Thursday, 25 August 2011

Trailing Engine's Boiler Feed Pump Valve Regrinding

The last episode left the inlet and outlet valves in need of a quick regrind. The process is simple and requires only a little fine grade grinding paste and a screwdriver to rotate the two halves together.

The rotation action is backwards and forwards in a two steps forward, one step back arrangement with the two rubbing surfaces never being allowed to stay in the same place for long. Otherwise the surfaces could stray from being flat and a good seal would only take place when the valve and seat had a particular position relative to each other. This would be clearly undesirable so hence the continual back and forth rotational movement.

Inlet Valve being reground.
After grinding, the remaining paste must be removed from all surfaces so that the paste does not get where it shouldn't during the pump's operation. I used Duck oil and a cloth to wipe away the residue. Paraffin is actually recommended but I didn't have any. However, there did not seem to be any residue remaining!

Inlet Valve

I did the inlet valve first and the result is below (apologies for slight lack of focus).
Inlet valve after the regrind
Deposits on the valve have gone and
the marks on the seat are lessened
At this point I spotted a problem which I had not previously noticed but was there all the time. The cap over the valve had clearly been over-tightened at some time sufficiently to break it apart.
Cap viewed from the side/below
Cap viewed from above
It had been tightened so much that it had pressed the centre section through so that the outer rim would seat but the whole piece would not seal. Whilst there would be little consequence to the pump operation because there is an outer cover to hold it in place, it has been remade to avoid any further trouble from it in future.
The original cap seems to have been made from gunmetal; however, a 1.5 inch diameter piece of brass rod has been machined for the new one.
Old and new
I decided to mill a groove across the top to enable the cap to be rotated. With valve grinding paste between the mating surfaces, it can now produce a good seal. At first I didn't think that water escaping into the cap cavity would be important; however, it could possibly act as an air bubble in the system and hence reduce the effectiveness of the pump (which was designed to work with an incompressible fluid). So I've convinced myself it will be better as a result!

Needless to say, the outer cover which holds the new cap in place should only be delicately 'nipped' tight to avoid further destruction!
New valve cap installed
Outlet Valve

The outlet valve was reground in a similar manner to the inlet valve.
Valve deposits removed compared to before
Seat deposits reduced
The outlet valve is now ready for action.

Sunday, 21 August 2011

200HP Pre-war Sentinel Locos (1)

Sentinel 7109 is a 200 HP type; however, Sentinel also produced various other 200 HP types before they settled on the 7109 configuration. One such type proposed was the double centre-engined type shown below. However (see comments below the posting), this type was never apparently built although others were (but I don't have diagrams for them!).
Double Centre-engined 200 HP Locomotive
The front engine was intended to be linked to the front axle and the rear engine to the rear. Those specified to be low geared (and hence high torque) also had their engines locked together to prevent wheel-spin on one axle.

Compare this to Sentinel 7109 with its engines at the front (and check the comments below).

Sentinel 7109 - A balanced double-engined 200 HP locomotive
Both the types and others could be built with double gearing; however, 7109 is only single geared.

Saturday, 20 August 2011

Cab Repaint

Wednesday 10th August 2011 saw more work to tidy up the cab before parts become inaccessible with the boiler reinstated.

Red paint is now getting everywhere...

...Right and...
And who's idea was it to do a 'Banksy' of a road railer on the RH window?
Progress continues!

Friday, 19 August 2011

Sentinel 8837

I paid a swift visit to the Middleton Railway in Hunslet, Leeds on 14th August 2011 hoping to see their Sentinel (8837) in action. I was given a very warm welcome and, after a ride up the 1 in 37, was provided with a guide to show me around the workshops and in particular to the Sentinel.

Sentinel 8837 is not the priority restoration project at the moment and is unlikely to see steam for perhaps four years. The body and chassis are currently in the workshop with the boiler and engine stored away elsewhere safely.

Rear view...
...front view (or is it the other way round?)
Apologies for the camera shake. (There are two possible reasons for this: (1) I'd been to a party the previous night and was in need of restoration (2) I'd recently been shown how to use the manual controls on the camera to get the very best pictures. I'll leave you to figure out which was the dominant cause. Needless to say, being shown how to and knowing how to use a camera's manual mode when in a hurry are two different things. I'll stick to automatic in future!).

Many thanks to the Middleton Railway for their warm welcome and I look forward to seeing 8837 in action in the future.

