Pin Retention Bands and Shims

In 1984, Thiokol of Brigham City, Utah, approached Voss for assistance in development of a new, high-strength pin "retention band" used on the joints of the Space Shuttles Solid Rocket Motors (SRMs).

The SRMs consist of a series of sections approximately 12 feet in diameter and stacked together and joined by means of radially-pinned rings.

The ends of each segment are machined to form tang and clevis joints. Each joint is fastened with 177 one-inch diameter steel pins that are held in place with the Voss manufactured retention bands. 

Voss also supplies shims that are used to "make up" out-of-roundness in the SRM casings.

The retention bands not only help hold the SRM together during launch and subsequent 124-second "burn", but must also hold the locking pins in place during parachute recovery descent into the ocean when the SRMs strike the water at nearly 60 mph. The bands must also resist salt water corrosion for periods up to several weeks during recovery operations. The bands were made well enough that they can be reconditioned for reuse on subsequent Shuttle launches.

Socket head bolts and trunnions are used to assemble the three-segment pin retention bands. This latching arrangement provides a very low profile with high-strength characteristics. The low profiles is necessary to accommodate the aerodynamic fairing and heating elements that cover each joint.
Retention Band