{"id":8384,"date":"2026-09-07T23:50:27","date_gmt":"2026-09-08T07:50:27","guid":{"rendered":"https:\/\/szlmi.com\/?p=8384"},"modified":"2026-09-08T00:16:01","modified_gmt":"2026-09-08T08:16:01","slug":"how-to-choose-a-load-moment-indicator-for-your-machine","status":"publish","type":"post","link":"https:\/\/szlmi.com\/ar\/how-to-choose-a-load-moment-indicator-for-your-machine\/","title":{"rendered":"How to Choose a Load Moment Indicator for Your Machine"},"content":{"rendered":"

If you are weighing how to choose a load moment indicator (LMI)<\/a> for a crane, excavator or wheel loader, this guide walks the decision the way our field engineers do \u2014 machine first, catalog second. The regulation requires one, the insurance policy mentions one, and the supplier’s quotation lists three different models at three different prices. What buyers discover too late is that an LMI is not an accessory you pick from a catalog page. It is a measuring system engineered around a specific machine \u2014 buy the wrong one and you get a display that lights up, alarms that fire at the wrong moments, and an operator who learns to ignore both.<\/p>\n

This guide is the checklist we use internally when matching a system to a customer’s machine \u2014 truck cranes, crawler cranes, excavators, loaders and the less common frames in between. It covers what to answer before comparing prices, how to read a spec sheet, and the calibration step that decides whether the system gets used or quietly switched off.<\/p>\n

What a load moment indicator actually does<\/h2>\n

An LMI does not weigh the load directly. It measures the\u00a0geometry<\/i>\u00a0and the\u00a0hydraulic effort<\/i>\u00a0of each lift \u2014 boom angle, boom length, cylinder pressure \u2014 calculates the moment in real time, and compares it against the rated capacity chart stored in the controller. Approaching the limit, it warns the operator. Crossing it, it cuts the dangerous movements through a relay.<\/p>\n

If you are deciding between an indicator and a cutoff-only device, start with\u00a0the difference between an LMI and a load limiter<\/a>\u00a0\u2014 the rest of this guide assumes you want the full monitoring chain. Our\u00a0crane-by-crane LMI hub<\/a>\u00a0keeps the complete machine list in one place.<\/p>\n

Step 1 \u2014 Start with your machine, not with the catalog<\/h2>\n

The most common buying mistake is choosing by one number: rated capacity. Two 25-ton cranes can need completely different sensing chains. What the system must\u00a0watch<\/i>\u00a0is decided by the machine’s structure, not by its badge.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Machine<\/th>\nWhat the system must monitor<\/th>\nTypical range<\/th>\nReference system<\/th>\n<\/tr>\n
Truck crane \/ rough-terrain crane<\/td>\nBoom length, luffing angle, hoof pressure<\/td>\n10\u2013100 t<\/td>\nSZ-M100<\/a> mobile<\/a> cra<\/a>ne<\/a> LMI<\/a><\/td>\n<\/tr>\n
\u0631\u0627\u0641\u0639\u0629 \u0645\u062c\u0646\u0632\u0631\u0629<\/td>\nSame chain, larger range, crawler-specific charts<\/td>\nup to 260 t<\/td>\nCrawler crane LMI<\/a><\/td>\n<\/tr>\n
Spider \/ mini crawler crane<\/td>\nOutrigger posture + multi-configuration moment<\/td>\n0.8\u201320 t<\/td>\nSZ-SC01 spider crane LMI<\/a><\/td>\n<\/tr>\n
Marine & ship crane<\/td>\nMoment under pitch and roll, marine sealing<\/td>\nvaries<\/td>\nShip crane LMI<\/a><\/td>\n<\/tr>\n
Excavator<\/td>\nBoom \/ arm \/ bucket cylinder pressures<\/td>\n10\u2013100 t<\/td>\n\u0645\u0624\u0634\u0631 \u062d\u0645\u0648\u0644\u0629 \u0627\u0644\u062d\u0641\u0627\u0631<\/td>\n<\/tr>\n
Wheel loader<\/td>\nLift cylinder pressure + trigger position on the arm<\/td>\n1\u201320 t<\/td>\nthird-generation wheel loader scale<\/a><\/td>\n<\/tr>\n
Forklift \/ telehandler<\/td>\nMast load, stability moment at height<\/td>\n2\u201325 t<\/td>\nTelehandler LMI<\/a><\/td>\n<\/tr>\n
Reachstacker<\/td>\nBoom moment at eccentric load centers<\/td>\n10\u201345 t<\/td>\nReachstacker load indicator<\/a><\/td>\n<\/tr>\n
Side boom pipelayer<\/td>\nBoom moment with offset CG loads<\/td>\nup to 90 t<\/td>\nSide boom load indicator<\/a><\/td>\n<\/tr>\n
Material handler<\/td>\nContinuous-duty moment under cycling loads<\/td>\n10\u201350 t<\/td>\nMaterial handler load indicator<\/a><\/td>\n<\/tr>\n
Articulated boom crane<\/td>\nKnuckle angle compensation<\/td>\n3\u201350 t<\/td>\nArticulated boom LMI<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

