Push Pull Freight

[Beveridges]

You might think they are more efficient, but they are considerably less reliable and thus less effective. In terms of cost per output (clean rails) they are much less efficient. Hence more loco based RHTTs are on the way.

Great news, so does this mean the North West of England is getting loco based RHTT's instead of the MPV's we get every year on everything except the North Wales RHTT ?

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I believe an MPV was used on a freight trial for the feasibility of using them for fixed formation freight trains. It was a log train and the MPVs couldn't carry any freight due to weight concerns (when empty).

Why did the ill-fated MPV freight trials on logs not come to anything ?

That log train does not even run anymore.





RHTT's run as push/pull when they are loco based. Finally, there is one freight train I can think of that is push/pull. The High Output Ballast Cleaner. These weigh around 3000 tons and are an impressive sight. They have to be push/pull due to their immense weight.

 

[Tomnick]

The HOBC and most (all?) loco-hauled RHTTs are top n tailed, not push-pull.

 

[The Planner]

Oil trains out of Immingham etc are very often 3000 tonnes with a single 66. They then propel the things into Kingsbury oil terminal. Weight doesn't always require top and tail, it is more often double heading that gets used. We certainly asked it to be looked at for the HOBC.

 

[edwin_m]

I've seen a RHTT with one 66 and the EWS Executive DVT on the other end, so the wagons must include through cables for multiple working. However I'm not sure there's any need for both locos to be working as it's a very light train.

 

[headshot119]

The HOBC and most (all?) loco-hauled RHTTs are top n tailed, not push-pull.

Actually both locos on the HOBC can be powering, communication between the two drivers (one on each loco) is by radio.

 

[Beveridges]

Oil trains out of Immingham etc are very often 3000 tonnes with a single 66

The Class 66 does seem to perform better than other traction that has similar (or slightly more) horsepower, however I really don't think one of these is going to cope with the HOBC on all routes without rear end assistance. It was certainly being pushed from the rear when I last saw it - I could clearly hear the 66 on the rear being thrashed.

Yes a single fred will move the 3000 tons easily enough, but when it comes to running on the WCML south of Crewe and keeping up with the Pendos and Desiros, it usually will need both locos powering.

 

[Tomnick]

Actually both locos on the HOBC can be powering, communication between the two drivers (one on each loco) is by radio.

Yes, that's still top n tailed in my book though! Push/pull generally refers to trains that are hauled in one direction and propelled in the other.

 

[LWB]

Most freight trains are heavier than passenger trains and it is possible that there would be a derailment risk with the loco propelling them, except at very low speeds as happens now for shunting etc.

Indeed, and more to the point I thought that propelling passenger coaches can only work because the couplings they use confer rigidity on the consist. Aren't freight wagons still coupled with buffers and screw links? It'd be like pushing a string of beads at speed surely?

 

[HSTEd]

Indeed, and more to the point I thought that propelling passenger coaches can only work because the couplings they use confer rigidity on the consist. Aren't freight wagons still coupled with buffers and screw links? It'd be like pushing a string of beads at speed surely?

Most new freight vehicles tend towards AAR type couplers now.
And Mark 1 derived multiple units used standard buffers and chains IIRC, including the 4REP/4TC formations.

 

[Penmorfa]

There are some photos of the Aberystwyth - Chirk Kronospan MPV trial here:
http://www.flickr.com/photos/penmorfas/8020582632/in/set-72157623902783378

 

[Rugd1022]

Top 'n' tailing the HOBC with the rear loco powering up is vital to keep it on the move, plus some times it comes back out of a possession the same way it went in, so it's win win all round. The radios we use to talk to each other (''gizza push mate...'' etc) are sometimes a little unreliable so we have to resort to using our company mobile phones on occasion.

The last time I was 'tail end Charlie' on the HOBC I had to give my mate a shove all the way from Wembley to Tring before we'd reached 60mph - it really does take some shifting (and stopping).

 

[talltim]

Mid-trains helpers in the US are often radio controlled now, at mainline speeds. I don't see that as any different to push pull operation from a technical remote engine driving viewpoint
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Yes, that's still top n tailed in my book though! Push/pull generally refers to trains that are hauled in one direction and propelled in the other.

I think that's referred to as banking (pushing in the US, bankers are referred to as pushers), To my mind top and tail is when the rear loco is powered down. You're right, I wouldn't call it push pull either, there is no link between the locos and both require driving.

 

[bronzeonion]

Most new freight vehicles tend towards AAR type couplers now.
And Mark 1 derived multiple units used standard buffers and chains IIRC, including the 4REP/4TC formations.

Don't think so, afaik all MK1 EMU's have buckeyes between carriages and drophead buckeye couplers on either end of the unit

 

[talltim]

I think you right, however I'm sure I read recently about Swiss or French push-pull (passenger) trains that use screw link and buffers.

 

[hairyhandedfool]

The Scottish 47/7s were screw/chain link and were regularly used on push-pull trains, though the coaches would have been (drophead) Buckeye coupled.

 

[simon.exd]

So what is being said is that push pull would not work because of the cost etc in running the relevant conbectors down the length of the train...

