Dawson Hydraulic Impact Hammers are "double-acting" hydraulic hammers, whereby the ram-block is hydraulically lifted up AND hydraulically accelerated down on the downstroke.  This "double-action" ensures:

a.  By accelerating the ram-block on the downstroke, the impact velocity is increased and consequently the maximum energy per blow is increased, when compared to a "single-acting" (uplift only) or a "free-fall" impact hammer.  This means that Dawson hydraulic impact hammers deliver higher energy for less hammer weight, so can outperform larger / heavier hammers.  This has numerous advantages including - being able to use smaller cranes (less cost) or being able to reach further (less setups) with the lighter, more powerful Dawson hammers;

b.  By being "double-acting", the ram block is lifted upwards and thrust downwards more quickly than a "single-acting" (uplift only) or a "free-fall" impact hammer.  This means that Dawson hydraulic impact hammers can achieve a higher blow rate per minute than other hammers, which translates to higher productivity.  (Note : blow rate is 80-120 blows per minute);

c.  The high blow rate discussed in b. (above) also ensures that the Dawson hydraulic impact hammers keep a pile moving whilst being driven.  This enables piles to be driven deeper into harder and 'stickier' soils than a hammer with a slower blow rate where the pile stops between blows, and often resulting in premature refusal.

Note : being accelerated, Dawson hammers are best suited to steel pile applications, such as : sheet piles, tube pile, I-beam sections etc.  they are not recommended for use on timber piles or concrete piles.

Pilequip has both Dawson HPH1200 and HPH1800 hydraulic impact hammers in its rental fleet.  Please click on the links below to access the spec sheets for these hammers.  Both of these hammers can be fitted with sheet pile leg guides (standard), which are suitable for single and double sheet pile sections as well as I-beams etc.  The hammers can also be fitted with tube pile guides.  The HPH1200 is limited to max 380mm OD tube piles and the HPH1800 is limited to 475mm OD tube piles.

Dawson1200 Spec Sheet.pdf 

Dawson1800 Spec Sheet.pdf