A telehandler boom that stops part-way through an extend, while it still raises and retracts normally, is almost never broken. That is the load moment indicator cutting the function to stop the machine tipping forward, and it is the first thing to rule out before anyone opens a hydraulic line.

A telehandler boom problem falls into one of three families, each needing a different response: the machine is protecting itself, the hydraulics are weak, or something has worn. This guide works through them by symptom, using the boom speeds and pressures published for the telescopic handlers sold in India.

One term first. The boom is the telescopic arm, and it does two separate jobs that people lump together: it raises and lowers (the whole arm pivots) and it extends and retracts (the sections slide in and out of each other). A telehandler can lose one and keep the other, and which one it loses is the most useful clue you have.

Why has my telehandler boom stopped extending?

The most common reason a telehandler boom stops extending is the load moment indicator, and it is not a fault. A load moment indicator, usually shortened to LMI, measures how hard the load is trying to tip the machine forward. As the boom goes out, the same load pulls harder, because it sits further in front of the front wheels. This is the mechanism the telehandler load chart puts into numbers.

Near the tipping limit the LMI does not just beep. It takes boom functions away, and it takes them away selectively, which is the part that confuses people on site. It blocks the two movements that make things worse, extending further out and lowering, because lowering an extended boom swings the load out and down. It leaves the two that make things better: raising and retracting, both of which bring the load back towards the machine. So the boom feels dead in one direction and perfectly healthy in the other.

What the cut-out blocks, and what it leaves you

Extend: blocked Lower: blocked Raise: available Retract: available

Blocked as the machine nears its limit: boom extend, boom lower. Left working: boom raise, boom retract. If that pattern matches what your machine is doing, the hydraulics are fine and the load is too far out. Retract the boom, or set the load down and re-read the chart for the attachment you have fitted.

Two things make this look like a breakdown when it is not. On many machines the system only arms once the machine is standing still with the boom out, which is why an operator can travel across a site with no trouble and then find the boom will not go out at the stack. And the limit belongs to the attachment that is fitted, not to the machine’s headline capacity, so a jib or a bucket can cut you out at a reach plain forks handled yesterday.

JCB’s own listing for the 530-70 telescopic handler describes both halves of this: a load moment indicator with visual and audio alerts, and a hydraulic cut-off that keeps operations inside the safe load capacity. EN 15000 is the European standard defining how these limiters must behave on variable-reach trucks. India has no equivalent public standard for telehandlers, so whether a particular machine has the system, and how it behaves, is a question for the operator manual and the dealer.

How do you tell an LMI cut-out from a real hydraulic fault?

You tell them apart by which functions survive, and by whether the machine recovers once the load is off. A cut-out is selective and reversible. A hydraulic fault is not fussy about direction and does not care whether you are loaded. Run this table before anything else; it costs nothing and takes two minutes.

Table 1: Reading a dead boom function on a telehandler
What you see What it usually is What to do next
Extend and lower are dead; raise and retract work Load moment cut-out doing its job. Not a fault. Retract the boom or set the load down. Re-read the chart for the fitted attachment.
Boom is dead in every direction, but steering and drive are normal Boom circuit, or a control lockout that has been left engaged Check the boom isolator or lockout switch and the seat sensor first, then the boom control valve.
Every hydraulic function is dead or very weak, including steering Pump, drive to the pump, or oil supply Check oil level and the suction line before suspecting the pump.
Boom works unloaded but stalls with a load on Pressure is not reaching its setting Workshop job. Main relief valve or a worn pump.
Machine empty, boom retracted, still cut out Sensor or calibration fault in the LMI, not a genuine overload Dealer. The system needs reading and re-calibrating; do not bypass it.

That last row matters. An LMI that cuts out on an empty machine is faulty, and the temptation is to find the override and carry on. The override exists so an operator can recover a load safely, not so the machine can work all day with its protection off. A telehandler that tips forward does it quickly, usually with the load high.

Comparing against something newer? Browse telehandler models and specifications and speak to a dealer near you.

How fast should a telehandler boom lift?

