One thing that I have noticed over the years with models is how what are standard sizes on the prototype, when the model manufacturers replicate somehow the accuracy is lost in translation.  
 

I guess the biggest debated model in diesel world exemplified by the many models by difference manufacturers is the Class 37, a popular class of loco, which people scrutinise the dimensions even down position of the rivets and screws head positions. Questionable when the prototypes where built at a time when the was shall we say more “craftsmanship” was applied in series production and built between two factories, and have had numerous depot and works modifications over their operational life. 
 

In the more humble world of the second generation DMU (I.e. Sprinters and Pacers), some standard items should be standard within tolerance. For the Sprinter fleet I’m thinking the outer gangway connection and across both fleets the height of the BSI coupler above the rail head. 
 

So now for the some research regarding how the manufacturers have interpreted the outer gangway connection across the 4mm Sprinter models available so far. I don’t have access to a Dapol Class 150/2 nor a Realtrack class 156 so these are excluded. 
 

First, a table of dimensions for the outer gangway connector and inner gangway connector across the models I have available. These external measurements of the gangway connector.  All are measured using a Mitutoyo Digital Verner Caliper.

 

 

As the table shows, there is quite a variation in height and width. The lowest height is on a Dapol Class 155 with the Hornby Class 153 not far behind. The highest height is the Bachmann Class 150/2 with the Bachmann Class 158 (2020 Release) not been far behind. Yet the width between these two 1mm difference. 
 

Sadly without access the manufacturers drawing of the prototype, it’s hard the verify any further whether these are accurate representations and the outer gangway between Sprinter classes does vary. Or the prototype is a standard design, which because these units do couple up in different permutations, and the outer gangway is used, the manufacturers have made their own interpretations of the dimensions.
 

If anyway out there has access to the manufacturers drawings or can take measurements off the prototype that would very helpful to verify the above table, please get in touch. 
 

One further dimensions I’d like compare is the BSI coupler height above the rail head.  Again on the prototype this is standard height with tolerance for wheel tyre wear and suspension height again within a tolerance. The models should reflect this. Although measuring that height accurately will probably need a tool making. To verify again would need prototype manufacture drawings and dimensions / tolerances. So maybe a future investigation in the depths of a cold miserable winter evening or weekend.…

 

However here are some photo taken more so the lighting clearly demonstrates the difference between the models and the outer ganagway connectors. 
 

Bachmann Class 150/2

 

Bachmann Class 150/2 to Hornby Class 153

 

Bachmann Class 150/2 to Dapol Class 155

 

 

Bachmann Class 150/2 to Lima Class 156

 

 

Bachmann Class 158 Original Version to Bachmann 150/2 

 

Bachmann Class 150/2 to Bachmann Class 158 (2020 version)

 

 

Bachmann Class 150/2 to Realtrack Class 144

 

 

Hornby Class 153 

 

Hornby Class 153 to Dapol Class 155

 

Hornby Class 153 to Lima Class 156

 

 

Bachmann Class 158 Original Release to Hornby Class 153

 

 

Hornby Class 153 to Bachmann Class 158 (2020 Release)

 

 

Hornby Class 153 to Realtrack Class 144

 

 

 

Lima Class 156

 

Lima Class 156 to Bachmann Class 150/2

 

Lima Class 156 to Hornby Class 153

 

Lima Class 156 to Dapol Class 155

 

Bachmann Class 158 (original release)  to Lima Class 156

 

Lima Class 156 to Bachmann Class 158 (2020 Release)

 

Lima Class 156 to Realtrack Class 144

 

Bachmann Class 158 (Original Release)

 

Bachmann Class 158 (Original Release) to Bachmann Class 150/2

 

Bachmann Class 158 (Original Release) to Hornby Class 153

 

Bachmann Class 158 (Original Release) to Dapol Class 155

 

Bachmann Class 158 (Original Release) to Lima Class 156

 

 

Bachmann Class 158 (Original Release) to Bachmann Class 158 (2020 Release)

 

Bachmann Class 158 (original release) to Realtrack Class 144