JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,912
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Post by JonL on Nov 8, 2021 10:47:11 GMT
950g, with a chassis to floor ride height of 3mm. Anyway, I digress, sorry.
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Post by Roger on Nov 8, 2021 12:37:16 GMT
950g, with a chassis to floor ride height of 3mm. Anyway, I digress, sorry. No problem, it's all interesting. So that's about 60 times less massive
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Post by Roger on Nov 8, 2021 20:43:33 GMT
After filling all of these with 100cst Silicone Oil, I could feel that the one on the RH side was definitely providing more resistance. That's because on the others, I'd pocketed the hole in the piston with a 1mm hole, with just the last 0.5mm being 0.4mm diameter. However, on the first one I made, the 0.4mm hole went all of the way through the 2.5mm piston. It's surprising just how much difference that additional 2mm of 0.4mm diameter hole makes to the flow resistance. So I removed the piston and opened out the hole to make it the same as the others, and they all feel the same now. I've ordered some 200 and 300cst Silicone Oil in case I want to increase the damping effect. I'll experiment with that before the final fitting. I'm trying to picture the loading on one axle, and that ought to be carrying 1/6th of the total weight, ie approximately 10Kg. I'm imagining that the damper ought to be able to deliver at least 1Kg of load at modest rates of displacement, with up to say 2Kg at the highest. I suppose I could try to estimate the values and the spring constant so they could be modelled, but I don't think it's terribly useful. I'll just experiment and see what results I get. 20211108_202931 by Timothy Froud, on Flickr Anyway, I now need to make a split collar to stop one of the front bearing from sliding sideways.
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Post by andyhigham on Nov 8, 2021 21:01:39 GMT
Why only 4?
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Post by chris vine on Nov 8, 2021 22:21:28 GMT
Hi Roger,
They are objects of beauty and complexity!
My one thought is that you should fit them in a fairly weak state to start with. Reason: It is important that when a rail dips, that the wheel can follow it quickly enough for the flange to not lift above the rail head.
on car dampers they absorb bumps easily and rebound slowly. This works for cars, but I would not have thought would be good for rail wheels.
Your dampers have equal effect in either direction, so I would start soft. I am pretty certain that any damping will be much much better than no damping!!
Chris.
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Post by Roger on Nov 8, 2021 22:35:13 GMT
It's physically impossible to fit anything next to the firebox unfortunately. Starting from scratch, designing the axleboxes differently, it might be possible to have a rocker to a damper further back, but it's not easy. I figured that any porpoising motion would mostly be damped by two axles.
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Post by Roger on Nov 8, 2021 22:46:59 GMT
Hi Roger, They are objects of beauty and complexity! My one thought is that you should fit them in a fairly weak state to start with. Reason: It is important that when a rail dips, that the wheel can follow it quickly enough for the flange to not lift above the rail head. on car dampers they absorb bumps easily and rebound slowly. This works for cars, but I would not have thought would be good for rail wheels. Your dampers have equal effect in either direction, so I would start soft. I am pretty certain that any damping will be much much better than no damping!! Chris. Hi Chris, Agreed, you wouldn't want them to be too effective. Presumably, if the track under one wheel dips, not only will the wheel want to follow with less force applied to the rail, the load will be transferred to the other wheels. I guess this is how it smooths out the motion. It will be interesting to see how it rides. I imagine that really stiff springing is even worse, because the wheel could unload significantly, regardless of the speed. At least this setup is benign when the speeds are low. I suppose I could make them assymetric, with a small flap of rubber over one of the holes, but I'm not sure what would be the best way to set it up. I'll keep it simple for the moment, I have a feeling it's going to make a big difference over just having coil springs.
