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-   -   Doxford Engines 3-legged (https://www.shipsnostalgia.com/showthread.php?t=14518)

hamishb 5th October 2011 17:37

3 Legged Doxford
 
Quote:

Originally Posted by jolee (Post 161090)
I am researching details of 3-cylinder Doxford Engines built prior to turboblowers becoming standard about 1940.
A few main features I've found out so far but need verification: 1. They are famous for economy (helped win the battle of the Atlantic). 2. The throw of the crank for the Upper Cylinder was half the throw for the Lower Cylinder. 3. Some may have had open crankcases. 4. The scavenge pump was driven by a pair of parallel levers connected to the upper No 2 cylinder con rods. 5. Their Engine Frames were cast rather than fabricated.
I've been trawling the www for details so I can build a representative model. There must have been hundreds of these 3-legged Doxfords built but now its hard to find enough drawings to show how they were made and operated.
I'd be very appreciative if any reader could throw some light on this not-too-distant piece of Marine Engineering history.
best regards,
Jolee

Hi Jolee
If you send me a personal message with your address I will mail a CD with a set of drawings for a 1930/40s Doxford 50/1 scale 60LB3
engine.
The original bore was 600m/m.
To get an idea of the finished job see the avatar used by averheijden which is a photo of the engine.
Best reghards
Hamish.

averheijden 19th February 2012 10:44

Quote:

Originally Posted by demodocus (Post 161091)
There was a 3 cylinder Doxford on at least 1 of the following China Nav. ships ..... Shansi, Soochow, Szechuan, Sinkiang all built UK 1945/46

Dear Sir,
I can not find that one of them had a 3-legged DOXFORD see the following links

SINKIANG
http://www.clydesite.co.uk/clydebuil...p.asp?id=19305

SOOCHOW
http://www.clydesite.co.uk/clydebuil...ip.asp?id=2129

SHANSI
http://www.clydesite.co.uk/clydebuil...p.asp?id=19307

Szechuen (had Sulzer Engines)
http://www.ssmaritime.com/CN-Anking-Anshun.htm

Regards
Alfons
http://users.telenet.be/doxford-matters

Strachan 19th February 2012 20:23

Then one of the sources is wrong.

I sailed on Shansi and Soochow and one of them was a 3-cyl Doxford but I can't remember which.

NoR 19th February 2012 20:43

Quote:

Originally Posted by cubpilot (Post 539535)
The China Nav vessel MV Chefoo (sp) which was on the Papua New Guinea service out of Sydney about 1970 and renamed Island Chief was 3 cyl Doxford. She was built in Hong Kong at the company shipyard and the engine was also built at Taikoo yard. The neatest, trouble free Doxford that I sailed on. 6 months on her and not one stoppage

Didn't they have a ship called the New Guinea Chief also HK built ex ??

R58484956 20th February 2012 14:50

MV 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.

averheijden 21st February 2012 10:11

Quote:

Originally Posted by R58484956 (Post 577480)
MV 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.

Probably you mean this one?

But not a 3-Legged
http://i50.photobucket.com/albums/f3...n/64d34eae.jpg

http://i50.photobucket.com/albums/f3...n/90013e4d.jpg

Picture as “ms STRAITS STAR”
http://www.shipspotting.com/gallery/...hp?lid=1247280

So far as I know on this moment TAIKOO DOCKYARD built only this type of DOXFORD
670 LB4, 4500 BHP, at 115 rpm, not a Mushroom Type , but with 2 attached lever driven scavenging pumps

Here a model made by the TAIKOO people
http://i50.photobucket.com/albums/f3...n/23e7f393.jpg

Is that correct?, if not please let me know, I am working on a list from Taikoo Doxford’s and CNC

Regards
Alfons
http://users.telenet.be/doxford-matters


PS: It looks to me, that no pictures are allowed on this Topic?

Varley 21st February 2012 10:26

I was always told that Doxford's demise was down to NO them having licensee builders. Obvious from this not completely true. Can anyone expand on this? David V

(Sorry idiotic typo!)

Mike S 21st February 2012 10:55

I was under the impression that the classic Doxford was a victim of it's own design in that the crankshaft was unable to handle the increasing horsepower of it's rivals and they reached the design limit.
Still a wonderful engine and a famous part of maritime history.

TIM HUDSON 21st February 2012 11:44

Ellermans "City of Bristol" (ex Sacremanto) had twin screw 3 cylinder Doxfords. The engines were installed displaced by one cylinder as their side scavenge pumps were on centre cylinder. Built by Cammell Laird 1945, 670mm bore I think. The 'wrong way' alarm was in very frequent use during manoeuvring !

ccurtis1 21st February 2012 15:25

Quote:

Originally Posted by NoR (Post 577346)
Didn't they have a ship called the New Guinea Chief also HK built ex ??

Yes they did. I sailed on her. Sydney/Brisbane/Port Moresby/Madang/Lae/Wewak then back to Sydney to start all over again. Great times on a good run. She was a Doxford and built if memory serves me correctly in HK. I think she was originally the Kwangsi but may be wrong

Duncan112 21st February 2012 17:03

43 Attachment(s)
Quote:

Originally Posted by Mike S (Post 577709)
I was under the impression that the classic Doxford was a victim of it's own design in that the crankshaft was unable to handle the increasing horsepower of it's rivals and they reached the design limit.
Still a wonderful engine and a famous part of maritime history.

