Trains.com

What does the percentage number mean on a steam locomotive?

13266 views
18 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    January 2009
  • From: Arkansas
  • 10 posts
Posted by quartering machine on Sunday, January 18, 2009 12:50 AM

I had not thought about that way of listing tractive effort, it would be handy data where many engines are used or where a high number of new emploees are working.

  • Member since
    January 2009
  • 2 posts
Posted by Joe6167 on Saturday, January 17, 2009 10:53 PM

Just to avoid confusion, the percent listed on the side of a CNR, GTW, CV, etc. locomotive and has absolutely NOTHING to do with Cut-Off.

It is a short-hand reference to the amount of Tractive Effort that a given locomotive (either Steam or Diesel) produces. 1% = 1,000 lbs of Tractive Effort so 57% = 57,000 lbs.

(If you don't believe me, check CN's mechanical Department Diagrams and look at the Tractive Effort and the Haulage Rating.

 http://www.trainweb.org/j.dimech/roster/diagrams.html )

http://www.imagescn.technomuses.ca/railways/index_view.cfm?photoid=2767360&id=55

Joe

  • Member since
    February 2005
  • 2,366 posts
Posted by timz on Saturday, January 17, 2009 9:28 PM

JimValle
52% might mean that this particular engine operated at a maximum of 52% cutoff

The PRR 2-10-0 and 2-8+8-0 originally had about 50% maximum cutoff; AFAIK they were the only engines in North America with that low a maximum. The engine in question probably had a maximum cutoff of 80% or more.

  • Member since
    January 2009
  • From: Arkansas
  • 10 posts
Posted by quartering machine on Saturday, January 17, 2009 9:05 PM

 I don't know about the % on the cab side but I was a back shop machinist and for a short time a oilburner fireman so I have a comment on the cutoff.  My experience was making parts and installing them. Most other subjects are way above me!

 Valve gear and timing are very detailed subjects...Max cutoff or running in the front corner for starting a train means you have about 80% cutoff OR 80% of the bullring "piston" stroke is pushed by steam from the boiler, the remaining 20% which is the end of the stroke is "cutoff" from the steam supply. But steam admission starts at the begining of the next stroke, this is called "lead".  This 20% is when the valve wether slide or spool is switching "lap". However the combination lever on the Walscheart valve gear ensures that "lap movement" happens quickly.  This is another subject if anone is interested.

IN VALVE GEAR EACH SETTING OF THE REVERSE LEVER DOES MORE THAN CHANGE CUTOFF AND DRIVER DIRECTION. Thats another subject.

 When on the road under normal load with no speed or grade changes the cutoff is about 25% with the throttle mostly open. This means that the first 10% of the bullring stroke has no admission or exhaust but it has "compression" the next 25% of the stroke is moved by boiler steam but the remaining 65% is pushed by expanding steam. This is where super heaters are useful and you are getting your economy.

 "Compression" cushions the recipricating parts and also prepressurizes the space between the bullring and cylinder head, this reduces further the amount of steam needed to operate. If you now have a head ach don't be supprized!

 Slide valves are external admission and spool valves are internal admission. These are basic design changes that came about through locomotive evelution. Russell.

  • Member since
    January 2009
  • 2 posts
Posted by Joe6167 on Monday, January 12, 2009 9:36 PM

Hi All,

I wanted to add something to my explanation of Haulage Rating on my website. As some of you may have noticed, some Early CN Diesels also had a Haulage Rating written on the side of the cab.

I have a document in my possecsion which lists the wherabouts, and various other stats for all Motive Power owned by CN in December 1947. Among other things, this record lists the Tractive Effort. Here is where it gets scary. This record lists the Tractive Effort for an ALCo S2 (for example) as 60,000 lbs or (60%), which is more then my Northern (57%). However some sleuthing revealed that this quantity is in fact the STARTING Tractive Effort, whereas the CONTINUOUS Tractive Effort is only 34,000 lbs (34%).

Eventually CN realised no one was interested in STARTING Tractive Effort, and eventually reclassified all of its Motive Power by its CONTINUOUS Tractive Effort. This seems to have happened by 1949.

 In 1954, CN completely re-did the paint scheme for everything except steam (which stayed black for the most part) and around that time introduced a new Classification system for Diesels (which it still uses to this day) which lists the Locomotive;s HORSEPOWER instead of Tractive Effort.

Hope this helps some of you get some sleep.

