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GRADIENTS (AGAIN)

HauteSaoneFrance

Joined: 2-01-14

Topics: 27

Replies: 91

Posted: Tue 5th Jul 2016, 5:05pm
GRADIENTS (AGAIN)

Still kicking around the subject of gradients on my private garden railway. A question how do trams cope with such steep gradients? I have heard about 1 in 16 I see even network rail have some track at 1 in 37. Interestingly my adopted home City of Bristol has some very steep hills which pre WW2 were used by the tram system
 

Replies To This Post

johnprice

Joined: 1-01-75

Topics: 0

Replies: 1

Posted: Sat 20th Aug 2016, 9:38pm

My understanding is that the limit of adhesion on a nomal railway is 1 in 13. So how do trams cope with steep gradients? The answer is the power to weight ratio. Trams usually just pull themselves with sometimes power to all wheels, whereas locomotives pull unpowered carrages or trucks. There are a few very steep railways but the locomotives can only pull a few trucks. The biggest problem is comeing down the gradients, sufficient braking power is required, Some trams have magnetic track brakes which grip the rails.
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 27

Replies: 91

Posted: Sun 21st Aug 2016, 4:47pm

Hi John and thanks for your reply my site is to say the least difficult nowhere near level at almost any point, The proposed initial loop is only about 1/2 kilometer but with 2 entrances to cross, I had thought about swing bridges and going for some pretty steep gradients but in the end I've moved some very large amounts of earth and established a new entrance from the road so as to be able to get 8 wheel 20 ton payload lorries in both for stone and concrete, I'm estimating that the amount of stone (gravel) needed to adjust levels here will run into hundreds of tons. The upside of these site works is that max gradient will be
1 in 47. Problems still exist in order to extend the track to the higher levels but that will come later.
 

RETBDavid

Joined: 18-02-15

Topics: 0

Replies: 3

Posted: Tue 23rd Aug 2016, 9:52pm

Have you thought about a rack and pinion system to access the higher levels later on?
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 27

Replies: 91

Posted: Thu 13th Oct 2016, 7:20pm

Work is still going on but with a 30 metre retaining wall now built and hundreds of tons of gavel laid the initial loop is looking that it will be a reality next spring given a not too severe winter to allow some work to continue, I'm on a big learning curve as have come into the folds of this hobby only fairly recently though I do have some construction (Civil type) expertise. Phase 11 will be a much greater challenge though and I'm wondering if I need to consider a multi (electric) motor loco? I have long since had this idea of a longish loco which because of my radiuses (9 metres) would have to be of the twin bogie type, are there any 4 wheel bogies available with drive to all wheels and is that a practicality?
 

Mick

Joined: 1-01-89

Topics: 7

Replies: 114

Posted: Fri 14th Oct 2016, 2:23pm

My Rio Grande U-25B 'diesel' (known as the U-Boat) has electric motor/gearbox on each axle. It was designed and built by myself and Tony Martin of Cromar White. The motors are 24 volt and it has eight 6V batteries, but unless you intend to run all day hauling carriages you wouldn't need that many batteries. Of course you need the electronics to go with it. Cromar White have produced other electrically powered bogie equipment.
My Rio Grande U-25B 'diesel' (known as the U-Boat) has electric motor/gearbox on each axle. It was designed and built by myself and Tony Martin of Cromar White. The motors are 24 volt and it has eight 6V batteries, but unless you intend to run all day hauling carriages you wouldn't need that many batteries. Of course you need the electronics to go with it. Cromar White have produced other electrically powered bogie equipment.
 
 
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