Torpedo Spelter Buttons for High Strength Non-Rotating Ropes up to 2160 N/mm2, ASTM 1023, Category 1

Spelter Buttons were developed to solve two basic problems using high performance non-rotating cranes ropes:

1. Standard old fashioned wedge sockets are not made to accomodate high density and high strength non-roating ropes. Bulging of the ropes over too small wedges was one problem. The other was that standard wedge sockets were not able to maintain the required 80% rope strength efficiency.

Traditional Wedge Sockets were not designed for high strength rotation resistant ropes.
Parts of a S 421 Wedge Socket. Note the small D/d ratio of the wedge vs the rope.
If you need to use a wedge socket with high strength rotation resistant rope use Crosby S 423 sockets which are designed with a larger wedge radii and they meet the 80% breaking strength retention requirement.

2. Installing a relatively stiff high performance rope into a standard wedge socket is not easy (try that in winter in sub freezing temperatures).Torpedo Spelter Buttons permit hoist line re-reeving without first removing a cumbersome wedge socket and dealing with a ‘kinked’ rope to feed through tight spaced sheave blocks.

Example of a mobile crane standard lower sheave block.
Note the tight spaced sheaves and the close gap between the retention bar and the sheave groove bottom.
Torpedo buttons are small enough to fit through the sheave blocks making re-reeving much easier and faster as with wedge sockets.
Note the button pouch below the top sheaves.
Most hoist blocks require the correct Torpedo Button diameter. Not ALL Button styles fit EVERY sheave block.
This is especially important when replacement- or non OEM sheave blocks are installed.

Typical crane tip installed attachment fitting
Typical button pouch