Rummaging among the cogs
As a boat owner practical enough to cope with most maintenance I still had to think twice before delving into the guts of my gearbox. One imagines the need of special tools and workshop facilities, maybe a hydraulic press, and the prospect of shrapnel pinging off the walls as some unsuspected spring escapes captivity.
However, on relaunching Tudor Rose in 2018 after a 15-year refit (what can I say? I work slowly!) I found myself cocking a critical ear to her old gearbox, built by PRM in Coventry. It came second-hand long ago together with her BMC 1.8 diesel engine and now has at least 40 years’ service under its cogs. It was working perfectly except for a slight grumbly whir. Nobody else seemed to notice but as the gearbox ran more quietly astern, when more gearwheels are under load than ahead, this curious behaviour nagged at the back of my mind. Suspecting a failing thrust bearing I resolved to inspect its innards.
’s gearbox is either a PRM 100 or 140 – the ID plate has long since disappeared so it’s hard to tell the difference. Either way it is an old model no longer made. Spares are not available from PRM-Newage but some parts are obtainable commercially and