Most telehandlers sold in India publish a boom raise time and a boom lower time in seconds, and that turns a vague complaint into a test you can run with a phone stopwatch. Across the machines available here, a full boom raise takes 8.4 to 15 seconds and a full lower takes 8.6 to 19 seconds. Nine of the thirteen machines publish both figures; the ACE AT 30 and the three rotating MANITOU MRT-X machines do not.

Table 2: Published boom raise and lower times, telehandlers available in India
Machine Boom raise Boom lower Max lift height Rated capacity
JCB 540-70 8.4 s 8.6 s 7,000 mm (7.0 m) 4,000 kg (4.0 Ton)
JCB 530-70 9.1 s 10.3 s 7,000 mm (7.0 m) 3,000 kg (3.0 Ton)
JCB 530-110 9.2 s 9.2 s 11,000 mm (11.0 m) 3,000 kg (3.0 Ton)
SANY STH634A 11 s 9 s 10,400 mm (10.4 m) 2,721 kg (2.72 Ton)
MANITOU MXT 840 K 13 s 9 s 7,600 mm (7.6 m) 4,000 kg (4.0 Ton)
SANY STH844A 13 s 13 s 13,400 mm (13.4 m) 3,629 kg (3.63 Ton)
MANITOU MXT 1740 K 14.3 s 10.4 s 17,400 mm (17.4 m) 4,000 kg (4.0 Ton)
SANY STH1056A 15 s 19 s 17,100 mm (17.1 m) 4,540 kg (4.54 Ton)

The India variant of the MXT 840 K publishes the same 13 and 9 seconds. Figures are as per the current September 2026 specifications.

Boom length is not what sets the time. The JCB 530-110 raises to 11.0 m in 9.2 seconds while the MANITOU MXT 840 K takes 13 seconds to reach 7.6 m — a shorter boom on a slower time. Pump output lines up far better. The three JCBs all run 108 L/min and are the three fastest on the list, while the two SANY machines at 60 and 63 L/min sit at 11 and 13 seconds. The STH634A and the 530-110 reach almost the same height, and the machine with nearly double the oil flow gets there about two seconds sooner. The pump types, flows and relief-valve settings for each machine explain more of this table than boom length does.

Lowering is not simply gravity. Three of the eight take longer to lower than to raise and two take exactly the same time, which could not happen if the boom were just falling under its own weight. The descent is metered by a valve so a heavy load does not run away downwards. That is why “the boom comes down slowly” is a weak complaint on its own. On a JCB 530-70 or a SANY STH1056A, slow lowering is the machine working as designed.

To use the table, time your machine from fully down to fully up, unloaded, at working temperature, and compare it against its own published figure. Two or three seconds off is worth investigating; matching it is not.

Why is the telehandler boom slow to lift?

A boom that is genuinely slow in every direction is an oil problem before it is a pump problem, and the cheap checks come first. Work down this order.

Oil level and condition. A low tank pulls air in with the oil, and air compresses where oil does not, so the boom goes soft and jerky rather than simply slow. Check the level cold with the boom down, then look at the oil: dark, cloudy or burnt-smelling oil moves badly and damages everything downstream. Check when it was last changed against the service schedule for the machine.

Oil temperature. Cold oil is thick, so every function is slower on the first lift of the morning. That clears in minutes, and it is why the timed test above is only fair at working temperature.

The filters. A blocked return or suction filter starves the pump. Filters are the cheapest parts on the machine and the ones that decide how long the expensive parts last.

The pump and the relief valve. If the oil is good and the machine is warm and it is still slow, the fault is in the pump or the pressure setting. Relief-valve settings on the telehandlers sold here run from 170 bar to 350 bar depending on the machine, and the valve that caps system pressure is not one to adjust by guess. A wrong setting either weakens the machine or over-stresses the hoses. Our guide to hydraulic system maintenance covers those checks.

One symptom deserves its own line. If the boom is slow and the pump is noticeably noisier than usual, stop. A whine or rattle with slow functions usually means it is running short of oil, and running it on is how a slow machine becomes an expensive one.

Why does the boom rattle or sag at full extension?

