West Highland Line - Class 67s and brakes

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driverd

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Hi all,

Just a question I had long pondered and never really had a definitive answer to; why was there a special pool of 67s for WHL workings, and why did/do they require block/tread brakes (and the 80mph speed restriction)?

Seems a tad peculiar as I'm sure other disk braked trains use the route - thinking specifically, though please correct me if I'm wrong, of class 66s, 73s and 43s and, of course, the mk5s.

So, was this restriction as a result of a special local instruction or is just something traction specific? I can't imagine there's a world of difference in terms of the gradients, leaf fall etc to that experienced on the HML - just seems like a rather curious requirement.
 
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driverd

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I see - is that just the pads used on the disks, rather than conversion to direct acting tread/block type brakes (as per 156s etc)?

Also, is there a reason other than loading gauge/clearance issues that 158s/170s haven't made it onto the WHL? I presume it's nothing to do with them having disk brakes? (In other words, have I been putting 2+2 together and getting 5?)
 

hwl

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I see - is that just the pads used on the disks, rather than conversion to direct acting tread/block type brakes (as per 156s etc)?

Also, is there a reason other than loading gauge/clearance issues that 158s/170s haven't made it onto the WHL? I presume it's nothing to do with them having disk brakes? (In other words, have I been putting 2+2 together and getting 5?)
Probably, WHL is 75mph max with lots of climbs.
156 = 75mph max
158 = 90mph max
170 = 100mph max
The 158/170 transmission efficiency and fuel consumption is comparatively worse at typical WHL speed sand gradients.
 

driverd

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Probably, WHL is 75mph max with lots of climbs.
156 = 75mph max
158 = 90mph max
170 = 100mph max
The 158/170 transmission efficiency and fuel consumption is comparatively worse at typical WHL speed sand gradients.

Going to disagree on the climb performance re: 158s, I have driven/drive both traction types and can assure you they get up hills better than 156s.

May be correct on fuel consumption but its clearly not a major concern, seeing as they introduced 2+4 HSTs, which are horrific compared to 170s.
 

hwl

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Going to disagree on the climb performance re: 158s, I have driven/drive both traction types and can assure you they get up hills better than 156s.

May be correct on fuel consumption but its clearly not a major concern, seeing as they introduced 2+4 HSTs, which are horrific compared to 170s.
Scotrail also focused 156s on routes out of Glasgow with maintenance at Corkerhill with the 158/170 maintained in Edinburgh, Inverness, Perth, Aberdeen.
The 158s certainly have more power but the losses are higher.
 

waverley47

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I see - is that just the pads used on the disks, rather than conversion to direct acting tread/block type brakes (as per 156s etc)?

Also, is there a reason other than loading gauge/clearance issues that 158s/170s haven't made it onto the WHL? I presume it's nothing to do with them having disk brakes? (In other words, have I been putting 2+2 together and getting 5?)

Can't answer about the brakes, but did a little bit of work on plans for the west highland.

The issue was, back in the old days, the coping stones of the platforms hitting the step boards of the 158s, but it goes a bit deeper than that. The 156s are quite squat and narrow units, being built for the narrowest BR loading gauges, however the 158s are a bit taller and tend to sway more. The solution suggested was to cut back the platform edge stones, however it wasn't really that simple.

The track can't really be relayed, and tends to shift a lot under the trains on poor foundations. In some places, Rannoch and Corrour in particular, the track formation is floating on the marsh, and so relaying for a better formation isn't an easy science. In addition, it's not really had much work done in the same way as more important lines, and platform heights are a bit random (and built by two different railway companies).

So NR couldn't deliver on the promise of making the whole line passable for the 158s by the time they were supposed to, about the time electrification and the 385s came online. This meant they had to stick with the 156s on the line, however NR were told in no uncertain terms to get on with it, and subsequently have done.

Now however, even through it is in theory cleared for 158s, even if noone has done the paperwork, they don't have the spare units to shift around. The 158s are being used on much more important commuter and intercity routes, and lots have been sent south. When more electrification comes in to displace these, it's likely we'll see more 158s shifted across until such a time as an electric battery/hydrogen unit can be bought, and as the 156s start to literally fall apart.

In the case of 170s, again, they're not really going spare. However, they also have doors at thirds without vestibule doors, meaning you'd have to open the whole carriage to either freezing winter air or hordes of midges every twenty minutes, and that wouldn't be very acceptable for tourists or ScotRail themselves. Additionally, it doesn't really work (given short platform lengths) for the current set up of 2 cars to Oban and 4 cars to Fort Bill.
 

driverd

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@waverley47 - thank you for such a detailed response! Very much answers my question.

