Sentinels.

[Corbs]

I know I sort of started this but I admit I did not know the 200HP had larger wheels when I posted the first time!

[Sandhole]

On 11/07/2020 at 23:37, Ruston said:

If anyone is going to use their Ruston chassis for a Sentinel, and wants rid of the Ruston body, I'm in the market for one. Not the Queen Anne one though.

Being ignorant, what's the Queen Anne one?
The side window cab?

Edited July 13, 2020 by Sandhole

[PenrithBeacon]

9 hours ago, Poor Old Bruce said:

...

I see that, so far, nobody has commented on the glaring errors in the dimensions on the drawing posted by Corbs.

I think the drawing posted by Corbs was of a narrow gauge engine.

Cheers

Edited July 13, 2020 by PenrithBeacon

[Corbs]

4 hours ago, PenrithBeacon said:

I think the drawing posted by Corbs was of a narrow gauge engine.

Cheers

 

Maybe, but the wheelbase measurement is definitely wrong as it doesn't come anywhere near 17ft long if you add them all up, even adding a bit on for the buffers! Plus the next measurement along is shorter but labelled as longer.

[Phil Traxson]

The drawing that Corbs put up is almost certainly the same as the one in the 1974 reprint of the Sentinel catalogue of the 1930's and is of the 100-HP "Industrial Type" which I have in front of me now.

Quotes from the book on this version of loco are:- "For all gauges from 3 ft to 5ft 6 ins in weights from 11 to 21 tons."

And then goes on to the design:- "This arrangement lends itself to wide variations in dimensions, weights and coal capacity."

And:- "The standard wheelbase is 4ft 9ins enabling it to negotiate the sharpest curves likely to be met with. Longer wheelbases can be provided if desired."

 

Common sense says that there would have been quite a lot of adjustment for chain stretching, particularly on the cab end axle as this had to allow for the engine to front axle chain adjustment plus the chain connecting the two axles, as both axles moved in the same direction, unlike the more well known centre engined type where they moved away from each other. This means that the front buffer beam to front axle, the wheelbase and the rear axle to rear buffer beam dimensions all varied dependant on the wear and stretch of the drive chains, lots of scope for the modellers there then!  For anyone with the book it's on page 53. 

 

Book reference for anyone interested---- "Sentinel" Patent Locomotives and Concrete Cases. EP Publishing Ltd, 1974, ISBN 0 85409 958 1 . A very useful little book, full of sales bull, but with lots of photo's and drawings of locos and of the engines and gearboxes and ancillaries too. Just don't rely on the dimensions given!

Edited July 13, 2020 by Phil Traxson

[Phil Traxson]

19 minutes ago, Corbs said:

 

Maybe, but the wheelbase measurement is definitely wrong as it doesn't come anywhere near 17ft long if you add them all up, even adding a bit on for the buffers! Plus the next measurement along is shorter but labelled as longer.

Dead right Corbs, if the wheelbase was 2 ft 5 1/2 ins as quoted the 2 ft 6 ins wheels would overlap each other by 1/2 an inch! Fortunately the words on the opposite page say the wheel base is 4 ft 9 ins. Even then it only makes it about 16 ft over buffers not 17 ft 8 1/4 ins as shown. 

[Poor Old Bruce]

14 hours ago, Corbs said:

 

I couldn't get my head around that. Are the 2 and the 5 the wrong way around?

 

On 12/07/2020 at 09:11, Corbs said:

 

The 100HP Sentinels had smaller diameter wheels than the 200HP didn't they?  

Listed as 2'6" on this drawing. 

 

13 hours ago, PenrithBeacon said:

I think the drawing posted by Corbs was of a narrow gauge engine.

Cheers

 

8 hours ago, Phil Traxson said:

Dead right Corbs, if the wheelbase was 2 ft 5 1/2 ins as quoted the 2 ft 6 ins wheels would overlap each other by 1/2 an inch! Fortunately the words on the opposite page say the wheel base is 4 ft 9 ins. Even then it only makes it about 16 ft over buffers not 17 ft 8 1/4 ins as shown. 

 

It's not just the wheelbase dimension that's wrong, the rear axle to buffer beam, at 3ft 2.5in must be wrong as well.

[Corbs]

What sadist drew this to torture us?

[PenrithBeacon]

I would imagine that it was drawn by the most junior of junior draughtsmen and not give a proper check over. Later, I would think, the errors were found but nobody told the sales department so it came down to us.

