The Measurements That Matter: What Load, Moment, Radius, Height, Slew, Wind and Tilt Tell a Crew

▌  APPLICATION NOTE  ·  OCTOBER 2026  ·  THE MEASUREMENTS THAT MATTER

The Measurements That Matter: What Load, Moment, Radius, Height, Slew, Wind and Tilt Tell a Crew

A modern tower crane can report a great many numbers, and a cab screen can display them all at once. That is not the same as giving the operator a better decision. The useful question is not how much the system can measure but which measurements change what a crew does. The ZNAO-TG2 tower crane safety monitoring system, product code CR-SMS-TG2, senses load weight, moment, trolley radius, hook height, slew angle, wind speed and tilt, and each of those seven values answers a different question on site.

This note takes them one at a time and explains, plainly, what each one tells a crew and what it does not. The point is not to memorise specifications but to understand which number to look at when something feels wrong, and why the seven are more useful together than any of them is alone. The stated accuracies are radius 0.1 m, height 0.1 m, slew 0.1 degrees, load 0.01 percent and wind 0.1 m/s.

01  LESS DATA, BETTER DECISIONS

It is tempting to treat a monitoring system as a dashboard that should show everything. In practice, a screen full of numbers that nobody reads is no better than a blank one. Value comes from knowing which of the seven quantities is relevant to the lift in front of you, and from having those quantities presented where they can be seen without stopping work.

The ZNAO-TG2 presents them on an 11.6-inch 1920x1080 sunlight-readable industrial display in the cab, which matters because the numbers are only useful while the crane is moving. An operator who has to look away, shade the screen or wait for a stable reading has already lost the benefit. Readability is not a luxury here; it is part of whether the measurement is used at all.

▌  SEVEN VALUES, SEVEN QUESTIONS  Each measurement answers a different question, and knowing which one to read is the real skill.

▌  PRESENTED WHILE MOVING  An 11.6-inch 1920x1080 sunlight-readable display keeps the values usable during the cycle.

▌  READABILITY IS FUNCTION  If the numbers cannot be read at a glance, the measurement is not doing its job.

02  LOAD AND MOMENT

Load is the weight on the hook, and it is the measurement everyone thinks of first. On its own, however, load is incomplete. The same load is easy at a short radius and severe at a long one, which is why the load chart is a curve rather than a single figure. Moment is what ties load and radius together into the quantity that actually loads the crane.

For a crew, load tells you what is on the hook and whether a component is heavier than expected. Moment tells you how hard the crane is working to hold it at that position. Watching both is how an operator learns to feel a lift: the moment climbs as the trolley runs out, even though the load has not changed, and the alarm that matters is often the one about moment rather than the one about weight.

▌  LOAD IS NOT ENOUGH  Weight alone does not describe the difficulty of a lift, which is why the load chart is a curve.

▌  MOMENT TIES THEM  Moment combines load and radius into the quantity that actually loads the crane structure.

▌  THE TROLLEY EFFECT  As the trolley runs out, the moment rises while the load stays the same; that is the shift a crew must watch.

▌  STATED RESOLUTION  Load is stated to 0.01 percent, fine enough to distinguish a lift near a limit from one well inside it.

03  RADIUS AND HEIGHT

Radius is the horizontal distance from the slewing centre to the hook, and it is the value that changes most during a normal cycle as the trolley travels. Height is the vertical position of the hook, and together they describe where the load is in space. Both are stated to 0.1 m on the ZNAO-TG2.

Radius matters because it sets the permissible load and because it decides whether the load will clear the structure it is being lifted over. Height matters because it decides whether the load will clear what is underneath, and because a hook raised higher than intended changes the geometry of the lift. For the signalman, radius and height are the two numbers that explain why an operator is moving the way they are.

▌  RADIUS SETS THE LIMIT  Radius determines the permissible load and whether the load clears the structure.

▌  HEIGHT SETS THE CLEARANCE  Hook height decides what the load passes over and under, and it changes the geometry of the lift.

▌  SHARED REFERENCE  Radius and height explain an operator's movements to the signalman and the supervisor.

