RMweb Gold Re6/6 Posted October 15, 2011 RMweb Gold Share Posted October 15, 2011 These rack points have two motors one to move the rails and one to move the rack..or do they? In the switching movement which normally moves first, the switch blades or the rack? Is the route change movement at the switch end all done in one go with the rack? One of the things that puzzle me is how are the movable rack sections supported when they move across the running rails during a route change. Link to post Share on other sites More sharing options...
RMweb Premium DIW Posted November 1, 2011 RMweb Premium Share Posted November 1, 2011 (edited) Hi John, I notice that your question has gone unanswered for a while, so I'll share the limitations of my knowledge in the hope that it will prompt some further replies....... I see that the track in your picture is Abt-rack-equipped, with what appears to be the small plough of an electric loco in the far left of the picture. I'm not familiar with any Abt-equipped metre gauge lines beyond the steam-operated Furka Dampf Bahn - and I've not taken any recent pictures of the track there. I have added to this missive some pictures of a rack point at Wilderswil on the Riggenbach-equipped 800mm gauge Schynige Platte Bahn. The points all use castings which are of Straub appearance; indeed the pointwork along the line is (from memory) all on sections which are less steep that the rest of the line. (Straub is (or was until the last decade) less well suited than Riggenbach to steeper inclines. I noticed though that rack renewal on the BOB has seen Riggenbach replaced by Straub). The point in the pictures is manually operated, with several cranks and levers running from the main point lever. This means that the rack sections move simultaneously with the point blades. Of course the all-important lever mechanism is missing from those pictures, but it can be seen here: I have somewhere in the parts box some N scale signal ladder on which the pitch of the treads is the same as the pitch of the rack teeth on Fleischmann rack - needless to say I have not yet got around to building a rack point! Dave Edited July 12, 2022 by DIW Pictures re-installed 1 Link to post Share on other sites More sharing options...
RMweb Gold Re6/6 Posted November 1, 2011 Author RMweb Gold Share Posted November 1, 2011 Many thanks Dave. I had forgotten about the post as I had no takers until now! I've never seen Riggenbach rack points before. The pics are most enlightening. It could be that I may now consider using it instead of Abt. The question is for a planned 0 scale metre gauge (protoscale..P0m?!) layout, with one rack point. I could use Riggenbach instead of Abt as the location is a 'might have been' joining the Furka Oberalp (Abt) with the Brünig (Riggenbach) over the Grimsel Pass which was actually proposed before WW1. So a choice has to be made! Link to post Share on other sites More sharing options...
RMweb Gold Re6/6 Posted November 2, 2011 Author RMweb Gold Share Posted November 2, 2011 John, P0m? Would that be 7 mm scale or Continental O scale? The difference is marginal: 1:43.5 vs 1:45 but multiplied by 1,000... It's 22.99 mm vs 22.22 mm gauge. Nothing is simple any more is it Vincent! You are quite right to point out the difference. I reckon that I should call it P43 as it will be using Swiss Fama/UTZ stock Dutch video production company v/d Burgh Videoproducties in Leiderdorp does a set of cab rides on the RhB and MGB lines on DVD. Disk 5 is the GGB and ex-BVZ while disk 6 has the ex-FO sections of the current MGB. The GGB has no less then 35 rack points, system Abt, from Zermatt to the top of the Gornergrat Disks 5 and 6 start at the Gornergrat and go all the way to Disentis. As for your last question (in the original post), the rack moves in its entirety, the railhead moves with it (and is displaced to have the rack continues throughout the point). You can clearly see it in the photo you posted: look at the blade in the foreground and follow it through the point. At one point it suddenly stops, this is where the rack passes when the point changes position. Many thanks for the information. It is all very helpful. Best wishes John Link to post Share on other sites More sharing options...
Horsetan Posted November 7, 2011 Share Posted November 7, 2011 Snowdon Mountain Railway uses the Abt system - are there any photos of their points out there? Link to post Share on other sites More sharing options...
RMweb Gold Re6/6 Posted November 7, 2011 Author RMweb Gold Share Posted November 7, 2011 Thanks Ivan. I didn't know that. Link to post Share on other sites More sharing options...
Horsetan Posted November 8, 2011 Share Posted November 8, 2011 Have found a good clear photo of the Snowdon Abt system rack point: http://upload.wikimedia.org/wikipedia/commons/a/a2/Rails_Snowdon_01.JPG Link to post Share on other sites More sharing options...
RMweb Gold Re6/6 Posted November 8, 2011 Author RMweb Gold Share Posted November 8, 2011 Terrific. Many thanks Ivan. Link to post Share on other sites More sharing options...
Brian Harrap Posted November 9, 2011 Share Posted November 9, 2011 Seeing as you've brought the rack subject onto the front burner, or out of the closet John, may I air my little conundrum? It's the one about Abt rack and how do the parallel rows of teeth stay in register (or alignment if you like) on a substantial, say 180deg, curve. Surely the outer row of teeth have to stretch or reach further than the inner row? Discuss, Brian. Link to post Share on other sites More sharing options...
RMweb Gold Re6/6 Posted November 9, 2011 Author RMweb Gold Share Posted November 9, 2011 Seeing as you've brought the rack subject onto the front burner, or out of the closet John, may I air my little conundrum? It's the one about Abt rack and how do the parallel rows of teeth stay in register (or alignment if you like) on a substantial, say 180deg, curve. Surely the outer row of teeth have to stretch or reach further than the inner row? Discuss, Brian. Trust you...! Link to post Share on other sites More sharing options...
