Understanding tare weights

Paul M said:
Sounds like you fell the railway equivalent of asking for a long weight!
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Well, for surveying we used an invar-steel band which was tensioned to something like 5lbs force with a spring tensioner. Invar steel has a very low coefficient of expansion, and the tensioner was to take out any irregularities in the band (tape). If you have any catenary, then a calculation was necessary to adjust, as was an adjustment for wind if, again, you were spanning a cap.

All of the calculations were performed with seven-figure logarithms which, themselves, required a calculation - co you needed to perform a calculation in order to carry out the real calculation :confused::confused:

Fortunateley, I didn't have to do that much surveying :whew::whew::whew:

Laing (John Laing Construction) were ahead of the field in computer applications for construction at the time (and hired out their computer services to other construction companies) but from the survey, having accurate fixes for all of the survey stations, we input the data into pro forma and the computer programme produced an 'angle bible'. This allowed you to set up a theodolite on any survey station, and sight any other survey station, and the angle bible would tell you the angle to turn to intersect a known line - building grid line or offset from the building for a base line. A second theodolite would be similarly set up on another station, angle turned and the intersection would be an accurate point on that base line (usually a pre-determined grid line of the building.

Still with me ? :cool::cool::cool:
 
Rhinochugger said:
Well, for surveying we used an invar-steel band which was tensioned to something like 5lbs force with a spring tensioner. Invar steel has a very low coefficient of expansion, and the tensioner was to take out any irregularities in the band (tape). If you have any catenary, then a calculation was necessary to adjust, as was an adjustment for wind if, again, you were spanning a cap.

All of the calculations were performed with seven-figure logarithms which, themselves, required a calculation - co you needed to perform a calculation in order to carry out the real calculation :confused::confused:

Fortunateley, I didn't have to do that much surveying :whew::whew::whew:

Laing (John Laing Construction) were ahead of the field in computer applications for construction at the time (and hired out their computer services to other construction companies) but from the survey, having accurate fixes for all of the survey stations, we input the data into pro forma and the computer programme produced an 'angle bible'. This allowed you to set up a theodolite on any survey station, and sight any other survey station, and the angle bible would tell you the angle to turn to intersect a known line - building grid line or offset from the building for a base line. A second theodolite would be similarly set up on another station, angle turned and the intersection would be an accurate point on that base line (usually a pre-determined grid line of the building.

Still with me ? :cool::cool::cool:
Click to expand...

Looks like we both speak the same language. Our steel band came with a repair kit.
 
Rhinochugger said:
Well, for surveying we used an invar-steel band which was tensioned to something like 5lbs force with a spring tensioner. Invar steel has a very low coefficient of expansion, and the tensioner was to take out any irregularities in the band (tape). If you have any catenary, then a calculation was necessary to adjust, as was an adjustment for wind if, again, you were spanning a cap.

All of the calculations were performed with seven-figure logarithms which, themselves, required a calculation - co you needed to perform a calculation in order to carry out the real calculation :confused::confused:

Fortunateley, I didn't have to do that much surveying :whew::whew::whew:

Laing (John Laing Construction) were ahead of the field in computer applications for construction at the time (and hired out their computer services to other construction companies) but from the survey, having accurate fixes for all of the survey stations, we input the data into pro forma and the computer programme produced an 'angle bible'. This allowed you to set up a theodolite on any survey station, and sight any other survey station, and the angle bible would tell you the angle to turn to intersect a known line - building grid line or offset from the building for a base line. A second theodolite would be similarly set up on another station, angle turned and the intersection would be an accurate point on that base line (usually a pre-determined grid line of the building.

Still with me ? :cool::cool::cool:
Click to expand...
Completely lost but interesting as to how complex these surveys are. Puts one in awe of guys that used to set off in virgin lands and survey a complete new Railway as will be happening now for HS2 and of course what has been done in Mountainous zones saw Switzerland and the Rockies. Puts our Garden Railway efforts into perspective with out “oh well it can go through there and over that”! Well that is how I do it but I expect you have your theodolite out. Actually to be honest a cheep Lazer Level does work wonders with a few bits of stick stuck in the ground here and there.
 
Today, I will be studying weights and measures, along with (usually lack of) dividends...... off for a day at the races. Going by tain, of course, down a line I don't normally travel.
 
A bit of a late entry to this thread, but the thing that I can never understand is why do Americans express the weight of something as massive a locomotive in pounds ? I can envisage the weight (mass) of, say sledge hammer in pounds and maybe a black bear in pounds, but to say a loco weighs 210,000 lbs seems disingenuous - - all I can think is 'wow ! That's a lot of bananas ' . Luckily the Americans also decided to simplify the expression of a 'ton' to just 2000lbs, so it only takes a mo to do a little mental arithmetic to determine that what they mean is 105American Tons , which really only means around 93 imperial tons. But why don't they express the weight of really big stuff in Tons ?
 
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