Vulcan and Hammer Leaders

Leaders is the generic term for the guide which allows the pile hammer to be positioned on top of the pile and then started to drive the pile to its desired head elevation. Although not a prominent part of Vulcan product line, the company did produce leaders of many kinds. This page is also intended to give an overview of pile hammer leaders in general.

Additional Sources:

Leaders can be broadly categorised in two ways: the method by which they interface with the hammer and the way by which they are connected to (and guided by) the crane.

Hammer Interface

Pile hammer leaders basically guide the hammer in one of two ways: from the side or from the back.

Vulcan hammers–in common with most American pile hammers–were guided from both sides of the hammer, with both hammer and pile between the guides. Leaders such as this are referred to as “U-type” leaders. Most of the Vulcan hammers shown on this site are riding in U-type leaders, both onshore and offshore.

Onshore-Leaders-Jul-73
Onshore, “U-type” leaders, at the West Palm Beach yard in July, 1973. The hammer (and driving accessory) rode between the two large pieces of square tubing at the bottom of the leaders. Structurally sound, the leader system suffered the disadvantages of a)bolted connections (most contractors preferred pinned ones for easy assembly and disassembly, and b) the protruding triangular gussets on the back caught the air hose.

European practice prefers to guide the hammer from the back. This is generally referred to as a “spud” type leader. The spuds have both a structure for stiffness and rails to interface with the hammer. These rails can be of several types, including round rails (Delmag, Nilens) or two channels back to back (Russian.)

 

Crane Interface

There are several methods of interfacing the leaders with the crane, depending upon the nature of the job and the preference of the contractor:

  • Swinging Leaders
  • Underhung Leaders
  • Fixed Leaders and Spotters
  • Offshore Leaders, Stub-Type Leaders or Flying Extensions

Swinging Leaders

The most common type of leaders, these are simply suspended from the crane (at some distance.) For most plumb pile applications, they are suitable.

 

Underhung Leaders

Underhung leaders are attached to the boom point, either rigidly or through a cable.  Underhung leaders at one time were popular, but have been largely displaced by fixed leaders.

 

Fixed (Extended) Leaders

 

Stub (Offshore) Type Leaders

These leaders are a shortened version of swinging leaders. They are intended for use with a template, which both holds the pile in place and sets the batter angle of the pile as well. Virtually all of Vulcan hammers used offshore were run in these leaders.

Vulcan-560-Daelim-1991
A Vulcan 560 in Vulcan manufactured offshore leaders driving pile for the Korean contractor Daelim in 1991. Although Vulcan would have considered this an “onshore” job, it is a classic example of an offshore style hammer used to install a steel jacket. Note that the jacket is acting as the template, which in turn aligns and positions the piles. The leader and hammer assembly is lowered through the conical, adjustable stabbing bell and than the pile is threaded onto the pile cap, the assembly assuming the batter of the piles. The assembly is suspended from the hinged lifting bale at the top of the leaders. As the hammer drives the pile, the leaders are lowered to keep up with the hammer’s progress.
Advertisements

4 thoughts on “Vulcan and Hammer Leaders

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s