Shinkansen trainset aerodynamic noise question

[Sacto1985]

YouTube member atsutaka2012 posted this excellent video of 700, N700 and N700-8000 trainsets passing Higashi-Hiroshima Station at full speed:

 

 

Question: where is that very distinct and quite loud "whistling" sound generated whenever a 16-car N700 trainset passes by? (You hear it around 40-45% of the trainset passing by.) Note that you don't normally hear that distinct sound with the shorter N700-8000 trainsets in Sakura service.

 

Interestingly, whenever the older 700 trainset passes by at the fuil 270 km/h top speed, you can hear the quite loud aerodynamic "whistle" of the trainset passing by almost the full length of the train.

[spacecadet]

I actually think you're probably hearing either the wheels on the track or the pantographs. I don't think it's aerodynamic.

[Sacto1985]

I actually think you're probably hearing either the wheels on the track or the pantographs. I don't think it's aerodynamic.

 

I'd almost agree, but when the shorter N700-8000 trainset passes by, you don't hear that very distinct whistling sound like I described when a full N700 16-car trainset passes by at full speed. 

[railsquid]

I wonder if it's the extra length of the train making the track "sing" more intensely?

 

Damn, need to get me on a proper Shinkansen station platform again.

[200系]

The difference in sound isn't aerodynamic in nature but mechanical.

 

What you're hearing is the difference in drive system between the three green cars (775形, 776形 and 777形 using a TD Drive) and the ordinary cars (using a WN drive), you can time the difference to the moment the green cars come sailing through.

 

As this subject covers almost all of my (train related) interests (shinkansen, history, electric traction, power transmission and (traction)sounds), allow me to indulge a little and delve deeper into the subject: :) 

 

The shinkansen have historically used the WN (Westinghouse-Natal) drive system, from the 0系 to the N700系, from the 200系 to the E7系 they've all used the WN drive as drive unit.

In the 1950's the Japanese railway companies (both J.N.R. and quite a few of the private railway companies) where introducing new rolling stock. Up till then the preferred drive units for EMU and EL units was via Nose-Suspension in which the traction motor and the transmission gearbox are a fixed unit. With this system the motor/gear unit is mounted over the powered axle using bearings, and connected to the frame of the bogie in such a way that it still allows the unit to pivot (usually with rubber blocks, dampening torsion during acceleration). With this system the traction motor/gear unit follows the axles vertical movements, keeping the drive gear (the gear wheel connected to the axle) and pinion (small gear mounted to the motor) connected at all times. This system is often referred to as 吊りかけ (Tsuri-Kake) by railfans in Japan, while in English it can be referred to as Nose-suspension (referring to the motor nose being suspended at the bogie frame) or as Axle-Hung.

 

The nose-suspension system has been used for streetcars, electric motor cars, a selection of diesel-electric units and EMU's since they where introduced in the late 1800's early 1900's and is a relatively simple and reliable form of transmission. It does however have a few drawbacks: Due to only half of the motor's mass being sprung as well as the need for higher tolerances between the gears, this drive produces quite a bit of noise and resonance (the famous 'nose-suspension' sound often associated with older EMU's is a result of the above mentioned factors), It is also due to those factors that a nose-suspension drive needs to be greased at regular intervals adding to maintenance costs. Another drawback is speed, though nose-suspension drives have been used for units capable of speeds up to 140 Km/h or even 160 Km/h outside of Japan, the drive system isn't suited for speeds approaching 200 Km/h. All these factors combined resulted in a number of different drive systems being developed over the years, one of them being the hollow shaft parallel cardan drive.

 

The hollow shaft parallel cardan drive was developed by BBC of Switzerland in 1941, in this system the electric motor transmits it's power trough a hollow shaft (the shaft runs through the motor itself) with a deflection plate and joint at the end of the shaft, this plate is fixed to the actual drive shaft which runs inside the hollow shaft back towards the opposite side of the motor (i.e. if the pinion is mounted on the left side of the motor, the deflection plate is placed on the right side before running through the hollow shaft to the left) ending at a second deflection plate on the gear box, driving the pinion. Due to the two deflection plates and the hollow shaft, the drive shaft itself is allowed some freedom of movement in relation to the fixed hollow shaft (the deflection plates act as pinion/hinge points). This means the motor can be fixed to the bogie frame while still allowing for the vertical and lateral movements of the axle, which allows the transmission to be constructed as a fixed unit (e.g. there is no lateral or vertical movement between the drive gear and the pinion at all) which in turn allows for tighter gear tolerances a lot less vibrations and a lower noise footprint (producing a much smoother sound). It also, due to it's lower unsprung mass, can use lower grease intervals (only 1/3th the interval of a nose suspension drive I once read).