Thursday, 18 August 2011

100HP Pre-war Sentinel Locos

I found a wonderful book recently named "Sentinel" Patent Locomotives that covers much more than just Sentinel 7109. Although it was reprinted in 1974, my copy was the genuine article published by the Sentinel Waggon Works in 1931 as a kind of technical marketing catalogue for pre-war locomotives.

For example, here's a LNER Y3 type in drawing format.

And the Y1 type; however, the difference is not apparent except to those who looked underneath. 
The Y3 had a gearbox below its engine to enable two levels of capability whereas the Y1 drove directly from the engine's crankshaft. The Y3 was thus the more flexible locomotive.

Sadly, no Y3s have survived.

Wednesday, 17 August 2011

The little engine that could...or maybe could not?

My OO gauge Sentinel Y3 model arrived from Model Rail Magazine (9th Aug 2011) as pictured.

MRM (Dapol) Y3
(with a distracting back-drop from another interesting book I've found lately)
The supplied instruction sheet set me wondering due to the comment that the model was produced from detail obtained from Isebrook at Quainton road.

Extract from instruction sheet
However, Isebrook is a single geared type as with the Y1!

Isebrook's chains drive from the crankshaft sprockets
So is the model actually a Y1 or Y3? I'll leave it to you to figure out; this posting might help. In reality, it's not important; it is a fine, tiny model which runs very nicely. For more information have a look at the Model Rail Magazine's website.

Here is a small video of Isebrook in preserved action on YouTube at the Buckinghamshire Railway Centre, Quainton Road. The occasion was the Sentinel Drivers' Club 'Noggin & Natter' held on 10th April 2011.

Tuesday, 16 August 2011

Leading Engine's Boiler Feed Pump and Valve Regrind

Having said in the first episode that the leading and trailing engine-mounted pumps look the same, here's the leading one to compare with the trailing one.

Leading Engine's Feed Pump in situ
The regrinding process for improving the inlet and outlet valves was exactly the same as for the trailing engine's pump; these photos show the leading engine's pump valves' condition for comparison. Regrinding took place on Wednesday 10th August 2011.

Inlet Valve

Inlet valve on opening for view
Valve cap is intact
Deposits on valve...
...and on the seat...
...but flushed clean away after regrinding
I also decided to mill a slot across the top and regrind the valve cap as with the trailing engine's pump. Now it seats itself more positively and should perform better as a result.
Leading engine's pump valve cap cleaned, reground and in place
(11th Sept 2011)

Outlet Valve

Unlike the trailing engine's pump, there was no washer sitting on top of the valve. I don't know why this should be unless a botch was used on the trailing pump to reduce the maximum opening of the valve. Comments welcome.
Outlet valve and seat were fairly dirty on opening...
...but much improved after a good grind!

Thursday, 11 August 2011

Mount Rainier Scenic Railroad

So what has this to do with Sentinel 7109, I hear you ask! Well not an immediately obvious lot except that on my travels to Washington State USA in July 2011, I landed almost accidentally on the Mount Rainier Scenic Railroad. Not expecting too much to begin with, I was pleased to be cordially invited to visit the 'shops' and see the steam locos not in use at the time.

I was stunned to be presented there with a Heisler, a Climax and a Willamette - all in working order. A Shay under restoration was also there in the shed.

On returning home, the photos I'd taken in the 'shops'' shed (yes, the apostrophes are correct; a quote of a genitive plural!) were far from as good as I'd hoped. However, here are some of the best ones.

Willamette 34
Not a Shay
The less mechanical side
Leading drive-train
Trailing and tender drive-train
And finally, the Climax!
Having had a good look around the Mount Rainier Scenic Railroad website, I can't come close to their pictures. Try these:

Heisler, Climax, Willamette (On the right).

Have a look around the Gallery; it's a superb collection of photos of Steam Logging locos.

Meanwhile, Sentinel 7109's whistle has featured prominently during its refurbishment. Strange noises from my garage have kept the neighbours bemused for hours (well, minutes anyway). So if Midsomer Norton station can manage to replace its missing Silver Street bridge with a level crossing, how about if we upgrade 7109's whistle and blow it like this to frighten the traffic away! (Also on YouTube)

Whistling in the USA!
The culprit in the video: July 29th 2011,
MRSR's newly restored Baldwin 2-8-2 Rod Locomotive
No 70, Polson Logging, near Elbe, Washington State, USA.
And after all that, there is a connection with Sentinel 7109 - it is also a gear driven locomotive!
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