TRW HIS­TORY

Classic Bike (UK) - - Triumph TRW Battles On -

The TRW wasn’t Triumph’s first mil­i­tary twin. The Ed­ward Turner-de­signed 350cc 3TW ohv light­weight twin had just com­menced pro­duc­tion when bombs de­stroyed the Coven­try fac­tory in 1940. When the new Meri­den fac­tory opened in 1942, build­ing thou­sands of 350cc 3HW ohv sin­gles was the pri­or­ity. Turner re­turned to Triumph from a brief stint at the ri­val BSA fac­tory, hav­ing re­port­edly de­signed a 500cc side-valve mil­i­tary twin while there – but Triumph re­solved to trump the BSA twin and was first to have a pro­to­type run­ning, in 1943. Coded 5TW, it was pit­ted against the BSA and a 600cc Dou­glas side-valve flat-twin in post-war Min­istry of Sup­ply com­par­i­son tests.

The 5TW had the fac­tory’s first tele­scopic forks and a crank­shaft sim­i­lar to the Speed Twin’s, but camshaft drive was by chain in­stead of gears. To help meet a 300lb max­i­mum weight stip­u­la­tion, the crank­case was of mag­ne­sium al­loy.

The MOS, which would have sub­sidised tool­ing and pro­duc­tion, can­celled tri­als in 1948. A spe­cial mil­i­tary ma­chine would be too costly, so the pol­icy in­stead would be to adapt an ex­ist­ing pro­duc­tion model to mil­i­tary trim, should the ne­ces­sity arise. See­ing fu­ture or­ders likely, Meri­den re­vised the de­sign so as to share 80% of com­po­nents with ex­ist­ing mod­els. The frame and other cy­cle parts came from the TR5 Tro­phy tri­als iron, while the en­gine used a crank­shaft like that in the 350cc 3T com­muter ohv twin, with one-piece con­rods on crankpins clamped with cot­ters in a cen­tral fly­wheel. Meri­den could then of­fer a mil­i­tary bike at a keen price and did not rule out a pos­si­ble civil­ian ver­sion. The TRW, known at the fac­tory as the Hy­brid, ap­peared at the 1949 Scot­tish Six Days Trial in the hands of MOS rider WA Ran­dall, who also rode one to a Gold Medal in that year’s ISDT. Pro­duc­tion batches be­gan in 1950, the big­gest by far be­ing more than 2000 in 1957. While the Bri­tish Army stuck with BSA’S M20 side-valve sin­gle as its stan­dard is­sue for low-rank­ing sol­diers, it or­dered some TRWS, in­clud­ing for the Royal Sig­nals White Hel­mets dis­play team, who fa­mously car­ried 22 sol­diers on one bike. Triumph found sev­eral other buy­ers in­clud­ing NATO forces and au­thor­i­ties as far afield as South Africa and Pak­istan. Nearly 16,000 were built in batches un­til 1964, one leav­ing the fac­tory with a swingarm frame. Lit­tle-used TRWS can now fetch £10,000 and caches of NOS parts have popped up (see bur­ton­bikebits.net). As Chris Evans dis­cov­ered, the TRW is no longer scorned for its util­i­tar­ian char­ac­ter. Mod­est per­for­mance does not pre­clude it from be­ing a cool ur­ban ride that can be made more glam­orous with a pe­riod civil­ian fin­ish.

Triumph TRWS about to be testrid­den at Meri­den

Cut­away en­gine shows gear-driven camshaft

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