The 73/9 modification was specified to haul RHTT and other Infrastructure trains. This was then stretched to haul mark 3 sleepers. This was then stretched to haul the much heavier Mk5 sleepers with their much higher ETH load. There's also been creep with the challenging Fort William route increasing to 5 coaches for much of the year.
2 of them occasionally haul a load 12 to Inverness when the WHL is closed, that will be happening again fairly soon as well with some more closures coming up in the coming months.
What about Class 68?
When did they ever haul Mark 3s?
Do 68s have delner couplers? Do GBRF own any 68s?
73/9s hauled Mark 3s between February 2016 and October 2019 when the Mark 3 sleepers finished.
Not at the moment, but nor did 92s and 73s until they were converted.
I highly doubt there are any plans to convert DRS 68s to make them capable of hauling the sleeper stock.
Whilst the 68s are the same ETS index as a 73/9 are their inverters capable of supplying the higher voltage specified for the Mk5 s because of the 16 coach train length? I suspect that requires a rebuild along with the Dellners.
I seem to recall the Mk5 sleeper voltage is double the standard for all other trains so it is not just a fudge it amount.
I may be wrong but believe the 73s provide standard ETS voltage.
The 68's ETS index isn't enough for 16 coaches anyway. It is the same as a 73/9, which can take eight (maybe nine at a pinch).
I thought they were designed from the outset for use with the mk5s. It was planned that they'd haul the mk3s for an interim period but that interim period turned out to be rather longer than initially intended due to the dealys in getting the mk 5s fully into service.
Has a 73 ever been tasked with five Mark 5s on the West Highland without assistance from a 66?
Yes, that has happened from time to time, as have pairs of 73s. A single 73 has worked an 8 coach Mark 5 formation on the Highland line on a few occasions when circumstances have dictated it.
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When the 73/9 was specified GBRF didn't have the sleeper contract. The specification was basically limited to increasing the size of the diesel to provide the same output at the rail that the 73/1 had enjoyed on dc.
A mk5 is 43 tonnes, the same as a mk3 is it not?
They seem to be quite happy doing stock moves.
I think having 66s floating around the area already is the best bet. GBRF seem to add a 66 on the front of a 73/9 quite often. No conversion work required.
66 is purely there as 'insurance' due to the unreliability of the 73s with all the gradients on the HML and WHL. That in turn limits the top speed of the train to 75mph which is no good when running late unless it can 'skip' stations.
Is the line speed much more than 75mph on the HML and WHL?. I would have thought power was of more use. Getting reliability sorted out further South would be better as that impacts the lowlander as well.
Theres lots of sections where the line speed is over 75mph on the HML, not so sure about the WHL though.
50mph is the max for the WHL itself (north of Craigendoran).
57s, especially the already Dellner equipped 57/3s might be an interesting option, though no doubt the Dellners will be different in some way. 57s, even using rebuild date as a zero, are also rather long in the tooth now and therefore they presumably would only offer a medium term solution.
GBRf returned 67023 and 67027 to whoever they got them from. They reportedly couldn't be put into appropriate shape for the sleeper portions.
I believe (according to a Platform 5 book I have) Mk3 s were in the region of 33 to 36 tons depending on the configuration.
I think thats wrong mate. A Mk2 was 34 tonnes, a Mk3 was 43 tonnes and I'm pretty certain a Mk5 is also 43 tonnes.