Hook tracking across a telescoping boom: a camera aimed once cannot hold the hook, so the view has to travel with the boom.

▌  APPLICATION NOTE  ·  OCTOBER 2026  ·  BOOM-MOUNTED HOOK VIEW

Hook tracking across a telescoping boom: a camera aimed once cannot hold the hook, so the view has to travel with the boom.

A pendulum hanging from the end of a moving boom is the hardest thing on a crane site to watch. On a truck crane the boom is not a fixed mast; it telescopes out and draws back, and every metre of travel swings the hook across the background the moment the operator changes radius. A camera that is bolted down once and aimed at the start of the shift will be looking at empty air by the time the boom has run out to full length, so the crew loses the hook exactly when the load is farthest away.

Running a video cable along the boom to a monitor in the cab is the workaround nobody wants. A telescoping boom folds into itself, so a cable dressed along it can be pinched, kinked, scraped or cut on the first extension of the shift. The industrial wireless bridge is what makes a boom-mounted camera practical, because there is no cable to route and nothing to snag or crush when the boom moves. This note covers the mounting, the auto-zoom, the transmitter and receiver pairing, and the checks the crew must complete before the lift rather than during it.

01  THE PROBLEM WITH A FIXED AIM

The geometry is simple. When the boom is retracted and the radius is short, the hook sits in one small part of a fixed frame. As the boom telescopes out, the hook sweeps across that frame and then leaves it altogether. A fixed camera cannot follow that motion, so crews compensate by re-aiming the head, by leaning harder on radio calls from a banksman, or by giving up on the hook view entirely. None of those is a system; each one puts another task on a person who is already watching something else.

▌  WHAT CHANGES  as soon as the boom telescopes, the hook leaves a fixed frame, so the visual reference disappears exactly when the load is furthest away and hardest to judge.

▌  WHY NOT A CABLE  a cable dressed along a moving telescoping section is exposed to crushing, kinking and abrasion every time the boom extends or retracts.

The hook-tracking camera is aimed down the boom toward the hook, so it shares the motion of the boom instead of watching it from a distance. Keeping a usable image then becomes a question of zoom and focus rather than of re-aiming, and the operator is no longer the only thing holding the picture together.

02  MOUNTING THE HOOK-TRACKING CAMERA ON THE BOOM

The camera is mounted on the boom and looks along it at the hook and the load below. Because it rides the boom, the hook stays in roughly the same part of the frame no matter how far the boom is run out. The mounting is part of a split-modular arrangement built for mobile truck cranes, and it uses magnetic wireless sensors that need no body cutting and no circuit modification, leaving the boom and the chassis as the manufacturer built them.

▌  MOUNTED WITHOUT CUTTING  magnetic wireless sensors mean the installation does not cut the body or rewire the machine, which matters for a crane that has to stay inside its type approval.

▌  SEALED AGAINST THE WEATHER  the camera carries IP67 protection and is rated from −30 °C to +70 °C, so a machine that works a cold yard in winter and a hot laydown area in summer keeps the same view.

A second camera in the package is a 360° panoramic unit on the chassis. The two views answer different questions: the boom camera answers where the hook is, and the panoramic camera answers what is around the machine. Neither replaces the other, so the cab is arranged to show both, and the operator chooses between them without leaving the seat.

03  AUTO-ZOOM AS THE BOOM EXTENDS AND RETRACTS

The distance between the camera and the hook is never constant. When the boom is short the hook is close; when the boom is long the hook is far away. Auto-zoom changes the lens angle to hold the hook and its load at a consistent size in the frame, so the operator is not chasing a wide shot in which the hook shrinks to a speck at full extension and then floods the screen when the boom comes back in.

▌  FOCUSED ON THE HOOK AND LOAD  the auto-zoom is centred on the hook and the load beneath it, so the object the operator actually needs is the object the image is built around.

▌  CONSISTENT BOTH WAYS  the same behaviour runs in reverse as the boom retracts, so the frame does not suddenly fill as the hook travels back toward the machine.

A stable, slowly changing image is what makes the hook view trustworthy. An operator who sees the same framing at short and long radius learns to read the position of the load against the frame, and can then judge the last metre of a set-down without waiting for a radio call from the ground.