Cheers,

Joe

http://www.trainweb.org/j.dimech/

P.S. I've added this to my website http://www.trainweb.org/j.dimech/roster/rosnotes.html

  • Member since
    July 2006
  • From: Central New York
  • 335 posts
Posted by MJChittick on Thursday, January 8, 2009 10:46 PM

JimValle

I note a lot of emphasis on tractive effort but I think that there may be a different answer.  Steam engines were designed to operate at various valve cutoff settings.  52% might mean that this particular engine operated at a maximum of 52% cutoff, meaning that at its optimum intended speed the engineer should adjust his valve setting with the reverse lever to no more than 52% cutoff.  That means he was allowing only 48% of the steam delivered by the boiler to actually enter the cylinders.    

This link was referrenced earlier in the thread and fully explains CN's definition of this "Haulage Rating"  notation:

http://www.trainweb.org/j.dimech/roster/rosnotes.html

 

Mike

  • Member since
    March 2003
  • From: US
  • 460 posts
Posted by JimValle on Thursday, January 8, 2009 4:26 PM

I note a lot of emphasis on tractive effort but I think that there may be a different answer.  Steam engines were designed to operate at various valve cutoff settings.  52% might mean that this particular engine operated at a maximum of 52% cutoff, meaning that at its optimum intended speed the engineer should adjust his valve setting with the reverse lever to no more than 52% cutoff.  That means he was allowing only 48% of the steam delivered by the boiler to actually enter the cylinders.    

  • Member since
    November 2005
  • 4,190 posts
Posted by wanswheel on Wednesday, January 7, 2009 4:56 PM
  • Member since
    December 2006
  • From: Michigan City, In.
  • 781 posts
Posted by spikejones52002 on Wednesday, January 7, 2009 3:22 PM

Just a couple more inches and it will be under the coaling tower.

  • Member since
    December 2006
  • From: Michigan City, In.
  • 781 posts
Posted by spikejones52002 on Wednesday, January 7, 2009 3:17 PM

 Just When you think you seen it all.

Someone shows up with another strange engine.

CN  7700.

 

  • Member since
    November 2005
  • 4,190 posts
Posted by wanswheel on Saturday, January 3, 2009 5:15 PM

Of all God's critters one always remembers CV belongs to the Grand Trunk.

http://216.94.16.48/_images/common/photos/original/CN005344.jpg

Mike

  • Member since
    August 2005
  • From: At the Crossroads of the West
  • 11,013 posts
Posted by Deggesty on Saturday, January 3, 2009 11:34 AM
wanswheel

This link to trainweb page explains % is the "haulage rating."

http://www.trainweb.org/j.dimech/roster/rosnotes.html

CV 601. Old book says its tractive effort was 44000 pounds.

http://imagescn.technomuses.ca/structures/index_view.cfm?photoid=77900020&id=37

http://imagescn.technomuses.ca/railways/index_view.cfm?photoid=-865848423&id=55

http://imagescn.technomuses.ca/people/index_view.cfm?photoid=775793097&id=26

http://i43.photobucket.com/albums/e390/MikeMacDonald/CV601a.jpg

http://i43.photobucket.com/albums/e390/MikeMacDonald/CV_601b.jpg

The 601 (with 600, 602, 603) is a favorite of mine because my grandfather drove it. American Locomotive with a Canadian-born engineer. If there's any interest, here is the CV history:

The Vermont Central Railroad Company was incorporated under the laws of the state of Vermont on 31 October 1843. Between 1848 and 1849 a total of 116.85 miles of line was opened for traffic between Windsor, Vermont, and Burlington, Vermont. Between 1852 and 1884 the company was operated under various forms of receivership. On 30 June 1884 the property of the Vermont Central Railroad Company was acquired by the Consolidated Railroad Company of Vermont

The Vermont and Canada Railroad Company was incorporated under the laws of the state of Vermont on 31 October 1845 to build a rail line from a point on the Vermont Central Railroad near Burlington, Vermont, to the US/Canada border. This 59.14 miles of line was opened for traffic in sections between 1850 and 1864. In August 1849 the line was leased to the Vermont Central Railroad Company. On 30 June 1884 the lease was passed to the Central Vermont Railroad. On 14 December 1891 the Vermont and Canada Railroad Company and two other companies merged with and took the name of the Central Vermont Railroad Company.

The Consolidated Railroad Company of Vermont was incorporated under the laws of the state of Vermont on 28 November 1882. It was a legal entity created to assist a merger of the Vermont Central and Vermont and Canada Railroads to form the Central Vermont. On 30 June 1884 the Consolidated Railroad Company of Vermont acquired the line of the Vermont Central Railroad, leasing it the same day to the Central Vermont. On 14 December 1891 the Consolidated Railroad Company of Vermont along with two other companies, merged with and took the name of the Central Vermont Railroad Company.

