|
|
Post by Deleted on Feb 23, 2021 22:52:58 GMT
I could be wrong (probably am) as it's been a while since I did mine but you may find that Don's system doesn't need a valve to break the vacuum? there are pins in the relief valves to do that...I think, the mind is a little foggy these days. As for condensate, there's a working condensate valve just under the tender standpipe. 4472 didn't have one on the front as it's an express and rarely would it need to use the front standpipe but I have noted during my research that some Gresley Pacific's did have the front condensate valve fitted.
Pete
|
|
Gary L
Elder Statesman
Posts: 1,208
|
Post by Gary L on Feb 23, 2021 23:37:33 GMT
I could be wrong (probably am) as it's been a while since I did mine but you may find that Don's system doesn't need a valve to break the vacuum? there are pins in the relief valves to do that...I think, the mind is a little foggy these days. As for condensate, there's a working condensate valve just under the tender standpipe. 4472 didn't have one on the front as it's an express and rarely would it need to use the front standpipe but I have noted during my research that some Gresley Pacific's did have the front condensate valve fitted. Pete A condensate valve would be an interesting device to try to build, but I’ve never heard of them on miniature trains. But condensation can definitely be an issue, so never use any non-stainless springs or similar in your vac system. We have had a lot of trouble at Bristol, to the extent of fitting glass bowl water separators to the train pipe in every carriage. A valve to admit air to each reservoir is also an essential fitting, but it doesn’t have to be on the reservoir itself. It is common to run an extension pipe from the reservoir to somewhere that the valve can be mounted so you can ‘pull the strings’ more conveniently. Gary |
|
tim
E-xcellent poster
Posts: 236
|
Post by tim on Feb 28, 2021 19:01:46 GMT
Hi guys, thanks for all the advice on my last post, all points taken on board. On to the Brake shoes this weekend, I've seen a lot of clever methods of making these on here, and this is how I went about them. First I machined the outer profile and drilled the 1/8 hole. I didn't machine a taper on the radius as yet because I needed to hold them in soft jaws for the next op.  Next it was the loong task of hacksawing them off the bar! I always say to our apprentices, "if you get the technique right you can hacksaw all day long", but I ended up eating my own words on this occasion!  Back to the mill where I machined the outer profile into some soft jaws for the vice, to hold them to skim the back face.  Next they were stood up to machine the slot to accept the brake hangers.  And lastly another profile in soft jaws to hold them up the other way to remachine the wheel radius with the taper to suit the wheels.    And here they are sitting on their hangers yet to have pins fitted to secure them.  More soon, Tim |
|
|
|
Post by Deleted on Feb 28, 2021 19:40:26 GMT
I could be wrong (probably am) as it's been a while since I did mine but you may find that Don's system doesn't need a valve to break the vacuum? there are pins in the relief valves to do that...I think, the mind is a little foggy these days. As for condensate, there's a working condensate valve just under the tender standpipe. 4472 didn't have one on the front as it's an express and rarely would it need to use the front standpipe but I have noted during my research that some Gresley Pacific's did have the front condensate valve fitted. Pete A condensate valve would be an interesting device to try to build, but I’ve never heard of them on miniature trains. But condensation can definitely be an issue, so never use any non-stainless springs or similar in your vac system. We have had a lot of trouble at Bristol, to the extent of fitting glass bowl water separators to the train pipe in every carriage. A valve to admit air to each reservoir is also an essential fitting, but it doesn’t have to be on the reservoir itself. It is common to run an extension pipe from the reservoir to somewhere that the valve can be mounted so you can ‘pull the strings’ more conveniently. Gary Hi Gary Sorry I seem to have missed your reply, Doncaster has working condensate valves fitted below the stand pipes. I didn't fit the front valve as research showed 4472 didn't have one at the front and further investigation suggested such valves were rarely fitted to the front of an express as the vacuum pipe was rarely used. Pete |
|
Gary L
Elder Statesman
Posts: 1,208
|
Post by Gary L on Mar 1, 2021 2:13:26 GMT
A condensate valve would be an interesting device to try to build, but I’ve never heard of them on miniature trains. But condensation can definitely be an issue, so never use any non-stainless springs or similar in your vac system. We have had a lot of trouble at Bristol, to the extent of fitting glass bowl water separators to the train pipe in every carriage. A valve to admit air to each reservoir is also an essential fitting, but it doesn’t have to be on the reservoir itself. It is common to run an extension pipe from the reservoir to somewhere that the valve can be mounted so you can ‘pull the strings’ more conveniently. Gary Hi Gary Sorry I seem to have missed your reply, Doncaster has working condensate valves fitted below the stand pipes. I didn't fit the front valve as research showed 4472 didn't have one at the front and further investigation suggested such valves were rarely fitted to the front of an express as the vacuum pipe was rarely used. Pete Interesting! Any chance of showing how they work Pete? Gary |
