The innovative screw pump

Winning elements

Operating economy, modern design, avant-garde technology, are the strong points of this extraordinary plastering machine. Hundreds of machines sold all over the world demonstrate its success. The S28R combines highly professional performances with an interesting price. A product, then, that applies to both general contractors and professionals. We do our best to meet your requirements of quality, performance, reliability and assistance. That attention has led to the development of new and interesting features. We needed an innovative screw pump able to satisfy the needs of modern building sites. With the S28 from BUNKER, plastering – pumping – injecting is a pleasure.

Completely hydraulic

The S28 is a silenced plastering machine with a complete hydraulic operation. This solution avoids the use of unnecessary mechanical parts improving performance and control.


Screw pump
Designed for an exceptional resistance against wear, it guarantees perfect plastering for dozens of houses even of 15 storeys, all thanks to the hydraulic control of the flow.
The hydraulic inversion of the pumping direction allows mortar to be sucked back and thus to lower pressure. This advantage can be used to easily eliminate clogging… A good advantage. The pumping can be interrupted directly from the nozzle as well as from the control panel. In this case the motor moves to minimum rotation, reducing fuel consumption. There are further advantages to this plaster sprayer as you will discover yourself.

Powerful and versatile
The high power and variability of the flow allow S28 to pump, spray or inject: Traditional plasters for indoors and outdoors, Pre-mixed plasters for interiors and exteriors, Special plasters, Fibre-reinforced mortar, Refractory mortar, Mortar for joint filling, Self-levelling floor screeds, Pre-mixed mortar and special products for the recovery of concrete structures and brickwork buildings


  • Spraying pre-mixed plaster
  • Concrete spraying and fibre-reinforced mortar
  • Injections of cement grouting under controlled pressure
  • Pumping mortar and insulation materials

Technical Data

Quality and performance add up to a robust and compact chassis, making the S28 the product the market has been long waiting for. A plastering machine pump able to guarantee the greatest satisfaction of the users. The S28 is equipped with the most modern safety systems protecting the operator from any risk. The coating with sound-absorbing materials keeps the emission of sound within the enforced regulations, allowing the S28 to work near hospitals, schools and residential areas.

The S28 plastering machine can stand the most varied operating conditions, all the parts are given a treatment of sandblasting, painting and treated in the oven. This process ensures the greatest protection of the covering and gives a higher value to the second-hand machine.

The controls of your S28 are all on the same side protected by a door with a lock and allow you to control all the operations, indicating their status with LEDs. It also has an hour counter that helps to schedule work and maintenance.

The door of the control panel is protected by a strong lock to avoid tampering and damage.

The electric box is further protected by a highly resistant plexiglas screen.

The special S28 screw pump is designed for exceptional resistance against wear even with difficult mortars.

It is possible to easily invert the rotation of the screw pump allowing you to empty the hoses.

The progressive regulation of the flow guarantees a perfect plastering, avoiding waste of material.

Mixing, factor not to be underestimated
Modern plasters need to be guaranteed to undergo a thorough mixing so as to obtain the chemical combinations and performances desired. The standard consistency control,the mixing blades, their shape and number and the arrangement have been designed for that purpose.

The diesel motor has been designed to guarantee the highest reliability, tested together with the manufacturer it satisfies the toughest operational needs.

New Kubota

The most powerful of the category. Reliable and quiet.

3 cylinders
1305 cm³
29,5 cv a 3000 g/m
used at 2000 g/m
Cooling: Water
Automatic minimum


Powerful and reliable.

2 cylinders
1248 cm³
29 cv a 3000 g/m
used at 2000 g/m
Cooling: Air
Automatic minimum

The fuel tank with mesh prefilter and bumper bar has a capacity of 25 liters.

The S28 plastering machine is equipped with the most modern safety systems. A special valve stops the rotation of the hydraulic motor by blocking the mixing blades when the protective grille is opened, ensuring maximum safety for the operator.

The pressure washer available on request is designed to operate directly from the hydraulic circuit of the S28 by inserting two practical couplings. This choice allows you to wash your S28 and other construction machinery quickly in total autonomy … A great advantage.

A large and practical drain facilitates the washing of your S28.

The cover equipped with gas springs is large and easy to open, making checks and maintenance easy. The internal coating of sound-absorbing material reduces the noise level to the regulations in force, allowing the S28 to work even near hospitals, schools and residential areas.

Una robusta chiusura meccanica impedisce l’apertura della cappotta evitando sabotaggi e manomissioni.

Il nuovo e più potente compressore, installato di serie sulla S28 R è dotato di un segnalatore di livello che vi consentirà di tenere sotto controllo il livello dell’olio lubrificante.

Il compressore è inoltre montato su un dispositivo che consente il Tensionamento Automatico Cinghia (TAC system) aumentandone la durata e facilitandone la sostituzione.


Mounted on a robust elastic axle, your S28 will move on the roads and on the construction site with maximum stability, its low weight contributes to easy positioning. The 1000 kg Alko axle with 165 tires guarantees exceptional stability, for safe towing even at high speeds.

Moving your plastering machine comfortably and effortlessly is finally reality. Thanks to two retractable handles that disappear inside the frame, the Spritz 28 R stands out once again for its practicality and its surprising technical solutions.
Placing it on the construction site, in the workshop, in the garage will be a breeze.

It is possible to equip the S 28 R with a dust attenuator complete with a water meter.

Special nozzles nebulize the water necessary for the dough and break down the powders that are released with the opening of the bag of material.

  Misuratore d’acqua integrato nel quadro comandi.

Ugelli nebulizzatori.

Dettaglio ugello.

Two practical hydraulic stabilizers facilitate effortless positioning of the machine quickly on site.

The control lever is integrated into the control panel.

It is possible to equip your S28 R with the DAT system device (Automatic Pipe Decompression) which, when the air / mortar valve on the lance is closed, automatically reverses the direction of rotation of the screw pump for a few seconds, thus relieving the pressure from the pipe .

The special Bunker lance allows, with a single lever, to interrupt both the passage of air and that of the mortar.

The lance is supplied as an option with the DAT system device.


Type  Lombardini 9LD626/2 – Kubota D 1305  400V 50Hz
Power  29cv – 21kW  9kW
Flow  400l/min  400l/min
Max pressure  4bar  4bar
Screw pump*  2L6  2L6
Theoretic flow  0-60l/min  0-60l/min
Max Granulometry  6mm  6mm
Max theoretic pressure  30bar  30bar
Transport distance
Horizontal**  100m  100m
Vertical**  40m  40m
Load height  800mm  800mm
Capacity  180l  180l
Capacity  200l  200l
Weight  740Kg  720Kg

* Pump bodies on request: 1L6 – 2L7 – 2L74
** Depending on the material, consistency and diameter of the tubes

Spritz 28 – Projection de enduits

S28 Machine a projeter avec béquilles hydrauliques