Ships Nostalgia - View Single Post - Doxford Engines 3-legged
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Old 4th October 2012, 14:44
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averheijden averheijden is offline  
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Quote:
Originally Posted by XFullFatTim View Post
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.
L.S.
The STARTING ASSISTER (JS3 DOXFORD ENGINES)

The S.A. consist of 2 pneumatic power cylinders (1) , on for ahead and one for astern
They are mounted vertically at the forward end of the engine and pivoted at the top so that the roller at the end of the piston rod can be engaged to a wheel (2) at the forward end of the crankshaft to turn the shaft the required amount.
Each power cylinder is brought in engagement by means of an engagement cylinder (3) acting through a lever mechanism (4)
They are disengaged at the end of the stroke and brought back to their storage positions by means of return springs (5)

These springs (5) will keep the power cylinders firmly away from the wheel (2) while the engine is running.
Special plates on the wheel prevent the ahead power cylinder from engaging in the astern grooves, and vice versa.

According the above story from "XFullFatTim" was the starting assister not ALWAYS a big success?
(Perhaps the spring 5 was broken in the above mentioned accident?)
Who can tell more about his experience with the starting assister?

Kind Regards
Alfons
Attached Images
File Type: jpg COMBI CITY OF PLYMOUTH.jpg (240.7 KB, 38 views)
File Type: jpg starting assiter.jpg (88.8 KB, 44 views)
File Type: jpg Start Assister half.jpg (78.5 KB, 40 views)
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