(Although, from a purely personally biased point of view, I would say I'd take the midges and the snow for the more comfortable seats and better luggage space of the 170s, just a shame they are so lethargic on the power!)

Scotrail also focused 156s on routes out of Glasgow with maintenance at Corkerhill with the 158/170 maintained in Edinburgh, Inverness, Perth, Aberdeen.
The 158s certainly have more power but the losses are higher.

Absolutely re: the maintenence depots, although in fairness, allocated TMD doesn't make too much difference to workings. For instance, TFW 153s are allocated to Canton, but manage to cycle all the way to Llandudno and back again spending numerous days away from depot. In a similar vein, itd be quite possible for a Scotrail 158 to cycle from Aberdeen/Perth or Edinburgh into GLQ, get fuelled/tanked at Eastfields and then on for a day on the WHL, before cycling back out via another fuel stop at Eastfields (I only exclude Inverness units as I'm not sure what the current allocations are like for 158s on the HML, or indeed if Inverness units ever make it to the central belt).

In terms of performance, 158s outdo 156s in all regards, all gradients, 0-60 and 0-75. They also perform better putting power down and during low adhesion (158s have WSP and auto-sanding, 156s dont, although it is being fitted quite widely). There's certain locations where you can test this, where I'm based there are a few steep climbs away from stations where you can open up the units to line speed and you're always there first in a 158 (and can brake later into stations too).

Anywho, in answer to my original question, would appear I was absolutely incorrect to think there was a restriction on brake types. Thanks all for the help clearing this up!
 

Efini92

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@waverley47 - thank you for such a detailed response! Very much answers my question.

(Although, from a purely personally biased point of view, I would say I'd take the midges and the snow for the more comfortable seats and better luggage space of the 170s, just a shame they are so lethargic on the power!)



Absolutely re: the maintenence depots, although in fairness, allocated TMD doesn't make too much difference to workings. For instance, TFW 153s are allocated to Canton, but manage to cycle all the way to Llandudno and back again spending numerous days away from depot. In a similar vein, itd be quite possible for a Scotrail 158 to cycle from Aberdeen/Perth or Edinburgh into GLQ, get fuelled/tanked at Eastfields and then on for a day on the WHL, before cycling back out via another fuel stop at Eastfields (I only exclude Inverness units as I'm not sure what the current allocations are like for 158s on the HML, or indeed if Inverness units ever make it to the central belt).

In terms of performance, 158s outdo 156s in all regards, all gradients, 0-60 and 0-75. They also perform better putting power down and during low adhesion (158s have WSP and auto-sanding, 156s dont, although it is being fitted quite widely). There's certain locations where you can test this, where I'm based there are a few steep climbs away from stations where you can open up the units to line speed and you're always there first in a 158 (and can brake later into stations too).

Anywho, in answer to my original question, would appear I was absolutely incorrect to think there was a restriction on brake types. Thanks all for the help clearing this up!
I’d say 156’s are easier to get going in low adhesion. 158’s can be a pain
 

driverd

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I’d say 156’s are easier to get going in low adhesion. 158’s can be a pain
Just don't whack them open? (I jest)

Absolute tangent and just a curiosity, but do you use sand taking power? I usually find 158s no issue in notch 3/4 with a little.
 

hexagon789

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I see - is that just the pads used on the disks, rather than conversion to direct acting tread/block type brakes (as per 156s etc)?
I assume so, photos of the 3 treated locos show no tread brakes equipment that I could see.




Probably, WHL is 75mph max
70mph in 3 sections and for SP passed trains only. The loco-hauled ceiling remains the pre-Sprinter 50mph limit.


Seems a tad peculiar as I'm sure other disk braked trains use the route - thinking specifically, though please correct me if I'm wrong, of class 66s, 73s and 43s and, of course, the mk5s.
Afaik 66s and 73s are tread braked. 43s have one brake block per wheel in addition to disc brakes.
 

Efini92

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Just don't whack them open? (I jest)

Absolute tangent and just a curiosity, but do you use sand taking power? I usually find 158s no issue in notch 3/4 with a little.
I did on 156’s but not on 158’s. I found with 158’s setting off in notch 3 (cardinal sin I know) then gradually work up through each notch it’ll get going.
 

westcoaster

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Could the tread brakes be down to leaf fall, they are able to scrub the wheels and clean the tyres, where as a disk braked unit the wheels become contaminated.
 

hexagon789

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Can someone confirm they did actually fit tread brakes to certain of the class?

Photos don't seen to bear this out.
 
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