I was not really sure how to title my question, but…before the advent of dynamic brakes, did the railroads simply run Smaller/Lighter rains.?
In the days of steam, was there anything besides traditional brakes that could be used to slow a train on downgrades.?
Are there trains today that could not have been safely run before the Diesel Electric Locomotive came into being.?
Thank You
Without dynamics and pressure-maintaining locomotive brake valves train crews were required to set retainers in order to safely descend long, steep grades. Sometimes trains also had to make stops to allow the wheels to cool before proceeding.
A retainer is a valve found on the exhaust pipe from a car’s brake cylinder. It’s normal position (Direct Exhaust) allows the air brake to release normally, but the retainer can also be set to different positions which make the car take longer to release (Slow Direct), or not release completely (High Pressure). Older cars had a “Low Pressure” position too, which kept a lighter brake application than “High Pressure”.
Pressure-maintaining is a feature of the locomotive’s automatic brake valve which adds just enough air to the train’s brake pipe to compensate for leaks, but not enough to trigger a release.
To understand the rationale behind these features one must learn a bit more about how the air brake system works. Once the system is charged one reduces the brake pipe pressure to set the brakes, and any futher leakage will result in a heavier brake application. When descending a long, even grade without a pressure-maintaining brake valve this leakage will eventually result in the brake application becoming heavy enough that the locomotive(s) cannot pull the train downhill anymore (even in full throttle), so the Engineer must release the brake in order to continue.
A car’s air brake (except for some passenger equipment) can only be released completely, the Engineer cannot back off a bit to a lighter application. It only takes a 1 or 2 PSI rise in brake pipe pressure to trigger a release. The brakes will then release fairly quickly, long before the system has fully recharged. Now the Engineer must make another application to control the train, but will have to make a larger reduction in brake pipe pressure in order to achieve the same bra
Here is a first-hand account of retainer operation, from my area. This train still runs today (using modern diesels with dynamic braking) but retainers are still used while loading the train.
http://caboosecoffee.blogspot.com/2011/11/air-brakes-on-alberta-coal-branch.html
I’ve actually gotten to work that train a few times, and CN crews are still expected to set retainers before train loading starts (fortunately not while the train is moving!).
The railroad world of steam and the railroad world of today are as different as night and day. In freight service steam was not able to move the size of the trains that exist today. Car sizes and capacities were smaller in the steam era. In the steam era a 50 foot box car was a giant. The majority of the cars had a load capacity of 50 tons or less. Where sustained braking was required over a several mile mountain grade - retainers were used to keep train brakes applied on the cars that had their retainers activated. With driver tires being shrunk fit on driver wheels, sustained engine braking was not an option - heating the driver tires could cause them to expand and come off their whees (a uncommon but potential occurence).
Digging through a FRA Accident Report of a runaway that happened on CSX. FRA testing revealed on the 2% grade involved car brakes would fade to ineffectiveness when subjected to speeds over 15 MPH with 100 ton loads, which present a total car weight of 130-145 tons per car. In the particular incident the train had 3 units all dynamic brake equipped, however DB wasn’t functioning on the rear two units. TTSI stated that if a train was exceeding 15 MPH at a particular point that the train was to be brought to a stop. The train was doing about 18 MPH at that point with a application on the train and DB at max amps indicated and the crew then place the train brake in emergency - and the train continued to gain speed until it finally derailed.
The FRA then instructed the carrier not to operate trains in excess of 15 MPH on the grades in that territory.
Getting todays trains up a grade is a relative piece of cake; getting todays trains SAFELY down the grades is where the Engineers earn their pay.
Wow…thanks to Both Of You. I certainly did not realize the complexity of the braking system.
I have seen Youtube Videos of workers in the repair shops, where they would ignite a Ring Of Fire around the tire for a locomotive and then just hammer it onto the wheel i guess.? So yeah, it would make sense that a certain amount of heat, while train is moving, might be a bad idea for the Loco Tire. [:)]
BTW…BaltACD, are those Formula Fords in your Avatar.?
The tire would be heated, causing it to expand slightly. It would then be slipped over the wheel where it would shrink to a tight fit as it cooled.
BRC used tires on its diesels until relatively recently.
No they are Formula 500’s. My son is in the red car passing me going through the Carousel at Road America outside Elkhart Lake, WI as we competed in the Sports Car Club of America National Champinship Runoff’s back in 2010. My son is fast, I am only half fast.
