Tensioning construction equipment health diagnosis method and system based on online monitoring

Abstract

The invention provides a tensioning construction equipment health diagnosis method and system based on online monitoring, and the method comprises the steps: arranging an engineering Internet of Things terminal with a flowmeter on an oil inlet path of the tensioning construction equipment, and enabling the engineering Internet of Things terminal to be connected with an application server and a cloud platform, so as to achieve the monitoring of the operation state of a tensioning jack; in the working process of the tensioning jack, the stroke displacement of a piston rod of the tensioning jack, whether oil leakage exists in a tensioning system composed of the tensioning jack and a hydraulic pump station or not and whether oil absorption of a pump head of the tensioning jack is abnormal or not are monitored, and the health condition of the tensioning jack is analyzed and judged. According to the invention, the engineering Internet of Things terminal is integrated on the tensioning construction equipment, so that the operation condition of the tensioning construction equipment is automatically monitored on line, the fault problem of the tensioning construction equipment is automatically diagnosed, the specific problems of large reason troubleshooting difficulty, long time, low efficiency and the like in the manual maintenance process are solved, and the maintenance efficiency is improved. And the large-area disastrous engineering problem caused by'operation with illness' of a tensioning construction machine is also avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of tensioning construction, and particularly relates to a health diagnosis method and system for tensioning construction tools based on online monitoring. Background Art

[0002] In the prestressed engineering field, there are mandatory requirements for quality acceptance and construction quality process control. At present, the quality acceptance of prestressed projects still adopts the method of sampling inspection. By determining the sampling rules in advance, the inspectors carry out sampling inspections according to the on-site preparation situation, which basically loses the meaning of randomness and there are basically no unqualified reports, so the value significance is very limited. Therefore, the quality of prestressed projects highly depends on the operating conditions of tensioning construction tools (such as tensioning jacks).

[0003] At present, there are no specific means and methods for the health supervision of tensioning construction tools. It is very difficult to even detect when the tool fails, let alone analyze the failure and point out the cause. Generally, the failures of tensioning construction tools can be divided into two categories. One category is that the tool cannot operate, and the power system of the tool cannot work. Personnel can judge by whether there is displacement of the jack piston. The other category is that the tool can operate, but there are deviations in construction quality, etc. The jack piston has displacement, but the applied load and elongation are inaccurate. On-site, only the elongation value of the jack piston rod can be measured to roughly judge. This method can only roughly understand the quality situation through simple measurement. When quality problems occur, the cause cannot be clarified, and the health status of the construction tool cannot be locked.

[0004] For the quality of prestressed projects, if intelligent tensioning construction tools are used and equipment failures and failures are not diagnosed in time, it will cause large-scale disasters. For tensioning construction tools, the method of personnel supervising the tool status is inefficient. It can only simply judge whether it can work normally and cannot judge the health status based on the behavior data during the operation of the tensioning tool. Even if personnel master the failure of the tensioning tool through auxiliary means, it is very difficult to analyze the cause and repair it in time.

[0005] Related patents provide technical implementation methods in some aspects, but they are not comprehensive and systematic enough for the health diagnosis of prestressed tensioning construction tools. For example, CN117608274A discloses a fault diagnosis method, system, device, and medium for construction machinery, which is used to solve the problems of classifying and grading faults of construction machinery parts and providing the priority for solving problems. However, it is not very targeted for prestressed tensioning construction tools with a high degree of specialization. Another example is that CN113700700A discloses a displacement measuring device and measuring and calculating method for a prestressed jack piston rod using the measured oil inlet flow of the jack, which is used to solve the measurement of the jack piston rod displacement and convert it to the control of prestressed construction quality, and does not involve the supervision of the status and health of tensioning construction tools. Summary of the invention

[0006] The present invention aims to solve the technical problems existing in the prior art. The first object of the present invention is to provide a health diagnosis method for tensioning construction machinery based on online monitoring. The second object of the present invention is to provide a health diagnosis system for tensioning construction machinery based on online monitoring.