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Post by Roger on Nov 9, 2021 23:23:07 GMT
This is the split collar that stops the Hydraulic Damper from sliding sideways on the front axle. The slitting saw is 0.8mm thick. I cut this with 2mm deep cuts. 20211108_222105 by Timothy Froud, on Flickr These are the cap head pockets being machined with a 4mm cutter. 20211109_105654 by Timothy Froud, on Flickr Then they were parted off long... 20211109_194333 by Timothy Froud, on Flickr ... before facing off on a mandrel. 20211109_200518 by Timothy Froud, on Flickr And this is where it fits. The other side is retained by the eccentric, while the ones on the centre axle are retained by the anti-roll bar. 20211109_224444 by Timothy Froud, on Flickr I'm going to oil these through a hole drilled in the centre of the axle. I don't need that for the axleboxes, they are well catered for by the reservoir on the top of the axlebox. So the question is, what size do people use for the holes in the axle, and do they fit a reducer on the outer end so that the Oil doesn't dribble out? 20211109_224531 by Timothy Froud, on Flickr
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Post by chris vine on Nov 9, 2021 23:46:31 GMT
Hi Roger,
Yes, simpple wins nearly every time. Just not too stiff to start with.
It was Colin Chapman who realised that soft springing was much better for road holding than the bone jarring rides that other car designers specified.
He also worked out that if you made, say, the seat 1 kg lighter, then the bracket that held the seat could be lighter, that meant that the suspension components could be lighter, so you needed a smaller engine etc to give the same performance. That was lighter too, so the chassis could be lighter. Eventually you get to the point where the most significant mass in the vehicle is the driver - who is not so easy to lighten. All this led to the original Lotus elan, super 7 etc.
Chris.
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JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,912
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Post by JonL on Nov 10, 2021 0:19:07 GMT
The holes in my axle ends and counter bore at the axle boxes are about 2mm at a guess. I don't think it acts as a reservoir, it just uses what's applied at the time and you top up now and then
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Post by simplyloco on Nov 10, 2021 8:53:53 GMT
Hi Roger, Yes, simpple wins nearly every time. Just not too stiff to start with. It was Colin Chapman who realised that soft springing was much better for road holding than the bone jarring rides that other car designers specified. He also worked out that if you made, say, the seat 1 kg lighter, then the bracket that held the seat could be lighter, that meant that the suspension components could be lighter, so you needed a smaller engine etc to give the same performance. That was lighter too, so the chassis could be lighter. Eventually you get to the point where the most significant mass in the vehicle is the driver - who is not so easy to lighten. All this led to the original Lotus elan, super 7 etc. Chris. "Speed through lightness" I believe he said.
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Post by 92220 on Nov 10, 2021 9:15:20 GMT
Hi Roger, Yes, simpple wins nearly every time. Just not too stiff to start with. It was Colin Chapman who realised that soft springing was much better for road holding than the bone jarring rides that other car designers specified. He also worked out that if you made, say, the seat 1 kg lighter, then the bracket that held the seat could be lighter, that meant that the suspension components could be lighter, so you needed a smaller engine etc to give the same performance. That was lighter too, so the chassis could be lighter. Eventually you get to the point where the most significant mass in the vehicle is the driver - who is not so easy to lighten. All this led to the original Lotus elan, super 7 etc. Chris. Hi Chris. I'd not heard of that, and it seems very strange, as rally cars have/had stiffer suspension than road cars, since the first Minis were driven on the Monte Carlo Rally. My Chevette HS rally car, of 1979, had very stiff suspension, but very soft tyres. It was the tyres that made the car not slide on corners. I remember when I first got the car, I was on a rally and was doing 70, coming up to a bend that turned out to be a fairly sharp right angle bend. I thought I was about to lose it, but the car went around the corner as if on rails, with no hint if slide. It was the tyres that kept it on the road. High performance cars, also have harder than normal suspension. Race cars, stay absolutely flat when cornering, which they couldn't do with soft suspension. Again, it's the tyres that stop it sliding. That is why they get the tyres hot for racing....to soften the surface and make it stick to the track. With their sticky tyres they would tilt over, with soft suspension, because as they went around a bend they would want to roll over. That is also the reason that anti-roll bars are fitted to most, if not all, performance cars. Bob.