Ah, OK…after my time. Not even aware of that category.
I wrenched on a Formula Ford for 2 seasons in 1978 and 1979. We were leading our first race when my driver crashed in (what was then) turn-9 at Laguna Seca. Kelly was still just 18 years old at that point, we would not be 19 until September.!
I never got to Elkhart Lake. But all the pics i have ever seen look beautiful. I went to Road Atlanta twice for The Nationals…1979 and 1980. I towed a car back for an MGB guy…maybe that was C-Production back then.?
I was walking around the track one night (Atlanta) and i ran into two older guys that turned out to be Buddy Baker and Paul Newman. I was able to hang-out with them, Just The Three Of Us, for about 20 minutes that night. They both seemed like decent guys.
So anyway…that is why i asked. [:)]
There is at least one photograph out there of a steam engine that threw off a driver tire while underway. Because of the side rods, the tire didn’t fly off into the ditch but would’ve sort of flailed around until they stopped. Which the crew was able to do before the train was derailed.
Jeff
Formula 500 originated in 1979 as Formula 440 - The class uses snowmobile engines and CVT drive trains. The class was redesignated at Formula 500 in 1996 when 500cc engines were permitted, both the 440cc and 500cc engines were 2-strokes. in 2009 a class with 4-stroke 600cc motorcycle engines and transmissions was created as F600. In 2014 that class was ‘forced’ into F500 with restrictor plates being required. In the 2015 Runoff’s at Daytona, one of the MC engine cars turned at trap speed of 159.868 MPH, the fastest 2-strokes topped out at about 145 MPH. There has been a ‘war’ over what size restrictors the MC engine need to run for the sake of equal competition.
I last raced at Road Atlanta in 2005 - which I think is the last year Paul Newman competed in GT-1. Saw him in the paddock and on track but never hat the opportunity to talk with him.
There’s at least one photograph out there of a GG1 that threw off a driver tire while underway.
One of the principal reasons blended air and independent braking was restricted on large steam locomotives is that any significant amount of driver braking to slow the mass of the locomotive can result in the tires expanding enough to work off the center. Various kinds of clips, Gibson rings, etc. were used in an attempt to preclude the issue.
The GG1 problem came about when the ‘second era’ of Gs substituting on Metroliner schedules came about in the late 1970s. The problem was that the light Amfleet equipment couldn’t supply “its share” of braking effort to help decelerate the 250±ton locomotive, which threw a somewhat disproportionate share of the high-speed braking on the (non-Decelostat-equipped) G’s driver brakes. Didn’t take long for the effects to become notorious – and that was probably after a certain amount of tire walking and separation in service. (Something to consider: once the tire has expanded even a slight degree, it’s no longer in contact with the effective heat sink of the driver center over most of its rotation, which enhances the relative isolation of brake-induced heating (during the time the tire is clamped to the center by brakeshoe force) in the metal of the tire…). I suspect that helping to address this may be part of the effect of German system of crossed brakeshoes/levers used for driver braking on some of the faster locomotives.
[quote user=“BaltACD”]
10-4…thanks for the info.
kenny dorham
Ah, OK…after my time. Not even aware of that category.I wrenched on a Formula Ford for 2 seasons in 1978 and 1979. We were leading our first race when my driver crashed in (what was then) turn-9 at Laguna Seca. Kelly was still just 18 years old at that point, we would not be 19 until September.!
I never got to Elkhart Lake. But all the pics i have ever seen look beautiful. I went to Road Atlanta twice for The Nationals…1979 and 1980. I towed a car back for an MGB guy…maybe that was C-Production back then.?
I was walking around the track one night (Atlanta) and i ran into two older guys that turned out to be Buddy Baker and Paul Newman. I was able to hang-out with them, Just The Three Of Us, for about 20 minutes that night. They both seemed like decent guys.
So anyway…that is why i asked.
Formula 500 originated in 1979 as Formula 440 - The class uses snowmobile engines and CVT drive trains. The class was redesignated at Formula 500 in 1996 when 500cc engines were permitted, both the 440cc and 500cc engines were 2-strokes. in 2009 a class with 4-stroke 600cc motorcycle engines and transmissions was created as F600. In 2014 that class was ‘forced’ into F500 with restrictor plates being required. In the 2015 Runoff’s at Daytona, one of the MC engine cars turned at trap speed of 159.868 MPH, the fastest 2-strokes topped out at about 145 MPH. There has been a ‘war’ over what size restrictors the MC engine need to run for the sake of equal competition.