RMweb Gold Re6/6 Posted November 9, 2011 Author RMweb Gold Share Posted November 9, 2011 PS: John, the Fama stuff is 1:45 Thanks Vincent. I can now start working things out! Link to post Share on other sites More sharing options...
Brian Harrap Posted November 10, 2011 Share Posted November 10, 2011 Theoretically Brian, you're right. But, unless our models, the prototype has some build-in slop that takes up the slack It hasn't been a problem in the Swiss mountains for a century (and more) likewise for the one going up Snowdon, so the system works PS: John, the Fama stuff is 1:45 Yes I know it works Vincent, it just irritates me that it does - like theoretically the bumble bee can't fly but it does, Brian. Link to post Share on other sites More sharing options...
10800 Posted November 10, 2011 Share Posted November 10, 2011 Seeing as you've brought the rack subject onto the front burner, or out of the closet John, may I air my little conundrum? It's the one about Abt rack and how do the parallel rows of teeth stay in register (or alignment if you like) on a substantial, say 180deg, curve. Surely the outer row of teeth have to stretch or reach further than the inner row? Discuss, Brian. Because the CERN particle accelerator passes beneath Switzerland, the Swiss developed an ingenious system whereby they tapped into it from above and made use of a slight aberration in the space-time continuum to enable the pitch of the teeth to adjust as required. Or maybe they just cast special variations for curves ... Link to post Share on other sites More sharing options...
Brian Harrap Posted November 11, 2011 Share Posted November 11, 2011 Nah! but is there a diff (differential) in the twin rack cogs?. I believe there is/was some triple abt rack in South America, with the the eloks fed from catenary and third rail to boost the supply uphill. Verification required. Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted November 13, 2011 RMweb Premium Share Posted November 13, 2011 like theoretically the bumble bee can't fly but it does, Brian. That's an urban myth which has been de-bunked by science several times. Keith Link to post Share on other sites More sharing options...
RMweb Premium DIW Posted November 14, 2011 RMweb Premium Share Posted November 14, 2011 (edited) On 11/11/2011 at 11:14, Brian Harrap said: Nah! but is there a diff (differential) in the twin rack cogs?. It wouldn't surprise me if that was the case (think for a moment about the fancy levers and springing in a Buechli drive mechanism). Certainly on the Schynige Platte Bahn He2/2 locos, where (given the lack of suspension springing on the loco) one would expect that the two rack cogs (in line astern formation) would have a fixed relationship to each other and the rack. However there is an elaborate springing mechanism to take account of variations in the rack pitch in the Riggenbach rack, even within the short distance between cog axles. Looking at the pictures so far, the Abt rack points carry the rack over the rail by swinging across a complete Abt rack section in place of a swinging piece of rail. I've found a picture of the depot at Brienz (800mm gauge) which being less steep than the majority of the line has a fair amount of single-section Abt, with the dual Abt appearing where required for point transitions. There is still a section of rail which swings but it is much shorter than those on the previous pictures: Dave Edited July 12, 2022 by DIW Pictures re-uploaded Link to post Share on other sites More sharing options...
Brian Harrap Posted November 16, 2011 Share Posted November 16, 2011 That's an urban myth which has been de-bunked by science several times. Keith OK I can accept that the bumble bee myth is exploded, but whats your take on the curved rack? Link to post Share on other sites More sharing options...
Foulounoux Posted November 20, 2011 Share Posted November 20, 2011 OK I can accept that the bumble bee myth is exploded, but whats your take on the curved rack? Just had a look at Tracknet site (makers of ABT rack) and the inference is that the repetition of the rack teeth are modified on curves Colin Link to post Share on other sites More sharing options...
Brian Harrap Posted November 21, 2011 Share Posted November 21, 2011 Just had a look at Tracknet site (makers of ABT rack) and the inference is that the repetition of the rack teeth are modified on curves Colin Brilliant, Colin, Thank you so much for finding this out and letting me know. It really has settled a long outstanding little niggle. The teeth being cut (made) in line with the angle appropriate to the radius of the curve means of course that the effect is not cumulative and therefore easily taken up by the inherent slack between the cog and the rack. Thanks again, Brian. Link to post Share on other sites More sharing options...
Lachlan Posted September 29, 2012 Share Posted September 29, 2012 Ferrotrains make narrow guage model track and points Link to post Share on other sites More sharing options...
Gordon A Posted September 29, 2012 Share Posted September 29, 2012 Are these pictures of Abt rack points of any help? Taken in Spain this year. Gordon A Bristol 3 Link to post Share on other sites More sharing options...
RMweb Gold Re6/6 Posted October 3, 2012 Author RMweb Gold Share Posted October 3, 2012 Gordon. Utterly brilliant! Thank you so much. These snaps are exactly what I've been looking for. Link to post Share on other sites More sharing options...
Brian Harrap Posted October 3, 2012 Share Posted October 3, 2012 Are these pictures of Abt rack points of any help? Taken in Spain this year. Gordon A Bristol Hello Gordon, Wonderfull bit of rack track, can you please tell me where it is. I thought it was that industrial line in Switzerland but you say Spain. Anyway it needs a visit by me, thanks, Brian. Link to post Share on other sites More sharing options...
Gordon A Posted October 3, 2012 Share Posted October 3, 2012 Hi Chaps, The first two pictures were of a point on the Montserat Rack Railway, which is I think, to the north of Barcelona. The plain track was also of interest. Also a retired loco and coach: The third picture I will cover in a seperate post as I have to find the details. Gordon A Bristol 1 Link to post Share on other sites More sharing options...
Brian Harrap Posted October 3, 2012 Share Posted October 3, 2012 Thanks Gordon, fascinating stuff, Brian. Link to post Share on other sites More sharing options...
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