For the original DOXFORD from the SOOCHOW see the story from George Robinson and Angus Mac KinnonMV Soochow 3 cyl Doxford 20 1/2" x 81 7/8ths" built by Doxfords. Ship built by A & J Inglis Glasgow. The other 3 had 4 cylinder diesels.
Sailed on the Soochow in 1965 when CNCo sold it to a Singapore company.As Demodocus has written at least one of the immediate post war S class ships built for China Navigation was a three legged Doxford. This was the Soochow built by A & J Inglis Ltd Glasgow in 1947 using an engine recovered from a vessel sunk in the Mersey. This was the story accepted by all onboard in the late fifties, including myself. The other three ships were four cyl. Doxfords.
L.S.They weren't terribly reliable but once started they ran beautifully smoothly. The unreliability was on the starting and stopping but this was resolved with some major redesigning of the liners and piston crowns of the City of Oxford that transformed the engine's maneuverability. Part of the starting problem was a "dead band" detector that sometime didn't detect that all 3 units were "in line" and the start assister didn't engage to give the engine a half a turn by hydraulic ram............. IIRC the City of Plymouth had the start assister detect a dead band start situation while the engine was turning at 220 rpm, which didn't do it or the rest of the engine room a lot of good.
Hmmmmm! Increasing RPM does not necessarily increase power as fuel burn time (cetane index), scavenging efficiency and gas flow rates are all going to compromise power output after passing through the "sweet spot" where max power and torque are produced."That's always been my opinion because there are only 4 ways to increase the power of a reciprocating engine:"
There is a fifth way, increase the revs.
EGTON'38 SR(RUNSWICK/GLAISDALE Doxford "Economy")I have served on a Post War 3 cy unit which was in the Egton, however, the pre War 3cy was (barring for the Scott-Still) one of the most highly rated Marine Engine's available at a mechanical efficiency at about 82% other's being around 73%
L.S (XFullFatTim;624748)I sailed as 2nd Mate and Chief Officer on 5 ships operated by Ellerman City Liners from 1981 though to 1988 that had the last Doxford 3 legged engines built. They weren't terribly reliable but once started they ran beautifully smoothly. The unreliablity was on the starting and stopping but this was resolved with some major redesigning of the liners and piston crowns of the City of Oxford that transformed the engine's manoeuvrability. Part of the starting problem was a "dead band" detector that soemtime didn't detect that all 3 units were "in line" and the start assister didn't engage to give the engine a half a turn by hydraulic ram............. IIRC
The piston and liner mods were to improve the compression, particularly when starting astern as there was a lead on the exhaust piston which made starting sometime a bit of a lottery with a bit of liner and piston ring wear!L.S (XFullFatTim;624748)
I am curious to know, what means exact the major redesigning of liners and pistons crowns which transformed in better manoeuvrability?
According DOXFORD the starting assiter was only necessary 1 in 100 times starting?
This was find out on the testbed, perhaps in reality it was different?
Awaiting your answer
Certainly on the 58JS3s we only designed the ships to carry 1 spare liner but I seem to recall City of Bristol (2 x 60[?]LB3) that there were "quite a few" although I' not sure why as she ran on diesel and the wear rates were very low. However I think in her early days she had a few liners crack.