A2 986 - Coming Together

 
  Clarke Hudswell Junior Train Controller

My figures are calculated thus:

Train mass 280 ton (recorded from the underframe weights on the day)

A2 mass 121 ton

R mass 187 ton

A2 dbhp 1240 (from Dynamometer Car charts)

R dbhp 1605 (from Dyno Car ref “Hudson Power” p.86)

Power/weight A2 = 1240/(280 + 121) = 3.1

Power/weight R = 1605/(280 + 187) = 3.4

Of course, all steam locos can produce much less or a bit more than their rated power, but actual test results from the dynamometer car are the most accurate measure.


Broadford has an elevation of 221 m, Heathcote Jnc 349 m, a rise of 128 m over 22 km, an average grade of 1 in 172.

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  Carnot Minister for Railways

My figures are calculated thus:

Train mass 280 ton (recorded from the underframe weights on the day)

A2 mass 121 ton

R mass 187 ton

A2 dbhp 1240 (from Dynamometer Car charts)

R dbhp 1605 (from Dyno Car ref “Hudson Power” p.86)

Power/weight A2 = 1240/(280 + 121) = 3.1

Power/weight R = 1605/(280 + 187) = 3.4

Of course, all steam locos can produce much less or a bit more than their rated power, but actual test results from the dynamometer car are the most accurate measure.


Broadford has an elevation of 221 m, Heathcote Jnc 349 m, a rise of 128 m over 22 km, an average grade of 1 in 172.
Clarke Hudswell
I also read on page 92 of "Hudson Power" of R-class locos producing around 1840 dhp in dyno car tests.  When R761 was first restored in the mid-1980s there were also reports of it producing well over 2000 dhp.

Another thing I noticed in the old newspaper reports is how the A2 locos rode much smoother on the footplate at 60 mph than at 45 mph.  Obviously a machine designed for high-speed running.
  Clarke Hudswell Junior Train Controller

I read the 1840 dbhp for the R class in the book as R.L.Abbott’s estimate of power using Maitland coal based on the recorded dynamometer car 1605 dbhp on Lithgow coal (see p.87 and Table 21). An extra 235 hp for better coal on an engine designed to burn the lower grades? Actual tests on A2s comparing Maitland and State Mine coal (I understand Lithgow coal to be better than State Mine, but am open to correction) gave a difference of 100 hp.


The Dynamometer car test on R 761 in 1986 (refer to Newsrail April 87) shows the best from this locomotive as 2190 rhp, or 1905 edbhp. This was really pushing it -18” cut off and full throttle!! Rail horsepower was usually about 300 higher than edbhp on these tests.

The conclusion of the Dynamometer Car test to Bendigo was that R 761 was capable of producing 1600 edbhp continuously and up to 1900 edbhp for short periods.


Maybe we should ask Steamrail (nicely) if we could be permitted to travel on the footplate to evaluate the ride!
  NSWGR 3827 Deputy Commissioner

Location: South of the Border
My figures are calculated thus:

Train mass 280 ton (recorded from the underframe weights on the day)

A2 mass 121 ton

R mass 187 ton

A2 dbhp 1240 (from Dynamometer Car charts)

R dbhp 1605 (from Dyno Car ref “Hudson Power” p.86)

Power/weight A2 = 1240/(280 + 121) = 3.1

Power/weight R = 1605/(280 + 187) = 3.4

Of course, all steam locos can produce much less or a bit more than their rated power, but actual test results from the dynamometer car are the most accurate measure.


Broadford has an elevation of 221 m, Heathcote Jnc 349 m, a rise of 128 m over 22 km, an average grade of 1 in 172.
Clarke Hudswell
Thanks for clarification.

With a average grade of only 1 in 172 (the max load on this grade would be huge), with only a few short stretches of 1 in 50 the majority of this could easily dealt with by use of momentum, as seemed to be the case on Saturday.

A further question, are the above Dbhp figures peak or sustained?
  Clarke Hudswell Junior Train Controller

The hp figures are continuous (stable fire) = sustained ratings.


You cannot climb 128m using momentum alone. There is less than 4 km of downgrade in the 22 km between Broadford and HJunc. If I had the speeds at the beginning and end of this section, I could calculate the average power output to illustrate the point (but I don’t have them).
A steam locomotive is not a constant horsepower machine like a diesel electric. A locomotive’s ability to slog up a steep grade only tests its adhesion and tractive effort, the harder task of operating at higher speeds on the less steeply graded sections is when boiler power comes into it. For example, an R class exerts its full 1600 edbhp at 35 to 40 mph. At 15 mph, it is only capable of 1100 hp.
  NSWGR 3827 Deputy Commissioner

Location: South of the Border
You cannot climb 128m using momentum alone. There is less than 4 km of downgrade in the 22 km between Broadford and HJunc. If I had the speeds at the beginning and end of this section, I could calculate the average power output to illustrate the point (but I don’t have them).
A steam locomotive is not a constant horsepower machine like a diesel electric. A locomotive’s ability to slog up a steep grade only tests its adhesion and tractive effort, the harder task of operating at higher speeds on the less steeply graded sections is when boiler power comes into it. For example, an R class exerts its full 1600 edbhp at 35 to 40 mph. At 15 mph, it is only capable of 1100 hp.
Clarke Hudswell
No smeg, but the undulating profile of that section does help substantially.

My comment was with reference to your comment on the Broadford to Wandong Section (118m climb over 18km) with what I would call no substantial grades.
  bevans Site Admin

Location: Melbourne, Australia
For those interested an image of the streamer via Albion on the DOWN from Newport last Saturday:

https://www.railpage.com.au/railcams/albion2/photo/28561741451
  bevans Site Admin

Location: Melbourne, Australia



  bevans Site Admin

Location: Melbourne, Australia
Video now online

http://bit.ly/2aTaKOm
  BigTrain2015 Junior Train Controller

Video now online

http://bit.ly/2aTaKOm
bevans

@bevans thanks so much for putting this online for all of us.
  micka_3019 Station Staff

Location: gippsland
Congrats to all that help rebuild the A2, I would love to see it on the snow train next year.
  Carnot Minister for Railways

A2'986 conducted a test run to Geelong and back last night with a T-class, some E-cars and water tank in tow.  It also doubled as a prop for film set at Shanghai Railway Station in the 1920s.  (Not the first time Geelong Station has been used for filming - Phar Lap had a K-class make an appearance)

Won't be long now until its official public launch I would imagine.

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