High-pressure large-flow quick-return anti-impact hydraulic circuit
Patent Information
- Application Number
- CN202522692135.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-19
- Publication Date
- 2026-10-27
- Estimated Expiration
- 2035-12-19
AI Technical Summary
这种方案能够有效地降低液压冲击，但在工作频率高、节奏快的液压系统中应用时，其控制反应时间会影响工作节拍
1、本实用新型泄压过程中采用节流阀和第三二通插装阀两次节流，减小阀口的压差，降低阀口的液压油流速，从而降低液压油流动时的噪音；
Smart Images
Figure CN224903612U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of hydraulic control technology, and in particular to a high-pressure, high-flow, fast-return, shock-resistant hydraulic circuit. Background Technology
[0002] When a high-pressure, high-flow hydraulic system rapidly returns after loading, the high pressure is released instantaneously, causing a rapid pressure change that can generate hydraulic shock. This can lead to vibration and even damage to pipelines, the hydraulic system, and mechanical equipment. To reduce hydraulic shock, a pressure relief function is typically added before the rapid return stroke to release the high-pressure hydraulic oil, and then the rapid return circuit is opened via a pressure signal. This solution effectively reduces hydraulic shock, but in hydraulic systems with high operating frequencies and fast cycles, its control response time can affect the work cycle. Utility Model Content
[0003] The purpose of this invention is to provide a high-pressure, high-flow, fast-return, shock-resistant hydraulic circuit that seamlessly switches between pressure relief, slow start, and fast return processes, enabling the hydraulic system to operate quickly and without impact.
[0004] The above-mentioned technical objective of this utility model is achieved through the following technical solution: A high-pressure, high-flow, fast-return anti-shock hydraulic circuit includes an oil circuit board, a first two-way cartridge valve, a second two-way cartridge valve, a one-way throttle valve, a third two-way cartridge valve, a solenoid ball valve, a throttle valve, a fourth two-way cartridge valve, and a hydraulically controlled directional valve. The hydraulic circuit board is provided with oil ports PA, PB and PC, and oil port PB is connected to the rodless chamber of the hydraulic cylinder; the first two-way cartridge valve is provided with oil ports AA, AB and AC, and oil port AA is connected to oil port PA of the hydraulic circuit board, oil port AB is connected to oil port PB of the hydraulic circuit board, and oil port AC is connected to oil port AB and oil port PB of the hydraulic circuit board. The second two-way cartridge valve is provided with oil ports BA, BB and BC, and oil port BA is connected to oil port AB of the first two-way cartridge valve, and oil port BB is connected to oil port PC of the oil circuit board. The one-way throttle valve is provided with oil ports EA and EB, and oil port EA is connected to the oil port BC of the second two-way cartridge valve. The third two-way cartridge valve is provided with oil ports CA, CB and CC, and oil port CA is connected to oil port EB of the one-way throttle valve, and oil port CB is connected to oil port PC of the oil circuit board. The solenoid ball valve is provided with oil ports GA, GP, GT and electromagnet YVGA, and oil port GA is connected to oil port CC of the third two-way cartridge valve, oil port GP is connected to oil port PB of the oil circuit board and oil port AB of the first two-way cartridge valve, and oil port GT is connected to oil port PC of the oil circuit board. The throttle valve is provided with oil ports FA and FB, and oil port FA is connected to oil port AB of the first two-way cartridge valve and oil port PB of the oil circuit board, and oil port FB is connected to oil port EB of the one-way throttle valve and oil port CA of the third two-way cartridge valve. The fourth two-way cartridge valve is provided with ports DA, DB and DC, and port DA is connected to port CA of the third two-way cartridge valve, and port DB is connected to port BC of the second two-way cartridge valve. The hydraulic control directional valve includes ports HA, HB, HC, HP and HT, with port HA blocked, port HB connected to port DC of the fourth two-way cartridge valve, port HC connected to port PB of the circuit board and port AB of the first two-way cartridge valve, port HP connected to port EA of the one-way throttle valve, and port HT connected to port PC of the circuit board. The flow area of the throttling port from port EA to port EB of the one-way throttling valve is smaller than the flow area of the throttling port from port FA to port FB of the throttling valve and the flow area of the throttling port from port CA to port CB of the third two-way cartridge valve, and the flow area of the throttling port from port FA to port FB of the throttling valve is larger than the flow area of the throttling port from port CA to port CB of the third two-way cartridge valve.