[0007] In order to achieve the above-mentioned first purpose, the present invention adopts the following technical scheme: a health diagnosis method for tensioning construction equipment based on online monitoring, wherein the tensioning construction equipment is a tensioning jack, and the oil inlet of the tensioning jack is connected to the hydraulic pump station through an oil inlet line, and an engineering Internet of Things terminal with a flow meter is provided on the oil inlet line, and the engineering Internet of Things terminal is connected to the data server through a data transmission module, and the data server is connected to the application server and the cloud platform, and the application server and the cloud platform display the operating status of the tensioning jack, so as to realize the monitoring of the operating status of the tensioning jack; during the working process of the tensioning jack, the stroke displacement of the piston rod of the tensioning jack and whether the tensioning system composed of the tensioning jack and the hydraulic pump station exists are monitored. Oil leakage, whether the tensioning jack pump head has abnormal oil absorption, analyze and judge the health condition of the tensioning jack, the specific methods are as follows: Piston rod stroke displacement monitoring: through the value of the flow meter, obtain the stroke displacement of the tensioning jack piston rod, when the stroke displacement of the piston rod reaches the high stroke threshold, issue an early warning to protect the tensioning jack and achieve healthy stress; whether there is oil leakage in the tensioning system: according to the difference between the process flow volume of the tensioning jack and the return flow volume of the tensioning jack, judge whether the tensioning system has oil leakage; whether the tensioning jack pump head has abnormal oil absorption: when the tensioning jack pump head is equipped with n oil nozzles, judge whether the pump head has abnormal oil absorption and the number of damaged oil nozzles according to the proportion of the actual flow of the oil inlet circuit in the theoretical flow.

[0008] The above technical solution integrates the engineering Internet of Things terminal into the tensioning construction machinery and realizes automated online monitoring of the operating status of the tensioning construction machinery and automatic diagnosis of tensioning construction machinery failures. It solves specific problems such as the difficulty, time and efficiency of troubleshooting during manual maintenance, and avoids large-scale catastrophic engineering problems caused by the "sick operation" of the tensioning construction machinery.

[0009] In a preferred embodiment of the present invention, the stroke displacement of the piston rod is monitored in the following manner: L=V / A, wherein L is the stroke displacement of the piston rod, V is the flow rate of the oil inlet circuit, and A is the nominal cross-sectional area of ​​the piston rod.

[0010] The above technical solution is based on the flow data collected by the engineering Internet of Things terminal, and uses the flow of the oil inlet circuit and the cross-sectional area of ​​the piston rod to calculate the stroke of the tensioning jack. When it exceeds a certain safety threshold, a protection mechanism is set to issue a safety warning.

[0011] In a preferred embodiment of the present invention, the determination of whether there is oil leakage in the tensioning system is carried out in the following manner: V + -V - > 0 indicates that there is oil leakage in the tensioning system, and vice versa indicates that there is no oil leakage in the tensioning system. Among them, V + is the volume of the process flow rate of the tensioning jack, and V - is the volume of the return flow rate of the tensioning jack.

[0012] Based on the flow data collected by the engineering Internet of Things terminal, the above technical solution uses the measured difference in the oil inlet and return oil flow rates to diagnose whether there is oil leakage and whether the tensioning system is not airtight during the construction process.

[0013] In a preferred embodiment of the present invention, the determination of whether the pump head of the tensioning jack has abnormal oil suction is carried out in the following manner: the actual flow rate of the oil inlet circuit is V, and the theoretical flow rate of the oil inlet circuit is Vn. V = Vn indicates normal oil suction, and V < Vn indicates abnormal oil suction; if the oil suction is abnormal, then determine the value that is closest to the value, then there are nozzles damaged and not sucking oil, = 1, 2,..., n, where n is the number of nozzles.

