Vibrating plate, rammer or roller: which compaction machine?

For sand, gravel and stabilised aggregate the right machine is a vibrating plate; for clay soils or narrow trenches you need a trench rammer (the “jumping jack”); for roads and large areas, a vibrating roller. In the data sheets cited in this article, plates and rammers weigh from 67 to 140 kg and have petrol or diesel engines from 2.6 to 4 kW, plus battery-powered models; the rollers weigh several hundred kilos. The heavier the machine and the stronger its thrust, the thicker the layer it can compact in one pass.

The types

• Vibrating plate. It moves over the ground while vibrating: it is the machine for pavements, sub-bases and paving-stone laying. Forward-only plates go in one direction, like the Breaker Breaker BK100 (the range also includes BK85, BK140 and BK160). The Sea Technology Seaplates, such as the Seaplate 18/95 Sea Technology, run on petrol; the Seaplate 12/60, 18/95 and 24/115 come with a water tank and a wheel kit. Reversible plates go forward and back without turning the machine, handy in trenches: the battery-powered Piastra Vibrante MX FUEL Milwaukee is one, and so is the Unimec FG27130 Reversible Vibrating Plate.
• Trench rammer (jumping jack). It strikes vertically: it is used on cohesive soils and where a plate cannot fit. The collection includes the Vibrocostipatore XC80 Breaker (diesel, 85 kg), the Searammer 80D Sea Technology, also diesel, the petrol Searammer 80 and the battery-powered Milwaukee MX FUEL MXF RAM60 Milwaukee.
• Vibrating roller. For wide surfaces; in the data sheets cited here the drum width goes from 650 to 700 mm. The range runs from the Rullo Vibrante Imer Group, reversible with hydrostatic drive, to the Unimec double-drum rollers: the FG28700 is walk-behind, the Unimec FG28100MS has an operator seat.
• Pneumatic rammer. It runs on compressed air, so it is for those who already have a compressor on site: without one it will not start.
• Accessories. Water system for asphalt, rubber mat for paving stones, trolley and transport wheels.

Compacting means forcing the air out of the material and letting the grains settle, so that the surface does not sink after laying. The soil, the layer thickness and the space available decide the machine: first look at the material, then the weight, and only last the engine.

How to choose according to the job

The features to look at

• Weight. In the data sheets cited here, plates and rammers go from 67 kg (Seaplate 12/60) to 140 kg (Seaplate 22/140): heavier machines compact thicker layers, but they are harder to transport. On battery models check whether the weight is given with or without batteries: the RAM60 weighs 72 kg without batteries, the MX FUEL plate 79 kg with the battery fitted.
• Plate size. In the data sheets cited here, from 330 × 450 mm to 508 × 558 mm. A wider plate covers more, a narrower one fits through gaps: the Seaplate 12/60 measures 330 × 450 mm, the 18/95 450 × 565 mm, the Milwaukee plate 508 × 558 mm. For rammers the foot matters: 280 × 333 mm on the XC80.
• Centrifugal force (kN). It is the thrust the machine transmits to the ground. Compare it only between machines of the same type: the Seaplate 12/60, 18/95 and 22/140 go from 12 kN to 22 kN, the Milwaukee plate declares 16 kN. On the data sheets of the Unimec rollers the same quantity appears as impact force.
• Frequency. For plates and rollers it is given in Hz: 92 Hz the Seaplate 12/60, 100 Hz the 18/95, 81 Hz the 22/140, 55 Hz the Imer roller. For rammers it is given in blows per minute (640/680 on the XC80). There is no absolute best frequency: weight and force say more than a single figure, and for a special material it is wise to ask the manufacturer.
• Engine. Petrol (Honda GX120, GX160, GXR120) or diesel (Yanmar, Kubota, Lombardini). Diesel suits continuous work better. In the plates and rammers cited here, power goes from 2.6 to 4 kW, but it is not everything: weight matters too. Starting can be recoil or electric, the latter more convenient.
• Gradient. If you work on a ramp or an embankment, look at the maximum working gradient: 30% for the Seaplate 18/95 and 22/140, 40% for the 12/60, 35% for the Imer roller.
• Equipment. Transport wheels, water tank, hour meter: on the Seaplate 12/60 and 18/95 they are already included. The hour meter helps schedule servicing.

