crack gauge
Kingmach crack gauge include the JMCW-21XXADT Magnetostrictive Displacement Meter for absolute linear position measurement. This sensor uses magnetostrictive effect and internal non-contact sensing, which avoids mechanical wear and supports continuous operation in harsh environments. Product information lists 0 to 1000 mm measuring range, 0.01 mm resolution, plus or minus 0.05%FS accuracy, repeatability within 0.1 mm, DC24V plus or minus 10% input, RS485 communication, average operating current below 60 mA, and an operating temperature range from -30 degrees Celsius to +80 degrees Celsius. It also lists IP67 protection and reverse polarity protection up to -36V. Wiring details include red for DC24V, yellow for power ground, blue for RS485A, and green for RS485B. These features make the product suitable for hydraulic cylinders, gate position, machine stroke, structural deformation, railway and highway movement, retaining walls, and industrial automation equipment that requires stable absolute position data. During project setup, the measuring point should be matched with the expected travel direction, available mounting space, cable route, and required acquisition interval. This prevents a short-range joint instrument from being used on a long-travel point, or an exposed sensor from being placed where an embedded anchor is needed. It also helps the monitoring team set a baseline that can be defended during acceptance and later maintenance review.

Application of crack gauge
In foundation pit and deep excavation projects, crack gauge are used to watch retaining walls, soldier piles, soil nails, nearby pavements, basement walls, and adjacent structures as excavation stages remove support from the ground. The main site concern is not only how far one point moves, but whether movement grows after each excavation layer, support installation, dewatering step, or backfill stage. Kingmach JMDL-32XXAT single-point bedrock meters can measure embedded displacement at a selected reference layer, while JMDL-22XXAT crack gauges follow opening at nearby structures or retaining elements. JMDL-52XXADT differential meters provide high-resolution relative movement at joints or structural interfaces, and JMLS-22XXADT wire rope sensors can cover longer exposed paths where access is available. A useful pit monitoring plan records excavation depth, support timing, groundwater level, construction vibration, and surrounding building observations beside each displacement curve. This helps engineers distinguish bracket disturbance from real ground movement, and it supports faster decisions when a wall, road edge, or adjacent building begins to respond to excavation. During review, the same point should be compared with nearby settlement, tilt, support force, groundwater, and inspection notes so the movement is interpreted as part of the excavation behavior rather than as a single isolated value. during maintenance.

The future of crack gauge
Future crack gauge will also become easier to install in cramped and irregular field locations. Many monitoring points are not clean laboratory setups; they are narrow tunnel headings, wet dam galleries, crowded bridge joints, temporary formwork frames, steep slopes, and machinery spaces with limited room for tools. Smaller housings, clearer mounting accessories, stronger cable exits, and simpler alignment checks will reduce installation errors. Kingmach already uses several physical formats, including crack gauges with measuring rods and bases, draw-wire sensors for longer travel, embedded bedrock assemblies, flexible geogrid meters, and non-contact magnetostrictive meters. Future product development can make these formats more modular, so engineers select the mounting kit, cable protection, connector type, and acquisition method together. That would shorten commissioning time and make later maintenance less dependent on the original installer. For projects with many measurement points, practical installation improvements can be as important as another decimal place of resolution, because a well-mounted sensor gives cleaner data from the beginning.

Care & Maintenance of crack gauge
For magnetostrictive crack gauge, maintenance should protect the non-contact sensing advantage by keeping wiring, power, and mounting clean. Kingmach JMCW-21XXADT lists DC24V input, RS485 communication, IP67 protection, reverse polarity protection up to -36V, and wiring colors for power and RS485 lines. Confirm red, yellow, blue, and green wires before energizing the device, and check grounding in cabinets where motors, pumps, or hydraulic equipment may create electrical noise. Because the sensor is used for absolute position measurement over 0 to 1000 mm, inspect mechanical alignment and travel stops so the moving part remains within range. Do not clamp the sensing body in a way that transfers bending force from the machine frame. During service, compare repeatability at known positions and review whether position drift appears after temperature swings, maintenance work, or hydraulic cylinder repair. Keep the installation photo, point number, zero value, and expected movement direction with the commissioning record for later review. If a reading changes after maintenance work, inspect the base, anchor, cable, and cabinet before assuming the structure itself has moved.
Kingmach crack gauge
crack gauge are used when a structure needs movement data that can be reviewed, compared, and acted on before deformation becomes visible. Kingmach covers short range crack movement, expansion joint travel, rock layer displacement, geogrid deformation, draw-wire movement, and long stroke position tracking. The category includes JMDL-21XXAT general-purpose displacement meters, JMDL-22XXAT crack gauges, JMDL-24XXAT flexible meters, JMDL-31XXAT multipoint meters, JMDL-32XXAT bedrock meters, JMDL-49XXAT formwork meters, JMDL-52XXADT differential meters, JMCW-21XXADT magnetostrictive meters, and JMLS-22XXADT wire rope sensors. On site, this means one product group can cover bridge joints, tunnel portals, slope movement, dam deformation, railway subgrade settlement, and industrial linear motion. The value is not only the displayed millimeter reading. It is the ability to connect movement, time, temperature, construction activity, and warning limits into one record. The point should be named on the drawing, linked with its cable route, and checked against the expected movement direction before the first automatic reading is accepted. For daily review, the reading should be compared with nearby points, recent weather, site operations, and any loading event that could explain the movement.
FAQ
Q: Which crack gauge fit crack monitoring?
A: The JMDL-22XXAT Smart Crack Gauge is designed for cracks, joints, and expansion joints in bridges, buildings, roads, railways, dams, tunnels, and slopes.
Q: What ranges does the crack gauge list?
A: Listed models include 20 mm, 50 mm, 100 mm, and 200 mm ranges, with 0.01 mm resolution on the 20 mm to 100 mm versions and 0.05 mm on the 200 mm version.
Q: How many records can the crack gauge store?
A: Product information states that it can save up to 600 measurement results, including time, temperature for temperature versions, displacement values, and zero-point value.
Q: What installation details matter most?
A: Base stability, rod alignment, connector sealing, cable protection, and a clear zero reading matter more than a polished-looking installation.
Q: Can it be used for long-term observation?
A: Yes. The product is described for long-term monitoring, especially where crack width changes need stable and repeatable measurement.
Reviews
Michael Anderson
The strain gauges and load cells are extremely accurate and stable. They performed very well in our bridge monitoring project. Highly recommended!
Andrew Lee
The visualization software is intuitive and powerful. It helps us analyze monitoring data efficiently.
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- Magnetostrictive Displacement Meter

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