[0014] Based on the flow data collected by the engineering Internet of Things terminal, the above technical solution uses the oil inlet flow rate to determine the oil suction capacity of the plunger pump, diagnoses the normal or abnormal conditions of the pump head, and can also specifically diagnose the number of damaged nozzles.

[0015] In a preferred embodiment of the present invention, the following method is used to determine whether the piston rod of the tensioning jack is in the extending process or the retracting return stroke: Tensioning jack process judgment: The flow meter works in the forward direction, the test data is a natural number, and the marked direction is "+"; Tensioning jack return stroke judgment: The flow meter works in the reverse direction, and the test data is a natural number, and the marked direction is "-".

[0016] Based on the above technical solution, it is simple and fast to judge whether the tensioning jack is in the process or the return stroke by the direction of the flow meter.

[0017] In a preferred embodiment of the present invention, when there are various specifications of tensioning jacks at the construction site, each tensioning jack is numbered. According to the specifications of each tensioning jack, the oil supply per unit time of the oil inlet circuit of the tensioning jack with the corresponding specification is stored. When the tensioning jack works, it is judged whether the specifications of the tensioning jack match by the stored oil supply per unit time. When they do not match, an alarm is issued.

[0018] In the above technical solution, by storing the oil supply per unit time (i.e., the oil inlet flow rate) of the oil inlet circuit of the tensioning jack, the oil inlet flow rate conditions of each tensioning jack supporting the construction site are memorized. When there is a difference in the oil inlet flow rate after replacing the tensioning jack, it is determined that the tensioning jacks do not match, and an alarm is issued to avoid the situation of cross-using tensioning jacks, which is also conducive to the use management of tensioning jacks at the construction site.

[0019] To achieve the second above-mentioned object, the present invention adopts the following technical solution: a health diagnosis system for tensioning construction machinery based on online monitoring, an engineering Internet of Things terminal with a flow meter installed on the oil inlet circuit of the tensioning construction machinery, the engineering Internet of Things terminal is connected to a data server through a data transmission module, the data server is connected to an application server and a cloud platform, and the operating status of the tensioning jack is displayed by the application server and the cloud platform; the engineering Internet of Things terminal or the data server uses the diagnosis method described in the present invention to detect the health of the tensioning construction machinery.

[0020] In another preferred embodiment of the present invention, the engineering Internet of Things terminal includes a flow meter, a data memory, a controller, a power supply system, and a mechanical housing. The signal output end of the flow meter is connected to the controller, the controller is connected to the data memory, the output end of the data memory is connected to the data transmission module, the flow meter, the data memory, the controller, and the power supply system are integrated in the mechanical housing, and the power supply system supplies power to the flow meter, the data memory, and the controller.

[0021] In the above technical solution, the flow meter, the data memory, the controller, and the power supply system are integrated in the mechanical housing to form an engineering Internet of Things terminal, which is convenient for the overall installation of the engineering Internet of Things terminal on the oil inlet circuit, easy to install, and the engineering Internet of Things terminal has universality and strong versatility.

[0022] In another preferred embodiment of the present invention, the flow meter adopts a vector flow meter, which is used to measure the volume and direction of the hydraulic oil of the tensioning jack.

[0023] In the above technical solution, a high-precision vector flow meter is used to measure the oil inlet flow rate and the oil return flow rate of the tensioning system, and the direction of the movement of the hydraulic oil is identified and marked, so as to facilitate judging whether the piston rod extends or retracts.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and easy to understand from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 is a principle block diagram of the diagnosis system of the tensioning construction machinery of the embodiment.