The comparison, with data-sheet figures

Some machines from the collection side by side, with the values declared in each data sheet:

* With the battery fitted. ** Without batteries. For the Unimec FG28100MS the data sheet is the source of the weight: check it before loading. The force is the centrifugal one, or the impact force for the Unimec rollers.

What the rammer data sheets say

A rammer is read differently from a plate: blows per minute, stroke and foot count. The XC80 declares a stroke of 40/80 mm, 640/680 blows per minute and an output of 210 m²/h. The Searammer 80D declares a compaction depth of 0.50-0.70 m and 108 dB of sound emission; the petrol Searammer 80 has extensions available in 250, 500 and 1000 mm. The battery-powered RAM60 declares 17 kN and a foot of 280 × 345 mm.

What the roller data sheets say

The Imer MRH 601 DS roller has a Ø 355 × 650 mm drum, a 4.6 kW Kubota diesel engine, a top speed of 3 km/h and overall dimensions of 692 × 2265 × 1165 mm: before buying it, check that it fits where it has to go and how you will load it. The Unimec FG28100MS has 700 mm wide drums, 65 Hz, a 67 litre water tank and a turning radius of 2600 mm. The Unimec FG28700 has a 7.5 HP Lombardini engine, 55 Hz and 11 kN.

Vibration and noise: what to ask before ordering

Plates and rammers are guided by hand, so the operator is exposed to hand-arm vibration. Italian Legislative Decree 81/2008 (art. 201) sets an action value and a limit value for daily exposure to vibration, to be checked against the figures in the regulation. Two data sheets in the collection report a vibration figure: the RAM60 rammer declares 7.2 m/s² (uncertainty 1.5) and the MX FUEL plate 4.3 m/s² (uncertainty 1.5).

How long a machine can be used depends on the calculation the regulation sets on the data-sheet figures; the risk assessment is the employer’s duty and must be made on the real machine and the real working times. For noise the rule is the same: a data sheet may give the sound power level or the sound pressure level, two different quantities. The Milwaukee plate declares 106 dB(A) of sound power and 95 dB(A) of sound pressure; for the other machines ask which of the two is the figure given.

Common mistakes

• Layers that are too thick. The machine only compacts the top part: spread in thinner layers.
• Material too dry or too wet. It must be slightly damp.
• A light plate on heavy material. Many more passes are needed and the result is uncertain.
• Passes that do not overlap. Uncompacted strips are left: each pass must cover a little of the previous one.
• Forgetting the water system on asphalt. The material sticks to the plate.
• Starting without checks and without protection. Before starting, check the oil and the air filter; while working you need safety shoes, hearing protection and anti-vibration gloves.

Frequently asked questions

Plate or rammer: which do I choose?

A plate suits granular materials (sand, gravel, stabilised aggregate) over large areas. A rammer is for cohesive soils, narrow trenches and awkward spots.

Plate or roller?

A plate suits small and medium areas and finishing work; a roller pays off on large areas, where it cuts the number of passes.

Petrol, diesel or battery?

Petrol for normal sites, diesel for heavy machines and continuous work, battery where silence and no emissions matter. With a battery machine consider the weight of the batteries and how many you need for the day.

How many passes are needed?

You work with overlapping passes, going over the area until the surface no longer gives. The number changes with soil, layer and machine.

Do I need the rubber mat?

Yes, if you compact paving stones: it protects the units from plate marks. On asphalt, instead, you need the water system.

Does the pneumatic rammer work on its own?

No. It runs on compressed air, so you need a compressor suited to the tool.

How do I transport a heavy machine?

Many models have transport wheels or a dedicated trolley, which is in the collection as an accessory. For the heaviest machines plan on two people or a lifting device anyway.

The full catalogue is in the vibrating plates, rollers and trench rammers collection. To choose the machine or ask for a quote, contact the AMES technicians.