[Phil Traxson]

3 hours ago, Poor Old Bruce said:

 

 

 

 

It's not just the wheelbase dimension that's wrong, the rear axle to buffer beam, at 3ft 2.5in must be wrong as well.

Of course you're right there. From other, hopefully more accurate, drawings the boiler on the 100HP locos was 3ft 6 ins diameter over the outside of the barrel, so would hang out of the cab backsheet if that dimension was right. Heaven alone knows where the driver would stand. I hope they sacked the tech. illustrator and the proof reader who allowed these dimensions on this drawing to escape.  

Edited July 14, 2020 by Phil Traxson

[Michael Edge]

This sort of obvious error is remarkably common in GA drawings, I've found lots of them over the years. It's not usually so much that the drawing is inaccurate but that the quoted dimensions are wrong, misreading numbers creates quite big errors in fractional feet and inches drawings, more modern metric ones aren't usually so problematical with all dimensions in mm - big numbers but very clear and not subject to the usual misplaced decimal point errors of the metric system. Don't forget that GAs were never intended to be used to build anything from, that's what the detail drawings are for, there aren't nearly as many errors on these.

[Sandhole]

2 hours ago, Michael Edge said:

This sort of obvious error is remarkably common in GA drawings, I've found lots of them over the years. It's not usually so much that the drawing is inaccurate but that the quoted dimensions are wrong, misreading numbers creates quite big errors in fractional feet and inches drawings, more modern metric ones aren't usually so problematical with all dimensions in mm - big numbers but very clear and not subject to the usual misplaced decimal point errors of the metric system. Don't forget that GAs were never intended to be used to build anything from, that's what the detail drawings are for, there aren't nearly as many errors on these.

Thanks Mike, once again, the calm voice of reason.

[Phil Traxson]

4 hours ago, Michael Edge said:

This sort of obvious error is remarkably common in GA drawings, I've found lots of them over the years. It's not usually so much that the drawing is inaccurate but that the quoted dimensions are wrong, misreading numbers creates quite big errors in fractional feet and inches drawings, more modern metric ones aren't usually so problematical with all dimensions in mm - big numbers but very clear and not subject to the usual misplaced decimal point errors of the metric system. Don't forget that GAs were never intended to be used to build anything from, that's what the detail drawings are for, there aren't nearly as many errors on these.

I can understand your point but this drawing was in a publication intended for prospective customers so surely should have been checked for accuracy, hence my comment on tech illustrator and proof reader.

[PenrithBeacon]

35 minutes ago, Phil Traxson said:

I can understand your point but this drawing was in a publication intended for prospective customers so surely should have been checked for accuracy, hence my comment on tech illustrator and proof reader.

A small company like Sentinel would probably not have had tech illustrators pre war. The quality of the drawing is telling me that it was made by a very junior draughtsman. Just look at the lettering, it's awful!

[neilkirby]

Hi,

 

I have drawn up the Radstock twins:

 

And Joyce

 

I have had two prototypes Printed by a friend:

 

But sadly , I have got to wait until my Eleogoo Saturn is delivered in september to do anything more with these.

 

Regards,

 

Neil

 

[Sandhole]

10 hours ago, neilkirby said:

Hi,

 

I have drawn up the Radstock twins:

 

And Joyce

 

I have had two prototypes Printed by a friend:

 

But sadly , I have got to wait until my Eleogoo Saturn is delivered in september to do anything more with these.

 

Regards,

 

Neil

 

Nice job.

[Adam]

On 14/07/2020 at 18:31, PenrithBeacon said:

A small company like Sentinel would probably not have had tech illustrators pre war. The quality of the drawing is telling me that it was made by a very junior draughtsman. Just look at the lettering, it's awful!

 

I'm really not sure that's the case. They certainly were not a small, local company in the way that say Tasker, Savages or Robey were. Sentinel were a relatively tiny player in railway applications but were a major player in steam-powered commercial vehicles (with a substantial factory - using innovative, quasi production line techniques - and fairly extensive housing for its employees in Shrewsbury and a subsidiary in Chester (which is where the loco conversions were done). They made literally thousands of steam lorries between 1920 and the late-30s and 100 S types for Argentina as late as 1950. Steam locos were a sideline really, albeit a significant one, and one of many that they applied their high pressure boilers and high speed steam engines to, pretty successfully.

 

They would certainly have had a tech pubs department producing manuals and other things and these would have been illustrated.

 

Adam