[0026] Figure 2 It is a schematic diagram of the health diagnosis result of the tensioning construction machine tool. Specific implementation manners

[0027] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0028] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "vertical", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0029] In the description of the present invention, unless otherwise specified and defined, it should be noted that the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the communication inside two elements. It can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific situations. Embodiment 1

[0030] This embodiment provides a method for health diagnosis of a tensioning construction machine tool based on online monitoring. As Figure 1 shown, in the present invention, the tensioning construction machine tool is a tensioning jack. The oil inlet of the tensioning jack is connected to the hydraulic pump station through an oil inlet oil circuit, which is prior art and will not be elaborated here. An engineering Internet of Things terminal with a flowmeter (the flowmeter adopts a vector flowmeter for measuring the volume and direction of the hydraulic oil of the tensioning jack) is provided on the oil inlet oil circuit for online monitoring of the operation data of the tensioning jack; the engineering Internet of Things terminal is connected to the data server through a data transmission module. For example, a data transmission module including but not limited to a 5G network is installed on the engineering Internet of Things terminal for wireless transmission, so as to achieve the collection and transmission of the hydraulic oil flow data on the oil inlet oil circuit during the tensioning construction process. The data server is used for storing and managing data and providing database services; the data server is connected to the application server and the cloud platform. The application server and the cloud platform are used for running and managing business application programs, providing various business functions and services, and displaying the operation status of the tensioning jack by the application server and the cloud platform, so as to realize the monitoring of the operation status of the tensioning jack.

[0031] During the operation of the tensioning jack, monitor the stroke displacement of the piston rod of the tensioning jack, whether there is oil leakage in the tensioning system composed of the tensioning jack and the hydraulic pump station, and whether the pump head of the tensioning jack has abnormal oil suction. The flow data collected by the engineering Internet of Things terminal is transmitted to the data server through the data transmission module. The application server and the cloud platform call the data received by the data server, and diagnose the health status of the tensioning jack through algorithms. The specific method is as follows: Monitoring of the stroke displacement of the piston rod: L = V / A, where L is the stroke displacement of the piston rod, V is the flow rate of the oil inlet circuit (volume flow rate), and A is the nominal cross-sectional area of the piston rod. In the present invention, the stroke displacement of the piston rod of the tensioning jack is obtained through the value of the flow meter. When the stroke displacement of the piston rod reaches the high stroke threshold (such as 195 mm), a warning is given to protect the tensioning jack and achieve healthy stress.

[0032] Whether there is oil leakage in the tensioning system: V + -V - > 0 indicates that there is oil leakage in the tensioning system, otherwise it indicates that the tensioning system does not leak oil. Among them, V + is the volume of the process flow of the tensioning jack, and V - is the volume of the return flow of the tensioning jack. In the present invention, according to the difference between the volume of the process flow of the tensioning jack and the volume of the return flow of the tensioning jack, it is diagnosed whether there is oil leakage and whether the tensioning system is not airtight during the construction process.

[0033] Whether the pump head of the tensioning jack has abnormal oil suction: When the pump head of the tensioning jack is configured with n oil nozzles, the actual flow rate of the oil inlet circuit is V (measured by the flow meter of the engineering Internet of Things terminal), and the theoretical flow rate of the oil inlet circuit is Vn (the main destination of the flow rate of the oil inlet circuit is the cylinder of the tensioning jack. According to the product of the extended length of the piston rod and the nominal cross-sectional area of the piston rod, the theoretical flow rate is calculated as Vn. Among them, the extended length of the piston rod can be obtained through the detection unit that measures the elongation of the prestressed steel strand during the construction process or by setting a distance sensor to measure, and the extended length of the piston rod is equal to the elongation of the prestressed steel strand). V = Vn indicates normal oil suction, and V < Vn indicates abnormal oil suction; if the oil suction is abnormal, then determine the one closest to the value of value, then there are oil nozzles damaged and not sucking oil, = 1, 2,..., n, where n is the number of oil nozzles. For example = then there is 1 oil nozzle damaged and not sucking oil, = When the oil inlet is too large, two oil nozzles are damaged and cannot absorb oil, and so on. The present invention determines whether the pump head has abnormal oil absorption and the number of damaged oil nozzles according to the proportion of the actual flow rate of the oil inlet oil circuit to the theoretical flow rate.

