nariq-01: This is not completely true. Only the C855s and U50Cs were scrapped before their time. The U50, DD35 and DDA35 designs generally lasted at least 15 years. The 15 year date was the measuring stick of the depreciation cycle applied to all heavy pieces of equipment.
Ed
narig01 Comment on double engines of the 1960's. Darwin really worked hard on these. Only the EMD's survived for very long. And then only because they had very reliable equipment with much parts commonality with other EMD designs. The C855, U 50 C & U 50 B designs were very short lived. I thing the U 50 s went to scrap after only 10 years. Baldwin had stopped building locomotives by the time these ideas were being tried. Rgds IGN
Comment on double engines of the 1960's. Darwin really worked hard on these. Only the EMD's survived for very long. And then only because they had very reliable equipment with much parts commonality with other EMD designs. The C855, U 50 C & U 50 B designs were very short lived. I thing the U 50 s went to scrap after only 10 years. Baldwin had stopped building locomotives by the time these ideas were being tried.
Rgds IGN
Hey Jim;
Can you settle this for me once and for all: Are they officially DDA40Xs or DD40AXs?? I have seen them listed both ways in the railroad press for years - one has to be the "Right" way, right?
Gary
glh3751Hey Jim; Can you settle this for me once and for all: Are they officially DDA40Xs or DD40AXs?? I have seen them listed both ways in the railroad press for years - one has to be the "Right" way, right? Gary
DDA40X
RWM
RWM is right -- here is the UP's brief history of the class:
Don't know why the plaqe states the maximum speed as 85 mph. Wherever a train with one of these locos could attain it they ran at 90 mph. Tests with them when new were performed with the Wheel Overspeed Module disabled and the Speed Recorder overspeed switch disabled, the loco got to 106 mph before motor flashover. To quote from the famous Union Pacific advertising gingle of the 1970s "a thousand wheels of freight train doing 90 miles per hour" refered to the DDA40X and a group of SD40-2 locos also geared for 90 mph that typically ran between 2 DDA40X locos on high priority intermodal trains.
This is from the DDA40X Locomotive Service Manual, General Information section:
Gearing......................................................................59:18
Ratio..................................................................3.277
Full Horsepower Low Speed - Nominal................28.3 MPH
Full Horsepower Max. Speed - Nominal................82 MPH
Minimum Continuous Speed (Full Throttle)..........11.3 MPH
Gear Ratio Max. Speed......................................90 MPH
DP Man
Is there a "maxumun" speed limit for freights set by the FRA? Looks like the DDA40X is just a hude locomotive all together1 I just noteced that the train at the top of TRAINS mag.com is beig pulled bu a Centinial too.
The road to to success is always under construction. _____________________________________________________________________________ When the going gets tough, the tough use duct tape.
Thanks guys - I knew the "AX" part couldn't be right... but it seemed to be used as often as the right way: DDA40X. Either way, one thing is for sure: UP Did (Does?) stand for Unlimited Power!
bubbajustinIs there a "maxumun" speed limit for freights set by the FRA? Looks like the DDA40X is just a hude locomotive all together1 I just noteced that the train at the top of TRAINS mag.com is beig pulled bu a Centinial too.
The FRA sets maximum speeds for freight trains based on two things (1) track standards, and (2) Method of Operation.
Track standards is the maintenance quality of the track -- whether the track is in gauge, the amount it's out of cross level, the number of defective ties, the location of defective ties, and so forth. Maximum freight train speed is:
Method of Operation is the system of train control under which a railway is operated. Methods of Operation include Yard Limits, Centralized Traffic Control (CTC), Track Warrant Control (TWC), Direct Traffic Control (DTC), Automatic Cab Signals (ACS), and so forth. Methods of Operation are either Block Systems (the track is permanently subdivided into blocks with fixed limits) or non-block. The FRA sets speed limits as follows for freight:
The more restrictive applies. Thus if a line has track maintained to FRA Class 3 and its Method of Operation is TWC-ABS, it is allowed 40 mph for Class 3 and 49 mph for TWC-ABS, and the lesser of the two, 40 mph, is the maximum speed.
Thanks RWM. So the more sophistacated, well mantained, well kept up track you have the faster you can run on it. I knew that Amtrak had a set limit (79 mph) but I didn't know if the class 1's had that or not.
You guys may be following the thread, How Is Horsepower Determined.
A DD40X has 6600hp, is that at the crank shaft or is that the h.p. actually going to the rail head? How would you figure that out? The mechanical energy goes to the altrnator and when it comes out as electrical it goes to the cooling systems blowers, electronic systems, compressers, and motors. So tecnically it isn't 6600 h.p. moving the wheels right?
