The Amfleets probably can go 135 mph, but until they are tested at various load and track conditions, you won't know for sure. Things to look for are perturbations caused by natural frequency excitation, spring deflections, side loading forces, bearing temperatures, etc. The higher speed will probably require a revised maintenance program which will have to be determined.
The body design is essentially that of the original Metroliners, which did run up to 150 on occasion and up to 135 in regular service. Trucks are different, however, and might require some modification, but probably not replacement.
FRA crash specs for Tier 1 cover up to 125 MPH and Tier 2 up to 150 MPH. Amfleet were not analyzed for Tier 2. It is physically possible? More than likely, yes.
Editor Emeritus, This Week at Amtrak
I have so often questioned speed matters on the NEC ever since riding to Boston in 1981. At that time going through Connecticut near Groton on Amfleet, I was clocking mile markers and caught a 28 second mile. Shortly afterward a kid sitting just ahead of me asked a train crew member how fast the train can go. He opened his timetable and read back about F40PH's, that they can go 103 mph (110, in reality) and he believed we going that speed. It appears the Amfleet cars can handle it.
I had wondered more about the F40 than the cars, but it was when working for Conrail and doing an inspection on an SD40-2 and running a speed recorder playback to find the engine ran 120+ at one point in it's last trip.
Mark H
Modeling in HO...Reading and Conrail together in an alternate history.
BuslistBut it involves far more complex issues than body structure and crashworthyness. FRA has set limits for maximum wheel/rail forces under a variety of track conditions. These forces will be a function of truck type, spring rates, damping stiffness, wheel and rail profile and more. For tier II rolling stock FRA requires that these forces are measured using an instrumented wheelset. There is probably no reason an Amfleet car couldn't be configured to be successful at 148 (10% over 135) although I'm not sure the Budd Pioneer III trucks would make it.
I agree with you and Dave. It's a "maybe". Those trucks are rather simple. All the "softness" is in the secondary suspension - bolster to carbody. The primary is just some rubber pads between the bearings and truck frame. Very stiff. I imagine this isn't the best arrangement for isolating lateral...
The big trick with higher speeds is keeping wheel profiles in good shape. Even with standard 1:40 taper, as the wheels wear, the effective taper becomes more and lowers the hunting threshold speed. It's part of the reason Amtrak added supplemental tread braking to the Amfleet cars.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
crhostler61I had wondered more about the F40 than the cars, but it was when working for Conrail and doing an inspection on an SD40-2 and running a speed recorder playback to find the engine ran 120+ at one point in it's last trip.
Oh my, Mark! You'd have had 6 birdsnests at 120 mph on a CR SD40-2 at 120 mph. Something was goofy with that speed recorder...or the playback calibration.
Two data points.
The original qualification run of an EMU set for high speed operations on the NEC was a DOT four-car Budd Silverliner set, that was tested as exceeding 150 MPH.
My Poppa, who had contributed to the high-speed roller test at Pueblo and had worked at GATX on a mathematical model of hunting in high-speed designs that was presented at ASME, he told me that the rough-riding Metroliner truck (it was -- I rode a Metroliner and experienced it) was a substitution at the insistence of the (then) Pennsylvania Railroad from what the DOT and Budd wanted to use. This is along with the Amfleet design is evidence that the original Metroliner was supposed to use a Pioneer III truck.
Whether the Amfleet/Pioneer III's meet current FRA specs is unknown. But the Amfleet/AIM-7 combination was the Metroliner replacement, and it would appear that Amfleet was intended as a high-speed design.
From my reading of the scholarly literature on truck hunting so far, you don't want to hold the axles in a truck perfectly rigid in from steering relative to each other. If you do that, you have a driver set from a steam locomotive, which I believe Carter established takes up the steering error with wheel slide, which makes the whole set behave as a single coned axle. This accounts for the high driver wear on steam along with the need for guide wheels at anything above yard limits speed.
You need a controlled amount of compliance "springiness" of the axles in yaw relative to the truck frame (not lateral displacement -- that is taken up by the "swing hangers" or other arrangement in the secondary springing. The thing that you don't want is any kind of "horn gap" or play in something like a pedestal truck. You see in a lot of the Japanese and European designs something more like an automotive suspension with a link constraining the axle fore-and aft (just like on the back end of my Taurus) rather than a sliding guide. Look at the truck of a Genesis Diesel and you will see this type of arrangement.
I am speculating here, but this speculation is informed from a least looking at technical papers on the subject, that you want a good deal of lateral stiffness in the primary suspension of a high-speed truck. The Pioneer III's rubber pads may be a good high-speed design, so why isn't anyone else (Siemens, SIG, Nippon-Sharyo) using it? Besides patents, it may be that as Don suggests that the Pioneer III is too stiff in the vertical degree-of-freedom in that unique and simple primary suspension. The Pioneer III may be a workable high-speed design, but competing designs may offer lower effective unsprung mass and be easier on the track?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Thanks for the abundant information, Paul.
On your second-to-last question, my best guess is "technology has improved".
oltmannd crhostler61I had wondered more about the F40 than the cars, but it was when working for Conrail and doing an inspection on an SD40-2 and running a speed recorder playback to find the engine ran 120+ at one point in it's last trip. Oh my, Mark! You'd have had 6 birdsnests at 120 mph on a CR SD40-2 at 120 mph. Something was goofy with that speed recorder...or the playback calibration.
provided the wheel profile and general truck maintenance is up to snuff.
The main issue would be braking, but as someone else pointed out speeds over 125 can not be done without violating FRA rules, and speed over 125 requires tier II high speed equipment.and falls under a complete different set of FRA rules, including no trap doors (no break in side sill) , crush zones, etc etc etc.
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