Wagons - to carry 10.0.0 - tare 6.4.0 - what does it all mean ?

[Killybegs]

3 hours ago, billbedford said:

No worse than hexadecimal.

 

I had to look that up Bill. Totally over my head being brought up on duodecimals (shillings and pence, feet and inches). 

 

And weights, don't forget the metric tonne = 1000kg!

Edited April 20, 2019 by Killybegs

[The Johnster]

On 18/04/2019 at 01:02, Dave John said:

14 pounds to a stone, 8 stones to a hundredweight. 112 pounds. 20 Cwt to a ton. 200 sacks to a 10 ton wagon. 

 

Why ? Well traditionally a lot of things were in 1 cwt sacks. Coal, cement, plaster. It's about what a tradesman could put over his shoulder and carry. Metrication changed it to 50 Kg bags , and the safety elves halved it to 25 Kg, roughly half a cwt. Good thing they did, shifting stuff in 112 lb sacks was damn hard work. 

 

A lot of measurements were based on what a man could do. An acre, a furlong by a chain, what a man could plough in a day. 

 

A Firkin is about 9 gallons. If I humpfed 20 sacks up a close in a day ( And you would need that to plaster a traditional Glasgow flats ) I'd drink a firkin of beer. And I wouldnae be bothered aboot the next firkin wagon..... 

 

(sorry , couldn't resist an old joke ..... ) 

I understood it to be a standard unit of 2 firkin.  2 firkin long, 2 firkin heavy, 2 firkin slow, etc...

[Compound2632]

3 hours ago, Killybegs said:

 

I had to look that up Bill. Totally over my head being brought up on duodecimals (shillings and pence, feet and inches). 

 

And weights, don't forget the metric tonne = 1000kg!

 

The term "metric tonne" is illegal in trade - it's just "tonne". Personally I think correct use of SI prefixes is preferable, so its a megagram. And it's a unit of mass, not weight. For weight, please use newtons and your local value of gravitational field strength.

Edited April 20, 2019 by Compound2632

[34theletterbetweenB&D]

On ‎17‎/‎04‎/‎2019 at 17:41, Brinkly said:

... tare weight... why did they vary so much from vehicle to vehicle? I've been looking through my wagon books and noticed that BR standard box vans had tare weights of 7-4, 7-11, 7-6 etc. Was it just down to the density of the material? I've noticed similarities on BR built steel mineral wagons, essentially the same diagram of vehicle...

This is little known to the large majority who have never been involved in any form of manufacturing, but random variation is ubiquitous, and its control a significant aspect of production management. I wouldn't trust the marked tare weights either, unless I knew about the calibration of the weight bridge and any operator error.

 

(Very early in my career I was set to discover why the late shift was consistently 'less productive' than the early shift. The workforce swapped early/late every week. All except the two goods in and out clerks, who by agreement stayed put. The early man weighed 'heavy', the late man weighed correctly, slightly lighter. This because the early man was very short and couldn't read the weighbridge head on - had to stand on a bank to one side to get the indicator at eye level - whereas the late man was tall and could sight the indicator head on. Since the batch production process took several hours, the offset in 'productivity' between the two shifts was the best part of double the early operator weighing error. In reality there was no difference to speak of, which those in charge of the work already knew in their bones.)

[jim.snowdon]

3 hours ago, 34theletterbetweenB&D said:

This is little known to the large majority who have never been involved in any form of manufacturing, but random variation is ubiquitous, and its control a significant aspect of production management. I wouldn't trust the marked tare weights either, unless I knew about the calibration of the weight bridge and any operator error.

The railway companies would have been under the same legal requirement as any other trader to have, in this case, weighed their wagons using an accurate measure. That meant keeping the weighbridges regularly maintained an calibrated, for which purpose Messrs. Avery and Pooley between them had quite a fair fleet of mobile workshop vans at their disposal. When a wagon (or a road vehicle, for that matter) said it had a tare weight of x, x was what any weighbridge operator could legally deduct from the gross weight of the wagon in order to calculate the load. From the extent to which it became normal to quote the wagon tare weight to the nearest hundredweight, rather than quarter, it has to be presumed that this was considered sufficiently accurate by the Weights and Measures authorities. The percentage error created by half a hundredweight in the typical weight of a railway is small enough to quite probably have been considered insignificant. Mathematically,  the sums of a large number of errors is zero, ie over a large enough sample the "unders" cancel out the "overs", and with bulk traffics, that rule would certainly apply.

