Home > PB21AM-3R Formwork-Climbing Concrete Placing Boom — 21 m

PB21AM-3R Formwork-Climbing Concrete Placing Boom — 21 m

The PB21AM-3R is a formwork-climbing concrete placing boom — a placing boom that rides on the climbing formwork itself and rises with it, pour after pour. Instead of climbing the finished structure on a frame, it is mounted on the jump-form or climbing-form rig that shapes a wall, core or pier, and ascends with that formwork as each lift is cast. It places concrete over a 21 m radius through a three-arm R-fold boom, and because it is carried by the form rather than standing on its own, its free-standing height is just 4.2 m and the whole machine weighs only 6,400 kg — light enough to ride on the formwork without overloading it.

This makes the PB21AM-3R the placing tool for vertical, formwork-built structures: shear-wall cores, bridge pylons, piers, silos, chimneys and similar elements raised with climbing or slip formwork. As with every placing boom, it does not pump — a separate stationary or line concrete pump delivers concrete up a riser, and the boom distributes it into the form. It is fully hydraulic on a 380V/50Hz supply with a 7.5 kW motor, assembled from modules that pin together quickly, and built and tested at the TRUEMAX factory in Haining to ISO 9001:2015 and CE standards, as part of a placing-boom line exported to over 120 countries.

1. Climbs with the formwork — Mounted on the climbing or jump-form rig, it rises with the formwork as each lift is poured — no separate climbing frame or crane lift between pours, which cuts climbing workload and speeds the cycle.

2. R-type three-arm hydraulic boom — Three R-fold arms, fully hydraulic, open and fold flexibly for a wide 21 m placing range and stow neatly on the form.

3. 220° end-section fold — The third arm articulates to 220°, folding back sharply so the hose can drop straight down into a wall or core form close to the boom.

4. Light enough to ride the form — At 6,400 kg the machine is light, so it can be carried by the formwork system without overloading the rig or the structure.

5. Modular pin-shaft assembly — Modules connect quickly with pin shafts, making the boom fast to install, dismantle and transport between projects.

6. Radio and cable remote control — Two operating modes — wireless radio remote and cable remote — let the operator place concrete from the best vantage point on the form.

7. Full 360° gear slewing — Gear-driven slewing turns the boom a complete circle to reach all sides of the form from one position.

8. Quality components — Hydraulic and electrical parts are sourced from well-known international brands for stable, reliable operation.

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Technial Parameters

Item	Unit	PB21AM-3R
Performance
Max. Radius of Placing Boom	m	21
Free-Standing Height (to boom root joint)	m	4.2
Slewing Range	/	360°
Mode of Slewing	/	Gear Slewing
Application Scenario	/	Formwork Climbing
Circumstance Temperature	℃	-20 ~ 55
Power Supply (customisable)	/	380V / 50Hz
Boom (3-Section R-Fold)
1st Section — Length	m	8.4
1st Section — Articulation	°	0 ~ 90
2nd Section — Length	m	6.9
2nd Section — Articulation	°	0 ~ 180
3rd Section — Length	m	5.7
3rd Section — Articulation	°	0 ~ 220
Delivery Line
Delivery Pipeline Diameter	mm	Φ125 × 4.5
Delivery Hose Diameter	in × mm	5" × 3000
Power & Hydraulics
Motor Power	kW	7.5
Hydraulic Pressure	MPa	28
Hydraulic Oil (5℃–55℃)	/	HM46 anti-wear
Hydraulic Oil (-20℃–5℃)	/	HM32 anti-wear
Weight
Total Weight	kg	6400
Max. Lifting Unit	kg	5200

Dimensions & Working Range

The working-range diagram shows the 21 m radius swept through 360° from the boom's position on the formwork, with the steep downward reach the 220° end fold gives for placing into a wall or core form. Because the boom is supported by the climbing formwork, the install plan centres on the interface between the boom's base and the form rig — read the diagram with the formwork supplier's drawings.

Applications

The PB21AM-3R is built for vertical structures raised with climbing or slip formwork, where the placing boom needs to rise lift by lift with the form.

