Why can't you have two locomotives on the rear?

[trainmania100]

Someone has told me you can't have two locomotives tailing on a train, with the exception of class 20 and 73

In the scenario of the 69s arriving at Paddington on the tour, they were removed from the train at Paddington, a 66 brought the train out, and the 69s followed behind.

You'd think that if they were dead / turned off, they'd roll just like coaches no?

 

[GB]

Might have something to do with the weight pushing against the coaches/wagons under braking.

 

[PHILIPE]

Up to 4 x 94xx WR Pannier Tanks and previously 0-6-0 ex LMR "Jinty" tanks used to bank in the rear up the Lickey

 

[The exile]

Up to 4 x 94xx WR Pannier Tanks and previously 0-6-0 ex LMR "Jinty" tanks used to bank in the rear up the Lickey

Banking will be a different situation from locos coupled to the train

 

[4F89]

High weight of the locos and different braking characteristics can potentially lead to buffer lock.

 

[thesignalman]

. . . and to the train taking a short cut on a sharp curve.

John

 

[furnessvale]

. . . and to the train taking a short cut on a sharp curve.

John

Doesn't seem to affect the USA. Video of Tehachapi can be very entertaining.

 

[Sunset route]

Doesn't seem to affect the USA. Video of Tehachapi can be very entertaining.

Knuckle couplers and no buffers would seem to help when it comes to US railroad practices.

 

[zwk500]

Knuckle couples and no buffers would seem to help when it comes to US railroad practices.

Also the sheer length, and the fact that all locos in the consist are usually in power, connected by satellite to the driver's loco so it's not dead weight but 'distributed power', as they say.

 

[edwin_m]

Also the sheer length, and the fact that all locos in the consist are usually in power, connected by satellite to the driver's loco so it's not dead weight but 'distributed power', as they say.

Stringlining derailments are far from unknown in North America.

 

[Sean Emmett]

Those rules must have changed as I distinctly recall 34027 Taw Valley being assisted at rear from St Davids to Central in c 1993 by a pair of cl 50s, diesels uncoupled at Central.

Also railtour with pair 37s as main motive power, but needing a release loco in a few places.

Also Black Five and 8F and train being dragged back from Newquay to Par by cl 47, slipping to a stand on the (then) A30 Tregoss Moor bridge, and needing some help from the 8F.

 

[najaB]

Those rules must have changed as I distinctly recall 34027 Taw Valley being assisted at rear from St Davids to Central in c 1993 by a pair of cl 50s, diesels uncoupled at Central.

Rules? Changed in nearly thirty years? Perish the thought.

 

[LAX54]

Doesn't seem to affect the USA. Video of Tehachapi can be very entertaining.

and Cajon Pass, Hill 582 etc

 

[furnessvale]

and Cajon Pass, Hill 582 etc

Indeed, I have a shelf full but the loop at Tehachapi, and Williams etc, is very indicative of how much curvature a train can take and still not derail.

 

[James James]

Who says you can't have two on the back (no knuckle couplers or other special gubbins). Or even two in the middle? Mind you, they've probably checked what combinations are safe and sensible for the specific stock/track (more common combinations are one on each end, or one in the middle and one on front or back).

 

[LAX54]

Indeed, I have a shelf full but the loop at Tehachapi, and Williams etc, is very indicative of how much curvature a train can take and still not derail.

Tehachapi is a fascinating place, been to Williams, but never really sought out any trains there.

 

[4F89]

Who says you can't have two on the back (no knuckle couplers or other special gubbins). Or even two in the middle? Mind you, they've probably checked what combinations are safe and sensible for the specific stock/track (more common combinations are one on each end, or one in the middle and one on front or back).

Well, the rulebook for a start......

 

[najaB]

Who says you can't have two on the back (no knuckle couplers or other special gubbins). Or even two in the middle? Mind you, they've probably checked what combinations are safe and sensible for the specific stock/track (more common combinations are one on each end, or one in the middle and one on front or back).

Neither of those examples are in the UK though, unless I've missed something?

 

[Sean Emmett]

Rules? Changed in nearly thirty years? Perish the thought.

Interested to know when the rules changed, and whether it applies to failures too?

Fewer than 10 years ago was on a trip to Wensleydale with Great Marquess and cl 47 top and tailed. The 47 leading uphill to Redmire failed with a flashover. Marquess huffed and puffed at the back, to no avail.

So we retreated downhill to Northallerton. Meanwhile, another 47 was summoned from York to help the helper give a shove to Newcastle.

