We split into three groups today, all working on much the same sort of thing; Clamp-lock point machines.
The first of these is that going in on Ruddington Platform 2. The first job was to fit the centre thrust bracket to the soleplate. This will secure the ends of the hydraulic rams in the middle of the four-foot, with the other ends driving the locking mechanisms fitted last week.
Next was the essential (if not terribly photogenic) job of shimming the locking assembly to an exact fit. Since clamp-locks unify drive, locking and detection into a single assembly, it is safety-critical that they are correctly adjusted. Too tight, and the mechanism will not operate reliably. Too loose, and it will operate even when the switch and stock rails are too far apart for the safe passage of trains!
Here, our leader's expert knowledge of the equipment (and special set of feeler-gauges) was invaluable, and realised a very precise engagement. The rest of the group paid close attention to the techniques and specifications involved.
Not far away, another part of the team, armed with wiring diagrams and a good multimeter, investigated a reported fault with another clamp-lock set in the station throat. These are currently controlled by a temporary switch on the signalbox blockshelf, where there are also indicator lights for detection. The switch was ineffective, and only one light could be seen flashing: "Out Of Correspondence".
We checked the power supplies and fuses. Nothing wrong. Manually pumping the points both ways, we checked the detection. No problems there either, besides some stiffness from months of disuse. Based on the complete inactivity of the control logic, we eventually deduced that the fault must be in either the control switch or the cable to it. Sure enough, one core of the cable from the relay room to the signalbox had gone, and swapping-in one of the spare cores fixed the problem.
To finish-off that job, we scraped the usual grime off the the sliding faces in the locking mechanism, and replaced it with an appropriate lubricant.
Meanwhile the third contingent was busy prepping and painting the stretchers for those points in platform 2, to be fitted next. You may also have seen some of the work done during the week to fabricate yet another signal post. This will carry a position-light signal, and a split stencil box, to indicate routes along platform 2, or out onto the release road, and is now ready for painting.