 

Jim

[St Enodoc]

On 20/04/2019 at 01:19, The Johnster said:

Despite being brought (dragged) up and ejumacated, allegedly to 'O' level standard, in the imperial 'old money' era, I never really mastered it as a mental exercise in terms of weight, or some of the odder area/length units, despite repeating it by rote in primary school until you had it pat.  You didn't have to, as we all had 'Silvine' school note books with times tables and all the imperial units on the back cover as a ready reckoner, and jobs such as wagon checking that used the units regularly had their own versions.  When curmudgeonly old so and so's like me moan about millennials and their dependence on calculators or digital time, this should, I think, be taken into consideration.  

 

But I knew a bloke on the railway, a shed labourer, years ago, who claimed he could not do arithmetic, it was too hard for him.  Well, perhaps, but he could tell you what you'd get for any sum of money in pounds, shillings, and pence, for any horse at any odds for any bet, with the tax correctly deducted, in his head and in a few seconds, assuming the nag came in of course.  I'd have trouble doing that with a calculator, a device by which I can get any sum accurately wrong to 16 decimal places.

I knew a few like that. They could always work out if they'd been underpaid but, strangely enough, not if they'd been overpaid.

[St Enodoc]

On 20/04/2019 at 16:36, Enterprisingwestern said:

 

I would for one, fish, chips and mushy peas for half a crown, optional (proper Yorkshire) fishcake at sixpence, and imperial food tasted better than metric food!

 

Mike.

... and still 'ave change for t' tram 'ome.

[96701]

Taylor Hubbard refurbished diesel mechanical rail cranes were 10.16 tonne maximum SWL.

[Compound2632]

5 minutes ago, 96701 said:

Taylor Hubbard refurbished diesel mechanical rail cranes were 10.16 tonne maximum SWL.

 

... so someone wasn't prepared to derate them by 1.6% for the sake of simplicity?

[doilum]

16 minutes ago, Compound2632 said:

 

... so someone wasn't prepared to derate them by 1.6% for the sake of simplicity?

Because there was probably a very common load that was close to the limit. Downgrading them might make them obsolete.

[Compound2632]

2 minutes ago, doilum said:

Because there was probably a very common load that was close to the limit. Downgrading them might make them obsolete.

 

So the safety margin was less than 1.6%?

[doilum]

2 minutes ago, Compound2632 said:

 

So the safety margin was less than 1.6%?

Possibly. I would expect the manufacturer to build in a safety margin before rating the crane.

[jim.snowdon]

50 minutes ago, Compound2632 said:

 

... so someone wasn't prepared to derate them by 1.6% for the sake of simplicity?

That would have been short changing the customer, even if it would have been common sense.

 

Jim

[Compound2632]

My point was really about the spurious precision that arises when rounded approximate measurements in Imperial units, say 10 tons, are converted into SI units with the oucome quoted to excessive significant figures. The original 10 ton SWL wasn't designed in with great precision to the crane, it's just a nice round number with a reaonable megin of safety. The Highway Code stopping distances are (or at least were) another case in point,

Edited April 25, 2019 by Compound2632

[96701]

2 hours ago, Compound2632 said:

 

... so someone wasn't prepared to derate them by 1.6% for the sake of simplicity?

No, they were originally 10t maximum SWL. Refurbishing included fitting a safe load indicator calibrated in tonnes, hence 10.16. Items in the depots in which they were used were also labelled in metric units, so it made sense to re-calibrate the crane in metric too.