[0034] In the present invention, whether the tensioning jack piston rod is in the extension process or the retraction return process is judged according to the following method: tensioning jack process judgment: the flow meter works in the forward direction, the test data is a natural number, and the marking direction is "+"; tensioning jack return judgment: the flow meter works in the reverse direction, the test data is a natural number, and the marking direction is "-".

[0035] like Figure 2 As shown, in another preferred embodiment of the present invention, a label is also provided in the data server corresponding to each fault, and the label corresponds to the fault one by one, so as to facilitate the subsequent analysis and investigation of the cause of the tensioning construction equipment failure and maintenance.

[0036] In actual application, for a construction site equipped with multiple tensioning construction machines (or a hydraulic pump station equipped with multiple tensioning construction machines), an engineering Internet of Things terminal is installed on the oil inlet line of each tensioning construction machine. All engineering Internet of Things terminals are connected to the data server through a data transmission module, and the operating status of multiple tensioning construction machines is monitored through the application server and the cloud platform.

[0037] Preferably, the application server and the cloud platform have a memory function to memorize the oil inlet flow conditions of all tensioning jacks. When there are multiple tensioning jacks of different specifications at the construction site, the tensioning jacks at each location are numbered, and the oil supply per unit time of the oil inlet circuit of the tensioning jack of the corresponding specification is stored according to the specifications of the tensioning jacks at each location (that is, the oil inlet flow of the tensioning jack at that location is stored). When the tensioning jack is working, the actual oil inlet flow of the tensioning jack is compared with the stored oil supply per unit time to determine whether the specifications of the tensioning jack match. If they do not match, an alarm is issued (for example, a sound alarm is issued to alarm the number of the tensioning jack that does not match) to avoid cross-use of tensioning jacks. Embodiment 2

[0038] This embodiment provides a health diagnosis system for tensioning construction equipment based on online monitoring, which uses the diagnosis method of the first embodiment for detection. Figure 1 As shown, the diagnostic system includes an engineering Internet of Things terminal installed on the oil inlet line of the tensioning construction equipment. The engineering Internet of Things terminal is connected to the data server through a data transmission module. The data server is connected to the application server and the cloud platform. The application server and the cloud platform display the operating status of the tensioning jack. The engineering Internet of Things terminal or the data server uses the diagnostic method of the present invention to detect the health of the tensioning construction equipment.

[0039] Among them, the engineering Internet of Things terminal includes a flowmeter, a data memory, a controller, a power supply system, and a mechanical housing. The flowmeter adopts a high-precision vector flowmeter, which is used to measure the volume and direction of the hydraulic oil of the tensioning jack. The signal output end of the flowmeter is connected to the controller, the controller is connected to the data memory, and the output end of the data memory is connected to the data transmission module. The flowmeter, data memory, controller, and power supply system are integrated in the mechanical housing, and the power supply system supplies power to the flowmeter, data memory, and controller. Preferably, the data transmission module is also integrated in the mechanical housing and powered by the power supply system.

[0040] In the description of this specification, the description with reference to terms such as "preferred embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0041] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A health diagnosis method for tensioning construction machinery based on online monitoring, characterized in that: The tensioning construction machine is a tensioning jack, the oil inlet of the tensioning jack is connected to the hydraulic pump station through an oil inlet line, an engineering Internet of Things terminal with a flow meter is provided on the oil inlet line, the engineering Internet of Things terminal is connected to a data server through a data transmission module, the data server is connected to an application server and a cloud platform, and the application server and the cloud platform display the operating status of the tensioning jack, so as to realize the monitoring of the operating status of the tensioning jack; During the working process of the tensioning jack, monitor the travel displacement of the piston rod of the tensioning jack, whether there is oil leakage in the tensioning system composed of the tensioning jack and the hydraulic pump station, whether the tensioning jack pump head has abnormal oil absorption, and analyze and judge the health of the tensioning jack. The specific methods are as follows: Piston rod travel displacement monitoring: The travel displacement of the tension jack piston rod is obtained through the value of the flow meter. When the travel displacement of the piston rod reaches the high travel threshold, an early warning is issued to protect the tension jack and achieve healthy force. Whether there is oil leakage in the tensioning system: judge whether there is oil leakage in the tensioning system according to the difference between the process flow volume of the tensioning jack and the return flow volume of the tensioning jack; Whether the tensioning jack pump head has abnormal oil absorption: When the tensioning jack pump head is equipped with n oil nozzles, judge whether the pump head has abnormal oil absorption and the number of damaged oil nozzles based on the proportion of the actual flow rate of the oil inlet line to the theoretical flow rate.

