Background and History

SSS Clutches were first specified for marine propulsion in the late 1950’s when friction plate synchronising designs failed within the British Royal Navy Y-100 propulsion machinery.  Despite those friction clutch designs being successful within test rigs, it became obvious very quickly that seaway motion combined with high torque manoeuvres (hard rudder turns etc.) was a tough challenge.  The challenge was complicated by the high power, high speed and large inertia of steam turbines driving those warships.

The original marine design SSS Clutches were perfected within HMS Scarborough and Keppel (COSOS single and twin shaft).

Success in Y-100 lead to SSS Clutches being specified for the Type 81 Tribal Class frigates (COSAG) and County Class (COSAG) destroyers of the Royal Navy and later HMS Exmouth, the world’s first all gas turbine powered warship (COGOG and later COGAG).

The Canadian Navy followed this British development, thus SSS Clutches also became specified.

Entirely positive experience lead to SSS Clutches being specified for Types 82, 21, 22, 42 (COGAG) and 23 (hybrid CODELAG) as well as the Invincible Class carriers HMS Invincible, HMS Illustrious and HMS Ark Royal (COGAG).

Meanwhile, the US Navy had contracted 3 different types of propulsion clutch.  SSS Clutches were used on Oliver Hazard Perry Class FFG, whereas friction and forced dental toothed couplings had been specified within the US Navy’s PG Gunboats, Hamilton Class Cutters and Spruance Class destroyers.  Whilst the SSS Clutches within FFG enjoyed unrivalled success, others suffered failure.  On one particular occasions, lead of class DD-963 USS Spruance suffered simultaneous failure on all 4 friction clutches, rendering her a sitting duck.

Successful retrofit of Spruance class, PG Gunboats and Hamilton Class cutters as well as continued positive experience within FFG Oliver Hazard Perry Class lead to SSS Clutches being specified for all US Navy gas turbine powered warships from USS Arleigh Burke Class DDG-51 onwards, including the most modern US Naval propulsion designs.

Many of those early SSS Clutches still remain in operation today.  Notably, many FFG class ships remain in operation, notably with the Royal Australian Navy Adelaide Class FFG.  Despite 35+ years of operation, those SSS Clutches remain fully operational as do those within the many Type 21 and 42 class Royal Navy ships which are no leased to foreign navies.

There’s a reason SSS Clutch became specified for so many navies.  We hope those lessons are never forgotten.

Glossary of terms :

COSOS - COmbined Steam Or Steam turbines

COSAS - COmbined Steam And Steam turbines

COGOG - COmbined Gas Or Gas turbines

COGAG - COmbined Gas And Gas turbines

CODAG - COmbined Diesel Engine And Gas turbines

CODOG - COmbined Diesel Engine Or Gas turbines

CODELOG - COmbined Diesel Electric Motor Or Gas turbines

CODELAG - COmbined Diesel Electric Motor And Gas turbines

*(SIC) In XXXX, SSS Gears Chairman and Managing Director H. A. Clements wrote a technical paper detailing how the US Navy could use SSS Clutches, two speed gearing and an SSS-TOSI fluid coupling to operate AOE-6 in both forward and aft operations, using single directional gas turbines.  The 5,000 word technical paper was made most famous by a single correction requested by the US Navy, that being the US preferred spelling “maneuver” of the word “manoeuvre”.