 

It was the hollow shaft parallel cardan drive that found its way to Japan in the 1950's, introduced by Keihan with their 1800形 in 1953. The system was introduced to J.N.R. in 1957 with the introduction of the 101系. The system proved to be perfect for the Japanese 1067mm system, and the success of the 101系 led to the widespread adoption of the drive system by J.N.R. with every EMU designed after the 101系 using the cardan drive (J.N.R. locomotives would continue to use the nose-suspension drive, with the exception of the EF66形 which uses a quill/nose-suspension drive system (a somewhat unconventional mix of the two)). Following the example of the 101系 and 1800形, a lot of the private railways began specifying cardan drives for their new equipment.

 

The hollow shaft parallel cardan drive was ideal for the 1067mm network, as it provided for a compact drive system (most of it's length is buried inside the hollow shaft), as well as the ability to handle relatively large deflections. This in combination with the low unsprung mass providing lower axle loads, made the system  ideal for the Japanese narrow gauge network.

The system did have it's drawbacks however, the relatively thick hollow shaft did result in a larger diameter of the motor, the system wasn't ideally suited for high rated power outputs and speed either. This was no problem for the relatively light 20m class 1067mm cars, but when developing the shinkansen a different drive system was needed.

 

The WN drive was developed by Westinghouse and the former Natal company (integrated within Westinghouse at that point), and like the BBC hollow shaft parallel cardan, it's first practical use was in 1941. The WN drive consists of a joint connecting the output shaft with the drive shaft. Inside the joint there are two gears, once connected to the drive shaft and another to the output shaft (those two gears aren't directly connected to each other), the gears grip into the housing of the joint (which is constructed in two parts connected in the middle) transferring power from one shaft to the other. This allows for a flexible coupling between the output shaft and the drive shaft/gearbox, once again allowing for the traction motor to be mounted on the bogie frame.

The system proved to be quite popular within the USA, in particular with the NYC subway, where it was introduced with the R10 cars and has been used on all subsequent SMEE car classes (both A (R10 and up) and B division (R12 and up) cars). Due to the size of the system, In Japan, the WN drive found it's way to a few of the 1435mm gauge lines in the 1950's, with the Tōkyō metro 300形 introduced in 1953, being the first mass produced example (the 300形 itself was based on NYCTA SMEE technology). Other 1435mm railways would use the WN drive as well, and it even found it's way to a few of the 1067mm railways later on.

 

The WN Drive proved to be ideally suited for high speed performance and it was therefore selected as the preferred drive system for the shinkansen, then in development. The WN drive proved to be successful, and was subsequently used on all shinkansen series. It also proved to be highly reliable, however due to the mechanical nature of the WN joint (it is basically a longitudinal gear assembly, though geared 1:1) with ageing of the unit loser tolerances lead to a 'whizzing' sound to become audible, this sound was for example rather pronounced on some of the remaining 200系 K formations in their final years of service. Though not necessarily an unpleasant sound, it was decided to try and remedy the situation, at least for green car passengers. Which brings us to the TD drive.

 

The TD (Twin Disc) drive is similar to the WN drive in that it uses a joint to form a flexible coupling between the traction motor and the gearbox, though instead of a geared joint like on the WN drive, it uses a system of two deflection discs (similar, but more compact and stronger, to the ones used by the hollow shaft parallel cardan system) to connect the output shaft with the driving shaft. This system doesn't provide the 'whizzing' sound when ageing, and has also proven to be cheaper in maintenance. For this reason JR Tōkai decided to test the system on a new 700系 formation (formation C19 delivered in 2000) and it was decided to specify the TD drive for the green cars (717形, 718形 and 719形) of all remaining formations on order (C19~C60, I'm not sure if the JR West B formations received the same changes though I assume they did as well).

The same thing was done for the N700系 formations, with all 16 car formations (N and Z formations) using TD drives for the green cars (775形, 776形 and 777形) while the ordinary cars still use the WN drive.

The TD drive was introduced by J.N.R. on the 207系900番台 and has more or less supplanted the hollow shaft parallel cardan drive at JR East's 1067mm stock (from the 209系 and E217系 onwards), while JR Tōkai is also moving in this direction.

 

 

 

i'd almost agree, but when the shorter N700-8000 trainset passes by, you don't hear that very distinct whistling sound like I described when a full N700 16-car trainset passes by at full speed.

