Train descending grade with tread brakes applied.
Never too old to have a happy childhood!
oltmanndDisc brakes were used on passenger trains for a couple reasons. One is, from higher speeds, the wheels have a hard time taking and disapating the braking HP. Related, the heat caused brake fading, and longer stopping distances.
Another point of disc brakes on postwar lightweight stock was that they provided far more assured high-speed braking action and energy dissipation than any tread-brake system could, at a time when maintaining proper tread profile was important but underfloor lathes and the like were rare to come by. I suspect fade on a typical double-disc wheelset as used on a Budd car would be less than the corresponding braking effort on treads above a certain speed -- and Don would probably know that speed better than I could calculate it.
The other half, though, was that if the proportioning system (e.g. Decelakron/Decelostat or whatever the equivalents were) was wrong, the low-speed braking performance could be abysmal: juddering, shrieking, excessively sudden deceleration from low speed to full stop. This was the reason given for applying full tread brakes and a 'blended' braking approach (cf. Bing, Bath, and Beyond in 1996) but they don't provide either technical details or even a schematic drawing of the applied tread-braking system. For some reason I clearly recall the early application of just a couple of shoes per truck on dinky little levers (which wouldn't apply to the great majority of MU equipment in that era with nose-suspended motors), in fact think it was in a Trains news article. Was that explicitly done to produce continuous reprofiling on welded rail?
Overmod PJS1 Should the car manufacturer's engineers or Amtrak's engineers have seen the potential problem with disk brakes only at the time the cars were built? As I recall this was much less a disk-brake 'problem' than a wheel-taper (and tracking) problem initially. It's not 'bad design'if the truck, as designed and maintained, keeps the treads centered for long periods of time without either oscillation or required flange following... the issue of false-flange following being a consequence of how the truck and bolster handle the resulting nonlinear response to curve force. I also recall the issues with wheel electrical contact to be far more important in providing the 'shoe braking' initially ... the continuous reprofiling being something of an afterthought benefit. I remember something of a perception even in the early 1970s that 'wear' on the treads due to shoes was a Bad Thing that disc brakes had essentially eliminated, and the modern way was to dress the tread profile as part of regular periodic maintenance, all the way to design spec, rather than crudely via profiled or cutter-equipped shoes.
PJS1 Should the car manufacturer's engineers or Amtrak's engineers have seen the potential problem with disk brakes only at the time the cars were built?
As I recall this was much less a disk-brake 'problem' than a wheel-taper (and tracking) problem initially. It's not 'bad design'if the truck, as designed and maintained, keeps the treads centered for long periods of time without either oscillation or required flange following... the issue of false-flange following being a consequence of how the truck and bolster handle the resulting nonlinear response to curve force.
I also recall the issues with wheel electrical contact to be far more important in providing the 'shoe braking' initially ... the continuous reprofiling being something of an afterthought benefit. I remember something of a perception even in the early 1970s that 'wear' on the treads due to shoes was a Bad Thing that disc brakes had essentially eliminated, and the modern way was to dress the tread profile as part of regular periodic maintenance, all the way to design spec, rather than crudely via profiled or cutter-equipped shoes.
Disc brakes were used on passenger trains for a couple reasons. One is, from higher speeds, the wheels have a hard time taking and disapating the braking HP. Related, the heat caused brake fading, and longer stopping distances.
There were never any "rusty wheel" issues with Amfleet or any of the disc brake only commuter equipment that I ever heard of...
False flanges and truck hunting didn't become a "thing" until the widespread use of welded rail. Jointed rail gave enough irregularity to keep these things from happening. This led to the rise of the importance of wheel truing. (and gizmos like constant contact side bearings on freight cars)
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
I recall seeing disc brakes on the B&O 'Bird' cars (a series of sleepers with bird names) as well as the Slumbercoaches, both series of cars were manufactured by Budd Co. in the 1950's.