Shear-wall cores and walls

On jump-form cores and walls, the boom climbs with the form and places concrete into each new lift, keeping pace with the formwork cycle without a separate climbing structure.

Bridge pylons and tall piers

Tall piers and pylons built with climbing formwork suit the PB21AM-3R: it rides the form up the element and places concrete into the form at each stage.

Silos, chimneys and slip-form structures

Slip-form and climb-form silos, chimneys and similar continuous vertical pours benefit from a light placing boom that ascends with the moving form and distributes concrete evenly around it.

Fed by a separate concrete pump

On every job the boom works with a stationary or line concrete pump that feeds concrete up a riser to the form; the PB21AM-3R then places it precisely into the formwork through its three-arm boom.

FAQs

What is a formwork-climbing placing boom, and how is it different from a column-climbing one?

A formwork-climbing placing boom is mounted on the climbing or jump-form rig and rises with the formwork as a wall, core or pier is cast. A column-climbing boom, by contrast, climbs the finished structure on its own floor or shaft frame. The PB21AM-3R is the formwork type: it is carried by the form, which is why its free-standing height is only 4.2 m and it is light at 6,400 kg.

What construction methods does it suit?

It is built for vertical elements raised with climbing formwork, jump form or slip form — shear-wall cores, bridge pylons and piers, silos and chimneys. As the form climbs for each lift, the boom climbs with it and places the concrete into the form.

Why is the free-standing height only 4.2 m?

Because the boom does not stand on its own — it is supported and carried by the climbing formwork. The 4.2 m free-standing height is the short distance the boom holds above its own base; the formwork rig provides the structure that takes it up the building, so it does not need the tall self-supporting mast of a column-climbing boom.

Is the placing boom a concrete pump?

No. It places concrete, it does not pump it. A separate stationary or line concrete pump pushes concrete up a riser to the form, and the PB21AM-3R distributes it into the formwork. The two are used together.

Is it electric or diesel?

Electric — a 380V/50Hz supply driving a 7.5 kW motor, with voltage and frequency customisable to your market. It has no on-board engine, so it runs from site power or a generator while the concrete comes from a separate pump.

How heavy is it, and how is it installed?

Total weight is 6,400 kg, with a maximum single lifting unit of 5,200 kg. The modular, pin-shaft design lets it be assembled, dismantled and moved quickly, and its light weight is what allows it to be carried by the formwork system.

What is supplied, and how is it shipped?

The package is the boom, base, hydraulic and control system and remote. The interface to your climbing formwork, delivery line, hose, spares, installation and commissioning are configured to your project and quoted separately. Tell us your formwork system and element type and we will confirm the configuration.

Formwork-climbing vs column-climbing placing booms

TRUEMAX builds placing booms that climb in two different ways. A formwork-climbing boom like the PB21AM-3R rides on the climbing or jump formwork and rises with it — ideal for walls, cores, piers and other elements cast lift by lift with self-climbing forms. A column-climbing boom climbs the finished structure on its own floor or shaft frame and is suited to placing concrete across high-rise floors. The two solve different problems: one follows the formwork up a vertical element, the other distributes concrete across each completed floor.

The placing boom in formwork construction

In a climbing-formwork pour, concrete travels from the batching plant to the form by truck mixer and a stationary or line pump, which lifts it up a riser. The placing boom is what delivers that concrete into the form accurately, all the way around, without crews dragging end-hose by hand at height. Riding on the form, the PB21AM-3R keeps the placing point with the formwork as it climbs, so each lift is poured cleanly and the cycle keeps moving.

When to choose a formwork-climbing boom

Choose a formwork-climbing boom when the structure is a tall vertical element — a core, wall, pylon or silo — built with climbing or slip formwork, and you want the placing boom to ascend with the form rather than be relifted by crane. For placing concrete across the floors of a building, a column-climbing or a mobile/spider placing boom fits better. The PB21AM-3R is the formwork specialist in the TRUEMAX range, light and modular so it integrates with the form rig.