[0005] Furthermore, the third two-way cartridge valve is also provided with a valve core stroke adjusting rod, which adjusts the flow area of the throttling port between the oil port CA and the oil port CB of the third two-way cartridge valve.
[0006] Furthermore, when the electromagnet YVGA of the solenoid ball valve is de-energized, its oil port GA and oil port GP are connected; when the electromagnet YVGA is energized, its oil port GA and oil port GT are connected.
[0007] Furthermore, when the pressure at port HC of the hydraulic directional valve is lower than the spring force of the hydraulic directional valve, its ports HP and HA are connected, and its ports HT and HB are connected; when the pressure at port HC is higher than the spring force of the hydraulic directional valve, its ports HP and HB are connected, and its ports HT and HA are connected.
[0008] Furthermore, high-pressure oil enters the first two-way cartridge valve from port PA of the circuit board, and then enters the second two-way cartridge valve from port BC via a throttle valve and a one-way throttle valve to close the second two-way cartridge valve. Simultaneously, it enters the third two-way cartridge valve from port CC via a solenoid ball valve to close the third two-way cartridge valve. At the same time, after the pressure at port HC of the hydraulic directional valve exceeds the spring force of the hydraulic directional valve, the hydraulic oil from port EA of the one-way throttle valve enters the fourth two-way cartridge valve from port DC via the hydraulic directional valve to close the fourth two-way cartridge valve. Simultaneously, it also enters the rodless chamber of the hydraulic cylinder from port PB of the circuit board, and the piston rod of the hydraulic cylinder performs an extension loading action.
[0009] Furthermore, oil enters the rod chamber of the hydraulic cylinder, the electromagnet YVGA of the solenoid ball valve is energized, and the hydraulic oil from port CC of the third two-way cartridge valve returns through ports GA and GT of the solenoid ball valve and port PC of the circuit board. The third two-way cartridge valve opens, and the high-pressure oil from the rodless chamber of the hydraulic cylinder enters port AC of the first two-way cartridge valve through port PB of the circuit board, closing the first two-way cartridge valve. At the same time, the pressure is released through port PB of the circuit board, ports FA and FB of the throttle valve, ports CA and CB of the third two-way cartridge valve, and port PC of the circuit board until the pressure in the rodless chamber of the hydraulic cylinder drops below the pressure in the rod chamber, and the piston rod of the hydraulic cylinder slowly retracts.
[0010] Furthermore, during depressurization, the hydraulic oil pressure at port BC of the second two-way cartridge valve decreases as the hydraulic oil pressure at port EB of the one-way throttle valve decreases. However, due to the pressure difference formed by the throttle port of the one-way throttle valve, the hydraulic oil pressure at port EA of the one-way throttle valve and port BC of the second two-way cartridge valve is higher than the hydraulic oil pressure at port EB of the one-way throttle valve. Therefore, the second two-way cartridge valve remains closed throughout the depressurization process.
[0011] Furthermore, when the pressure at port HC of the hydraulic directional valve is lower than the spring force of the hydraulic directional valve, the hydraulic oil at port DC of the fourth two-way cartridge valve returns through ports HB and HT of the hydraulic directional valve and port PC of the circuit board to open the fourth two-way cartridge valve. The hydraulic oil at port BC of the second two-way cartridge valve returns through ports DB and DA of the fourth two-way cartridge valve, ports CA and CB of the third two-way cartridge valve, and port PC of the circuit board to open the second two-way cartridge valve. The hydraulic oil in the rodless chamber of the hydraulic cylinder returns in a large flow through ports PB of the circuit board, ports BA and BB of the second two-way cartridge valve, and port PC of the circuit board, causing the piston rod of the hydraulic cylinder to retract rapidly.