I last raced at Road Atlanta in 2005 - which I th
FYI.
Regenerative Braking.
In 1930 Twenty 20 streetcars in this class were equipped with Regenerative Braking to save on brake shoe wear descending Rte 11 Mountain which was 8% in places…
Bottom of the Grade. Curves were well guard-railed. Box left is for sand.
http://archivesdemontreal.com/documents/2018/03/11-VM094-U0739-017-600x587.jpg
These Observation Cars were fitted w RB. Note Sand Pipe beneath Front Step another in front of Rear Truck. Switch Iron on front handrail to throw in-street track switches.
https://www.flickr.com/photos/thomasfisherlibrary/6282751599/in/photostream/
Certain Electric Locomotives could use RB to hold back trains.
At some
Not quite, diesels can’t have regenerative braking since they have no way of returning current to the catenary or third rail. They do have dynamic braking which returns the current to onboard resistors, where the energy is dissipated as heat.
They can if they have a battery on-board, as in the case of GE’s proposed hybrid diesel-electric locomotive. [:-,]
OTOH, I think a switcher with bank of ultra-capacitors would make sense, the ultra-caps would recover energy from braking and also provide instant response for acceleration. Cost of energy storage based on cycle lifetime is abour $0.05/kwhr for the capacitor modules, and probably $0.10/kwhr when the auxiliaries are included. An additional benefit is that the throttling of the prime mover can be done at a much slower rate, which should improve emissions.
The first production engines with dynamic brakes on them were the FTs delivered to the Santa Fe in 1939 unit 100 her trial by fire was Cajon pass with a maximum tonnage frieght. They made it down without heating up the wheels at all.
It does, and I’d add that many of the approaches used for KERS would apply (as they do in wayside storage for hump applications etc.) This is particularly true for much of the current flat-switching emphasis where very high currents are involved for durations probably less than a minute, with very little transition between full charge and full discharge rate (all this being NOT conducive to long chemical-battery life)
BTW the translation of those figures into hp/hr is approximately 0.375 to 0.75 – then correct using the efficiency of what will likely be inverter AC drive.
Slow throttling up and down is an important reduction of emissions; I would add that slow throttle-up combined with transient reduction of alternator field will reduce nanoscale PM even more dramatically.
The UK does not use dynamic breaking. I believe they use the two pipe air brake system. Since they had very few single pipe freight cars the implementation was fairly straight forward.
I’ve know a couple of people who worked at Maxwell a long while back, so had been familiar with their “ultracap” technology, but was amazed by stumbling on their modules when looking up large value caps in Digi-Key. Price was reasonable for the project being worked on at the time and as a lark, decided to calculate cycle life energy costs (price/(energy capacity x number of cycles), the result was impressive. Only problem was that in order to get 500,000 cycles in ten years (expected calendar life), the caps would need to be cycled 6 times per hour for 24hrs/day). Flat switching fits the bill…
Ultracaps appear to be better suited for taking the shocks inherent with locomotive applications than lead acid batteries used on the first green goats. It probably would be a good idea to give them some shock protection and some form of environmental control to keep capacitor internal temperatures to under 60C. It would pay to be generous with energy storage capacity as less of the power would be used up by internal resistance, which nicely translates into less internal heating and longer cycle life.
One key selling point for this locomotive is instantaneous response, no waiting for the engine to load (or a genset to come on-line). A related note was that the Milwaukee actually strung wires on industrial spurs in the Butte/Deer Lodge area beacuse the electric switchers were much more responsive than the diesel switchers.
I’m not really sold on battery locomotives yet, though what may be the best test site for such beasts would be helper engines on the BNSF Cascade tunnel line. This may be a way to increase capacity of that line as the reduction in the number of diesel engines should allow for shorter wait times between trains.
One could also build shorter sections of catenary, to boost range and allow battery locomotives to charge “on the fly”.
Does the Cascade tunnel have enough clearance to allow both catenary and doublestacks?
CP in Rogers Pass would be another good test site, and the Mt. MacDonald tunnel was designed to allow for future catenary installation.