QUOTE (Prescotian @ 12 Jun 2011, 16:56)
<{POST_SNAPBACK}>... But what a fantastic video of the GWR loco being turned by one man .... what balance and engineering to move 60 tons plus just like that
You are underestimating the mass that has to be moved too; the turntable bridge is not a lightweight item.
The majority of UK turntables were 'balance' types, and the drivers developed the judgement necessary to get their loco in the right position on the bridge. It had to be done by 'seat of the pants' judgement because the exact condition of the loco could vary from visit to visit, the amount of water in boiler and tender the largest variable factor, then the amount of coal in the bunker and firebed, and ash in the ashpan and smokebox, this applying particularly if the turn was midway through the working day on an out and home working.
It is very noticeable in the later steam depot designs that the work flow for a loco coming in shed is standardised so that disposal of ash and fire cleaning, watering and coaling, are all accomplished before the loco runs on to the turntable. This was for no trivial reason, there were a significant number of larger classes that although their wheelbase would fit for length on a 70 foot turntable, they could not be got to balance, unless the tender was well loaded.
For those so inclined, a little tinkering with the Peco model using the contact studs with stronger springs, can make this unit act as a balance type, which gives a nice effect as the locos run on and off.