▌  0.1 M RESOLUTION  Both are stated to 0.1 m, close enough to trust when placing a load with care.

04  SLEW, WIND AND TILT

Slew is the rotation of the crane, stated to 0.1 degrees, and it matters wherever a load travels around the mast or where a zone boundary has been drawn. Wind speed, stated to 0.1 m/s, matters because it is the value that changes fastest and the one most likely to be disputed, since wind at the cab can differ from wind at the load. Tilt, the lean of the structure, matters on a crane standing on ground that moves or on a foundation that is settling.

These three are the measurements of conditions rather than of the load. They are the ones a crew checks when a lift feels wrong without an obvious reason: the value that has changed is often wind or tilt rather than load. Because they are logged, they are also the values that explain a decision after the fact, when someone asks why a lift was paused or slowed.

▌  SLEW AND ZONES  Slew to 0.1 degrees matters where a load travels around the mast or a zone boundary applies.

▌  WIND CHANGES FIRST  Wind to 0.1 m/s is the fastest-changing value and the one most often argued about on site.

▌  TILT TELLS ON THE GROUND  Tilt points to movement and settlement beneath the crane, which the load values will not reveal.

▌  CONDITIONS ARE LOGGED  Because wind and tilt are logged, they explain after the fact why a lift was paused or slowed.

05  READING THE NUMBERS TOGETHER

The seven measurements are worth more together than apart. A rising moment with a steady load means the trolley is running out. A rising moment with a steady radius means something heavier is on the hook than expected. A wind alarm during a slow cycle means the pause is about conditions, not the load. Learning to read those combinations is how a crew turns a monitoring system from a display into a sense.

None of this replaces the load chart, the lift plan or the standards that apply in a market, such as ISO 12480-1, EN 14439, BS 7121, LOLER 1998 or OSHA 29 CFR 1926 Subpart CC. The measurements describe what the crane is doing; the rules describe what it is allowed to do. A competent crew uses the first to respect the second, and the habit of reading the numbers together is what makes that possible.

▌  COMBINATIONS TELL STORIES  Rising moment with steady load, or wind during a slow cycle, describe situations that a single value cannot.

▌  DISPLAY INTO SENSE  Reading the seven together is how a display becomes an operator's understanding of the crane.

▌  RULES STILL APPLY  The measurements describe what the crane is doing; the standards and the lift plan define what it may do.

PROCUREMENT IMPACT

●  Check the stated accuracy of each measurement, radius 0.1 m, height 0.1 m, slew 0.1 degrees, load 0.01 percent and wind 0.1 m/s, against the precision your lifts require.

●  Look at the display as a working tool, since an 11.6-inch 1920x1080 sunlight-readable screen decides whether the numbers are read while the crane moves.

●  Confirm which values are logged, because a measurement that is not recorded cannot support an inspection or a later review.

●  Consider tilt and wind carefully on sites with moving ground or exposed positions, where those values decide whether a lift goes ahead.

●  Ask how the system presents values at a glance, since a screen that requires study will be read after the lift rather than during it.

WHAT TO WATCH

●  Watch which values the crew actually refers to; the ones they ignore are the ones worth reviewing in the settings.

●  Watch moment during trolley travel, because that is where an ordinary cycle gets closest to a limit.

●  Watch wind across the day, since it often explains alarms that look like load problems at first.

●  Watch tilt on ground that has been disturbed, because settlement shows there before it shows anywhere else.

●  Watch the pairing of measurements with the load chart, and keep the display language and units familiar to the crew.

ABOUT  ZN Industrial (Shandong Zhinuo) designs and manufactures crane safety monitoring systems, positioning systems and mechanical auxiliary handling equipment for overseas construction, industrial and steel markets.

Standards and regulations vary by market — local rules still govern your site.

▌  CONTACT  shandongzhinuo@outlook.com  +86 176 6371 0314 · en.znaqkj.com

SOURCES · ISO 12480-1 · EN 14439 · BS 7121 · LOLER 1998 · OSHA 29 CFR 1926 Subpart CC