Truck Mounted Crane: How Lorry Cranes Work on Site

A truck mounted crane is a crane permanently fixed to the chassis of a road-going lorry, so the same vehicle that delivers a load can also lift it into place. In Singapore the machine is usually called a lorry crane, and it is one of the most common lifting appliances on small and medium sites, from landed-house rebuilds to fit-out deliveries at the kerbside of an occupied building.

This article explains how these cranes are built, the main configurations, where they make sense and where they do not, and the safety framework that governs their use. It is written from the point of view of the engineer who has to think about what the crane stands on and what it is lifting, not from the point of view of someone hiring one.

What a truck mounted crane is

The defining feature is integration. The crane is bolted or welded to a subframe on the lorry’s chassis, normally just behind the cab or at the rear of the deck, and draws its hydraulic power from a pump driven by the truck engine through a power take-off. The lorry carries the load on its own deck, drives to site, deploys its outriggers and lifts. There is no separate transport or assembly, which is the main reason the machine is so widely used.

This distinguishes it from a full mobile crane, where the vehicle exists only to carry the crane. A lorry crane is a delivery vehicle first and a lifting appliance second. Its capacities are correspondingly modest, and its reach is limited by the length of boom that can be folded or telescoped onto a road-legal truck.

Knuckle-boom and telescopic configurations

Two arrangements dominate. The knuckle-boom (also called an articulating or loader crane) has a boom made of several hinged sections that fold into a compact Z-shape behind the cab. Hydraulic cylinders unfold it, and many have a telescopic extension at the tip. The articulation lets the operator reach over a hoarding or under a canopy and place a load precisely, which suits materials delivery and the placing of building components.

The stiff-boom telescopic type has a straight boom that extends in sections, with a winch and hook block at the tip, much like a small mobile crane. It generally gives a cleaner vertical hoist line and suits loads that need to be lowered some distance, such as plant into a basement opening or materials onto a roof.

Capacity is expressed as a load moment: the safe load falls as the radius increases, so the crane that lifts a pallet beside the truck may only manage a fraction of it at full reach.
Controls may be at a stand on the truck, at a seat above the crane column or by radio remote, which lets the operator stand where they can see the load.
Safety devices include load-moment limiters, outrigger interlocks and slew limits; these are part of the machine’s design and must not be bypassed.

Where lorry cranes are used

The truck mounted crane is at its best where loads are moderate, lifts are short and the site is accessible from a road. Typical uses include unloading steel reinforcement, blockwork and pallets of tiles; placing precast items such as drains, kerbs and small panels; lifting air-conditioning condensers, water tanks and plant onto low roofs; and setting out temporary site cabins.

It is not a substitute for a tower crane on a high-rise, nor for a crawler or large mobile crane on heavy lifts. Where reach or capacity runs out, the answer is a larger machine, not a stretched lift plan. Choosing the right appliance is itself part of the lift planning described below.

Ground, outriggers and the structural engineer’s concern

Most lifting incidents with small cranes start at ground level. When the crane slews and extends, the load and the crane’s own weight concentrate onto one or two outrigger feet. Those point loads can be very large relative to the size of the foot, and they are applied to whatever happens to be below: a road, a footpath, a drain cover, a basement roof slab or a backfilled trench.

Good practice is to know the outrigger reaction for the planned lift, to set the outriggers fully extended on firm, level ground, and to spread the load with mats or timber of adequate size. Where the crane must stand on a suspended slab, a car-park deck or close to an excavation edge, the bearing capacity is an engineering question rather than a judgement call on the day. The behaviour of soils under concentrated load is covered in our guide to soil mechanics basics; for a slab, the check is a structural one and may need a qualified engineer’s sign-off.

Overhead power lines, nearby trees, passing traffic and the public are the other common hazards. Kerbside lifts in particular need a barricaded exclusion zone, and traffic management where the lorry occupies a lane.

Lifting rules in Singapore

In Singapore, crane lifting is governed by the Workplace Safety and Health Act and its subsidiary regulations, administered by the Ministry of Manpower (MOM). The Workplace Safety and Health (Operation of Cranes) Regulations 2011 require a lifting plan to be established and implemented for crane lifts and set out roles for the lifting team, including a lifting supervisor, an appointed rigger and an appointed signalman, each of whom must complete training acceptable to the Commissioner for Workplace Safety and Health.

Under the WSH (General Provisions) Regulations, a crane is a lifting machine: it must be registered with MOM and periodically tested and examined by an Authorised Examiner, who is a Professional Engineer specifically approved by MOM for this work. Operators must be trained and competent for the machine they operate. MOM revised its test and examination requirements for lifting equipment in 2025, so the current intervals should always be checked against the latest MOM circular rather than an old site checklist.

These duties sit alongside the broader site regime described in our article on construction safety. For a contractor, compliance is a daily routine; for an owner, it is worth knowing that the paperwork exists and asking to see it.

Planning a safe lift

A sound lifting plan for a truck mounted crane answers a handful of plain questions: what the load weighs, including rigging; the radius at which it will be picked and placed; the crane’s rated capacity at that radius in that configuration; where the outriggers will stand and on what; what lies overhead and around; who is in the lifting team and how they will communicate; and what the exclusion zone is.

The most frequent errors are underestimating the load, ignoring the radius at the placing end, and setting up on ground that was assumed rather than checked. Each is avoidable with a few minutes of honest planning before the outriggers go down.

Frequently asked questions

Is a lorry crane the same as a truck mounted crane?

Yes. In Singapore the term lorry crane is used for a crane fixed to a lorry chassis, which elsewhere is called a truck mounted crane, loader crane or knuckle-boom crane. The machine both transports and lifts its load, unlike a mobile crane whose carrier exists only to move the crane.

How much can a truck mounted crane lift?

It depends on the model and, critically, on the radius. Capacity is rated as a load moment, so the safe working load falls as the boom reaches further out. The figure that matters is the rated capacity at the actual pick and place radius in the actual configuration, read from the manufacturer’s load chart for that crane.

Can a lorry crane stand on a basement roof or car-park deck?

Only if the slab has been checked for the outrigger reactions. Outrigger loads are concentrated and can exceed what a suspended slab was designed to carry. A qualified engineer should confirm the capacity and specify any load-spreading mats or back-propping before the crane sets up on a structure.

Does a lorry crane lift need a lifting plan in Singapore?

Crane lifts fall under the WSH (Operation of Cranes) Regulations 2011, which require a lifting plan and an appropriately trained lifting team. The contractor responsible for the lift should prepare the plan and make it available; the exact scope of duties should be confirmed against current MOM guidance.

Need a slab, retaining edge or temporary platform checked before a crane sets up on it? Talk to our consultancy or get in touch.