A spider crane working indoors illustrates why this matters. Its rated capacity changes with every outrigger extension, so the LMI must sense\u00a0support posture<\/i>, not just boom geometry \u2014 a truck-crane unit without outrigger inputs cannot protect this machine no matter what the box claims.<\/p>\n

If you run a\u00a0mixed<\/i>\u00a0fleet, resist the temptation to buy one model for everything. A wider range with configurable capacity charts is cheaper than three mismatched systems \u2014 but only if the sensing chain still matches each frame. Ask the supplier to quote per machine type and to show the sensing diagram for every unit, not just the first one.<\/p>\n

Step 2 \u2014 Follow the sensing chain, Every load moment indicator is only as good as its weakest sensor, so walk the chain in order.<\/h2>\n

Every LMI is only as good as its three sensing points. This is where low-cost systems cut corners, and where failures start.<\/p>\n

\"SeeZol<\/a>
SeeZol dual-output angle sensor used in a load moment indicator sensing chain<\/figcaption><\/figure>\n

\u0627\u0644\u00a0\u0645\u0633\u062a\u0634\u0639\u0631 \u0632\u0627\u0648\u064a\u0629<\/a>\u00a0sits on the boom pivot and reports luffing angle; a dual-axis unit also catches side tilt, which matters on crawler and spider frames. The\u00a0hydraulic pressure sensors (0\u201340 MPa, 4\u201320 mA, 0.5% FS)<\/a>\u00a0convert cylinder pressure into load \u2014 accuracy here is the ceiling for the whole system’s accuracy. A length or\u00a0trigger sensor<\/a>\u00a0closes the chain on telescopic booms and loader arms.<\/p>\n

\"SeeZol<\/a>
SeeZol 40 MPa hydraulic pressure sensors used in used in a load moment indicator systems<\/figcaption><\/figure>\n

Three environment numbers separate an industrial sensor from a showroom one:\u00a0IP65 sealing<\/b>\u00a0against dust and washdown, a\u00a0\u221220 \u00b0C to +70 \u00b0C<\/b>\u00a0window for winter pipeline work and summer decks, and EMC-hardened cabling that survives engine-bay interference. Ask for these three numbers before anything else.<\/p>\n

