Co-Co vs Bo-Bo-Bo

[Sweedy]

On 22/07/2021 at 23:25, jim.snowdon said:

I was seconded to Trans-Manche-Link, aka TML, who were the construction contractors for the whole of the tunnel project, including the locomotives and rolling stock.

Most interested to see your note and your commentary on the reasons for the Bo-Bo-Bo selection. I was aware of the primary reasons, since I was the Contracts Engineer for the procurement, again with TML and followed the procurement and development of the locomotives through to completion of the testing and commissioning. 

[SRman]

On 30/07/2021 at 06:18, Western Aviator said:

I’m no expert on Dutch trains and I don’t make that many journeys through The Netherlands but I can’t say I’ve ever seen these units coupled to anything else. I was quite surprised when I first noticed the wheel arrangement and I don’t know why they thought it necessary. Other NS double-deck EMUs have more conventional wheel arrangements. 

 

Maybe it's because of all the steep gradients on the NS system.    

[John ks]

This is QR 3205 during a test run.

It was parked on a siding at  Kuraby Station.

the curve was one of the sharpest in Qld & has since been removed.

This shows the centre bogie partially outside the loco body.

the springs usually sit vertically on straight track.

 

 

 

 

This is 3283 still at Comeng where it was being built, only 3 more were built after this one 

Comeng Queensland ceased to be after the last Loco was done.

As to why Tri-Bo was chosen, it may have been to spread the axel loading.

These Locos were primarily used to haul coal from the mines to the port at Hay Point Qld

John

[SRman]

11 hours ago, John ks said:

This is QR 3205 during a test run.

It was parked on a siding at  Kuraby Station.

the curve was one of the sharpest in Qld & has since been removed.

This shows the centre bogie partially outside the loco body.

the springs usually sit vertically on straight track.

 

 

 

 

This is 3283 still at Comeng where it was being built, only 3 more were built after this one 

Comeng Queensland ceased to be after the last Loco was done.

As to why Tri-Bo was chosen, it may have been to spread the axel loading.

These Locos were primarily used to haul coal from the mines to the port at Hay Point Qld

John

 

The tri-Bo arrangement can give a more even spread of the traction forces on uneven track where, for example, the weight might get lifted or concentrated on the centre axles of Co-Co bogies. The Swiss railways used the tri-Bo arrangement on some of their electric locomotives (Re6/6) as well.

[Edwin_m]

Are/were there any Bo-Bo-Bo diesels?  If so, where do they put the fuel tank?

[Claude_Dreyfus]

9 minutes ago, Edwin_m said:

Are/were there any Bo-Bo-Bo diesels?  If so, where do they put the fuel tank?

Yes, the JRF DF200. I believe the tanks are still between the bogies.

 

https://en.m.wikipedia.org/wiki/JR_Freight_Class_DF200

 

 

 

[DavidB-AU]

Not forgetting the New Zealand DJ class built by Mitsubishi in Japan. The fuel tank is up in the body.

 

 

[jjb1970]

The more unusual arrangement in some ways is B-2-B as per the DD51 diesel hydraulic locomotives  (a large and successful class) and Bo-2-Bo as per the ED76 electric locomotives. Both had a smaller carrying bogies between the two main power bogies.

Japan also had designs with a single centre carrying axle.

Edited December 10, 2023 by jjb1970

[rodent279]

So a related question, that may have been asked on here before-why did the Metro-Vick type 2s use the unusual Co-Bo arrangement?

Like wise the Brush type 2 - why use A1A-A1A, why not use 3 smaller traction motors in a Co-Co arrangement?

(There are also some Japanese Co-Bo diesel locos, more for shunting & short trip work I think.)

Edited December 10, 2023 by rodent279

[Wickham Green too]

Not to mention - and confuse matters with - some A1A-Bo diesels in Cuba .................. as with the Metro-Vicks, a question of weight distribution as the engine lump isn't mounted centrally. ( the Cuban locos were Bo-Bo rebuilds I think ) 

[keefer]

The New Haven FL9 electro-diesels were also Bo-A1A. Based on the Bo-Bo FP9, the body was extended to provide room for a train-heat boiler and other equipment, so the rear bogie became an A1A (think it also gave more room to fit the 3rd rail shoes).

