crack meters
Kingmach crack meters include the JMDL-21XXAT Smart General-Purpose Displacement Meter, a compact instrument for relative displacement and expansion joint movement. The product is used in buildings, railways, transportation works, hydropower structures, dams, and bridge projects where two structural components may move against one another. Listed ranges include 50 mm and 100 mm, with 0.01 mm resolution and 0.5%FS accuracy. The meter is based on inductive frequency modulation, which supports high sensitivity, stable long-term observation, and low temperature influence. A built-in memory chip stores sensor model, serial number, calibration coefficient, time, temperature data for temperature versions, absolute displacement, relative displacement, and zero-point value. It can save 800 measurement results, which is useful when checking site history after construction stages or weather events. When connected to an integrated tester or automatic acquisition system, readings can be reviewed quickly without relying on manual gauge notes. 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 meters
In industrial automation and equipment monitoring, crack meters are used for hydraulic cylinder stroke, machine tool positioning, gate movement, construction machinery displacement, and linear motion control. The site pain point is different from civil monitoring: readings must often be fast, absolute, repeatable, and resistant to wiring mistakes or mechanical wear. Kingmach JMCW-21XXADT magnetostrictive meters provide non-contact absolute displacement measurement over 0 to 1000 mm, 0.01 mm resolution, plus or minus 0.05%FS accuracy, RS485 communication, IP67 protection, average current below 60 mA, and reverse polarity protection up to -36V. For equipment with cable travel, JMLS-22XXADT wire rope sensors provide 500 mm, 1000 mm, and 2000 mm ranges with 0.2%FS accuracy and compact dimensions of 115 mm by 85 mm by 100 mm. These products help operators track position drift, stroke limits, gate opening, and machine movement in harsh workshops or outdoor installations. During operation, the monitoring team should keep the baseline, temperature, inspection notes, and nearby sensor behavior in the same review file. This makes it easier to tell whether a movement trend comes from normal service, a repair event, changing load, water influence, or developing structural risk. Clear records also help owners decide when a field inspection is needed instead of waiting for visible damage.

The future of crack meters
Future crack meters 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 meters
For long-term crack meters, maintenance should focus on trend credibility rather than only sensor survival. Review baseline drift, sudden jumps, flat lines, missing data, temperature influence, and disagreement between nearby points. A flat line may mean no movement, but it may also mean a stuck cable, broken rod, frozen channel, or communication failure. A sudden jump may be real deformation, but it may also follow bracket impact, cabinet work, lightning, or power cycling. Kingmach products with stored measurement records, calibration coefficients, zero values, and digital communication help with diagnosis, but field notes remain important. Inspect waterproof seals, cable glands, brackets, anchor heads, cabinets, grounding, and channel labels at planned intervals. Keep displacement data linked with photos, inspection comments, rainfall, water level, construction events, and nearby sensor readings so engineers can trust the long-term movement history. 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 meters
crack meters give field teams a direct way to watch components that are hard to judge by sight. A formwork pipe may shift during pouring, a rock layer may slide behind the excavation face, a geogrid may deform inside reinforced soil, and a dam joint may open after water level change. Kingmach's product range includes non-contact designs where the measuring rod and coil work independently, reducing mechanical wear and installation damage. The JMDL-24XXAT flexible displacement meter uses a bendable measuring rod for geogrid monitoring, with 30 mm and 50 mm ranges, 0.01 mm sensitivity, and 0.5%FS accuracy. The JMDL-49XXAT formwork meter offers 50 mm, 100 mm, and 200 mm ranges, IP68 protection, and temperature measurement accuracy of plus or minus 0.5 degrees Celsius. These details are useful when displacement monitoring must continue through wet, crowded, and fast-moving construction stages. 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 meters are used for rock layers or bedrock?
A: JMDL-31XXAT multipoint meters are used for different surrounding rock layers, while JMDL-32XXAT single-point bedrock meters are used for tunnel rock mass, dam bedrock, slope, or foundation pit movement.
Q: How many points can the multipoint meter support?
A: The multipoint installation kit supports three to five monitoring points, with anchor heads fixed at different depths by drilling and grouting.
Q: What ranges are listed for these models?
A: Both JMDL-31XXAT and JMDL-32XXAT list 50 mm, 100 mm, and 200 mm models with 0.01 mm resolution.
Q: Why monitor several depths?
A: Different layers may move differently. Separating shallow and deep movement helps engineers judge whether the problem is surface creep, deeper rock slip, or overall mass movement.
Q: What records should be kept?
A: Keep drilling depth, anchor location, grouting date, channel name, zero value, cable route, and first stable reading.
Reviews
Daniel Brown
Excellent environmental monitoring sensors. The data is consistent, and the system integrates smoothly with our existing setup.
James Thompson
The tiltmeters and accelerometers are very sensitive and provide precise data. Perfect for our structural health monitoring system.
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