This type of leader has connections at both the top or mid-point and the bottom of the leads.
The connection at the top is normally a pivot or rotational type connection, at the bottom there is normally a brace which extends from the crane to the leads.
This connection normally has a method for adjusting the in or out from the crane and left or right.
This allows any type of batter to be used.
This system severely limits what the crane can do and in general requires the most set-up time.
No template is required for fixed leads.
These leads are attached to the crane at the top by the main cable.
They have a gate at the bottom which holds the leads around the pile and will sometimes have spikes on the bottom which are stuck into the ground or template to assist in aligning the hammer.
This type of lead is best suited for piles with little or no batter.
The advantages of this type of lead include allowing the crane to be used for other activities, they can be swung into areas with difficult access, and they are relatively easy to set up. A template must be used in conjunction with swinging leads.
This type of lead has a pivot or sliding connection to the crane at either the top or bottom of the leads.
Normally the connection is at the top of the leads.
Semi-fixed leads can accommodate a greater batter than swinging leads, however, they limit what the crane can do and are more difficult to set up.
This type of lead also requires the use of a template.
Cushions are used to protect both the hammer and the pile.
Cushions that protect the hammer are called hammer cushions or hammer cushions.
Cushions used to protect the pile are called pile cushions.
Hammer cushions are constructed of man-made materials that are heat resistant, durable and absorb a
certain amount of shock. Common types of materials are aluminum, micarta and polymer which are in the form of disks.
Hammer cushions are located between the point of the ram or anvil and the pile cap.
Bruce adapted high quality and durable of MC-904 cushion material or Klinger Pad.
Pile cushions are placed between the pile top and the pile cap on concrete piles.
Pile cushions are not used on steel piles or timber piles.
Pile cushions consist of plywood. Pile cushions are generally replaced for each pile or as directed by the Engineer.
Pile cushions are located between the top of the pile and the bottom of the pile cap.
Pile Cap or Helmet
This is the section of the pile driving system which rests between the hammer and the
For concrete piles, it contains the striker plate or drive cap, a hammer cushion, and the pile cushion.
For steel piles, it will contain the striker plate or drive cap and hammer cushion only; no pile cushion is used on steel piles.
Bruce provides also Followers which is :
An extension, usually steel, used between the top of the pile and the hammer to extend the driving range of the pile (usually below water).