[0012] In summary, this utility model has the following beneficial effects: 1. In the process of pressure relief, this utility model uses a throttle valve and a third two-way cartridge valve to throttle twice, reducing the pressure difference at the valve port and reducing the hydraulic oil flow rate at the valve port, thereby reducing the noise when the hydraulic oil flows. 2. When this utility model is working, the pressure relief, slow start and fast return processes are seamlessly switched, realizing the rapid and shock-free operation of the hydraulic system and ensuring the working rhythm of the hydraulic system. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of a high-pressure, high-flow, fast-return, shock-resistant hydraulic circuit.
[0014] In the diagram, 1. Oil circuit board; 2. First two-way cartridge valve; 3. Second two-way cartridge valve; 4. One-way throttle valve; 5. Third two-way cartridge valve; 51. Valve core stroke adjustment rod; 6. Solenoid ball valve; 7. Throttle valve; 8. Fourth two-way cartridge valve; 9. Hydraulic directional valve; 10. Hydraulic cylinder. Detailed Implementation
[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.
[0016] A high-pressure, high-flow, fast-return anti-shock hydraulic circuit, such as Figure 1 As shown, it includes an oil circuit board 1, a first two-way cartridge valve 2, a second two-way cartridge valve 3, a one-way throttle valve 4, a third two-way cartridge valve 5, a solenoid ball valve 6, a throttle valve 7, a fourth two-way cartridge valve 8, and a hydraulically controlled directional valve 9, and is connected to the rodless chamber of the hydraulic cylinder 10 through the oil circuit board 1.
[0017] Specifically, such as Figure 1 As shown, the hydraulic circuit board 1 has ports PA, PB, and PC, and port PB is connected to the rodless chamber of the hydraulic cylinder 10. The first two-way cartridge valve 2 has ports AA, AB, and AC, and port AA is connected to port PA of the hydraulic circuit board 1, port AB is connected to port PB of the hydraulic circuit board 1, and port AC is connected to port AB and port PB of the hydraulic circuit board 1.
[0018] like Figure 1 As shown, the second two-way cartridge valve 3 has ports BA, BB, and BC, with port BA connected to port AB of the first two-way cartridge valve 2, and port BB connected to port PC of the circuit board 1. The one-way throttle valve 4 has ports EA and EB, with port EA connected to port BC of the second two-way cartridge valve 3. The third two-way cartridge valve 5 has ports CA, CB, and CC, with port CA connected to port EB of the one-way throttle valve 4, and port CB connected to port PC of the circuit board 1. The third two-way cartridge valve 5 also has a valve core stroke adjusting rod 51, which is used to adjust the flow area of the throttling orifice between ports CA and CB of the third two-way cartridge valve 5.
[0019] like Figure 1 As shown, the solenoid ball valve 6 has oil ports GA, GP, GT and an electromagnet YVGA. Oil port GA is connected to oil port CC of the third two-way cartridge valve 5, oil port GP is connected to oil port PB of the oil circuit board 1 and oil port AB of the first two-way cartridge valve 2, and oil port GT is connected to oil port PC of the oil circuit board 1. Specifically, when the electromagnet YVGA of the solenoid ball valve 6 is de-energized, its oil ports GA and GP are connected; when the electromagnet YVGA is energized, its oil ports GA and GT are connected.
[0020] like Figure 1 As shown, the throttle valve 7 has ports FA and FB. Port FA is connected to port AB of the first two-way cartridge valve 2 and port PB of the oil circuit board 1. Port FB is connected to port EB of the one-way throttle valve 4 and port CA of the third two-way cartridge valve 5. The fourth two-way cartridge valve 8 has ports DA, DB, and DC. Port DA is connected to port CA of the third two-way cartridge valve 5. Port DB is connected to port BC of the second two-way cartridge valve 3.
[0021] like Figure 1 As shown, the hydraulic directional valve 9 includes ports HA, HB, HC, HP, and HT. Port HA is blocked. Port HB is connected to port DC of the fourth two-way cartridge valve 8. Port HC is connected to port PB of the circuit board 1 and port AB of the first two-way cartridge valve 2. Port HP is connected to port EA of the one-way throttle valve 4. Port HT is connected to port PC of the circuit board 1. Specifically, when the pressure at port HC of the hydraulic directional valve 9 is lower than the spring force of the hydraulic directional valve 9, its ports HP and HA are connected, and its port HT and HB are connected. When the pressure at port HC is higher than the spring force of the hydraulic directional valve 9, its ports HP and HB are connected, and its port HT and HA are connected.