As with all diesel electric locomotives the horsepower rating is engine input to the main generator or traction alternator for traction with the engine at full throttle and conditions stabilized. There is an efficiency loss through the main generator or traction alternator, through electrical switchgear, in the traction motor, pinion and wheel gearing. Only the efficiency loss of the main generator or traction altenator (including the rectifier assembly) is considered when verifying the engine horsepower rating because the power is measured as output voltage and amperage while the main generator or traction alternator is connected to a fixed resistance, either a load box or the locomotive dynamic brake grids. The efficiency loss of the main generator or traction alternator has to be considered in the horsepower calculation; Volts x Amps / 746 x %efficiency. But in order to state the engine horsepower input using factors measured at the main generator or traction alternator output, the formula commonally used is V x A / 700. 746 watts = 1 HP at 100% efficiency, 700 represents 1 HP at 94% generator efficiency.
The service manual for the DDA40X recommends formula V x A / 715 which represents 96% traction alternator efficiency. The DDA40X employed an AR12 traction alternator instead of the sandard AR10 type and EMD considered it more efficient during load test conditions.
The air compressor is shaft driven off the front of the engine crankshaft, and like all EMD locomotives starting with the GP30, the traction motor blower and traction alternator blower are shaft driven off the engine grar train at the rear, the same shaft drives the auxiliar generator. All of these loads are mechanical and are a steady load, the compressor will vary between unloaded and loaded (pumping) but the difference in load on the engine is not significant in relation to the main generator or traction alternator load. The radiator cooling fans and the traction alternator field power are generated by the D-14 companion alternator mounted on the front of the main generator or traction alternator, by waiting for engine temperature to stabilize the number of cooling fans (1, 2, or 3) will remain steady over a long enough period to get a accurate calculation of engine traction input horsepower.
The above explains how engine tractive horsepower is determined. Another consideration is under what circumstances is all of the engine tractive horsepower delivered to the traction motors. From my previous message about the maximum operating speed of the DDA40X:
The locomotive power control system (RC, SB, SE, GX, GV, and PF modules) permitted full 3300 HP to be delivered to the traction motors between the speeds of 28.3 and 82 mph. If the locomotive traveled faster than 82 mph at full throttle, traction circuit voltage had reached its limit of 1450 volts, it could go faster but horsepower would drop off. If the locomotive was on a grade and slowed to less than 28.3 mph the traction circuit amperes began to approach its limit of 1500 amps/motor (6000 amps from the traction altenator) then engine horsepower would drop off to reduce motor heating with the high amperage associated with slow speed. The throttle and engine speed would remain at maximum (TH8) to produce maximum motor cooling while the power control system delivered high amperage at reduced power = high tractive effort at reduced motor heating. The DDA40X was the first locomotive to include a motor temperature sensor that worked to modify the slow speed power control (PF Module = Performance Control) according to actual motor temperature.
The DDA40X has a stated minimum continuous rating of 11.3 mph, but unlike an SD40 or GP40 it does not have a short-time rating (indicated on the Loadmeter by numbers of minutes it is safe to operate at motor amperage in excess of the continuous amperage). I have been on DDA40X locomotives at 8 mph with the Loadmeter hand on the 1500 amp stop since 12 mph and barely made the grade but the motors did not burn up. By that time the motor circuit horsepower was well less than 1000, but high amperage kept tractive efort high and the locomotive made the grade.
3300 HP is going to the input shafts of each of the two traction alternators ( 2 x 3300 = 6600). Of that 6600, probably 85% makes it to the rails (combination of losses in the alternator and motors), so the DDA40X's would have about 5600 HP at the rails.
erikem 3300 HP is going to the input shafts of each of the two traction alternators ( 2 x 3300 = 6600). Of that 6600, probably 85% makes it to the rails (combination of losses in the alternator and motors), so the DDA40X's would have about 5600 HP at the rails.
That's a-lot of power loss! But I guess a big locomotive needs lots of power. Thanks guys. I'll call this a sucessful thread.
Justin,
Bear in mind that the efficiency of electric transmissions have been improving over the last few decades (the DDA40X dates to 1969). AC transmissions are reported to be over 90% efficient (though that is peak efficiency) and there's room to squeeze a bit more efficiency out of the components.
- Erik
erikem Justin, Bear in mind that the efficiency of electric transmissions have been improving over the last few decades (the DDA40X dates to 1969). AC transmissions are reported to be over 90% efficient (though that is peak efficiency) and there's room to squeeze a bit more efficiency out of the components. - Erik
Yes that is tru though. back in 1969 things were al lot less efficent. The GEVO's are hills and hills more efficent, especially with the new AC technolagy, weather at run 8 or run 2. Thanks for bringing that up.
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