A boom that knocks, rattles or droops visibly when fully out has worn wear pads, and that is a service item rather than a failure. Wear pads are blocks of hard plastic or nylon bolted between the boom sections, so the sections slide on them instead of on steel. They are designed to wear out, because a pad is far cheaper to replace than a boom is to rebuild.

What you notice as they thin down, roughly in order: a knock as the boom starts to extend, then side-to-side play at the tip, then visible sag at full reach under load. Dust and grit between the sections kill pads, so a machine in crusher dust eats them far faster than one on a finished floor.

No manufacturer in this catalogue publishes a pad size or a pad life in hours, and no honest general figure exists — it depends on your ground, your hours and your operator. The interval comes from the machine’s own parts manual and your dealer. What you control is keeping the sections clean and greased; our guide to greasing a construction machine sets out the points and intervals, and the boom pivot pins belong on that list.

Do not confuse pad sag with a hydraulic problem. Worn pads let the boom droop because the sections have room to move inside each other, but it still holds pressure and still lifts its rated load. A boom that settles downwards over minutes with the engine off is a different fault.

Why does the boom creep down when the machine is parked?

A boom that sinks slowly with a load up and the engine off is losing oil past something that should be holding it. The mechanism is the same on any machine with a hydraulic boom, and our guide to boom drift and why a boom sinks sets out the three candidates in full: the lift cylinder’s piston seals, the load-holding valve that traps oil in the cylinder, and a worn spool in the main control valve.

The test is worth doing before anyone quotes for a repair: park level, raise the boom with a normal load, stop the engine, centre the levers, mark the boom tip against something fixed, wait ten minutes and measure. Repeat for the tilt. If only the boom drifts, the fault is in the boom circuit; if the tilt drifts too, suspect the main valve they share.

A telehandler has one extra place to look that an excavator does not: the extend circuit. A boom that slowly telescopes out under load, rather than dropping, points at the extension ram or its holding valve instead of the lift ram. Check which movement is actually happening before you chase the wrong cylinder.

How much drift is acceptable is set by the manufacturer in the service manual, model by model. No Indian maker publishes a public drift tolerance for these machines, so there is no honest single number to quote here — get it from your dealer for your model.

What can you check yourself, and what needs a workshop?

All the diagnosis above is free and none of it needs the machine opened: reading which functions still work, re-reading the chart for the fitted attachment, checking oil level, condition and filter history, timing the boom against its published figure, feeling for play at the tip, and running the mark-and-measure drift test.

Leave to a workshop or dealer: relief-valve settings, pump replacement, cylinder reseals, wear-pad replacement on a large machine, and every LMI fault. Calibration is not a field job. Two rules apply throughout: never work under a raised boom held only by hydraulics, and never test a boom fault under load when an unloaded test tells you the same thing.

If these faults are arriving together, it may be time to compare running costs against something newer. Look at fixed boom telehandlers, sometimes called boom loaders on site, and rotating telehandlers, and read our comparison of the telehandler brands sold in India before you commit.

Telehandler boom problems: the short version

Start with which movements still work. Extend and lower dead while raise and retract stay healthy is the load moment cut-out protecting the machine, not a fault: retract, set the load down, and read the chart for the fitted attachment. Everything dead, including steering, points at oil or the pump.

For a slow boom, time it. These machines raise in 8.4 to 15 seconds and lower in 8.6 to 19 seconds, and each publishes its own figure, so you can compare your machine against itself rather than against an opinion. Rattle and droop at full reach are wear pads, which are meant to wear. A boom that sinks with the engine off is oil escaping past a seal or a holding valve, and the mark-and-measure test says which circuit before anyone strips anything.

For the whole machine rather than the boom alone, start with our guide to the telescopic handler and how it works, and check its operating weight and transport dimensions and fuel and oil capacities when planning a service. When you are ready to buy, compare telehandler models, specifications and prices and talk to a dealer near you.

Prices, specifications and features are indicative, vary by variant, location and date, and should always be confirmed with the official OEM or authorised dealer before any purchase decision. DesiMachines is not liable for decisions taken on the basis of information that may have changed after publication.