[0022] like Figure 1 As shown, the flow area of the throttling port from port EA to port EB of the one-way throttle valve 4 is smaller than the flow area of the throttling port from port FA to port FB of the throttle valve 7 and the flow area of the throttling port from port CA to port CB of the third two-way cartridge valve 5. Furthermore, the flow area of the throttling port from port FA to port FB of the throttle valve 7 is larger than the flow area of the throttling port from port CA to port CB of the third two-way cartridge valve 5.
[0023] like Figure 1 As shown, high-pressure oil enters from port PA of the hydraulic circuit board 1 through ports AA and AB of the first two-way cartridge valve 2, and then splits into the following paths: it passes through ports FA and FB of the throttle valve 7, and ports EB and EA of the one-way throttle valve 4, entering port BC of the second two-way cartridge valve 3, which closes; simultaneously, it passes through ports GP and GA of the solenoid ball valve 6, entering port CC of the third two-way cartridge valve 5, which closes; it also passes through port HC of the hydraulic directional valve 9. When the pressure at port HC of the hydraulic directional valve 9 exceeds the spring force of the hydraulic directional valve 9, the hydraulic oil at port EA of the one-way throttle valve 4 passes through ports HP and HB of the hydraulic directional valve 9, entering port DC of the fourth two-way cartridge valve 8, which closes; it also passes through port PB of the hydraulic circuit board 1 into the rodless chamber of the hydraulic cylinder 10, where the piston rod of the hydraulic cylinder 10 extends and loads.
[0024] like Figure 1As shown, oil enters the rod chamber of hydraulic cylinder 10, the electromagnet YVGA of solenoid ball valve 6 is energized, and the hydraulic oil from port CC of the third two-way cartridge valve 5 returns through ports GA and GT of solenoid ball valve 6 and port PC of circuit board 1. The third two-way cartridge valve 5 opens, and the high-pressure oil from the rodless chamber of hydraulic cylinder 10 enters port AC of the first two-way cartridge valve 2 through port PB of circuit board 1, closing the first two-way cartridge valve 2. At the same time, it releases pressure through port PB of circuit board 1, ports FA and FB of throttle valve 7, ports CA and CB of the third two-way cartridge valve 5, and port PC of circuit board 1. During the depressurization process, the hydraulic oil pressure at port BC of the second two-way cartridge valve 3 decreases as the hydraulic oil pressure at port EB of the one-way throttle valve 4 decreases. However, due to the pressure difference formed at the throttle port of the one-way throttle valve 4, the hydraulic oil pressure at port EA of the one-way throttle valve 4 and port BC of the second two-way cartridge valve 3 is higher than the hydraulic oil pressure at port EB of the one-way throttle valve 4. The hydraulic oil pressure at port BC still ensures that the second two-way cartridge valve 3 remains closed during the depressurization process. Throughout the entire depressurization process, the throttle valve 7 and the third two-way cartridge valve 5 throttle twice, reducing the pressure difference at the valve ports and decreasing the hydraulic oil flow rate at the valve ports, thereby reducing the noise during hydraulic oil flow.
[0025] like Figure 1 As shown, when the pressure in the rodless chamber of hydraulic cylinder 10 drops below the pressure in the rod chamber, the piston rod of hydraulic cylinder 10 slowly retracts. When the pressure at port HC of hydraulic directional valve 9 is lower than the spring force of hydraulic directional valve 9, the hydraulic oil at port DC of the fourth two-way cartridge valve 8 returns through ports HB and HT of hydraulic directional valve 9 and port PC of circuit board 1, and the fourth two-way cartridge valve 8 opens, with its ports DA and DB connected. The hydraulic oil at port BC of the second two-way cartridge valve 3 returns through ports DB and DA of the fourth two-way cartridge valve 8, ports CA and CB of the third two-way cartridge valve 5 and PC of circuit board 1, and the second two-way cartridge valve 3 opens, with its ports BA and BB connected. The hydraulic oil in the rodless chamber of hydraulic cylinder 10 returns in a large flow through port PB of circuit board 1, ports BA and BB of the second two-way cartridge valve 3, and port PC of circuit board 1. The piston rod of hydraulic cylinder 10 retracts rapidly, completing the rapid return stroke. The entire process seamlessly switches between pressure relief, slow start, and rapid return, achieving rapid and shock-free operation of the hydraulic system.