2. The method for health diagnosis of tensioning construction equipment based on online monitoring according to claim 1 is characterized in that: The piston rod travel displacement monitoring adopts the following method: L=V / A, where L is the stroke displacement of the piston rod, V is the flow rate of the oil inlet circuit, and A is the nominal cross-sectional area of ​​the piston rod.

3. The method for health diagnosis of tensioning construction equipment based on online monitoring according to claim 1 is characterized in that: Whether the tensioning system has oil leakage is determined in the following manner: V + -V - >0, indicating that there is oil leakage in the tensioning system, otherwise it means that there is no oil leakage in the tensioning system. + is the flow volume of the tensioning jack process, V - is the return flow volume of the tensioning jack.

4. The method for health diagnosis of tensioning construction equipment based on online monitoring according to claim 1 is characterized in that: Whether the tensioning jack pump head absorbs oil abnormally is determined in the following manner: The actual flow rate of the oil inlet circuit is V, and the theoretical flow rate of the oil inlet circuit is Vn. V=Vn indicates normal oil suction, and V<Vn indicates abnormal oil suction. If the oil absorption is abnormal, confirm The value closest to The value of The oil nozzle is damaged and does not absorb oil. =1, 2, ..., n, where n is the number of nozzles.

5. The method for health diagnosis of tensioning construction equipment based on online monitoring according to claim 1 is characterized in that: Determine whether the piston rod of the tensioning jack is in the process of extending or retracting according to the following methods: Tension jack process judgment: the flow meter works in the forward direction, the test data is a natural number, and the marking direction is "+"; Judgment of the return stroke of the tensioning jack: the flow meter works in the reverse direction, the test data is a natural number, and the marking direction is "-".

6. The method for health diagnosis of tensioning construction equipment based on online monitoring according to any one of claims 1 to 5, characterized in that: When there are multiple tensioning jacks of different specifications at the construction site, each tensioning jack is numbered, and the oil supply per unit time of the oil inlet circuit of the tensioning jack of the corresponding specification is stored according to the specifications of each tensioning jack. When the tensioning jack is working, it is judged whether the specifications of the tensioning jack match by the stored oil supply per unit time. If not, an alarm is issued.

7. The health diagnosis system of tensioning construction machinery based on online monitoring is characterized by: It includes an engineering Internet of Things terminal with a flow meter installed on the oil inlet line of the tensioning construction machine, the engineering Internet of Things terminal is connected to the data server through a data transmission module, the data server is connected to the application server and the cloud platform, and the application server and the cloud platform display the operating status of the tensioning jack; The engineering Internet of Things terminal or data server uses the diagnostic method described in any one of claims 1-6 to detect the health of the tensioning construction machinery.

8. The health diagnosis system for tensioning construction equipment based on online monitoring according to claim 7 is characterized in that: The engineering Internet of Things terminal includes a flow meter, a data storage device, a controller, a power supply system and a mechanical housing. The signal output end of the flow meter is connected to the controller, the controller is connected to the data storage device, the output end of the data storage device is connected to the data transmission module, the flow meter, the data storage device, the controller and the power supply system are integrated in the mechanical housing, and the power supply system supplies power to the flow meter, the data storage device and the controller.

9. The tensioning construction machine health diagnosis system based on online monitoring according to claim 8 is characterized in that: The flow meter is a vector flow meter, which is used to measure the volume and direction of the hydraulic oil of the tensioning jack.

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