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A steep hill !

HauteSaoneFrance

Joined: 2-01-14

Topics: 33

Replies: 121

Posted: Thu 1st Nov 2018, 11:56am
A steep hill !

Currently planning stage 2 of my garden railway a winter project with new site knowledge gained last year. Stage 2 is the high level bit and the deep cutting originally planned to avoid too steep a gradient has now been thwarted by the knowledge of a second water main crossing my property, it wasn't on the plans.

I have been looking at trams to see how they cope with steep gradients and wikipedia publish a table of gradients for adhesion rail and tram tracks, Max quoted is an extreme 1 in 6 but the Sheffield Supertrams have 1 in 10. I know all wheels have to be driven and you need weight for adhesion but what about power available? The better mobility scooters are quoted at having a 21% (1 in 5) gradient capability so why is a loco so restricted?

I have a battery electric loco with 2 No, 4 wheel bogies each axle is individually driven with a 1 HP 750 watt motor so all wheels powered and up to 4 HP available, Given adequate battery power, loco weight and hauling a light load of say 1 passenger coach has anyone got experience of this sort of combination managing steep gradients?

 

Replies To This Post

George Coles

Joined: 4-08-09

Topics: 27

Replies: 172

Posted: Thu 1st Nov 2018, 2:56pm

The limiting factor is the Coefficient of Friction 'twixt the two components. Thus steel wheels 'stick' to steel rail better than do cast iron ones. And, of course, rubber tyres (or their modern synthetic equivalents) 'stick' even better then that, to almost any surface.

Personally, I would not plan to run anything at the limit - not much needs to change for the limit to be exceeded. Drop some oil on the track from an over-lubricated bearing, and oops, your are slipping. Famously, the Comrie Railway had a stiff gradient up to a level crossing, and their are many video records of locos slipping there. I can't find any info on that gradient, but someone on here will know!

George C
4373
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 33

Replies: 121

Posted: Thu 1st Nov 2018, 7:20pm

Thanks George my problem is one of hobsons choice, the prospect of abandoning a higher level circuit being linked to the lower level which would mean huge difficulties in getting Loco's and rolling stock up to that level or somehow linking with a steep climb. that or sell my property and find one with a level site?

Keith at Phoenix Loco's has given me some hope in that one of his customers has a loco of his manufacture that as an adhesion loco will climb the 1 in 10 of the Beamish rack railway,

Can anyone else offer hope?
 

MartynRedfearn

Joined: 1-01-94

Topics: 24

Replies: 160

Posted: Fri 2nd Nov 2018, 7:55am

Could you get a zig zag in? It is a way of gaining height and would add interest to the operation. Another option would be to have the steep section purely for access and accept separate running top and bottom.

Now the curved ball how about a hydraulic lift? You can get them reasonably priced that are capable of lifting the weight of a full train you would just need to extend the deck. Just thinking of the narrow boat lift at Falkirk.
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 33

Replies: 121

Posted: Fri 2nd Nov 2018, 4:26pm

Thanks George and Martyn. I have a 5 m height difference from lower to higher site levels and a linear distance of approx 150 m to reach the higher level then it reaches level ground, no chance of a zig zag so a I in 30 is possible as a constant climb or a steep 1 in 10 for 50 m is the former the better option? Not sure what the climbing ability is of the SRS 0-6-0 Big Feldbhan as no one seems to want to let on? Sounds like the all wheels driven with 4 HP available Phoenix electric loco will not have a problem certainly if I go for the 1 in 30 option?
 

MartynRedfearn

Joined: 1-01-94

Topics: 24

Replies: 160

Posted: Fri 2nd Nov 2018, 6:36pm

In the dry and if straight track 1 in 30 should be easily doable. Add a curve or a wet track and it starts to get interesting. We had a section of track with 39’ rad and at one time less than 1 in 50. Most locos made it with a reasonable load in the dry but often needed banking or the load reducing considerably in damp conditions

The other thing to think about will be braking spreading to braking effort over all the rolling stock will make it much safer coming down.
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 33

Replies: 121

Posted: Fri 2nd Nov 2018, 7:32pm

Thanks Martyn, My railway is purely private as in no public running though when the lower loop is connected up to form a complete circuit visitors are very welcome and there is now a 2.7 tonne hydraulic lift in the big loco shed with track to the turntable, There is no necessity to haul long trains and many bodies so it will be light running, I take your point about brakes it is proposed to have brakes on all rolling stock.

One point though my standard radius is 30 ft everywhere including on some of the gradients not ideal I know but inescapable on my site, up to now on a max of 1 in 46 no problem but the proposed track to the higher level it's 1 in 30 and will have 2 no 90 degree turns,
 

Colin Edmondson

Joined: 9-08-09

Topics: 3

Replies: 93

Posted: Wed 7th Nov 2018, 10:42pm

I have taken a Scamp up a 1 in 12 on dry rails without a problem, but I would be very wary coming back down with any kind of unbraked load behind. I would suggest a good run of track at the bottom with gentle curves so that a runaway has a chance to get back under control, it only takes a light shower of rain to make life rather too interesting!
 

Railrose

Joined: 25-06-07

Topics: 2

Replies: 30

Posted: Sat 10th Nov 2018, 5:32pm

The steepest gradient at the Comrie Railroad was 1 in 23. At the 2008 AGM I drove my NG petrol mechanic 'Panter' with a 10 wagon goods train (one time even with 4 passenging society members aboard) uphill from standstill without slipping. On wet track. The trick is the sandbox. With a little kick of my left foot on a pedal I open a valve and a little sand drops on the tracks, just before the front wheels. A Romulus pulling just a driving truck was spinning ahead of me...
You don't need much sand to make wet track behave dry, just sprinkle a bit of dry sand on the railheads in front of you. On my loco I fitted some pipework but it can be done by hand too.
The sander can be seen in action on my 'out of the Siding' video at this year's AGM (it is in the Gallery), when I drive out the second time I kick some sand, to reduce the slipping when pushing back in. I still have to make more pipework, to the rear axle. The climber has a 1 in 33 gradient.
 
 
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