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Typical Tractive Effort Data

wesau

Joined: 1-01-70

Topics: 1

Replies: 3

Posted: Thu 12th Apr 2012, 5:32am
Typical Tractive Effort Data

Hello Forum,
I am interested in obtaining measured tractive effort data pertaining to various 71/4" gauge locomotives, be they steam or otherwise.
Additionally, I would like to learn how tractive effort has been measured, by others within the fraternity.
Thanks and regards.
 

Replies To This Post

wesau

Joined: 1-01-70

Topics: 1

Replies: 3

Posted: Wed 18th Apr 2012, 11:34am

G'day Forum,
The 71/4" Society, so far, is a little disappointing in that I have not had one single reply to my call for information.
Is the nature of my request too inquisitive, or, is this matter of measuring the resultant tractive effort of 71/4" gauge models, once operational, of no interest to fraternity members?
In all my venturing into internet forums, this is the first time I have supplied the only reply, thus far, to my own forum topic!
Regards,
Bill.
 

ivanhewlett

Joined: 1-01-85

Topics: 8

Replies: 53

Posted: Wed 18th Apr 2012, 12:26pm

Hi Bill
Don't take it personally, this is perhaps not your typical internet forum.
The number of responses to questions is typically lower than on other forums that I participate on, this is probably because this is quite an exclusive forum, you have to be a seven and a quarter member to be eligible - at least I believe so. Whereas of course the only eligibility for most forums is having internet access !!

There is a 7 1/4" gauge efficiency trial I believe based around the IMLEC (International Model Locomotive Efficiency Competition) and this might be another source for answers to your question.

I would also comment that at least for my part I build locomotives for primarily my own pleasure and determining the absolute maximum power output is of no interest to me. As long as a I can pull a few coach loads of passengers I am happy - I tend not to stress my locomotives too hard since it is only me that will have to service and maintain them.

Someone out there will certainly share your interest though and I would be happy to point you in the direction of a more widely viewed forum - though not 7 1/4" specific - if you wish to make contact.

Best Regards, Ivan.
 

king6024

Joined: 1-01-70

Topics: 1

Replies: 12

Posted: Wed 18th Apr 2012, 3:08pm

hi bill
theoretical tractive effort can be worked out by using the following formula

tractive effort= __B2__x__S__x__P________ lbs
W

where B is the dia of the cly in inches
S is the stroke in inches
P is boiler presure (at 80% of boiler max working presure)
W is wheel dia at tread in inches
or you can always put a big spring balance between the loco and your rolling stock hope this helps mark
 

frankcooper

Joined: 9-08-09

Topics: 9

Replies: 58

Posted: Wed 18th Apr 2012, 3:54pm

Forum is only accessible to paid up members - we currently have less than 1,500 and a fair few do not look at the web site with any regular pattern.

I too just run my loco for my pleasure (and to pull a reasonable load) and the tractive effort at this scale is of no interest - it was more relevant when I was involved with larger railways.

Frank
 

Xz

Joined: 1-01-92

Topics: 17

Replies: 244

Posted: Thu 19th Apr 2012, 7:56am

I would also add that it is not unusual for an item to go unanswered for only a week, some go several weeks even a month or more, before someone with an interest, or info to add, picks it up. Yes, your question is a little unusual, but there will be someone out there who will have something further to add. Patience is the name of the game, and even if no one does answer, write up your experiments and findings for an article for the News, the Editor will be delighted.
 

wesau

Joined: 1-01-70

Topics: 1

Replies: 3

Posted: Fri 20th Apr 2012, 12:51am

G'day,
Thanks to all the people who have replied.
Ivan, I will be interested to receive details of the 'more widely viewed forum' you mention.
To king6024, thanks for the formula, but the model I am working on is that of a 0-6-0 diesel hydraulic type, and I have incorporated a petrol/hydraulic drive in the model.
I daresay the purpose of my opening topic is to get some idea as to the hauling capability of like models built in this gauge.
Again, thanks to all.
Regards,
Bill.
 

wesau

Joined: 1-01-70

Topics: 1

Replies: 3

Posted: Fri 20th Apr 2012, 2:58am

G'day Xz,
Thanks for your reply.
I daresay I have been a little too impatient.
Regards,
Bill.
 

ivanhewlett

Joined: 1-01-85

Topics: 8

Replies: 53

Posted: Mon 23rd Apr 2012, 7:57am

Hi Bill

I am not sure how these things work, or at least I am not sure whether there is some etiquette that says I shouldn't post other website addresses on this forum.
So I guess if I break any rules someone will tell me !??!

The other website I use is miniaturerailwayworld.co.uk

Cheers, Ivan.
 

bentrenchard

Joined: 1-01-70

Topics: 1

Replies: 3

Posted: Wed 27th Jun 2012, 3:14pm

I'm no expert, but I have an Excel spreadsheet which can be used to calculate theoretical tractive effort of a steam engine based on the cylinder bore and stroke, no of cylinders, boiler pressure and driving wheel dia. I seem to remember getting the formula of the internet (see wikipedia for an example). It gives the tractive effort of a Milner Hunslet as 342 lbs. If anyones interested, just email me, and I can send you a copy. (member no 4118).

Unfortunately, I have no such simple formula for a diesel (Or electric loco), but I guess it would be some fundtion of the torque of the traction motors, the gear ratio and the driving wheel dia.

Hope this helps,

Ben.
 

georgedavis

Joined: 1-01-89

Topics: 0

Replies: 5

Posted: Wed 21st May 2014, 8:24am

Most model locomotives are over powered in relation! to the wheel/rail adhesion. A reasonable tractive effort formula, used in full size, for dry rail, and for any loco (steam, diesel, electric) is to simply take the total weight on the driving wheels and divide by four. It is not accurate but will give a guide as to the haulage capacity. On level track, with free running ball bearing stock, a force of 15 - 20 lb should be sufficient to get a one ton train on the move. After that a lot less is needed to keep it rolling - until sharp curves and gradients are encountered.
 

paulkonig

Joined: 1-01-98

Topics: 2

Replies: 2

Posted: Fri 23rd May 2014, 2:23pm

"King6024" I own a loco you may be interested to learn more about.  Suggest you email me on secretary@pinewoodrailway.co.uk
"King6024" I own a loco you may be interested to learn more about. Suggest you email me on secretary@pinewoodrailway.co.uk
 
 
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