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MTA
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Lord NelsonJust got back from seeing SR 4-6-0 LN Class No. 850 'Lord Nelson' powering past my local crossing. What a handsome engine, clean lines and that distinctive eight beat per revolution which you get from a 4 cylindered engine! Alas I did not get a picture as my new camera froze   Although I met someone there who was taking video and pictures, and promised me a print of the best picture he took  I might go back to see her on the return journey and get a picture then, depending on the weather and whether it is dark or not! Plus no doubt she will be delayed by many hours 
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John Chapman
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Re: Lord Nelson | MTA wrote: | | Alas I did not get a picture ... |
No problem MTA. her is a picture of Lord Nelson for you 
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Sandman
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Re: Lord Nelson | John Chapman wrote: | | MTA wrote: | | Alas I did not get a picture ... |
No problem MTA. her is a picture of Lord Nelson for you
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Lewis
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Re: Lord Nelson | MTA wrote: | | Just got back from seeing SR 4-6-0 LN Class No. 850 'Lord Nelson' powering past my local crossing. What a handsome engine, clean lines and that distinctive eight beat per revolution which you get from a 4 cylindered engine! Alas I did not get a picture as my new camera froze Although I met someone there who was taking video and pictures, and promised me a print of the best picture he took I might go back to see her on the return journey and get a picture then, depending on the weather and whether it is dark or not! Plus no doubt she will be delayed by many hours |
sounds good MTA
never seen a lord nelson before 
what power rating are they ?
i now the battle of britains ect were 7p
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John Chapman
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Re: Lord Nelson | Lewis wrote: |
never seen a lord nelson before
what power rating are they ?
i now the battle of britains ect were 7p |
The only really meaningful classification of a locomotive's power is it's Tractive Effort. For a "Battle of Britain" this was 31,050 pounds and for the "Lord Nelson" 33,500 pounds. For comparison a GWR "Castle" had a T.E. of 31,625 pounds and a "King" 40,300 pounds.
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Lewis
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cheers mate 
lord nelsons sure do look nice
i preffer the light pacifics myslelf though
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John Chapman
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| Lewis wrote: | cheers mate
lord nelsons sure do look nice
i preffer the light pacifics myslelf though |
Very fond of them myself
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MTA
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Re: Lord Nelson | John Chapman wrote: | | Lewis wrote: |
never seen a lord nelson before
what power rating are they ?
i now the battle of britains ect were 7p |
The only really meaningful classification of a locomotive's power is it's Tractive Effort. For a "Battle of Britain" this was 31,050 pounds and for the "Lord Nelson" 33,500 pounds. For comparison a GWR "Castle" had a T.E. of 31,625 pounds and a "King" 40,300 pounds. |
I'm afraid it's time for another MTA Railway lesson folks 
It's strange how tractive effort is often wrongly interpreted as a measure of the effective power of a locomotive, but is really only a theoretical figure indicating the maximum pull that an engine can exert from a standing start given perfect adhesion and tight glands and pistons, and has little to do with the actual work of which it is capable. One example is a J94 Class 0-6-0ST has a comparable tractive effort to a Black 5! The late Dr. W.A.Tuplin, railway historian and engineer, describes tractive effort as 'the mean value (during any revolution of the driving wheel) of the backward push that the loco could exert on the rails when in full gear when in full gear with maximum boiler pressure if the friction between coupled wheels and rails was great enough to transmit the pull and there was no friction anywhere else'.
Drawbar Horsepower on the other hand is a much better way of measuring the haulage capability of an engine. This is normally calculated from readings taken by a dynanometer car attached to an engine during a soecially organised run with a known load over a substantial period of time or distance.
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MTA
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John, nice one with the Lord Nelson gag  Nice engine too, when in service. Blackmoor Vale seems prone to failing in service quite a lot of the time
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John Chapman
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Re: Lord Nelson | MTA wrote: | | John Chapman wrote: | | Lewis wrote: |
never seen a lord nelson before
what power rating are they ?
i now the battle of britains ect were 7p |
The only really meaningful classification of a locomotive's power is it's Tractive Effort. For a "Battle of Britain" this was 31,050 pounds and for the "Lord Nelson" 33,500 pounds. For comparison a GWR "Castle" had a T.E. of 31,625 pounds and a "King" 40,300 pounds. |
I'm afraid it's time for another MTA Railway lesson folks
It's strange how tractive effort is often wrongly interpreted as a measure of the effective power of a locomotive, but is really only a theoretical figure indicating the maximum pull that an engine can exert from a standing start given perfect adhesion and tight glands and pistons, and has little to do with the actual work of which it is capable. One example is a J94 Class 0-6-0ST has a comparable tractive effort to a Black 5! The late Dr. W.A.Tuplin, railway historian and engineer, describes tractive effort as 'the mean value (during any revolution of the driving wheel) of the backward push that the loco could exert on the rails when in full gear when in full gear with maximum boiler pressure if the friction between coupled wheels and rails was great enough to transmit the pull and there was no friction anywhere else'.