|
|
|
Post by Deleted on Mar 1, 2021 8:48:30 GMT
Morning Gary
It's a simple design, not much difference to a clack valve, or at least it wasn't after I modified it a little from Don's design which I couldn't get to work properly. Rereading my notes it's as simple as a length of bar threaded each end, female one end to screw onto the bottom of the standpipe and male the other for a plug to screw onto, the plug/cap having a small hole through the middle. The inside of the bar (I used hex explained in my blog) is bored out for most of the lower part for a stainless ball to float in, above that there's a small hole with a chamfered seat for the ball to seal against when sucked via vacuum. When the vacuum is destroyed the ball falls and thus any condensate drips out. Don used a 3/32 ball with a PTFE seal below that which has a hole in it. This proved to be problematic so I increased the ball size to 5/32, did away with the PTFE seal/collar below and I believe that I modified the cap hole so that when the ball fell it couldn't block the hole.
There is a picture of the valve parts in my build, probably easier to find in my blog, it's the entry that covers the tender chassis being painted.
Hope that helps and my apologies to Tim for taking up space in his great build thread.
Kind regards
Pete
|
|
Gary L
Elder Statesman
Posts: 1,208
|
Post by Gary L on Mar 3, 2021 1:09:03 GMT
Morning Gary It's a simple design, not much difference to a clack valve, or at least it wasn't after I modified it a little from Don's design which I couldn't get to work properly. Rereading my notes it's as simple as a length of bar threaded each end, female one end to screw onto the bottom of the standpipe and male the other for a plug to screw onto, the plug/cap having a small hole through the middle. The inside of the bar (I used hex explained in my blog) is bored out for most of the lower part for a stainless ball to float in, above that there's a small hole with a chamfered seat for the ball to seal against when sucked via vacuum. When the vacuum is destroyed the ball falls and thus any condensate drips out. Don used a 3/32 ball with a PTFE seal below that which has a hole in it. This proved to be problematic so I increased the ball size to 5/32, did away with the PTFE seal/collar below and I believe that I modified the cap hole so that when the ball fell it couldn't block the hole. There is a picture of the valve parts in my build, probably easier to find in my blog, it's the entry that covers the tender chassis being painted. Hope that helps and my apologies to Tim for taking up space in his great build thread. Kind regards Pete Thanks Pete, that makes perfect sense. A useful gadget to fit on a loco, which is where the condensation seems to come from. I think for our carriages I'll stick to the water-separators though, rather than add yet another potential leak point into the plumbing! Gary |
|
tim
E-xcellent poster
Posts: 236
|
Post by tim on Mar 13, 2021 13:13:58 GMT
Good afternoon guys, thanks for some interesting info and advice regarding the drain plug and condensate valves, and no need for any apology Pete, I value all advice regarding this project and will refer back to it when I reach that point. After having completed the brake shoes it was then just a case of fitting the shoes to the hangers and the hangers to the frames. However I have come up against a problem with the front hanger assembly. This being that the brake shoe is kinked over at its maximum pivot position and won't allow the wheel to travel up or down, nor will it mate correctly with the wheel surface. The hanger is clear of the stay, and can still move back from the wheel a bit. it's hard to explain very well, but to sum it up I think I need to make the slot in the brake shoe deeper to allow the shoe more room to pivot, or to remove material from the edge of the hanger that enters the shoe, however Don mentions to be critical of this depth to avoid the shoes tripping, so taking the depth oversize to fix the problem can't be the solution. Also this would mean that the shoe is pivoted well beyond its normal range of motion to begin with which makes me think I've done something wrong. Tim. I welcome any suggestions or advice here as I've been looking at this for 2 weeks now and have got nowhere.   |
|
|
|
Post by Deleted on Mar 13, 2021 16:22:44 GMT
Hi Tim
I re-read my notes to see if I had any issues with the tender brakes. I can only see a comment on the rear brake having a vlearance issue which I noted other builders had also reported this error. Alas I can't recall if I had any problems with the front?
