Nortrade

The Dawson hammers are double acting hydraulic hammers well suited for driving sheet piles, steel profiles and timber piles. They are good choices especially for cohesive soils (stiff clays) and dense granular material or soft rocks where vibratory hammers may meet problems

They have rapid blow rates and high energy transfer infinitely adjustable between minimum and maximum at the touch of a button. The enclosed design protects vital components and leads to low maintenance costs. Depending of the size, the hammers can be driven from hydraulic excavators, hydraulic crawler cranes and most powerpacks.

The model designation refers to the max transferable energy in kgm. Dawson manufacturers hammers from 1200 kgm (12 kNm) to 10.000 kgm (100 kNm).

The hammers are produced in several sizes up to an energy transfer of 100 kNm.

HPH-2400 Configured for Sheet Piling

Basically Dawson hammer sets consist of:
- a cast iron drop weight
- a hydraulic hoist cylinder in which the piston is not the drop weight
- a combination of guide cylinder and frame to tie everything together
- a cast steel anvil with resilient dolly
- a control pendant
- a power pack

Cast iron drop weight
The drop weight is driven up and down by a hydraulic ram inside a housing. The ram is double acting so the drop weight is accelerated both on the up­stroke and the downstroke. This gives the hammer a high energy output and high blow rate.

Hydraulic hoist cylinder
Dawson hammers use the motion of the drop weight to activate hydraulic pilot valves which provide a hydraulic pilot signal to the main control valve which activates the hoist cylinder. All of this is mounted on the hammer casing. Adjustment of hammer drop height takes place hydraulically from a control pendant.

Power pack
The oil supplied to the hydraulic ram comes from the power pack via a control valve mounted inside the top of the hammer. This control valve switches the oil supply on or off at the upstroke side of the hydraulic ram i.e. oil supply "on" lifts the drop weight and oil supply "off" drops it.

Main advantages by the Dawson hammers:

• Ability to give a powerful drive without massive weight.
• Blow control at the touch of a button - from single blows at the start to automatic blows for the rest, the operator has full control of the pile installation.
• Rapid blow rates from the double acting hydraulic cylinder reduces driving time and chisel through compacted sands, outdriving much heavier, slower hammers.
• High blow rate (up to 140 blows per minute) gives efficient penetration and higher productivity.
• Rapid, remote control of energy per blow and blows per minute.

HPH-6500 on Pipe

• All hydrulic operation. The abscence og electronic components produces simple and reliable fuctionality.
• Most single and double sheet piles can be driven using the same standard leg inserts and anvil.
• The standard insert configuration fits a wide variety of sheet and H pile types.
• Enclosed design protects sensitive components.

Thumb Rules for the Choice of Hammer
Dawson hammer HPH 1200
HPH 1200 is suitable for all driving until very dense or very stiff ground is encountered. At this time the HPH 1200 will toe the piles into, but not drive through the material. The SPT number (N value) at this level might be anything between 50 and 100.

Dawson hammer HPH 2400
This hammer is suitable for driving a pile 3 or more meters through very stiff clay.

Hammer with Legs for Installing Sheet Piles

Applications

Dawson hammers are often used for installing straight web piles in cells.

Dawson hammers are also used under water.