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ben_issacs

Spectacular derailment in Western Australia.

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marknewton
On 11/28/2018 at 6:48 PM, ben_issacs said:

If, on that train weight, we knock off the 620 tons for the four locos, we then get just on 160 tons per wagon.

130 tons for the load and 30 tons for the wagon, is that reasonable?

 

 

 

From memory the modern “GoLynx” wagons weigh about 25 tonnes. But 160 tonnes per wagon is right.

 

Mark.

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marknewton
9 hours ago, Ochanomizu said:

Perhaps the ECP brake can be upgraded to require manual release in future?

 

That’s one proposal being discussed at the moment.

 

Mark.

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marknewton
6 hours ago, ben_issacs said:

Using Mark's train weight and grade figures. on the 1:60 grade with a train of 43,620 tons, the component of the gravitational force parallel to the track , the 1:60 grade, is 727 tons.

This is the force tending to pull the train down the grade.

I've assumed that the four locos had a total weight of 600 tons.

Using the Static Co-efficient of Friction for steel wheel on steel rails of 0.78, it requires a force of 468 tons to move the locos against their brakes, less than the 727 ton force calculated above, so as Mark wrote, the independent loco brakes could not hold the train if all the train brakes went off.

Once the train starts to move the Co-efficent of Friction becomes a Sliding Co-efficent, which is much less than the Static one, so the train keeps on going.

With the loco wheels locked, they must have developed considerable flats at the place of derailment.

 

Had they remained locked then they would have had enormous flats, but I doubt they did. Even on the very best maintained locos the independent brake will leak off fairly quickly. It doesn’t take much to get the wheels turning even against the brake. As I noted earlier, I don’t know if the driver applied the independent or not before leaving the cab, but even if he did, I’d be very surprised if they stayed applied for the duration of the runaway. Once the train started moving and the wheels started to turn even a bit, the wheels and shoes would heat up very quickly and the braking effort would fall away. More so once the shoes stated to be worn away by the wheels.

 

Mark.

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ben_issacs

Mark, 

Fair comment about loco wheels and independent brakes.

If the wheels were turning, they would be turning the traction motors.

Would these run as gennys and feed current back into the electrical system, as a regen. brake, which wouldn't do much to slow the train down.

Regards, 

Bill,

Melbourne.

 

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kvp
5 hours ago, ben_issacs said:

Would these run as gennys and feed current back into the electrical system, as a regen. brake, which wouldn't do much to slow the train down.

Electrical motor brakes are normally very good at slowing a train down, especially in a ballastless cross connected or shorted configuration. (shorted means the motor contacts are shorted together for maximal emergency brake currents). I'm not sure if these locos were equipped with them at all and with such a huge train weight, they wouldn't really matter. Also not effective when the throttle and/or the reversing switch is in idle position, which effectively disconnects the traction motors on most diesels. The same is true for any disk brakes as they would get worn pretty quickly if they could'n keep the wheels locked.

 

Imho the only sure ways to keep a freight train like this stopped is to use the air brakes on all cars or turn the handbrakes on at least half of them or add lots of brake shoes under the wheels. Imho even a standard buffer clamped onto the rails couldn't keep them from rolling down the slope.

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ben_issacs

KVP,

Thanks for your comments on traction motors running as genneys.  

Most useful for me, as to modern elec. traction stuff, I'm disconnected!

Regards, 

Bill, 

Melbourne.

 

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ben_issacs

Mark, 

Many thanks for that info. 

The cab ride shots were of interest, North Coast Line I assume?

When the wagons are tippled, do the air and ECP lines disconnect?

Re-connected after progress through the tippler.

Regards, 

Bill, 

Melbourne.

 

 

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kvp
5 hours ago, ben_issacs said:

When the wagons are tippled, do the air and ECP lines disconnect?

On the linked pictures the lines are mounted to the couplers. One coupler is rotatry, the other is not, so two connected couplers always rotate together. This means the coupled lines could stay connected as long as the couplers stay together. Any flexibility issues must be handled on the side of the rotary coupler. Afaik the cars must rotate around the axis of the couplers, so the car movement around them is minimal.

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ben_issacs

KVP'

Thanks for that info.

Yes, of course, the couplers stay coupled as do the air and ECP lines, but the waggon rotates independently.

Regards, 

Bill,

Melbourne.

 

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ben_issacs

Folks,

The official investigation into this runaway is being conducted by the Australian Transport Safety Bureau (ATSB).

Looking at the ATSB web site, all that they say there is 'Collecting evidence'. 

The final report won't be issued until about the middle of next year. 

The ATSB reports on incidents involving marine, air and rail, and it's interesting to Googly up their web site, just put in ATSB.

Over the past three months there have been three railway runaways in various parts of Australia, the W.A. one was the most serious of these, all are under investigation, so their investigators would be pretty busy.

Regards, 

Bill, 

Melbourne.

 

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