The Lifting Sheave is for hammer lift and release from hammer mounting when pile driving so the crane is safe and not defected in the soft soil condition and safe from sudden pile driving penetration.
The Lifting Sheave is optionally provided for Fixed Leader Type of Bruce hydraulic pile hammers.
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
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 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
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
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 Cap or Helmet
This is the section of the pile driving system which rests between the hammer and the pile.
For concrete piles, it contains the striker plate or drive cap, a hammer cushion, and the pile cushion
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)