 

[furnessvale]

Interested to know when the rules changed, and whether it applies to failures too?

Fewer than 10 years ago was on a trip to Wensleydale with Great Marquess and cl 47 top and tailed. The 47 leading uphill to Redmire failed with a flashover. Marquess huffed and puffed at the back, to no avail.

So we retreated downhill to Northallerton. Meanwhile, another 47 was summoned from York to help the helper give a shove to Newcastle.

Reminds me of many years ago. I was working a track recording trolley south in the Lune Gorge. Flashing past us going north virtually at line speed was a class 50 with a dozen or so coaches. Attached in rear were 2 more class 50s and another dozen coaches! All locos were on line and I can only assume that the lead loco had failed and after recovery had been able to power up again. The drivers were really going for it. Such sights stick in the mind.

 

[apk55]

On the Woodhead line Worsborough incline from Wath to Penistone they would have 4 locomotives on a train with two at the front and two pushing. Initially with steam they were normally 8 driving wheel heavy freight locos such as O4s, later on they tried replacing the two pushers by a monster Garret loco (with 16 driving wheels) but later with electric operation they continued with 4 locos with two class 76s pushing.

 

[James James]

Well, the rulebook for a start......

The railway rulebook: sure, that's different there vs the UK.
The rulebook of Newtonian physics however: that's the same.

So I think it's fair enough for OP to ask why the rulebook doesn't allow it. Haven't heard of any related derailments in Switzerland (where those videos are from) for a start.

 

[LAX54]

The railway rulebook: sure, that's different.
The rulebook of Newtonian physics however: that's the same.

So I think it's fair enough for OP to ask why the rulebook doesn't allow it. Haven't heard of any related derailments in Switzerland (where those videos are from) for a start.

Assisting a failure, you can use anything to hand that is compatible, few years back we used an RHTT set to asisst a Freightliner all the way to Felixstowe North.
after it was there, the RHTT crew said, mmmm, all very well getting here, but we don't sign the route but with cooperation with the Signaller on the panel he made it safely
as for locos on the rear in general, its only in fairly recent years the rules changed, to have a loco on the rear always needed authorisation and advice to the boxes, now its done at the drop of a hat ! (Loco on rear....Train On (2) followed by 2-2 on the bell)

 

[James James]

Were you asking about 2 on the back, or 3 on the back? 3 on the back? (Again not the UK, again same physics rulebook.)

 

[najaB]

Again not the UK, again same physics rulebook.

Again, nobody is saying that it can't be done - it's just not allowed.

 

[AlbertBeale]

In the days of steam on the line up from Folkestone harbour, up a very steep incline, I often saw laden trains with tank engines (plural) both front and rear - and sometimes in the middle too.

 

[James James]

Again, nobody is saying that it can't be done - it's just not allowed.

Again, nobody is explaining why it's not allowed .

 

[najaB]

Again, nobody is explaining why it's not allowed .

That's been explained - the rule book says that you can't.

Why the rule exists is different, relevant question.

In the days of steam on the line up from Folkestone harbour, up a very steep incline, I often saw laden trains with tank engines (plural) both front and rear - and sometimes in the middle too.

Banking assistance in rear is still allowed.

 

[ac6000cw]

Might have something to do with the weight pushing against the coaches/wagons under braking

High weight of the locos and different braking characteristics can potentially lead to buffer lock.

I would expect those are the main reasons why one than one 'heavy' loco being hauled 'dead' on the tail isn't allowed

A pair of 66's or similar is about 260 tonnes, and relative to their weight have lower brake force than passenger stock (about 68 tonnes brake force per loco, according to Wikipedia). Cl. 20 & 73 are much lighter (less than 80 tonnes each), so a pair of those is only about 20 tonnes heavier than a single cl. 66.

Comparisons of numbers of steam locos versus modern diesel & electric locos pushing on the rear of trains are 'chalk & cheese' really, since modern locos can generate levels of tractive effort steam locos could only dream about e.g. the max TE of a cl. 59 is about 3x the max TE of a BR 9F 2-10-0.

That high tractive effort capability per loco is the reason you don't normally see more than two modern, AC-drive, locos on the rear of a US/Canadian freight train. Even with only two working hard climbing a hill, you can hear loud flange rubbing noises from the freight cars on curves sometimes - they are pushing the limits of what's safely possible (and living with the high rail wear on curves).

 

[Rob F]

The rail tour in this video from 2011 had 2, 117 ton class 50s on the back.