Just a thought, what happened in the days of steam when trains were banked? And if i am right, still happens on the Lickey? How does that work? Someone?
--- old post above --- --- new post below ---
*connectors

stupid touchphones!!!!

 

[The Planner]

The last time I was 'tail end Charlie' on the HOBC I had to give my mate a shove all the way from Wembley to Tring before we'd reached 60mph - it really does take some shifting (and stopping).

We did try and persuade them to stick a 92 on the front when it was pottering about the WCML, it wouldn't have broken sweat, would have cost too much apparently....

 

[jopsuk]

So what is being said is that push pull would not work because of the cost etc in running the relevant connectors down the length of the train...

Well, having to wire up every single last wagon that might work together- and then having to maintain the system. Plus choosing a system (though AAR would make sense given that's what 59s, 66s, 67s and the forthcoming 68s have)

 

[edwin_m]

Just a thought, what happened in the days of steam when trains were banked? And if i am right, still happens on the Lickey? How does that work? Someone?

The practice on the Lickey was to buffer up but not couple one or more banking locos to the rear of the train. The two crews would communicate by whistle codes and the banking engine would just push to the top, then close the regulator, drop back from the train and stop at the signal waiting to be crossed over and returned to the bottom. This is moreorless what still happens except that only one loco is used and there is some kind of plunger and indicator system for communication between the two crews at the bottom (details in the Sectional Appendix).

When banking passenger trains and all trains on certain inclines, it was necessary to couple up and connect the brake pipes, which means that another stop is needed at the summit to disconnect them. This wasn't done at Beattock some years ago when a passenger train was assisting another one on slippery rails, the front train suddenly got a grip and pulled away then dropped back and the driver of the assisting engine was killed in the resulting collision.

 

[bishdunster]

Most new freight vehicles tend towards AAR type couplers now.
And Mark 1 derived multiple units used standard buffers and chains IIRC, including the 4REP/4TC formations.

All REP/TC and 33 push/pull formations used buckeyes, there was the very rare occasion when a non 'pusher' 33 had to be used Bournemouth-Weymouth, which had to be coupled to the TC with the screw coupler, but I can only remember it being done on a couple of occasions in 7 or 8 years I was at Bournemouth.

 

[bnsf734]

I think you right, however I'm sure I read recently about Swiss or French push-pull (passenger) trains that use screw link and buffers.

That's correct, virtually all European mainline stock is screw coupled - even some of the early german ICE sets are screw coupled including the one which derailed at Enschede some years ago. I'm not sure how the later ones are coupled.

I seem to remember the Swiss Mk 3 stock was built with auto couplings but the Mark 4 stock reverted to screw coupling.

 

[HSTEd]

The original TGV Sud-Est power cars used screw and buffer couplings to attach to the trailer formations IIRC.

 

[D7666]

I think you right, however I'm sure I read recently about Swiss or French push-pull (passenger) trains that use screw link and buffers.

UK is non standard full stop in this sense, not just with push pull.

All main line mainland European loco hauled passenger stock I can think of and know of and travelled on is all screw coupling and side buffer, whether push-pull or hauled. I can't think of one single Western European example where normal stock has any type of buckeye or any other auto coupler.


I think that demonstrates it is not necessary to have buckeye or similar autocouplers for push pull as the laws of mechanics are not different in UK to anywhere else. Rather it was a case of UK got to the point where buckeyes were standard for all stock, BR SR did it for push pull 33s 73s and 74s so the idea stuck.


Further east on the Russian broad gauge lines they use SA3 centre couplers that are loosely cloned from a USA knuckle coupler, no doubt someone will be along and tell me which one.


--
Nick

 

[bronzeonion]

I don't understand why the UK and Europe didn't convert to using buckeye or similar couplers or havn't done so yet

 

[simon.exd]

The practice on the Lickey was to buffer up but not couple one or more banking locos to the rear of the train. The two crews would communicate by whistle codes and the banking engine would just push to the top, then close the regulator, drop back from the train and stop at the signal waiting to be crossed over and returned to the bottom. This is moreorless what still happens except that only one loco is used and there is some kind of plunger and indicator system for communication between the two crews at the bottom (details in the Sectional Appendix).

When banking passenger trains and all trains on certain inclines, it was necessary to couple up and connect the brake pipes, which means that another stop is needed at the summit to disconnect them. This wasn't done at Beattock some years ago when a passenger train was assisting another one on slippery rails, the front train suddenly got a grip and pulled away then dropped back and the driver of the assisting engine was killed in the resulting collision.

Thanks for explaining that friend... i understand now

 

[HSTEd]

I don't understand why the UK and Europe didn't convert to using buckeye or similar couplers or havn't done so yet

Because there has been no drive towards the heavier train weights than the buckeye type couplers are advantageous for, and no scandal over the number of people dying (or being crippled) in shunting accidents as there was in the US.
The movement will probably eventually occur now that the early adopter problems have been partial overcome by things like the C-AKv (which will probably lead to the adoption of through electronic wiring of freight trains thanks to the auto-coupler).

Everyone knows my views as to the economics of European sized freight trains as well I imagine by now?

 

[edwin_m]

The adoption of buckeyes for most passenger stock in the UK may be partly explained by a number of accidents where the inspector commended them for keeping the train upright and in line, or commented that they would have done if they had been fitted!