[0026] The foregoing description illustrates and describes preferred embodiments of the present invention. As previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or related technical or knowledge. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.
Claims
1. A high-pressure, high-flow, fast-return, shock-resistant hydraulic circuit, characterized in that: It includes an oil circuit board (1), a first two-way cartridge valve (2), a second two-way cartridge valve (3), a one-way throttle valve (4), a third two-way cartridge valve (5), a solenoid ball valve (6), a throttle valve (7), a fourth two-way cartridge valve (8), and a hydraulic control directional valve (9). The oil circuit board (1) is provided with oil ports PA, PB and PC, and oil port PB is connected to the rodless chamber of the hydraulic cylinder (10); the first two-way cartridge valve (2) is provided with oil ports AA, AB and AC, and oil port AA is connected to oil port PA of the oil circuit board (1), oil port AB is connected to oil port PB of the oil circuit board (1), and oil port AC is connected to oil port AB and oil port PB of the oil circuit board (1); The second two-way cartridge valve (3) is provided with oil ports BA, BB and BC, and oil port BA is connected to oil port AB of the first two-way cartridge valve (2), and oil port BB is connected to oil port PC of the oil circuit board (1); The one-way throttle valve (4) is provided with oil ports EA and EB, and oil port EA is connected to the oil port BC of the second two-way cartridge valve (3). The third two-way cartridge valve (5) is provided with oil ports CA, CB and CC, and oil port CA is connected to oil port EB of the one-way throttle valve (4), and oil port CB is connected to oil port PC of the oil circuit board (1). The solenoid ball valve (6) is provided with oil ports GA, GP, GT and electromagnet YVGA, and oil port GA is connected to oil port CC of the third two-way cartridge valve (5), oil port GP is connected to oil port PB of oil circuit board (1) and oil port AB of the first two-way cartridge valve (2), and oil port GT is connected to oil port PC of oil circuit board (1). The throttle valve (7) is provided with oil ports FA and FB, and oil port FA is connected to oil port AB of the first two-way cartridge valve (2) and oil port PB of the oil circuit board (1), and oil port FB is connected to oil port EB of the one-way throttle valve (4) and oil port CA of the third two-way cartridge valve (5). The fourth two-way cartridge valve (8) is provided with oil ports DA, DB and DC, and oil port DA is connected to oil port CA of the third two-way cartridge valve (5), and oil port DB is connected to oil port BC of the second two-way cartridge valve (3). The hydraulic control directional valve (9) includes ports HA, HB, HC, HP and HT, with port HA blocked, port HB connected to port DC of the fourth two-way cartridge valve (8), port HC connected to port PB of the circuit board (1) and port AB of the first two-way cartridge valve (2), port HP connected to port EA of the one-way throttle valve (4), and port HT connected to port PC of the circuit board (1). The flow area of the throttling port from EA to EB of the one-way throttle valve (4) is smaller than the flow area of the throttling port from FA to FB of the throttle valve (7) and the flow area of the throttling port from CA to CB of the third two-way cartridge valve (5). The flow area of the throttling port from FA to FB of the throttle valve (7) is larger than the flow area of the throttling port from CA to CB of the third two-way cartridge valve (5).
2. The high-pressure, high-flow, fast-return anti-impact hydraulic circuit according to claim 1, characterized in that: The third two-way cartridge valve (5) is also provided with a valve core stroke adjustment rod (51), which adjusts the flow area of the throttling port between the oil port CA and the oil port CB of the third two-way cartridge valve (5).
3. The high-pressure, high-flow, fast-return anti-impact hydraulic circuit according to claim 1, characterized in that: When the electromagnet YVGA of the solenoid ball valve (6) is de-energized, its oil port GA and oil port GP are connected; when the electromagnet YVGA is energized, its oil port GA and oil port GT are connected.