PJS1Should the car manufacturer's engineers or Amtrak's engineers have seen the potential problem with disk brakes only at the time the cars were built?
The only real difference I ever noticed and remember was farther-apart seat spacing and an attempt to better align seats with windows. Possibly the seats were more comfortable. Possibly also larger rest-rooms? Those on Amfleet-! were quite tiny
oltmannd The Amfleet cars were built with disc brakes - better for high speed braking performance. But, running along on mostly tangent track at speed for many miles can cause wheels to develop a "false flange" - a ridge on the middle of the tread. This can cause all sorts of rough ride. Amtrak added some shoe braking to the Amtfleet cars to try to reduce this. They act sort of like a poor-man's wheel true machine keeping the wheel profile cleaner.
Amtrak added some shoe braking to the Amtfleet cars to try to reduce this. They act sort of like a poor-man's wheel true machine keeping the wheel profile cleaner.
Should the car manufacturer's engineers or Amtrak's engineers have seen the potential problem with disk brakes only at the time the cars were built?
BTW, what are the major differences between the Amfleet I and II cars?
Rio Grande Valley, CFI,CFII
If there is any good news here, it's that there is a big difference between uncomfortable and unsafe.
Steve B500 Oltmannd-- Could you explain "shoe braking" for me? Air brakes employ brakeshoes, so what is different?
Oltmannd-- Could you explain "shoe braking" for me? Air brakes employ brakeshoes, so what is different?
The Amfleet cars were built with disc brakes - better for high speed braking performance. But, running along on mostly tangent track at speed for many miles can cause wheels to develop a "false flange" - a ridge on the middle of the tread. This can cause all sorts of rough ride.
You can see both the disc and the brake shoe here https://www.flickr.com/photos/emd111/8196748403
Electroliner 1935 Don, Back in the late 70 or 80's I was riding Amtrak down the former NYC Hudson Valley line in a heritage Budd coach and I think the train was doing about 90 mph. On some of the curves, i experienced a sensation that I had not had before or since which was a severe lateral jolt and audible bang that felt like something had struck the side of the axle with a heavy mallet. There was no vertical sensation, just a sideways jolt. This happened on a number of curves North of Harmen but I don't remember specifics. I have talked to a number of track people and some others but no one had any significant explanation. I thought perhaps the wheel was trying to climb the rail but if that were the case, I would expect a vertical force component which I did not. Have you ever experienced anything similar and/or have any thoughts about it? Thanks
Don, Back in the late 70 or 80's I was riding Amtrak down the former NYC Hudson Valley line in a heritage Budd coach and I think the train was doing about 90 mph. On some of the curves, i experienced a sensation that I had not had before or since which was a severe lateral jolt and audible bang that felt like something had struck the side of the axle with a heavy mallet. There was no vertical sensation, just a sideways jolt. This happened on a number of curves North of Harmen but I don't remember specifics. I have talked to a number of track people and some others but no one had any significant explanation. I thought perhaps the wheel was trying to climb the rail but if that were the case, I would expect a vertical force component which I did not. Have you ever experienced anything similar and/or have any thoughts about it? Thanks
The trucks probably hit the limit of their lateral suspension. The bolster is connected to the truck frame by swing hangers on those old Budd and PS coaches. If you hit the limit of the suspension, you hit some solid stops...sometimes with a bang. Has to be a combination of things to make that happen. Lack of damping on the truck plus some poor combo of track geometry and the car's suspension.
A number of years ago, similar experience south of Hudson at 90 mph in Turboliner.
At least until last June, one of the Pacific Surfliner trains consisted of Amfleet I or maybe Amfleet II cars. I am not sure of the difference.
I have ridden the Amfleet equipped Surfliner three or four times. The ride was smooth. Moreover, I kind of prefer the single level cars. Seems more like what I was used to in the 1950s
It's not the equipment that's the problem. It's the condition of the equipment and the track.
