Asimo wrote: ↑Wed Jun 14, 2023 5:41 pm
Last year this Sentinel locomotive visited the local "preserved" railway (GWSR / Cotswolds)
That one uses twin (almost) Super engines but running at 275 psi. The only major differences is a solid crank, a slightly different shaped crankcase, improved valve manifolds and pressure fed lubrication.
We used loco manifolds on our Super because they are a big improvement over the crappy waggon arrangement.
JimH wrote: ↑Wed Jun 14, 2023 6:08 pm
The fastest we spun the Super was about 1750. The S crank is less stiff so we tend to limit it to not much more than 1000.
That's where I was thinking wrongly then, I had assumed it would have been a much much lower rpm than that and a 2 speed rear axle would allow for faster speeds on the open road.
PhilA wrote: ↑Wed Jun 14, 2023 6:43 pm
Impressive, I was thinking somewhere in the region of 500.
The S type engine will spin a lot faster that 1000rpm. It is true that these waggons will pull a decent 45mph although I personally doubt the somewhat fevered tales of being clocked at 60 in some. The problem is that the S crank is little more that a bent piece of wire in comparison with what it needs to be. On top of that the case is one of the earlier attempts to make a crankcase in aluminum. The main bearings (all three of them) are not large and woefully undersized for what they are having to deal with. Both the rod and in particular the pistons (cast iron with a weird double skinned crown to try to minimise heat transfer from the steam side to the lubricating oil) are extremely heavy and when spinning at over 1000rpm all you can see in your head is four 1/2" BSF studs tapped into a very dubious quality casting trying to restrain the load.
1000rpm equates to 25mph on the road which is 25% higher than its design speed so that will do nicely.
The Super on the other hand has a massively stiff crankshaft sitting in what are safely described as colossal main bearings secured in very stout bearing housings. You don't have to look at an earlier Sentinel engine to see that Alley and MacLellan started life building big compressors. You can see the length of the main bearing journals in this shot here.
Sure the crank is very heavy soaking up both payload and energy with lashings of friction but I am much happier spinning this one faster because it is up to the job.
This is the only image we have managed to find of a USBC lorry (they didn't have many as most were smaller vans) in roughly maybe about the right era. Yes I know it is obviously later but we don't think that much later in terms of the design. You'll possibly notice that the highlighting on the letters is pretty detailed.
There needs to be a bit (lot) of interpretation to translate this sort of design onto the Sentinel mainly because of the big blank canvas at the front. The current thinking is that the side will look similarish to the side of that Albion with the exception that the registered office address and wheatsheaf will go on the cab side. The front panel will get a big UNITED to tie in with the UNITED on the side and will be the full height of the panel. The headboard will get the full name of the company stretched right the way round it.
The fleet number will go on the side of the front panel in front of the doors.
If you start looking closely you will start to see a lot of lining on the Albion. We are not big on lining but the lad doing the signwriting is the artist so it is up to him. The monograms might look good on the doors of the tool lockers.
UCBS went many years ago. Their factory on McNeill Street was demolished in the 70s. It isn't very easy linking to the Canmore site but you search on "McNeill Street" you'll find some cracking hi res images of the factory just before and during demolition.
JimH wrote: ↑Thu Jun 15, 2023 9:19 amYou don't have to look at an earlier Sentinel engine to see that Alley and MacLellan started life building big compressors.
Sure the crank is very heavy soaking up both payload and energy with lashings of friction but I am much happier spinning this one faster because it is up to the job.
That's definitely the Fast & Furious version of the crank.
Definitely designed for heavy shock load (pressure relief at top of stroke).