[burgundy]

Another view of a New Zealand Tri-Bo - in late 2019 on the Taieri Gorge service. 

Best wishes 

Eric 

[Claude_Dreyfus]

10 hours ago, jjb1970 said:

Japan also had designs with a single centre carrying axle.

Yes, the ED62 being a prime example of that. Originally a BO-BO design, a single unpowered axle was provided on a number of rebuilt examples (including the reclassification to class ED62) between the bogies to reduce the general axle weight for use on the Iida line.

Edited December 10, 2023 by Claude_Dreyfus

[Titan]

22 hours ago, Edwin_m said:

Are/were there any Bo-Bo-Bo diesels?  If so, where do they put the fuel tank?

There are quite a few BR locos that don't have fuel tanks below the solebar, e.g. class 20 - between the cab and the engine room.  There were some locos that had a boxed in underframe to form a tank - think peaks and 31's had this arrangement, no doubt someone will correct me if I am wrong!

[Titan]

3 hours ago, rodent279 said:

So a related question, that may have been asked on here before-why did the Metro-Vick type 2s use the unusual Co-Bo arrangement?

Like wise the Brush type 2 - why use A1A-A1A, why not use 3 smaller traction motors in a Co-Co arrangement?

(There are also some Japanese Co-Bo diesel locos, more for shunting & short trip work I think.)

Probably maintenance costs. 4 larger motors are cheaper to maintain/buy than 6 smaller ones.  It is notable that the Co-Bo's were the only type 2 with more than 4 motors, and then only just! This however meant that they also had the highest TE of any type 2.

[John ks]

Another unusual was a Burlington Northern SDP40 which operated for about year with the rear truck replaced by an experimental EMD "B+B" 4-axle radial bogie. They removed the centre motor from the front bogie making the loco an A1A-BoBo. The rear bogies were made by cutting & shorting 2 Co bogies to convert them to Bo bogies.

I think the reason making the Co into an A1A was so that the loco had 6 traction motors as it originally did, which would simplify the wiring by only powering 6 traction motors rather than 7.

John 

[Artless Bodger]

EMD E units were A-1-A A-1-A and I read that this was to allow the bogie pivot to be centrally mounted with a symmetrical axle layout - developed from the Blomberg B bogie. E units were the express passenger units, with twin engines, so the extra axle helped carry the extra weight. Other loco manufacturers in the US used C bogies (US nomenclature doesn't use the o afaik) but resorted to assymetric axle layouts as between the middle and one end there had to be 2 traction motors. There were various proprietary 3 axle bogie designs for C bogies - the Tri-mount comes to mind. Look at the bogies on locos like FM Trainmaster C-Cs. FM later produced the C-Line series, one option was for a B-C cab unit There is a lot of data on this in some US HO diesel drawing collections and class recognition books (Pinkepank & Marre? Kalmbach?). I don't have my copies anymore. 

[jjb1970]

2 hours ago, John ks said:

Another unusual was a Burlington Northern SDP40 which operated for about year with the rear truck replaced by an experimental EMD "B+B" 4-axle radial bogie. They removed the centre motor from the front bogie making the loco an A1A-BoBo. The rear bogies were made by cutting & shorting 2 Co bogies to convert them to Bo bogies.

I think the reason making the Co into an A1A was so that the loco had 6 traction motors as it originally did, which would simplify the wiring by only powering 6 traction motors rather than 7.

John 

 

EMD also built a large batch of DDM45 locomotives for Brazil which were basically SD45's with two four axle bogies for narrow gauge use. The A1A-A1A arrangement made a comeback in the NA market with the GEVO ES44C4 model.

[298]

10 hours ago, Wickham Green too said:

Not to mention - and confuse matters with - some A1A-Bo diesels in Cuba .................. as with the Metro-Vicks, a question of weight distribution as the engine lump isn't mounted centrally. ( the Cuban locos were Bo-Bo rebuilds I think ) 

 

Ex-CN GMD-1, the A1A trucks were imported later to decrease the axle loading on the heavier end. Rapido produced a model of it in HO a few years ago:

 

 

 

 

 

Edited December 10, 2023 by 298