pressure pump set; wherein, the motor in each motor-pump group drives the corresponding pump to work;
the control valve group comprises a plurality of overflow valves, a proportional overflow valve, an electromagnetic directional valve and a hydraulic control one-way valve;
the control pump, the main pump and the high-pressure pump are respectively and independently connected with an oil suction port of the oil tank through an oil suction filter; the oil return port of each valve in the control valve group is connected with the oil return port of the oil tank;
an oil outlet of the control pump (11) is respectively connected with an overflow valve (14), a proportional pressure reducing valve (15), an oil inlet of a first electromagnetic directional valve (19) and an oil inlet of a second electromagnetic directional valve (20); an oil outlet of the main pump (12) is respectively connected with oil inlets of a first proportional overflow valve (16) and a third electromagnetic directional valve (21); an oil outlet of the high-pressure pump (13) is respectively connected with oil inlets of a second proportional overflow valve (18) and a fourth electromagnetic directional valve (22) and an outlet of a one-way valve (17) of an outlet of the proportional pressure reducing valve through an outlet one-way valve; wherein, the proportional pressure reducing valve (15) is connected with an inlet of a proportional pressure reducing valve outlet one-way valve (17); the overflow valve (14), the proportional overflow valve I (16) and the proportional overflow valve II (18) are respectively connected with an oil tank oil return port;
two working oil ports of the third electromagnetic directional valve (21) are respectively connected with the left side and the right side of the hydraulic oil cylinder to be tested through a first hydraulic control one-way valve (24) and a second hydraulic control one-way valve (23); two working oil ports of the fourth electromagnetic directional valve (22) are respectively connected with the left side and the right side of the hydraulic oil cylinder to be tested; the first electromagnetic directional valve (19) is connected with a control oil way of the first hydraulic control one-way valve (24), and the second electromagnetic directional valve (20) is connected with a control oil way of the second hydraulic control one-way valve (23);
pressure sensors are respectively arranged in the left and right side chambers of the hydraulic cylinder to be tested, and pressure sensors are arranged on oil ways connected with the left and right sides of the hydraulic cylinder to be tested.
2. The performance test platform of the hydraulic oil cylinder according to claim 1, characterized in that the first electromagnetic directional valve (19) and the second electromagnetic directional valve (20) are two-position four-way electromagnetic directional valves, the first electromagnetic directional valve (19) is used for controlling the first pilot-controlled one-way valve (24), and the second electromagnetic directional valve (20) is used for controlling the second pilot-controlled one-way valve (23).
3. The performance test platform of the hydraulic oil cylinder according to claim 1, characterized in that the three (21) and four (22) electromagnetic directional valves are three-position four-way electromagnetic directional valves.
4. The performance test platform of the hydraulic oil cylinder according to claim 1, characterized in that the extending end of the hydraulic oil cylinder to be tested is provided with a pull rope type displacement sensor.
5. The platform for testing the performance of the hydraulic oil cylinder according to claim 1, characterized in that the control pump (11) and the main pump (12) are gear pumps, and the high-pressure pump (13) is a plunger pump.
6. The platform for testing the performance of the hydraulic oil cylinder according to claim 5, wherein the maximum output pressure of the plunger pump is 40 Mpa.
7. The performance test platform of the hydraulic oil cylinder according to claim 1, characterized in that the test platform further comprises a controller, the controller is connected with the pressure sensor and the displacement sensor to obtain sensor signals, the controller is connected with the motor-pump, and the controller is respectively connected with the first electromagnetic directional valve (19), the second electromagnetic directional valve (20), the third electromagnetic directional valve (21) and the fourth electromagnetic directional valve (22).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122538238.8U CN216382090U (en) | 2021-10-21 | 2021-10-21 | Performance test platform of hydraulic oil cylinder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122538238.8U CN216382090U (en) | 2021-10-21 | 2021-10-21 | Performance test platform of hydraulic oil cylinder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216382090U true CN216382090U (en) | 2022-04-26 |
Family
ID=81245613
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122538238.8U Active CN216382090U (en) | 2021-10-21 | 2021-10-21 | Performance test platform of hydraulic oil cylinder |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216382090U (en) |
-
2021
- 2021-10-21 CN CN202122538238.8U patent/CN216382090U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8813486B2 (en) | Hydraulic control system having cylinder stall strategy | |
| US20120216517A1 (en) | Hydraulic control system having cylinder stall strategy | |
| CN109058234B (en) | Performance test system and detection method for hydraulic system of electric proportional control valve compensation excavator | |
| EP1862599A3 (en) | Control system for an electronic float feature for a loader | |
| CN103644151A (en) | Energy-conservation and low-impact hydraulic cylinder test testbed hydraulic control system | |
| CN102032233B (en) | Multifunctional proportional multi-way valve | |
| CN101413522A (en) | Independent electrohydraulic load sensitive energy regeneration hydraulic system of engineering machinery load port | |
| CN107327432B (en) | A kind of pump control cylinder hydraulic circuit and its control method | |
| CN110966270B (en) | Digital electro-hydrostatic actuator system | |
| CN101571155A (en) | Digital electric-hydraulic synchronous control system | |
| CN108488112B (en) | Differential loop of large-flow hydraulic system and control method thereof | |
| CN105317785B (en) | Development machine multifunctional hydraulic testing stand | |
| CN201581382U (en) | Electro-hydraulic proportional control piston type two-lifting-point hydraulic hoist | |
| CN104989692B (en) | Compound control-type variable pump and control method thereof | |
| KR100790364B1 (en) | The active load simulator | |
| Lübbert et al. | Pressure compensator control–a novel independent metering architecture | |
| CN104389830A (en) | Intelligent synchronous type hydraulic hoist | |
| CN216382090U (en) | Performance test platform of hydraulic oil cylinder | |
| CN108999237B (en) | Intelligent control system and control method for hydraulic excavator | |
| CN104564862A (en) | Combined pump-controlled cylinder electric hydraulic control system | |
| CN111535393A (en) | Excavator bucket control system and method and excavator | |
| CN111577684B (en) | Hydraulic valve performance test experimental system | |
| CN112983909B (en) | Movable arm hydraulic system | |
| CN110005646B (en) | Digital electro-hydraulic loading device and method suitable for large-load interval | |
| CN203214470U (en) | Hydraulic manifold lifting control valve bank for hopper of heavy truck |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |