Traction of BO BO versus CO CO

 
  ab123 Chief Train Controller

My understanding re unprotected crossings and Vlocitys relates to the fact the front is about as strong as a cardboard box and the drivers seat is in the crumple zone!

Sponsored advertisement

  RTT_Rules Oliver Bullied, CME

Location: Dubai UAE
Guys, interesting comments on the LX and V/locities and thankyou for this.

Q, they (V's) are obviously running now to Swan Hill etc. The NE line I would have thought was busier and hence had better LX protection, however assume it doesn't now. Would you buy mongrel locos just because of outdated LX protection technology or simply fix what will need to be fixed eventually?

XPT some how survives on these tracks, is there that much difference between a 6 car V/locity and XPT?
  LancedDendrite Chief Commissioner

Location: Gheringhap Loop Autonomous Zone
The XPT has a loco at each end, so passengers have at least some degree of protection in the event of a front collision. Swan Hill services still exclusively use N sets, it's the Echuca line that got upgraded to run Vlocitys.
  ed31880 Train Controller

My understanding re unprotected crossings and Vlocitys relates to the fact the front is about as strong as a cardboard box and the drivers seat is in the crumple zone!
ab123
i think you will find that the front of a vlocity is a bit stronger than a cardboard box.  look at the cab of VL1105 after it hit the back of the spark at Paisley, a 50kph crash and the driver walked (limped) away with a sore toe.
  rwatts Junior Train Controller

Location: Adelaide SA
There was a PTSV report about a similar incident in Colac caused by a track obstruction that makes for interesting reading and can provide a little insight into the mechanics of predictor-based crossing circuits.
KRviator
Another vote for reading that PTSV report.  The simplistic ideas I had about how level crossings work were shattered by it.

More generally, I find from reading the various rail and accident investigation reports that I learn much more about how the systems involved work (or are supposed to) than just the circumstances of a particular incident.

Richard.
  ab123 Chief Train Controller

My understanding re unprotected crossings and Vlocitys relates to the fact the front is about as strong as a cardboard box and the drivers seat is in the crumple zone!
i think you will find that the front of a vlocity is a bit stronger than a cardboard box.  look at the cab of VL1105 after it hit the back of the spark at Paisley, a 50kph crash and the driver walked (limped) away with a sore toe.
ed31880

Perhaps a little over the top. However V/Line had a long running 65kph speed restriction on a certain unprotected level crossing on the Seymour line due to the lack of strength in a Vlocity (and Sprinters) in a collision.

All I know is I wouldn't want to hit a truck in one at 115kph let alone 160!



  RTT_Rules Oliver Bullied, CME

Location: Dubai UAE
anyway, so Vic has not only alot of LX compared to other states assumed because of the terrain and population density, but many are not up to scratch to protect modern rolling stock and need a 100t mass to protect the drivers. This is not a road block for V/locities on NE line, just something else that needs to be done.

And if I was the driver of the XPT, I wouldn't be that happy that its ok to use the XPT on the NE line and not the V/locity because the XPT has half a loco protecting the pax. Of course this all assumes a front on collision and while most common there are plenty of examples of other, such as Kerang.
  Duncs Chief Commissioner


On the other parts of the network, a single locomotive of a modern design (could be Vossloh light) with dual cabs can work. It would need to be the more powerful version 2800kw / 3750bhp. So it can move 6 - 7 cars at 120 -  130kph. The track can take this speed in lot of places already (RFR and RRL sections), and can be strengthened in other areas as required up to the current 115 kph locomotive top speed. Some of those 115 sections can go to 120kph. Eg Geelong to Warrnambool.

The main issue for me has been resolved, in that a Bo Bo can do as well as a Co Co so the lighter type 68 Vossloh Eurolight looks a good idea.
The problem here is with these new locomotives is the main prime mover is the only engine availible. a Engine power of 3800BHP is quoted, from that HEP must be deducted along with power for the main exciter, power for both the radiator and traction motor cooling fans, brake system electrics and compressor and the Auxiliary altenator. On a hot day one would end up with less than 2800bhp traction power. This would NOT be enough to allow for any meaning full aceelaration above 110kph. A 7 car VLocity has a maximum engine power of over 5000bhp, THIS IS the sort of power required for speeds above 110kph to enable the train to accelerate and climb hills without slowing down.
Note: the VLocity's speed up the Ingliston Bank is around 105kph, this is with the throttle flat out, these machines cannot climb this bank any faster.

Passenger trains over 110kph require large lumps of power a single loco will NOT be good enough.W
woodford
Woodford

I see your point. So either we stay with a loco, probably a co co with more wheels contacting the rail for hill climbing, so top speed 115 - 120kph at best, on flat ground. OR we take your suggestion of push pull with around 3000hp at each end, so after everything else, probably 2500hp at each end. For a top speed of around 120 - 140 kph at best.
  Clarke Hudswell Junior Train Controller

A few points of clarification for you, Duncs.

As M636C has been trying to point out, static wheel load and unsprung wheel load are what determine the maximum speed allowed on any given track. For track access accreditation, the locomotive user has to submit the calculation (or the masses to allow its calculation)for what is known as the P2 force, to the track access provider. The provider will approve a maximum speed for each section of its track based on this calculated P2 force and the track quality. You cannot get around this.


The P2 force is defined as the total vertical force generated at the interface between a wheel and a rail,


adding the static wheel load to the inertia forces associated with the dynamic response of the unsprung masses to variations in rail alignment.


 I cannot give the formula here as it is not suitable for a word document format, but to the static wheel load is added the square root of the unsprung wheel load (with factors included) multiplied by the speed. Thus, the higher the speed you want approved, the more the unsprung mass affects the outcome.

In terms of performance, the XPT with 2 power cars of 1980 bhp (1475 kW) each, and a lot less than this at the rail, can accelerate 7 passenger cars to 160 km/h. In the UK, with 2 x 1678 kW, they achieve 200 km/h. You do not need excessive power to achieve high speeds. You need excessive power (like a VLocity) if you have to stop and re-accelerate frequently to a tightly timed service.

All new Australian rolling stock (locomotives and DMUs) have to meet the same Australian Standard for collision protection, which is, reputedly, one of the toughest in the world for rail. Rolling stock imported from overseas would have to demonstrate conformance or it would not gain rail safety accreditation (i.e be allowed to run). Comments invoking cardboard boxes are simply uninformed (can you imagine the RTBULD allowing their members to operate vehicles that do not meet the highest safety standards?)
  Duncs Chief Commissioner

Thanks Clarke

I see what you mean. So obviously the lighter the locomotive the better. As the XPT power car only weighs 76 tons, so a static unsprung mass weight of 20 tones per axle, for a speed of 160kph. The Vossloh weighs 80 tones, so the calculations you referred to will be slightly different. Which is why in my post above I suggested 130 - 140 kph as a reasonable top speed. Which should fit into those types of calculations you mentioned.

Regarding collision safety standards, you raise an interesting question.

The Vlocity is a 12 year old technology. Are you suggesting that today's rail cars are stronger / safer than V Locities?
I ask because the V Locities cannot be run at above 80 kph unless all the level crossings are protected. Eg Bendigo to Echuca.

If there is a DMU out there today that CAN be run through unprotected level crossings at a higher speed, then this would be a very good solution to upgrading the long haul V Line fleet.

For example, Woodford (or Kuldalai?) mentioned that the XPT can travel at 120kph on the NE-SG line through a number of unprotected level crossings.


Duncs
  t_woodroffe Assistant Commissioner

Duncs, you still don't get it. The XPT does not have an unsprung mass weight of 76/4 tonnes. A 20 tonne unsprung mass would be a killer! Unsprung mass is that mass that is not spring borne ie the mass of components below the primary (axlebox) suspension springs. This includes the mass of the axle, wheel discs, brake discs, axle boxes, bull gear and a proprtion of the traction motor, gear case and pinion if the traction motor is axle hung, nose suspended (such as an N Class.) The XPT has bogie mounted traction motors driving the axles through a flexible drive so the traction motor is therefore spring borne and not unsprung mass. The critical P2 force that Clarke describes has unsprung mass input such that the higher the unsprung mass the greater the P2 force and thus the impact on the track at stepped joints etc. P2 force is easy to calculate but much more difficult to measure. For high speed operation the lowest P2 force is desirable.

For hydraulic transmission vehicles the unsprung mass includes the final drives and (part of) the cardan shaft mass.

TW
  Duncs Chief Commissioner

OK Thanks for clearing all that up.

But getting back to why I started this thread in the first place.

I was looking to see which type of locomotive was a better option, if/when we replace the N Class. It appears that CO CO has slightly better starting traction and hill climbing power, but less overall top speed. Plus its a heavier unit. So probably 120 tons is the maximum weight before things start to get too heavy for V Line's comfort.

BTW What does an N Class weigh these days? Some websites say 120 tons, some say 123 tons and others say 126 tons (with D77 traction motors?). Can someone clear this up?

A modern BO BO locomotive can weigh 80 tons, and have a slightly better speed on flat ground. But less climbing capacity for a train of 6 - 8 cars. Hence Woodford's very good suggestion that they be used in a push pull set up for larger trains.

BTW - Do the newer DMUS have better collision protection for the driver than the current V Locity fleet?
  RTT_Rules Oliver Bullied, CME

Location: Dubai UAE
OK Thanks for clearing all that up.

But getting back to why I started this thread in the first place.

I was looking to see which type of locomotive was a better option, if/when we replace the N Class. It appears that CO CO has slightly better starting traction and hill climbing power, but less overall top speed. Plus its a heavier unit. So probably 120 tons is the maximum weight before things start to get too heavy for V Line's comfort.

BTW What does an N Class weigh these days? Some websites say 120 tons, some say 123 tons and others say 126 tons (with D77 traction motors?). Can someone clear this up?

A modern BO BO locomotive can weigh 80 tons, and have a slightly better speed on flat ground. But less climbing capacity for a train of 6 - 8 cars. Hence Woodford's very good suggestion that they be used in a push pull set up for larger trains.

BTW - Do the newer DMUS have better collision protection for the driver than the current V Locity fleet?
Duncs
Probably not as they are still making V/locities so the crash standards must be acceptable.

As mentioned above all you need to do is reduce the speed to have the same crash worthyness as a higher rated vehicle.

Issue is today, who is rolling out more loco hauled trains over D or E MU's, few outside Nth America, so I stand by I think you will see Geelong line sparked and V/locities rolled out to replace the aging N class hauled sets.

Germany has a fleet of DEL and EL's BO-BO used to haul around its very large fleet of interurban units. On the shorter trains for reverse running they don't shunt (longer trains have loco at each end) and use the cab in the rear car to drive the train.

TRAXX - 2200kW, 270kN of tractive effort, 80t, max speed at least 140km/hr.

They also off now the TRAXX Dual mode so under the wires it runs off the wires.
  t_woodroffe Assistant Commissioner

Duncs refer to this regarding crashworthiness standards:

R3.114 Gap Analysis Crashworthiness Standards Updated

An N Class locomotive with D 77/78 traction motors weighs 127 tonnes fully provisioned.

TW
  Duncs Chief Commissioner

Duncs refer to this regarding crashworthiness standards:

R3.114 Gap Analysis Crashworthiness Standards Updated

An N Class locomotive with D 77/78 traction motors weighs 127 tonnes fully provisioned.

TW
t_woodroffe
Hi TW

I tried the link but it did not open. Can you please re send it.

Thanks for the update on the N Class. I take note of the words "fully provisioned" which means 6800 litres of fuel in the tank.

I suspect the earlier D43 traction motors were lighter, hence the lighter weight classification when these locomotives were first introduced.

Duncs
  Graham4405 Minister for Railways

Location: Dalby Qld
I tried the link but it did not open. Can you please re send it.
Duncs
Try  http://www.railcrc.net.au/object/PDF/get/download/id/r3114_gap_analysis_crashworthiness_standards_updated
  t_woodroffe Assistant Commissioner

Thanks Graham. The D43 traction motors are 500kg lighter than the D77/78 traction motors.

TW
  Duncs Chief Commissioner

Thanks Graham. The D43 traction motors are 500kg lighter than the D77/78 traction motors.

TW
t_woodroffe
That's quite a difference
  woodford Chief Commissioner

Thanks Graham. The D43 traction motors are 500kg lighter than the D77/78 traction motors.

TW
That's quite a difference
Duncs
The problem with the D43 traction motors is only the N class and another small loco class in Ireland use them, so there's only around 40 locos in the whole world use them, where as there are literaly thousands of D77 motors out there and they are still in production. I believe they fitted D77 traction to the N's because it was cheaper to buy new motors and redo the N's altenator and control system than to rebuild the D43's.

woodford
  woodford Chief Commissioner

Another reason for reducing unsrung weight is that not only does it reduce the impact forces applied to the track as already mentioned, the bogie also rides rough track better. As a consequence most modern most passenger rail vehicles have the motors mount on the frame and the axles are driven by carden shaft and right angle drives.

woodford
  woodford Chief Commissioner

anyway, so Vic has not only alot of LX compared to other states assumed because of the terrain and population density, but many are not up to scratch to protect modern rolling stock and need a 100t mass to protect the drivers. This is not a road block for V/locities on NE line, just something else that needs to be done.