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Post by Roger on Nov 10, 2021 10:22:58 GMT
The holes in my axle ends and counter bore at the axle boxes are about 2mm at a guess. I don't think it acts as a reservoir, it just uses what's applied at the time and you top up now and then Thanks Jon, Even if it's not intended to be a reservoir, it's surely going to be one? You have to fill the hole to get oil into the bearing, and once it's there, I feel sure it will wick into the bearing continuously while it's running. The turning axle will also give a small centrifugal force to encourage flow outwards at the feed hole to the bearing.
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Post by Cro on Nov 10, 2021 10:33:22 GMT
The holes in my axle ends and counter bore at the axle boxes are about 2mm at a guess. I don't think it acts as a reservoir, it just uses what's applied at the time and you top up now and then Thanks Jon, Even if it's not intended to be a reservoir, it's surely going to be one? You have to fill the hole to get oil into the bearing, and once it's there, I feel sure it will wick into the bearing continuously while it's running. The turning axle will also give a small centrifugal force to encourage flow outwards at the feed hole to the bearing. Some of our locos have this feature and I've never noticed it running back out. Countersink the end of the axle to get an oil can on the end and a good squirt of oil at begging on the run is all it needs. Our Black 5 has this for main axleboxes and works perfectly. I'm just doing it to Dad's 2 1/2" Grange main axle with all the eccentrics on to avoid having to try and oil them all separately. I just have to make sure I don't drill all the way through!
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Post by Roger on Nov 10, 2021 12:42:21 GMT
Thanks Jon, Even if it's not intended to be a reservoir, it's surely going to be one? You have to fill the hole to get oil into the bearing, and once it's there, I feel sure it will wick into the bearing continuously while it's running. The turning axle will also give a small centrifugal force to encourage flow outwards at the feed hole to the bearing. Some of our locos have this feature and I've never noticed it running back out. Countersink the end of the axle to get an oil can on the end and a good squirt of oil at begging on the run is all it needs. Our Black 5 has this for main axleboxes and works perfectly. I'm just doing it to Dad's 2 1/2" Grange main axle with all the eccentrics on to avoid having to try and oil them all separately. I just have to make sure I don't drill all the way through! Thanks Adam, what size hole do you use for the 5" gauge locomotives?
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Post by Cro on Nov 10, 2021 13:06:02 GMT
Can't remember from memory but I'm up club Friday afternoon to do some work on loco so I'll check - remind me Friday lunch to have a look!
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Post by ettingtonliam on Nov 10, 2021 14:45:21 GMT
If you are concerned about it running out, down the wheel and possibly onto the track, you could counterbore the axle ends 6mm dia and press in some of those ball loaded oil zerks. With all the outside valve gear bits masking the view, they shouldn't be too visually obtrusive.
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Post by andyhigham on Nov 10, 2021 15:34:21 GMT
PTFE liners in the shock bearings would probably be happy with no lubrication or the little oil that will ooze (great word) along the axle from the axleboxes
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Post by Roger on Nov 10, 2021 16:31:00 GMT
If you are concerned about it running out, down the wheel and possibly onto the track, you could counterbore the axle ends 6mm dia and press in some of those ball loaded oil zerks. With all the outside valve gear bits masking the view, they shouldn't be too visually obtrusive. That's an interesting idea. However, that would also probably stop any of the oil that remains in the hole from finding its way into the bearing. I suspect that the viscosity of the oil is enough to stop it running out, unless it's stationary for a long time. Even then, I think it's possible that a slug of oil will be kept in place since the other end is effectively sealed. It's an interesting issue. Really thin oil would probably run out.
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Post by Roger on Nov 10, 2021 16:32:25 GMT
PTFE liners in the shock bearings would probably be happy with no lubrication or the little oil that will ooze (great word) along the axle from the axleboxes That's a very good point, and something I could do if these wear out. I was picturing the oil coming out of the axlebox too, but concluded that it would probably not be sufficient with the bearings I have.
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