[96701]

36 minutes ago, Compound2632 said:

 The original 10 ton SWL wasn't designed in with great precision to the crane, it's just a nice round number with a reaonable megin of safety. The Highway Code stopping distances are (or at least were) another case in point,

I must take issue with you here as somebody who has added his signature to rail crane test certificates, I can assure you that some precision was necessary. The amber light of the Safe Load Indicator (SLI) had to come on between 92.5% and 97.5%  of Safe Working Load (SWL) at maximum, minimum and two intermediate radius points, with the red light and audible warning coming on between 102.5% and 107.5%. I spent ages drawing load charts with the necessary bands on and using calibrated test weights to set SLIs up with the occasional foray into proof load testing at 125% of SWL. A few twitchy sphincter moments have ensued including using one Coles crane to remove it's own buffers in order to get the test weights round it.

[sir douglas]

hmmm, imperial weight sounds very confusing, i'm glad i never had to learn it

[LMS2968]

A lot of us on here grew up with it and had no problems; it's metric we find confusing!

[Gareth 73]

10 hours ago, LMS2968 said:

A lot of us on here grew up with it and had no problems; it's metric we find confusing!

I still think its mad that what ever common model railway scale we deal with its Xmm to the foot. But then 2mm to the foot or 4mm to the foot makes some sense when it comes to 9, 6 and 3 inches but 3.5 and 7mm to the foot??

[rodent279]

Going back to wagon tare weights, and differences between supposedly identical wagons, another factor may have been of a wooden wagon was weighed when wet, the water absorbed by the wood would add to the tare weight.

[doilum]

13 hours ago, LMS2968 said:

A lot of us on here grew up with it and had no problems; it's metric we find confusing!

No confusion with metric ( an English invention?) . Simple base ten and an integration of weight, volume and area. 1000cc,= one litre = one kg of water. 1000 kg = one metric ton. Makes water collection and storage calculations a doddle!

That said, those of us brought up imperial were given an arithmetical agility that bewilders metric children. Money started in base 12 went to base 20,10 or 8 depending on whether you used shillings florins or half crowns. Weight went from base 16 to 14 to................

All good fun but anyone who thinks that poles, chains and acres are superior is welcome to them. The problem is that certain parts of our popular press have constantly undermined the metric system and that education has not celebrated and explained it's strengths. Rant over.

[meil]

On 25/04/2019 at 18:42, Compound2632 said:

 

So the safety margin was less than 1.6%?

1.57% actualy

[LMS2968]

Yes, I know. I qualified at university as a mechanical engineer so had to work in metric, but I can't envision it. If you told me that something is 15cm long, it means nothing. First, engineers don't use centimetres; we use metres and millimeters so I have to convert it to 150mm. That doesn't help much, but I know that 150mm is about six inches, and I know what that looks like!

 

Metric works on a base of ten, but nature doesn't. There are four seasons in a year; the moon takes 28 days to orbit the Earth, and the Earth 365 1/4 days to orbit the Sun.

 

When I was a student - a mature student - I was amazed at how many of my much younger companions simply couldn't work with fractions. And when we came to do long division . . !

 

Each system has its pros and cons.

[billbedford]

1 hour ago, doilum said:

No confusion with metric ( an English invention?) . Simple base ten and an integration of weight, volume and area. 1000cc,= one litre = one kg of water. 1000 kg = one metric ton. Makes water collection and storage calculations a doddle!

 

 

Unless you are dealing with seawater...

[Compound2632]

1 hour ago, LMS2968 said:

Metric works on a base of ten, but nature doesn't. There are four seasons in a year; the moon takes 28 days to orbit the Earth, and the Earth 365 1/4 days to orbit the Sun.

 

Ah, but... The metre as originally defined* was one 10,000,000th of the distance from the pole to the equator. (Established by surveying a meridian from Dunkirk to Barcelona.) Which is convenient for remembering the size of the Earth.

 

*As opposed to earlier proposals, based on the length of a pendulum having a period of two seconds.

 

Per @billbedford's likeable observation, the original definition of the kilogram was based on a cubic decimetre (litre) of pure water but this was impractical to realise with sufficient accuracy - not only the purity but the temperature has to be specified - hence the move to an artefact standard, only 18 months ago finally replaced by a definition based on the properties of nature (as is now the case for all the base units of the SI).

Edited December 16, 2020 by Compound2632