That's always been my opinion because there are only 4 ways to increase the power of a reciprocating engine:

1) Increase the cylinder diameter but this increases the distance between the main bearing centres, in the case of a Doxford this distance is already large because of the presence of the side rods and bearings. This would result in the crankshaft bending too much between the main bearings.

2) Increase the piston stroke - this would lead to an over long cylinder liner with associated casting problems, the tripartite liner as an attempt to overcome this was never really successful

3) Increase the mean effective pressure in the cylinder - this would increase the bending moment on the crankshaft - see 1 above

4) Increase the number of cylinders - this would lengthen an already long engine increasing the size of the machinery space and eating into cargo space.

Mind you, material science and technology has come on a great deal in the 30 years since the demise of the Doxford, maybe these problems could now be overcome.

One other problem was the additional survey requirements of the bearings for the side rods, 2 bottom ends and crossheads.

hamishb 21st February 2012 22:07

Quote:

Originally Posted by Varley (Post 577699)
I was always told that Doxford's demise was down to them having licensee builders. Obvious from this not completely true. Can anyone expand on this? David V

Hi David, if you go to doxford-engine.com you will find a fairly comprehensive history of the Doxford engine
Hamish

Varley 22nd February 2012 00:06

Quote:

Originally Posted by hamishb (Post 577881)
Hi David, if you go to doxford-engine.com you will find a fairly comprehensive history of the Doxford engine
Hamish

Hamish, much obliged (I did, of course, mean NO licensees - brainfade) David V

averheijden 22nd February 2012 08:41

Quote:

Originally Posted by ccurtis1 (Post 577769)
Yes they did. I sailed on her. Sydney/Brisbane/Port Moresby/Madang/Lae/Wewak then back to Sydney to start all over again. Great times on a good run. She was a Doxford and built if memory serves me correctly in HK. I think she was originally the Kwangsi but may be wrong

http://i50.photobucket.com/albums/f3...n/64d34eae.jpg

Yes it was the KWANGSI

Alfons

teb 23rd February 2012 15:27

Denholm family owned "Carronpark"blt 49 & "Lylepark" blt 51 were 3legged Doxford engined.

Chillytoes 25th February 2012 09:35

"That's always been my opinion because there are only 4 ways to increase the power of a reciprocating engine:"

Duncan
There is a fifth way, increase the revs.

averheijden 27th February 2012 12:36

Quote:

Originally Posted by R58484956 (Post 577480)
MV 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.

For the original DOXFORD from the SOOCHOW see the story from George Robinson and Angus Mac Kinnon

http://forums.clydemaritime.co.uk/vi...p?f=36&t=18722

Alfons

crowmountain 25th March 2012 02:41

Quote:

Originally Posted by Mac (Post 161122)
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.

Sailed on the Soochow in 1965 when CNCo sold it to a Singapore company.
Had cam driven LO and FW pumps and was difficult to start but easy to run. The ship was built in 1945 and the engine was a salvage job from world war 2.
We all could the "Doxford Dance"

averheijden 4th April 2012 15:40

L.S;

http://users.telenet.be/doxford-matt...20HONGKONG.pdf

When you click on row 3 on "Shansi(3) than it shows that it is a 4 legged??

Everything a bit frustrating sometimes after so many years

Alfons

http://users.telenet.be/doxford-matters

see also:
http://www.ssmaritime.com/CN-Changsha-Taiyuan.htm

ARRANMAN35 4th April 2012 18:05

Doxford Three Legged
 
Teb advised of the Carronpark and Lylepark of Denholms, in addition
managed by them were:
Arisaig
Clarkavon
Clarkeden
Craigallian
Crinan
Naess Trader
Wellpark
All operated satisfactory and gave good service over their respective
lifes.
Served on a few of them from J/E TO 2E.

Archie

HYLTON P 5th April 2012 11:11

3 Cyl Doxford
 
I Sailed On The Cyprian Prince As A Junior Engineer Back In 1967 She Did Have A 3 Cylinder Doxford And Steam Auxillaries A More Reliable Engine Would Be Hard To Find

R58484956 5th April 2012 12:10

Greetings Hylton P and welcome to SN. Bon voyage.

XFullFatTim 1st October 2012 15:03

A little off topic as it relates to later engines:-
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 were supplied to the City of Plymouth Class 300TEU "paragraph" ships built at A&P Addpledore in devon - a 6th Engine was also built but never fitted to a ship and the last I heard had been donated by Ellermans to the Glasgow Museum of Transport. The first engine was supposed to run on a homogenised coal dust/ oil slurry but it didn't work............... the engines were way too powerful for the ships giving a Dead Slow speed of 7.5knots and really should have been mated to a contollable pitch prop. 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 City of Plymouth had the start assister detect a dead band start situation while the engine was turning at 220rpm, which didn't do it or the rest of the engineroom a lot of good. I left Ellerman's in 1988 to join P&O Containers and remember seeing the City of Oxford trading in the Malacca Straits in 1992/3 as the Hyundai Malacca. Prince Line also had two vessel fitted with the same engine - Crown Prince and Royal Prince I think. They were handed over to OOCL when Furness was taken over by C Y Tung Group. I am now in command of some of the Maersk Line ships at the other end of the size/ power scale.

averheijden 4th October 2012 14:44

3 Attachment(s)
Quote:

Originally Posted by XFullFatTim (Post 624748)
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

Ian J. Huckin 4th October 2012 18:13

Quote:

Originally Posted by Chillytoes (Post 578874)
"That's always been my opinion because there are only 4 ways to increase the power of a reciprocating engine:"

Duncan
There is a fifth way, increase the revs.

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.


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