Bigmet wrote:Mountain wrote:I have always found that Lima steam loco chassis to be far too flexible to run well ...Another general shortcoming on some six coupled Lima steam engines are the budget way they make the centre pairs of wheels which are not coupled at all on some of their designs...
The two go together. If your chassis is going to flex, one way of preventing too much binding of the rod coupled axles is only to couple a pair of them.
I had all manner of trouble with a friend's Lima 08 which indulged in jerky running when given a heavy load to pull, which the motor and weight were well up to tractively. It was the chassis flexing under load that was the root cause, but happily taking out the intermediate gears and leaving the side rods alone to do the transmission job was enough to deliver smooth running, right up the point where the load caused the loco to slip.
I have not had a Lima class 08 but I do have three Lima class 09's, and one is now used with a 7mm narrow gauge body and the other two will also be used for this. All the ones I have drive the rearmost wheel via a cog and the con rods do the rest. I have not come across a design as you have mentioned as yet. The Lima class 09 chassis has quite a positive feature for narrow gauge use apart from its nice con rods extending from the frames (Con rods which may well be too large for 4mm scale but in 7mm scale they look the part!)
I do have a slight cog alignment issue on the chassis I use for the NG loco which I shortened to fit the body and reversed the chassis to hide the motor. I bought the class 09 secondhand with this issue and I corrected it and it ran lovely. It took trial and error and patience to get the gears to run nicely, but once they did it was a lovely runner and gave me no issues. However I must have disturbed something a little so when I do more as I have not quite yet finished with the build yet, so when I do I will spend time on it to get it running well again. I think it is about bending the retaining spring so it sits just right if I recall ,correctly as these seem a little sensitive to their position.
But why these chassis are ideal is because the other end to the motor one has a clear open platform to work with which for 7mm narrow gauge is ideal! One can add weight elsewhere instead if one needs to.
Some other 0-6-0 designs may have excellent mechanisms, but there is no way of hiding the bulk of the chassis when using them for other uses, and this is where the old Lima 09 comes in.
I assumed the Lima 08 had the same design but from what you write it does not. I know Lima gave the 08 more scaled down con-rods. There is so little external difference between the 08's and 09's that it puzzles me why Lima in years gone by did not simply apply 08 numbers to them to broaden the appeal, because apart from Wrenn, the Hornby examples in those days had underframes which did not even look anything like the prototypes, so Lima, even with its overscale con-rods in the 09 had the advantage. Wrenn (Hornby Dublo) apart from looking like an 08 did have a massive screw in the top of its body so though it had a running mechanism to die for as I have never seen such a lovely well made chassis in my life as the Wrenn class 08 example that I have, but that massive screw right in the top of the body... Surely they could have found a better less visual way or used a much smaller screw?
Anyway. Back to your lovely project.
I did once have a secondhand 45xx Lima loco and it stood too tall (Hence why you are addressing this) and I found it was too light in weight. It needed more weight. The little Hornby 0-4-0's were around the same weight. I wonder if someone had removed a weight before I had it, or if they were like that from the factory?
Though it was a few decades ago I was into the GWR, I also had a Mainline/Airfix large prairie which was supurb but I wanted my layout to be based in South Wales and the large praries were only used in the London area. The small praries were used everywhere on GWR metals.