Step 3 \u2014 Read the spec sheet like an engineer<\/h2>\n

Spec sheets list the same line items in a different order. Here is a real one \u2014 our SZ-M100 mobile crane system \u2014 with the questions each line should trigger.<\/p>\n\n\n\n\n\n\n\n\n\n\n
Spec line<\/th>\n\u0627\u0644\u0642\u064a\u0645\u0629<\/th>\nWhat to check against your machine<\/th>\n<\/tr>\n
\u0627\u0644\u0646\u0637\u0627\u0642<\/td>\n5\u2013260 t<\/td>\nCover your max capacity\u00a0\u0648<\/i>\u00a0the smallest lift you still want displayed \u2014 one range rarely fits a mixed fleet<\/td>\n<\/tr>\n
System error<\/td>\n\u00b13%<\/td>\nAt 100 t that is \u00b13 t. Is that acceptable for your lift plans and site rules?<\/td>\n<\/tr>\n
Display error<\/td>\n\u00b15%<\/td>\nWhat the operator sees vs what the controller computed \u2014 matters for trainees<\/td>\n<\/tr>\n
\u0627\u0644\u062d\u0645\u0627\u064a\u0629<\/td>\nIP65<\/td>\nEnough for washdown and dust; port and marine work should ask for higher<\/td>\n<\/tr>\n
\u062f\u0631\u062c\u0629 \u062d\u0631\u0627\u0631\u0629<\/td>\n\u221220\u2026+70 \u00b0C<\/td>\nWinter pipeline and desert quarry both sit inside; verify your extremes<\/td>\n<\/tr>\n
Supply voltage<\/td>\nDC 9\u201336 V<\/td>\nWide-input design tolerates cold-crank dips and 24 V truck electrics<\/td>\n<\/tr>\n
Relay output<\/td>\nAC220 V \/ 3 A<\/td>\nConfirm it can actually cut your crane’s motion circuit \u2014 ask for the wiring diagram<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Step 4 \u2014 Compliance and documentation<\/h2>\n

Regulators treat overload protection as mandatory equipment, not an option. ISO 10245 series for cranes, EN 13000 for mobile cranes and China’s GB\/T 12602 all describe what a load limiting device must detect and do. If your cranes cross borders \u2014 rental fleets, port contracts, EPC projects \u2014 the paperwork travels with the machine: a calibration certificate, the rated capacity chart used by the controller, and manuals in the operator’s language. Ask the supplier for all three at quotation stage, not after delivery.<\/p>\n

Step 5 \u2014 Installation and calibration decide whether it gets used<\/h2>\n

A correctly specified system can still fail in the field for one reason: nobody calibrated it. Installation places the sensors; calibration teaches the controller what “zero” and “known load” look like on\u00a0your<\/i>\u00a0machine.<\/p>\n

\"LoadSensor layout on an excavator: indicator, arm sensor, boom sensor, pressure sensor and vehicle body sensor positions<\/i><\/p>\n

Plan for a working day of sensor fitting and cabling, then a half day of calibration with known test weights across at least three points of the capacity chart. After a wire rope change, boom repair or seasonal temperature swing, re-check zero \u2014 an uncalibrated display trains operators to distrust the system, and that is how LMIs end up switched off.<\/p>\n

Calibration discipline is also what made our\u00a0Mongolia fleet rollout<\/a>\u00a0measurable: the customer’s XCMG wheel loader ran a 20-day field trial on our third-generation weighing system before committing to fleet-wide installation.<\/p>\n

What it costs \u2014 A properly specified load moment indicator costs a fraction of a single overload accident and what skipping it costs<\/h2>\n

We quote per machine rather than publishing a price list, because the sensing chain differs by frame. A better question for your budget: what does one incident cost? A tipped crane means a written-off machine, a stopped site, an investigation, and in the worst case injuries \u2014 costs that no LMI quotation will ever approach. Frame the purchase as insurance with a display, not as an accessory.<\/p>\n

Frequently asked questions<\/h2>\n

What is the difference between a load moment indicator and a load limiter?<\/h3>\n

An LMI continuously displays the measured moment against the rated capacity chart; a load limiter (SLI) focuses on intercepting dangerous movements at a set threshold. Most modern SeeZol controllers combine both.<\/p>\n

How accurate is a crane load moment indicator?<\/h3>\n

Typical figures are \u00b13% system error and \u00b15% display error of full scale \u2014 on a 100 t lift, \u00b13 t of system tolerance. Calibration quality with known test loads matters more than the datasheet number.<\/p>\n

