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  • Upgrade Wagon Running&Maintenance Qualities

  • General discussion about locomotives, rolling stock, and equipment
General discussion about locomotives, rolling stock, and equipment

Moderator: John_Perkowski

 #251879  by ZHEF84
 
One of the crucial indexes for running qualities of rail wagon bogie is the maximum tolerable deviation from ideal parallelism and designed distances between bogie axles, namely the axle-distance limit. Diversification of rotating directions between hundred pairs of wheels of a freight train, results not only a great loss of haulage capacity and train speed, due to increased resistances, but also deteriorated wear of rails and wheel flanges and worsened friction between all the working couples of the bogie. The higher the freight speed or the heavier the load it carries, the bitter the adverse effects. Of this, all the designers involved are quite aware. But, since axle distance deviation is an accumulation of a series of tolerances of the machinery parts from bolster center plate to freight wheels, even all the errors is minimized by careful, precision cutting and fitting, with high cost and long production period, improvements can be achieved is still quite limited. That is why axle-distance limit of, the well-known China –USA designed K5 and many other technically advanced bogies, preserve 2mm. designed axle –distance limit as a compromise. When composite coating technology is adapted, with its superior techniques, all the errors occurred during the repairs can finally be compensated through the coating of roller bearing adapter. Thus, axle-distance tolerance can be compressed to 0.1mm.quite easily. It is obvious, how remarkable the running quality and working live of wagon may be promoted, through the20 time upgrade of precision index. Similar achievements are true to other bogie machinery parts .
Moreover, 1, Data of tribological tests from M2000 testing machine indicates, performances of DP series composites used in the composite coating technology are profoundly superior to the conventional metals used in bogies at present, as follows:
Test conditions: 1,axle load 500 N 2,RPM 400 3,Lbrication oil drops 。

Materials tested Time tested Min. CoefficientOf friction Wear depth mm Temp. 0C Wear ratemm3/KM Wear con-dition
DP coating 1440 0.008 3.3 40 0.005 good
bronze 3 0.2 7.5 120 abnormal
Cast iron 5 0.09 110 abnormal
Babbitt metal 25 0.008 5 35 0.036 good

Not only the composite itself is wear resistant, even more important is, it protects the surface of the opposite work piece [usually the heavier piece or piece that is hard to strip or repair. For example, composite coated roller bearing adapter protects the much complex side frame structure ] almost intact. The principal and total amount of repair work are thus reduced, in contradiction to the traditional hardening process, which improves wear resistance of one work piece at the sacrifice of the other.
2, Composite coating technology relieves rail freight manufacture and repair from tedious welding, heat treatment, rough cutting, precision cutting , manual fitting ,cuts or simplifies 80 to 90% working procedures ; tap and fully utilizes potential life of work piece. For example, the roller bearing adapter, an important bogie part, have too many working surfaces to be repaired economically by welding and machining. is usually discarded when it approaches the allowable wear limit, even in well equipped wagon works .With precision technology it may be repaired easily everywhere, without any welding or machining facilities. The cost of the repaired bearing adapter ,with much longer working life and better performances, is about 1/3 of the cost of a new adapter only。There are nearly 500,000 wagons in China with 4,000,000 bearing adapter. Hundreds of millions of RMB may be saved annually in this single item
3,Composite coating technology is also a positive measure to promote rail safety. According to analysis published in Chinese rolling stock magazines, during the year 2004, over 80% of freight car breakdowns and accidental repairs were bred of three major causes: (1) inferior precision, (2) inferior tribological performance, and (3) high internal stress or crack arising from welding. All these causes representing the weakness of the traditional technology may be conquered naturally by the use of precision technology. For example a severe threat to railway safety today, is the repeatedly broken of connecting bolts of center plate. can be overcame easily by improving surface contacts between center plate, bolster and connecting bolts, to nearly100% with composite coating.
It is obvious, update wagon bogie Design principals ╂ composite coating Technology≡21st century wagon world level
Looking forward to your cooperation

Senior mechanical engineer Fan Zhe
E-mail [email protected]
Phone 86-562-6803200 86-21-64865068

 #252225  by GOLDEN-ARM
 
WHAT THE F&#%?????????

 #252479  by Nelson Bay
 
GOLDEN-ARM wrote:WHAT THE F&#%?????????

Ditto
 #253014  by ZHEF84
 
sorry it should be "Upgrade Wagon Running&Maintenance Qualities
through Composite Coating Technology"

 #253111  by natethegreat
 
Oh, that makes it so much clearer

 #254493  by GOLDEN-ARM
 
Yeah, thanks for clarifying that............
 #254520  by Komachi
 
What Mr. (Ms.?) Zhe is getting at, in "Engineer (mechanical-type) speak," is this...


Even though there is a lot of precision work done in the fabrication of trucks ("bogies" as they're called in British parlance), there is still a lot of "play" allowed in the design tolerances (for one reason or another). This play, while helpful, is responsable for a great deal of the "wear and tear" on the wheelsets and associated parts. Not to mention the additional micro-fisures (cracks at the molecular level) that occour when parts are heat-treated and welded that also contribute to component failure.

What our Chinese friend is hypothesizing, is that the use of composites, tighter manufacturing tolerances would result in a longer lifespan for the various components and assemblies and lower costs in maintanence and personnel.

I think he/she is asking us for our thoughts on their theory.


Yes, that is a rather simplified way of explaining all that, but a.) it's late and b.) I'm not an Engineer and am not going to pretend to be one (studied Architecture for two years, if that means anything), so if there are any Mechanical Engineers who can provide a better explanation, feel free to do so.

 #255076  by Sir Ray
 
Well, the best engineering practice where mechanical devices are concerned is to design for 'graceful degradation', meaning while things run best when new and tight, as wear progresses and things like bearings, axle ends, wheels etc erode, you have a gentle decline in operation, not a catastrophic failure (hopefully, before things really get bad, maintainence is performed).
But yes, close tolerance machining is definitely the preferred initial state - good engineering practice will take into consideration the extremes of operation (such as nice smooth track to unlevel, out of gauge track) and componsate for it.

 #255523  by GOLDEN-ARM
 
Thank God he finally answered that question, as ALL of us have been pondering lubrication qualities for ages. His "thesis" was just a bit suprising, printing a manifesto, that no-one seemed to have inquired about......... :-D