 

That's because the N700系 S and R formations don't use the TD drive for the green car, they use WN drives on all cars.

 

I hope my explanation is clear enough, and that this answers the question.

 

​for further reference (for fellow audiophiles as well  ;) ),

 

Nose suspension sound (unfortunately almost extinct for Japanese EMU's, though still widely in use with Japanese EL traction (with exception of the EF66形 and EF200形), even new units like the EF510形 use the nose suspension system) :

(5050系, モハ25形, EF65形 and EF510形)

 

 

hollow shaft parallel cardan drive: (103系)

 

 

WN Drive shinkansen: (200系 and N700系, you can hear the whizzing sound in the 200系 video)

 

 

TD drive shinkansen: (N700系, note that you can hear the mentioned sound )

 

 

TD Drive: (E217系 with GTO-VVVF propulsion)

 

 

 

further reference (in Japanese):

 

http://ja.wikipedia.org/wiki/%E5%90%8A%E3%82%8A%E6%8E%9B%E3%81%91%E9%A7%86%E5%8B%95%E6%96%B9%E5%BC%8F (Nose Suspension)

http://ja.wikipedia.org/wiki/WN%E9%A7%86%E5%8B%95%E6%96%B9%E5%BC%8F (WN Drive)

http://ja.wikipedia.org/wiki/%E4%B8%AD%E7%A9%BA%E8%BB%B8%E5%B9%B3%E8%A1%8C%E3%82%AB%E3%83%AB%E3%83%80%E3%83%B3%E9%A7%86%E5%8B%95%E6%96%B9%E5%BC%8F (hollow shaft parallel cardan drive)

http://ja.wikipedia.org/wiki/TD%E5%B9%B3%E8%A1%8C%E3%82%AB%E3%83%AB%E3%83%80%E3%83%B3%E9%A7%86%E5%8B%95%E6%96%B9%E5%BC%8F (TD Drive)

 

 

Another long post from me, my apologies, but I hope it is useful/interesting for some.

 

-Sander

[miyakoji]

m(_ _ )m

 

Hi Sander, happy new year and thanks for the post!

[kvp]

Super post and very interesting as always! Thanks!

[cteno4]

Sander,

 

Thanks, another super post!

 

Jeff

[miyakoji]

btw good catch Sacto, I had never thought about this.  When I first watched the video, I figured it was all due to the camera's microphones, angles, wind, sound reflection within the station, etc.

[Sacto1985]

200系, thanks for the explanations!  :) So it is the TD drive system on the Green Cars on the N700/N700A trainsets that make that very distinct whistling noise. 

 

By the way, if you watch the full video, note that a few of the N700-7000/8000 trainsets have a very distinct "whistling" noise when passing the station. I wonder did JR West or JR Kyushu modify a few of the trainsets to use all TD drive system traction motors?

[katoftw]

By the way, if you watch the full video, note that a few of the N700-7000/8000 trainsets have a very distinct "whistling" noise when passing the station. I wonder did JR West or JR Kyushu modify a few of the trainsets to use all TD drive system traction motors?

West Japan Railway (JR West)

• N700 Series 3000/4000/5000 series - N organization 3000 series · F organization 4000 series · K organization 5000 Bandai drive over to the Tokaido Shinkansen JR Tokai and the same specification. (S organization 7000 Bandai drive over to Kyushu Shinkansen all models WN drive system )

 

From the link in 200s post

[marknewton]

No apologies are needed Sander, that's a very interesting and informative post - well worth the effort you've put in.

 

The EMUs I run have WN drives. As they've aged the whizzing sound you mention has become very noticeable. No wonder we're all going deaf. :)

 

Cheers,

 

Mark.

[zartan]

thank you Sander!  super interesting.

[200系]

I'm glad to read it was appreciated, and thanks for the support. It means a lot to me.

 

cheers!

[cteno4]

Sander,

 

Your super informative posts are always appreciated, especially in the age where content is being trimmed down into tiny, tiny bits so small they are pretty much worthless! Nice to read something of substance and thought!

 

Cheers,

 

Jeff

Edited January 23, 2015 by cteno4

[Sacto1985]

Speaking of train noise, YouTube member whitewing681 just posted a video of a training run of a W7 Series Shinkansen trainset east of Kanazawa at full speed:

 

 

Note when the train passes, you hear a distinct whistling sound in the time the train passes at full speed. I wonder what kind of traction motors do the E7/W7 trainsets use.