4. The high-pressure, high-flow, fast-return anti-impact hydraulic circuit according to claim 1, characterized in that: When the pressure of port HC of the hydraulic directional valve (9) is lower than the spring force of the hydraulic directional valve (9), its port HP and port HA are connected, and its port HT and port HB are connected. When the pressure of port HC is higher than the spring force of the hydraulic directional valve (9), its port HP and port HB are connected, and its port HT and port HA are connected.
5. The high-pressure, high-flow, fast-return, anti-impact hydraulic circuit according to claim 4, characterized in that: High-pressure oil enters the first two-way cartridge valve (2) from port PA of the oil circuit board (1), and enters the second two-way cartridge valve (3) through port BC of the second two-way cartridge valve (3) via the throttle valve (7) and the one-way throttle valve (4) to close the second two-way cartridge valve (3). At the same time, it enters the third two-way cartridge valve (5) through port CC of the solenoid ball valve (6) to close the third two-way cartridge valve (5). At the same time, after the pressure of the hydraulic control directional valve (9) from port HC to port HC is higher than the spring force of the hydraulic control directional valve (9), the hydraulic oil of the one-way throttle valve (4) through port EA enters the fourth two-way cartridge valve (8) through the hydraulic control directional valve (9) to port DC to close the fourth two-way cartridge valve (8). At the same time, it also enters the rodless chamber of the hydraulic cylinder (10) through port PB of the oil circuit board (1), and the piston rod of the hydraulic cylinder (10) performs the extension loading action.
6. The high-pressure, high-flow, fast-return, anti-impact hydraulic circuit according to claim 3, characterized in that: Oil enters the rod chamber of the hydraulic cylinder (10), the electromagnet YVGA of the solenoid ball valve (6) is energized, the hydraulic oil in the oil port CC of the third two-way cartridge valve (5) returns through the oil ports GA and GT of the solenoid ball valve (6) and the oil port PC of the oil circuit board (1), the third two-way cartridge valve (5) opens, the high pressure oil in the rodless chamber of the hydraulic cylinder (10) enters the oil port AC of the first two-way cartridge valve (2) through the oil port PB of the oil circuit board (1) and closes the first two-way cartridge valve (2), at the same time it is depressurized through the oil port PB of the oil circuit board (1), the oil ports FA and FB of the throttle valve (7), the oil ports CA and CB of the third two-way cartridge valve (5) and the oil port PC of the oil circuit board (1) until the pressure in the rodless chamber of the hydraulic cylinder (10) drops to less than the pressure in the rod chamber, and the piston rod of the hydraulic cylinder (10) slowly retracts.
7. The high-pressure, high-flow, fast-return anti-impact hydraulic circuit according to claim 6, characterized in that: During depressurization, the hydraulic oil pressure at port BC of the second two-way cartridge valve (3) decreases as the hydraulic oil pressure at port EB of the one-way throttle valve (4) decreases. However, due to the pressure difference formed by the throttle port of the one-way throttle valve (4), the hydraulic oil pressure at port EA of the one-way throttle valve (4) and port BC of the second two-way cartridge valve (3) is higher than the hydraulic oil pressure at port EB of the one-way throttle valve (4). During the depressurization process, the second two-way cartridge valve (3) remains closed.
8. A high-pressure, high-flow, fast-return anti-impact hydraulic circuit according to claim 6, characterized in that: When the pressure at port HC of the hydraulic directional valve (9) is lower than the spring force of the hydraulic directional valve (9), the hydraulic oil at port DC of the fourth two-way cartridge valve (8) returns through ports HB and HT of the hydraulic directional valve (9) and port PC of the circuit board (1) to open the fourth two-way cartridge valve (8). The hydraulic oil at port BC of the second two-way cartridge valve (3) returns through ports DB and DA of the fourth two-way cartridge valve (8), ports CA and CB of the third two-way cartridge valve (5), and port PC of the circuit board (1) to open the second two-way cartridge valve (3). The hydraulic oil in the rodless chamber of the hydraulic cylinder (10) returns through ports PB of the circuit board (1), ports BA and BB of the second two-way cartridge valve (3), and port PC of the circuit board (1) in a large flow rate, and the piston rod of the hydraulic cylinder (10) retracts quickly.