I rode quite a few miles in Amfleet in Metroliner service at 125 mph and the ride was really quite nice. The track was in fine shape as were the trucks under cars.
I also rode the Pennsylvanian and Empire Service quite a bit, too. Same good ride. The track and equipment were in good shape.
In every case, the ride was better than the old Budd and PS coaches on Penn Central quality track!
I have riden the Crescent a few times in the past decade or so and the ride varied. My hunch is the greatest variable is the wheel contour. Amtrak added shoe braking to the Amfleet equipment to help keep the wheels from developing a "false flange" and needing wheel truing quite so often. I suspect there is quite a bit less airbraking going on in recent decades and the wheel contours develop some issues as a result. The problems can affect the ride, but generally not the safety, so the cars get turned at the end of each run and away we go.
On the NEC, I've noticed lots of bouncing from what might be longitudinal "waves" in the track. I have no idea what or why, but it wasn't that way in the mid 1980s.
Finally, if you want the best ride, sit in the middle of the car. The ends alway ride quite a bit rougher. (And Amtrak should allow you to select your seat on booking for an extra fee.)
I ride Acela Express often and find the ride to be some of the smoothest anywhere, except maybe on Metro North. And, i would hardly call the Piedmonts "near luxury". The coaches are fine but there is no business class and the cafe is a joke. Vending machines and no attendent.
I've ridden both. Acela rides much better than Amfleet cars. But there are some switches so poorly constructed nothing rides well through them at any speed over 40 mph. Part of the problem is also inferior engineering and construction of track ROWs in many places in the US (poor subgrades on unstable soils), coupled with overweight freight cars that damage track quickly, all in the name of short-term profits. [Heavier cars > fewer cars needed for same load. Longer trains > fewer crews = lower labor costs > higher profits.]
SCLyardmaster Oct 2018. Circumstances required me to take Amtrak #20 to Philly and a bus beyond to catch up with friends for a railfan vacation. While I've enjoyed riding NC's near-luxury Piedmont trains, I anticipated a sleep-manageable trip. Wrong! Amfleet cars were never designed for overnight travel with LED aisle lights, no window armrests, constant rattling and a lightweight design that leaps over grade crossings and slams through every turnout frog. Surely the Corridor will be better and I can get at least a little sleep. The ride was the roughest I'd ever experienced! The car slammed from left to right, vertical disturbances felt like speeding over a picket fence of speed bumps at 90+MPH, the luggage rack bounced up and down while seats shook from side to side. One passenger said it was so rough he couldn't text and other was unable to work on his laptop. If this were an airliner, I thought, people would be screaming and praying! Bottom line: NEC is supposed to be Amtrak's showcase but after several decades and billions of dollars we're left with a national disgrace. Better to rip it up and give it to Albania or Mozambique - if they'll have it!
Oct 2018. Circumstances required me to take Amtrak #20 to Philly and a bus beyond to catch up with friends for a railfan vacation. While I've enjoyed riding NC's near-luxury Piedmont trains, I anticipated a sleep-manageable trip. Wrong! Amfleet cars were never designed for overnight travel with LED aisle lights, no window armrests, constant rattling and a lightweight design that leaps over grade crossings and slams through every turnout frog. Surely the Corridor will be better and I can get at least a little sleep.
The ride was the roughest I'd ever experienced! The car slammed from left to right, vertical disturbances felt like speeding over a picket fence of speed bumps at 90+MPH, the luggage rack bounced up and down while seats shook from side to side. One passenger said it was so rough he couldn't text and other was unable to work on his laptop. If this were an airliner, I thought, people would be screaming and praying!
Bottom line: NEC is supposed to be Amtrak's showcase but after several decades and billions of dollars we're left with a national disgrace. Better to rip it up and give it to Albania or Mozambique - if they'll have it!
That's why people pay more to ride the Acela Express. The Amfleet cars are junk.
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