What is the wire?

[Pyewipe Junction]

Can anyone tell me the purpose of the wire (or cable) that extends from the cab to just in front of the cylinders on the left-hand side of a lot of Robinson locomotives?

You can see it quite clearly on the illustration of the B3 in the 'locomotives' section of the forum. I've noticed in most of the photos I've seen that it tended to sag, detracting from the appearance of what were otherwise handsome engines.

[jwealleans]

Aren't those the pipe runs from the sight feed lubricators?

[Atlantic 3279]

I thought so. I gather that lower, "stiffly horizontal" pipes with branches descending vertically denote replacement fountain lubricators on O4s for instance.

[Pyewipe Junction]

Thanks for that. It's a pity they couldn't come up with a neater arrangement.

[61070]

I expect the reason for the arrangement is to provide a steady 'fall' in the rather lengthy small-bore pipe runs, so as to help the (quite viscous) steam oil on its way. In the early 1900s engineers recognised that reliable, continuous lubrication of pistons and valves was a vital pre-requisite for the use of superheated steam. On stationary and marine engines, where superheating was applied before locomotives, valve and cylinder lubricators were situated quite close to the steam inlet to the cylinders, and pipe runs were short, because the engineers could walk around the machinery to observe lubrication. Also, the engine houses (or engine rooms on steam ships) were generally warm/hot, aiding the flow of the oil. On locomotives pipe runs had to be much longer if the 'sight-feed' principle was to be applied, and they were exposed to the chill winds of winter. Hence the oil was provided with all the encouragement it could be given to get to where it was needed. There was probably a reluctance to 'hide' the pipe runs beneath the boiler cladding because pipe breakages would not be seen then. An example of function taking precedence over over aesthetics.