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International Railroad Discussion > Details of the EMD GBB Truck (Brazil)


Date: 12/16/16 06:15
Details of the EMD GBB Truck (Brazil)
Author: pedrop

Hi, as friends use to ask me about the details of the new EMD BB truck developed to the narrow gauge SD70ACe-BB´s, I opened this thread to share pictures of these interesting trucks.  Some pics were a bit over exposed because the brand new trucks are difficult to photograph since the back painting use to reflect the flash light.

Pedro


Pedro Rezende
Vespasiano, MG
Minas Gerais Railways



Edited 1 time(s). Last edit at 12/16/16 07:08 by pedrop.








Date: 12/16/16 07:30
Re: Details of the EMD GBB Truck (Brazil)
Author: YukonYeti

Obrigado!
 



Date: 12/16/16 21:26
Re: Details of the EMD GBB Truck (Brazil)
Author: bogieman

Nice pictures Pedro! 

You can see the rubber pad between the bearing adapter and the equalizer in the first picture. One of the unique features of this truck is that the tractive force from the axles is transmitted to the two-axle bogie frame through the equalizer assembly via a traction rod above the first axle, rather than pedestals as are typical on equalizer trucks. In this arrangement there are no metal-to-metal wearing parts as on conventional equalized trucks. There is sanding on axles 1, 3, and 5 in the forward direction and 8, 6, and 4 in the reverse direction. This picture is of the rear truck since that is the parking brake location evidenced by the chain.

In your second picture you can see the tall rubber secondary spring that goes between the bolster arm and underframe, and below it, the short rubber spring that lets the two axle truck pivot with respect to the bolster. Most of the span bolster is tucked up inside the underframe which keeps the height of the underframe bottom plate as close to the rail as the 43 inch wheels will allow.

The GBB truck designation follows EMD practice of using a G as the first letter which denotes an export truck design, although nothing prevents the development of a standard gauge North American truck of similar design. Prior export truck designs starting back in the 1950's are GB, GC, GLC, GHC and now the GFC, the fabricated frame 3-axle truck under the current production GT38 - 46AC models.

Dave



Date: 12/17/16 14:26
Re: Details of the EMD GBB Truck (Brazil)
Author: pedrop

Dave, do you think it will be possible a common C version of this interesting truck?

Pedro Rezende
Vespasiano, MG
Minas Gerais Railways



Date: 12/17/16 14:28
Re: Details of the EMD GBB Truck (Brazil)
Author: pedrop

Dave, is this the traction rod you are talking about?
 

Pedro Rezende
Vespasiano, MG
Minas Gerais Railways




Date: 12/17/16 14:34
Re: Details of the EMD GBB Truck (Brazil)
Author: pedrop

The traction motor
Pics two shows the model:  A2909


Pedro Rezende
Vespasiano, MG
Minas Gerais Railways






Date: 12/17/16 20:02
Re: Details of the EMD GBB Truck (Brazil)
Author: bogieman

pedrop Wrote:
-------------------------------------------------------
> Dave, is this the traction rod you are talking
> about?
>  
That is the traction motor nose link - it reacts the force of the motor pinion on the bull gear and supports the traction motor.

The traction rod I mentioned is to the left of the rubber secondary spring and above the axle bearing housing in your second picture in the first post - the left end of the traction rod is pinned to the equalizer and the right end is in a bracket welded to the truck frame.

A C version of this style truck is not likely, particularly since EMD has some great fabricated frame 3-axle trucks already covering all gauges and axle loads.

Dave



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