Locomotive weight. How accurately measured is it?

[Nearholmer]

The descriptions of the weighing and weight distribution adjustment at Swindon are fascinating. Just to add that I went to the 'steam' museum last week, and, Because I'd been reading about the very fine limits that Swindon could work to, looked at the calbration details etched/stamped on various gauges.

 

I cannot imagine Swindon having weighing apparatus that wasn't calibrated, and kept calibrated, to the best practicable accuracy ........ I bet they knew 'exactly' how much each loco weighed, and how much of that was on each wheel.

 

Kevin

[45125]

Having visited a loco weigh bridge and see loco in the process of weighing, the whole process is quite accurate. Most weigh bridge had records of locos they had weighed previously and would often reference these against the loco that was on the weigh bridge to see if any variation had occurred.

 

When depots changed springs the new spring is made to the spec and would often not be that far out if the locos was later weighed. Having change spring on 350 shunters and class 40s the usually method was to measure the length of the spring hanger protruding at the bottom of the nut before undoing the nut to release the spring and using this measurement to fasten the nut which the new spring fitted.

[96701]

https://www.libraweighing.co.uk/train-weighers.html claim 0.5%

[jim.snowdon]

Having visited a loco weigh bridge and see loco in the process of weighing, the whole process is quite accurate. Most weigh bridge had records of locos they had weighed previously and would often reference these against the loco that was on the weigh bridge to see if any variation had occurred.

 

When depots changed springs the new spring is made to the spec and would often not be that far out if the locos was later weighed. Having change spring on 350 shunters and class 40s the usually method was to measure the length of the spring hanger protruding at the bottom of the nut before undoing the nut to release the spring and using this measurement to fasten the nut which the new spring fitted.

Although I can recall one occasion when I had a London Underground battery loco out on a test run, and on walking round the loco to do the run round at Uxbridge found that the springs on one bogie were all hard up against the stops. We had come all the way from Ealing with one end of a 60 ton loco effectively unsprung. I wouldn't ask what it did to the track, or indeed the old District Line bridge over the GW main line, since replaced.

 

Jim

[Pelham Street]

On the LSWR it would appear that some of the early Adams engines of the late 1870s were much heavier that the Civil Engineer allowed. The 46 class 4-4-0t had the weight diagram @doctored@ so it read less than the loco's actual weight!.