The Central Vermont Railroad Company was incorporated under the laws of the state of Vermont on 23 November 1872 for the purpose of purchasing the Vermont Central and/or the Vermont and Canada railroads. From 1873 to 1884 the Central Vermont operated, as managers and receivers, the Vermont Central Railroad Company, operating it under lease from 1884 to 1891. Between 20 March 1896 and 20 April 1899 the company's 228 miles of line was operated under receivership. On 20 April 1899 the property was passed to the Central Vermont Railway Company.

The Central Vermont Railway Company was incorporated on 16 November 1898 under the laws of the state of Vermont with the Grand Trunk Railway Company of Canada as the majority shareholder. In April 1899 it acquired the rights and property of the Central Vermont Railroad Company and its leased subsidiaries. [Grand Trunk Railway Company of Canada amalgamated with and took the name of Canadian National Railways in 1923.] In 1928, in order to permit refinancing, the company passed into receivership and was reincorporated on 12 August 1929 as Central Vermont Railway, Inc. with the Canadian National Railway Company as the majority shareholder.

The New London Northern Railroad Company was incorporated in 1859 and 1860 under the laws of the states of Connecticut and Massachusetts and, on 30 March 1861, acquired the property of the former New London, Willimantic and Palmer Railroad Company. On 1 March 1864 it acquired the Amherst, Belchertown and Palmer Railroad Company and on 8 October 1866 completed an additional 14.5 miles of line from Amherst to Millers Falls, Massachusetts. On 1 May 1880 the company acquired the 21 miles of line between Millers Falls, Massachusetts, and Brattleboro, Vermont, owned by the Vermont and Massachusetts Railroad Company. Thus, in its final form, the New London Northern had a 125.18 mile line between New London, Connecticut, and Brattleboro, Vermont. On 25 June 1873 the line was leased to and operated by the Central Vermont Railroad Company and its successor, the Central Vermont Railway Company. In 1951 the company's stock was acquired by the Central Vermont and, on 22 July 1952, the New London Northern Railroad Company was officially dissolved.

Happy New Year!

Another interesting fact about the CV (my mother learned this when she was at school in Northfield, a little over ninety years ago): it is mentioned in the Bible (God created all creeping things).

Johnny

Johnny

  • Member since
    October 2008
  • From: McKinney, TX
  • 70 posts
Posted by Road Fan on Saturday, January 3, 2009 9:21 AM

Thanks to all for solving this headscratcher of mine.

 Happy New year,

Road Fan

  • Member since
    November 2005
  • 4,190 posts
Posted by wanswheel on Thursday, January 1, 2009 11:50 AM

This link to trainweb page explains % is the "haulage rating."

http://www.trainweb.org/j.dimech/roster/rosnotes.html

CV 601. Old book says its tractive effort was 44000 pounds.

http://imagescn.technomuses.ca/structures/index_view.cfm?photoid=77900020&id=37

http://imagescn.technomuses.ca/railways/index_view.cfm?photoid=-865848423&id=55

http://imagescn.technomuses.ca/people/index_view.cfm?photoid=775793097&id=26

The 601 (with 600, 602, 603) is a favorite of mine because my grandfather drove it. American Locomotive with a Canadian-born engineer.

 Happy New Year!

  • Member since
    August 2005
  • 445 posts
Posted by Kootenay Central on Tuesday, December 23, 2008 3:42 PM

..

  • Member since
    December 2007
  • 416 posts
Posted by DSO17 on Tuesday, December 23, 2008 3:09 PM

     IIRC some railroads used the % sign to show tractive effort. 52%= 52,000lbs TE.

     I might be wrong about this as 52,000lbs seems to not be very much for a 4-8-4.

     At any rate thats a great photo of the GTW.

  • Member since
    October 2008
  • From: McKinney, TX
  • 70 posts
Posted by Road Fan on Monday, December 22, 2008 5:30 PM

In Classic Trains 'Steam Glory 2' in the steam color section (page 37; no.s 6405 thru 6409) is a photo of a Grand Trunk Western 4-8-4.  Under the engineers window it says:

U-4-b

           52%

Road Fan

  • Member since
    February 2005
  • 2,366 posts
Posted by timz on Monday, December 22, 2008 12:20 PM

At this point, nobody knows. Gives us a few examples and we'll see if we can guess.

  • Member since
    October 2008
  • From: McKinney, TX
  • 70 posts
What does the percentage number mean on a steam locomotive?
Posted by Road Fan on Monday, December 22, 2008 9:46 AM

On many photos of steam locomotive cabs, usually under the locomotive number, I'll see a number with a percentage sign- what does the percentage number mean?

 Example:

          2758

                      52%

Thanks,

Road Fan

SUBSCRIBER & MEMBER LOGIN

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

FREE NEWSLETTER SIGNUP

Get the Classic Trains twice-monthly newsletter