And if I was the driver of the XPT, I wouldn't be that happy that its ok to use the XPT on the NE line and not the V/locity because the XPT has half a loco protecting the pax. Of course this all assumes a front on collision and while most common there are plenty of examples of other, such as Kerang.
RTT_Rules
A couple of points, the XP loco's were built to cater to some extent for level crossing collisions.

Second point ARTC works under different rules than Victoria, hence the 120kph speed limit for unprotected level crossings. Also there are only 6 unprotected level crossings north of Seymour, each of them would be VERY lucky to see two vehicles a day. The drivers on the NE line will ALWAYS give you a special whistle on these crossings, to make sure they have been heard. I as a matter of course always signal that I have heard them, this is GREATLY apreciated by the drivers.

woodford
  woodford Chief Commissioner

anyway, so Vic has not only alot of LX compared to other states assumed because of the terrain and population density, but many are not up to scratch to protect modern rolling stock and need a 100t mass to protect the drivers. This is not a road block for V/locities on NE line, just something else that needs to be done.

And if I was the driver of the XPT, I wouldn't be that happy that its ok to use the XPT on the NE line and not the V/locity because the XPT has half a loco protecting the pax. Of course this all assumes a front on collision and while most common there are plenty of examples of other, such as Kerang.
A couple of points, the XP loco's were built to cater to some extent for level crossing collisions.

Second point ARTC works under different rules than Victoria, hence the 120kph speed limit for unprotected level crossings. Also there are only 6 unprotected level crossings north of Seymour, each of them would be VERY lucky to see two vehicles a day. The drivers on the NE line will ALWAYS give you a special whistle on these crossings, to make sure they have been heard. I as a matter of course always signal that I have heard them, this is GREATLY apreciated by the drivers.

woodford
woodford
Oops, I made an error, I believe there are now only 4,  couple that are most used between Benalla and Wang have had warning systems fitted.

woodford
  t_woodroffe Assistant Commissioner

Woodford, you forgot that the 450-odd Class 66 locomotives and quite a few narrow gauge locomotives including the new ones in Tasmania use D43 traction motors .........

The N Class was the prototype application of the D 43 traction motor. These are plain bearing suspension bearings whereas the later D 43s have roller suspension bearings. It is true the plain bearing D43s are relatively uncommon but not the D 43 genre. When the first D43s ex N Class fell due for overhaul Clyde (as EMDs sole supplier) wanted an outrageous amount to overhaul the motors. It was possible to purchase zero-timed overhauled D 77s for a good deal less than the cost of overhaul. No alteration to the alternator was necessary and little or no change to the Dash 2 control system was required. It was my idea to adopt the D 77s in lieu of the D 43s on some N Class. Money was scarce in the loco maintenance budget. The track and bridge people were fine with the higher P2 and pushing the Cooper's just a tad.

D 43 traction motors are now available from South African after-market suppliers with plain or roller suspension bearings.

TW
  Duncs Chief Commissioner

Woodford, you forgot that the 450-odd Class 66 locomotives and quite a few narrow gauge locomotives including the new ones in Tasmania use D43 traction motors .........

The N Class was the prototype application of the D 43 traction motor. These are plain bearing suspension bearings whereas the later D 43s have roller suspension bearings. It is true the plain bearing D43s are relatively uncommon but not the D 43 genre. When the first D43s ex N Class fell due for overhaul Clyde (as EMDs sole supplier) wanted an outrageous amount to overhaul the motors. It was possible to purchase zero-timed overhauled D 77s for a good deal less than the cost of overhaul. No alteration to the alternator was necessary and little or no change to the Dash 2 control system was required. It was my idea to adopt the D 77s in lieu of the D 43s on some N Class. Money was scarce in the loco maintenance budget. The track and bridge people were fine with the higher P2 and pushing the Cooper's just a tad.

D 43 traction motors are now available from South African after-market suppliers with plain or roller suspension bearings.

TW
t_woodroffe
Assuming a six car consist. Which traction motors for the N class perform better in terms of power output and maintaining the train's speed? D43 or D77?
  Duncs Chief Commissioner

Woodford

Whatever happened to the plan to run the N class at 130kph of the NE-SG line?

Duncs

Sponsored advertisement

Subscribers: Boss, Duncs, KRviator, RTT_Rules

Display from:   

Quick Reply

We've disabled Quick Reply for this thread as it was last updated more than six months ago.