Regards
Pete
|
|
don9f
Statesman
Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
Posts: 961 
|
Post by don9f on Mar 14, 2021 18:04:49 GMT
Hi, did you mean to type “tipping” with ref. to Don Young’s comment, as I didn’t understand a brake block “tripping”? Looking at the photo from above the block, I would have thought you could make the slots in the brake blocks a bit deeper without any problems....you probably won’t need that much extra depth. The other question though is are the other sets of brake hangers etc. ok and is it just the front set? If it is, there must be some difference somewhere. Some full size designs did indeed have an arrangement to stop the blocks rubbing their top edges against the wheels (with the brake off), but I wouldn’t be concerned about that in 5” gauge personally.
The Fowler tender I am currently building had a similar problem when I initially assembled the brakegear and as well as making the brake block slots a bit deeper, I actually reduced the wheel diameters a bit to help....fortunately, as originally machined, the tyres looked too thick anyway!
Cheers Don
|
|
|
|
Post by coniston on Mar 14, 2021 23:59:10 GMT
Hi Tim, I have just checked the drawings and there is no reason why it shouldn't be exactly the same for all axels. All the brake hanger pivots are in the same relative position to the axel centres as drawn and the hangers pivot centres to block pivot centres are the same for all three different shapes of hangers. The only thing I can see is the axel box in the picture is at the very bottom of the horn, would it be an idea to set all axels to their running height and check again? may be worth checking the pivot positions on the frames for each axel as well but I don't know how this could be different for just the front axel.
As drawn and if the axel box sits in the middle of the horn cheeks there should be 1/8" to 9/64" clearance above the axel box in the running position. Worth checking?
Chris D
|
|
tim
E-xcellent poster
Posts: 236
|
Post by tim on Mar 16, 2021 8:43:47 GMT
Hi, did you mean to type “tipping” with ref. to Don Young’s comment, as I didn’t understand a brake block “tripping”? Looking at the photo from above the block, I would have thought you could make the slots in the brake blocks a bit deeper without any problems....you probably won’t need that much extra depth. The other question though is are the other sets of brake hangers etc. ok and is it just the front set? If it is, there must be some difference somewhere. Some full size designs did indeed have an arrangement to stop the blocks rubbing their top edges against the wheels (with the brake off), but I wouldn’t be concerned about that in 5” gauge personally. The Fowler tender I am currently building had a similar problem when I initially assembled the brakegear and as well as making the brake block slots a bit deeper, I actually reduced the wheel diameters a bit to help....fortunately, as originally machined, the tyres looked too thick anyway! Cheers Don Thanks Don I’ve been looking them over some more and apart from the hangers that hang from the drag box, (these seem ok) the intermediates have the same problem as well. With regard to “tripping”, Don states, mill the 1/8”slot, 3/16” deep, the 3/16 being fairly critical so that the shoe cannot ‘trip’ when the brakes are fully released and make the wheel seize. To be honest I just made it as close to 3/16 as I could at the time, only now having a fitting issue. I will persevere. I’m now actually thinking of machining some more of the radused face of the shoe similar to your machining off the wheel. This would give more room to move round a marry up better. Tim. |
|
tim
E-xcellent poster
Posts: 236
|
Post by tim on Mar 16, 2021 8:53:04 GMT
Hi Tim, I have just checked the drawings and there is no reason why it shouldn't be exactly the same for all axels. All the brake hanger pivots are in the same relative position to the axel centres as drawn and the hangers pivot centres to block pivot centres are the same for all three different shapes of hangers. The only thing I can see is the axel box in the picture is at the very bottom of the horn, would it be an idea to set all axels to their running height and check again? may be worth checking the pivot positions on the frames for each axel as well but I don't know how this could be different for just the front axel. As drawn and if the axel box sits in the middle of the horn cheeks there should be 1/8" to 9/64" clearance above the axel box in the running position. Worth checking? Chris D Thanks Chris, I will re measure the all the relative positions when I next have a chance. I’m inching towards the leaf springs as well, so have decided that now might be a good time to get the tender permanently at the correct height and then modify whatever needs rectifying then. Tim. |
|
tim
E-xcellent poster
Posts: 236
|
Post by tim on Mar 16, 2021 8:56:36 GMT
Hi Tim I re-read my notes to see if I had any issues with the tender brakes. I can only see a comment on the rear brake having a vlearance issue which I noted other builders had also reported this error. Alas I can't recall if I had any problems with the front? Regards Pete Thanks for looking Pete. Tim. |
|