Can one load moment indicator fit different crane models?<\/h3>\n

No. The sensing chain, capacity chart and alarm logic are engineered per machine family \u2014 a spider crane needs outrigger posture sensing; an excavator reads cylinder pressures instead of boom length.<\/p>\n

Does an LMI work in extreme temperatures?<\/h3>\n

Industrial systems are rated \u221220 \u00b0C to +70 \u00b0C with IP65 sealing \u2014 winter pipeline work and summer decks are covered. Below \u221220 \u00b0C, request a low-temperature display option.<\/p>\n

How long does installation and calibration take?<\/h3>\n

About one working day for sensors and cabling, plus half a day of calibration with known test weights. Uncalibrated installs are the main reason operators stop trusting the display.<\/p>\n

How often should a load moment indicator be recalibrated?<\/h3>\n

Re-check after any wire rope change, boom repair, structural modification or long-distance transport, and verify zero at least once a season. Fleets on multi-shift duty add a mid-year check.<\/p>\n

Is a load moment indicator the same as an on-board weighing system?<\/h3>\n

No. An LMI is a safety device \u2014 its job is comparing moment against the rated chart and cutting dangerous movements. A weighing system is a production tool \u2014 its job is measuring bucket and payload weights for trade and logistics. The sensing chains overlap, but accuracy targets, alarms and data outputs differ.<\/p>\n

Can the system record data for fleet management?<\/h3>\n

Yes. Current controllers store local history, and third-generation platforms such as the SZ-LD100P upload load data to a cloud dashboard for multi-site oversight.<\/p>\n

Five buying mistakes we see most<\/h2>\n

After years of retrofitting fleets, the same five mistakes keep showing up in failed installations. None of them are about price.<\/p>\n

    \n
  1. Buying by tonnage alone.<\/b>\u00a0A 25 t rough-terrain crane and a 25 t truck crane share a badge, not a sensing chain. Match the structure first.<\/li>\n
  2. Treating calibration as optional.<\/b>\u00a0The system arrives “pre-configured” and goes to work uncalibrated. Within a month the operator ignores it.<\/li>\n
  3. Skipping the environment numbers.<\/b>\u00a0A display rated for an office fails its first winter; pressure sensors without proper sealing drift after the first washdown.<\/li>\n
  4. Accepting a generic capacity chart.<\/b>\u00a0The controller must run the chart that matches your boom configuration and serial range, not “a similar model”. Ask which chart version ships with the unit.<\/li>\n
  5. Forgetting the spare-parts chain.<\/b> Sensors fail before controllers do. Before signing, ask the lead time and price for a replacement angle sensor and pressure sensor \u2014 if the answer is “we will check”, keep looking.<\/li>\n<\/ol>\n

    How to Choose a Load Moment Indicator: The 5-Point Checklist<\/h2>\n
      \n
    1. Machine first:<\/b>\u00a0match the sensing chain to your frame, not the tonnage badge.<\/li>\n
    2. Sensors:<\/b>\u00a0confirm IP65, \u221220\u2026+70 \u00b0C, EMC cabling \u2014 in writing.<\/li>\n
    3. Spec sheet:<\/b>\u00a0\u00b13% system error understood against your real lift plans.<\/li>\n
    4. \u0627\u0645\u062a\u062b\u0627\u0644:<\/b>\u00a0ISO 10245 \/ EN 13000 \/ GB\/T 12602 documents promised at quotation.<\/li>\n
    5. \u0627\u0644\u0645\u0639\u0627\u064a\u0631\u0629:<\/b> scheduled with test weights, and re-checked after rope or boom work.<\/li>\n<\/ol>\n

      Answer these five and the quotation comparison becomes straightforward. If you want a second opinion on your machine list,\u00a0send our engineering team<\/a> your crane models, capacities and working environment\u00a0\u2014 we will return a configuration proposal within one business day.
      \n