04  PAIRING AND CHECKING THE WIRELESS BRIDGE

The video travels over an industrial wireless bridge, a transmitter and receiver pair that carries HD video across the telescoping boom. The transmitter sits on the boom with the camera and the receiver sits at the cab end with the host. Pairing the two is part of the installation, and proving the link is part of the routine, not something discovered mid-lift when the load is already in the air.

▌  PAIRED BEFORE, PROVEN ON THE GROUND  the transmitter and receiver are paired and the link is proven while the crane is still on the ground, so a lost picture is a found fault rather than a surprise in the air.

▌  LOW LATENCY MATTERS  an anti-interference, low-latency link is used because the operator times a set-down from the image, and a lagging picture is worse than no picture at all.

A cab power transformer supplies a stable 12 V to the video chain, which keeps the camera and the bridge on a clean supply rather than a fluctuating one. During the pre-lift machine check the crew powers the system and confirms that the picture is present, sharp and steady across the working range of the boom, retracted, at mid-length and fully extended, before any load is broken free of the ground.

05  SWITCHING BETWEEN HOOK AND 360° VIEWS

The host is an 11.6-inch 1080P IPS display measuring 285×181 mm, and it shows more than video. Beside the camera images it presents load, moment %, boom length, radius, height, tilt and wind, so the operator reads the state of the machine on the same screen that shows the hook, with no second instrument to glance away for.

▌  ONE WIRED MOUSE  switching between the hook view, the 360° view and recorded playback is done with a wired mouse, which is deliberate; a wired control in a cab is hard to lose and never needs charging.

▌  ALL THE NUMBERS IN ONE PLACE  load, moment percentage, boom length, radius, height, tilt and wind sit beside the image, so the decision to continue or stop is taken from one panel rather than from three instruments.

Playback matters after the lift as well as during it. If a near-miss has to be reviewed, the recorded views and the recorded numbers sit on the same unit, which shortens any argument about what actually happened and supports the debrief that follows.

06  WHAT THE RADIO LINK CANNOT PROMISE

It has to be said plainly that the link is radio. Radio does not know what stands between the transmitter and the receiver, and on a site with steel stacks, concrete, containers or another crane working nearby, obstruction and interference are real risk factors. A link that is perfect at the start of the shift can degrade as the boom swings behind an obstruction.

▌  VERIFY FIRST  site obstructions and interference must be checked before the lift, with the system powered and the boom moved through its working range, not assumed from the last time the machine worked at this address.

▌  THE CREW IS THE FALLBACK  the hook view is an aid and not an authority, so radio calls, taglines and a banksman stay in the plan whether or not the picture is good.

None of this makes the boom camera fragile; it makes it honest. The operator still owns the lift, the banksman still owns the communication, and the camera simply removes the parts of the job that depend on somebody else happening to have a clear line of sight at the moment it counted.

PROCUREMENT IMPACT

●  A fixed cab camera and a boom-mounted camera are not the same purchase; the truck package pairs them because the hook view is the one that changes with the boom.

●  Ask how the transmitter and receiver are mounted and proven across the boom working range, since the bridge is as much a deliverable as the camera head.

●  Confirm that the installation needs no body cutting and no circuit modification, so the crane stays inside its own documentation and its inspection history.

●  IP67 and the −30 °C to +70 °C rating set the markets and seasons the package can serve without a heated or sheltered cab.

●  Qualification documents for special-equipment inspection and smart-site acceptance are part of the delivery, together with a one-year warranty and lifetime free software upgrades.

WHAT TO WATCH

●  Before the first lift on a new site, walk the boom working area and note anything that will sit between the transmitter and the receiver.

●  Treat a picture that degrades as the boom turns as a radio question first, and check the pair before replacing the camera.

●  Keep the wired mouse where the operator can reach it without leaving the controls.

●  Record the boom ranges at which the link was verified, so the next shift starts from evidence rather than memory.

●  Never let the hook view stand in for the load chart; the numbers on the host support the decision, they do not replace the chart.

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 · BS 7121 · LOLER 1998 · EN 14439