Drawbar Horsepower on the other hand is a much better way of measuring the haulage capability of an engine. This is normally calculated from readings taken by a dynanometer car attached to an engine during a soecially organised run with a known load over a substantial period of time or distance. |
Tractive effort (TE) is, and as far as I am aware always has been, the normal way of expressing the power of a locomotive. You quote the late Dr Tuplin definition of TE, and this is indeed accurate. TE is a calculated figure based on the design parameter and can be applied equally to all locomotives for comparison purposes. The normal formula for TE is -
TE = 0.85Pds/D
Where
TE = Tractive Effort
P = boiler pressure (in pounds/square inch)
d = piston diameter squared
s = piston stroke
D = driving wheel diameter
I agree that Drawbar Horse power, being a measured figure, is a more accurate representation of the power of a particular locomotive, on a particular day and under particular conditions. However one must be aware that two readings taken at different times and under different conditions will show variance. Unfortunately Drawbar Horsepower figures are not widely enough available to make meaningful comparisons a simple matter. The use of dynamometer cars to arrive at Drawbar Horsepower was in most cases utilised in order to see how a locomotive performed against it's design specification i.e. tractive effort.
The TE figure is normally available for any locomotive, or can be calculated from the design parameters and so is, as I stated, the standard method of expressing a locomotive’s “power”
Regarding your comment about a J94 having comparable TE to a “Black 5”. This is indeed the case and a J94 could probably pull about the same load as a “Black 5”, given that both could get sufficient adhesion. Granted it would not pull it as far or as fast but that is not the point in question.
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Sandman
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That's easy for you to say. 
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Lewis
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| John Chapman wrote: | | Lewis wrote: | cheers mate
lord nelsons sure do look nice
i preffer the light pacifics myslelf though |
Very fond of them myself
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classic
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tree ted
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Re: Lord Nelson | John Chapman wrote: | | MTA wrote: | | John Chapman wrote: | | Lewis wrote: |
never seen a lord nelson before
what power rating are they ?
i now the battle of britains ect were 7p |
The only really meaningful classification of a locomotive's power is it's Tractive Effort. For a "Battle of Britain" this was 31,050 pounds and for the "Lord Nelson" 33,500 pounds. For comparison a GWR "Castle" had a T.E. of 31,625 pounds and a "King" 40,300 pounds. |
I'm afraid it's time for another MTA Railway lesson folks
It's strange how tractive effort is often wrongly interpreted as a measure of the effective power of a locomotive, but is really only a theoretical figure indicating the maximum pull that an engine can exert from a standing start given perfect adhesion and tight glands and pistons, and has little to do with the actual work of which it is capable. One example is a J94 Class 0-6-0ST has a comparable tractive effort to a Black 5! The late Dr. W.A.Tuplin, railway historian and engineer, describes tractive effort as 'the mean value (during any revolution of the driving wheel) of the backward push that the loco could exert on the rails when in full gear when in full gear with maximum boiler pressure if the friction between coupled wheels and rails was great enough to transmit the pull and there was no friction anywhere else'.
Drawbar Horsepower on the other hand is a much better way of measuring the haulage capability of an engine. This is normally calculated from readings taken by a dynanometer car attached to an engine during a soecially organised run with a known load over a substantial period of time or distance. |
Tractive effort (TE) is, and as far as I am aware always has been, the normal way of expressing the power of a locomotive. You quote the late Dr Tuplin definition of TE, and this is indeed accurate. TE is a calculated figure based on the design parameter and can be applied equally to all locomotives for comparison purposes. The normal formula for TE is -
TE = 0.85Pds/D
Where
TE = Tractive Effort
P = boiler pressure (in pounds/square inch)
d = piston diameter squared
s = piston stroke
D = driving wheel diameter
I agree that Drawbar Horse power, being a measured figure, is a more accurate representation of the power of a particular locomotive, on a particular day and under particular conditions. However one must be aware that two readings taken at different times and under different conditions will show variance. Unfortunately Drawbar Horsepower figures are not widely enough available to make meaningful comparisons a simple matter. The use of dynamometer cars to arrive at Drawbar Horsepower was in most cases utilised in order to see how a locomotive performed against it's design specification i.e. tractive effort.
The TE figure is normally available for any locomotive, or can be calculated from the design parameters and so is, as I stated, the standard method of expressing a locomotive’s “power”
Regarding your comment about a J94 having comparable TE to a “Black 5”. This is indeed the case and a J94 could probably pull about the same load as a “Black 5”, given that both could get sufficient adhesion. Granted it would not pull it as far or as fast but that is not the point in question. |
Im with you both on this but I have a friend whos very high up on the fleet engineering side at EWS and he absolutly hates the TE calculations. as he said to me just last week te is only any good from a standing start as soon as speed is picked up TE falls Rapidly Its the rate of this fall that determins how good a loco is.
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